From 57cdfaf1a196b02f293f3ffb754529880c9fcd2e Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Fri, 21 Jul 2017 13:04:31 +0530
Subject: [PATCH 01/21] Add syntax plugin for decorators2

---
 .../.npmignore                                |  3 ++
 .../README.md                                 | 35 +++++++++++++++++++
 .../package.json                              | 13 +++++++
 .../src/index.js                              |  7 ++++
 4 files changed, 58 insertions(+)
 create mode 100644 packages/babel-plugin-syntax-decorators-2/.npmignore
 create mode 100644 packages/babel-plugin-syntax-decorators-2/README.md
 create mode 100644 packages/babel-plugin-syntax-decorators-2/package.json
 create mode 100644 packages/babel-plugin-syntax-decorators-2/src/index.js

diff --git a/packages/babel-plugin-syntax-decorators-2/.npmignore b/packages/babel-plugin-syntax-decorators-2/.npmignore
new file mode 100644
index 000000000000..f9806945836e
--- /dev/null
+++ b/packages/babel-plugin-syntax-decorators-2/.npmignore
@@ -0,0 +1,3 @@
+src
+test
+*.log
diff --git a/packages/babel-plugin-syntax-decorators-2/README.md b/packages/babel-plugin-syntax-decorators-2/README.md
new file mode 100644
index 000000000000..99b86968b3e4
--- /dev/null
+++ b/packages/babel-plugin-syntax-decorators-2/README.md
@@ -0,0 +1,35 @@
+# babel-plugin-syntax-decorators-2
+
+> Updated parsing of decorators.
+
+## Installation
+
+```sh
+npm install --save-dev babel-plugin-syntax-decorators-2
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["syntax-decorators-2"]
+}
+```
+
+### Via CLI
+
+```sh
+babel --plugins syntax-decorators-2 script.js
+```
+
+### Via Node API
+
+```javascript
+require("babel-core").transform("code", {
+  plugins: ["syntax-decorators-2"]
+});
+```
diff --git a/packages/babel-plugin-syntax-decorators-2/package.json b/packages/babel-plugin-syntax-decorators-2/package.json
new file mode 100644
index 000000000000..005833819675
--- /dev/null
+++ b/packages/babel-plugin-syntax-decorators-2/package.json
@@ -0,0 +1,13 @@
+{
+  "name": "babel-plugin-syntax-decorators-2",
+  "version": "7.0.0-alpha.15",
+  "description": "Updated parsing of decorators",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-decorators-2",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {},
+  "devDependencies": {}
+}
diff --git a/packages/babel-plugin-syntax-decorators-2/src/index.js b/packages/babel-plugin-syntax-decorators-2/src/index.js
new file mode 100644
index 000000000000..4d0405790040
--- /dev/null
+++ b/packages/babel-plugin-syntax-decorators-2/src/index.js
@@ -0,0 +1,7 @@
+export default function() {
+  return {
+    manipulateOptions(opts, parserOpts) {
+      parserOpts.plugins.push("decorators2");
+    },
+  };
+}

From 9904b61f6e1b75f15208f1eb0e1c02076ccba1ea Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Fri, 21 Jul 2017 13:08:38 +0530
Subject: [PATCH 02/21] WIP decorator transform initial commit

---
 .../package.json                              |  20 +++
 .../src/index.js                              | 125 ++++++++++++++++++
 .../test/fixtures/options.json                |   3 +
 .../test/fixtures/wip/wip/actual.js           |   7 +
 .../test/fixtures/wip/wip/expected.js         |  26 ++++
 .../test/index.js                             |   3 +
 6 files changed, 184 insertions(+)
 create mode 100644 packages/babel-plugin-transform-decorators-2/package.json
 create mode 100644 packages/babel-plugin-transform-decorators-2/src/index.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/index.js

diff --git a/packages/babel-plugin-transform-decorators-2/package.json b/packages/babel-plugin-transform-decorators-2/package.json
new file mode 100644
index 000000000000..e42296272eec
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/package.json
@@ -0,0 +1,20 @@
+{
+  "name": "babel-plugin-transform-decorators-2",
+  "version": "7.0.0-alpha.15",
+  "author": "Peeyush Kushwaha <peeyush.p97@gmail.com>",
+  "license": "MIT",
+  "description": "Transformer for stage-2 decorators",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-decorators-2",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel",
+    "babel-plugin",
+    "decorators"
+  ],
+  "dependencies": {
+    "babel-plugin-syntax-decorators-2": "7.0.0-alpha.15"
+  },
+  "devDependencies": {
+    "babel-helper-plugin-test-runner": "7.0.0-alpha.15"
+  }
+}
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
new file mode 100644
index 000000000000..59598df8c930
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -0,0 +1,125 @@
+import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
+
+//TODO: will have to check for dot (.) access to reserved keywords in decorator members
+export default function({ types: t }) {
+  // goes over the methods of current class and prepares decorators
+  // expects path of a ClassExpression
+  function takeMethodDecorators(path) {
+    const body = path.get("body.body");
+
+    // a collection of [decoratedKey, decorators] or [decoratedKey, decorators, true] for static properties
+    const entries = [];
+
+    for (const method of body) {
+      const { node } = method;
+      if (!method.isClassMethod()) continue;
+      if (!node.decorators || !method.node.decorators.length) continue;
+
+      const decorators = method.node.decorators
+        .map(d => d.expression)
+        .reverse(); // reverse for correct evaluation order
+      node.decorators = []; //TODO: should we remove from path? method.get("decorators") doesn't work
+
+      const entry = [];
+      if (node.computed) {
+        // if it is computed, we need an identifier to refer to it later
+        // so we can avoid evaluating the expression twice
+        if (t.isAssignmentExpression(node.key)) {
+          entry.push(node.key.left);
+        } else {
+          const parent = path.findParent(p => p.parentPath.isBlock());
+          const ref = method.scope.generateUidIdentifier("key");
+          parent.insertBefore(
+            t.variableDeclaration("let", [t.variableDeclarator(ref)]),
+          );
+          const replacement = t.sequenceExpression([
+            t.assignmentExpression("=", ref, node.key),
+          ]);
+          //method.get("key").replaceWith(); FIXME: this should work
+          node.key = replacement;
+          entry.push(ref);
+        }
+      } else {
+        entry.push(t.stringLiteral(node.key.name));
+      }
+
+      entry.push(t.arrayExpression(decorators));
+
+      if (node.static) {
+        entry.push(t.booleanLiteral(true));
+      }
+
+      entries.push(t.arrayExpression(entry));
+    }
+
+    return t.arrayExpression(entries);
+  }
+
+  // expects path of a ClassExpression
+  function takeClassDecorators(path) {
+    // reverse for correct decorator evaluation order
+    const decorators = path.node.decorators.map(d => d.expression).reverse();
+    path.node.decorators = [];
+    return t.arrayExpression(decorators);
+  }
+
+  return {
+    inherits: syntaxDecorators2,
+    visitor: {
+      // export default is a special case since it expects and expression rather than a declaration
+      ExportDefaultDeclaration(path) {
+        const classPath = path.get("declaration");
+        if (!classPath.isClassDeclaration()) return;
+
+        if (classPath.node.id) {
+          const ref = classPath.node.id;
+          path.insertBefore(
+            t.variableDeclaration("let", [t.variableDeclarator(ref)]),
+          );
+          classPath.replaceWith(
+            t.assignmentExpression("=", ref, t.toExpression(classPath.node)),
+          );
+        } else {
+          classPath.replaceWith(t.toExpression(classPath));
+        }
+      },
+
+      // replace declaration with a let declaration
+      ClassDeclaration(path) {
+        const { node } = path;
+        const ref = node.id || path.scope.generateUidIdentifier("class");
+
+        path.replaceWith(
+          t.variableDeclaration("let", [
+            t.variableDeclarator(ref, t.toExpression(node)),
+          ]),
+        );
+      },
+
+      ClassExpression(path) {
+        const methodDecorators = takeMethodDecorators(path);
+        const classDecorators = takeClassDecorators(path);
+        if (
+          methodDecorators.elements.length == 0 &&
+          classDecorators.elements.length == 0
+        ) {
+          return;
+        }
+        path.replaceWith(
+          t.callExpression(t.identifier("decorate"), [
+            path.node,
+            methodDecorators,
+            classDecorators,
+          ]),
+        );
+      },
+
+      ClassMethod(path) {
+        if (path.get("decorators")) {
+          path.get("decorators").forEach(p => p.remove());
+          path.get("body").unshiftContainer("body", t.identifier("yo"));
+        }
+      },
+    },
+  };
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json b/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
new file mode 100644
index 000000000000..46ff9f3d5227
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-decorators-2"]
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
new file mode 100644
index 000000000000..f3913b9db341
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
@@ -0,0 +1,7 @@
+let decorate = () => void 0, dec, bar, foo = {bar: () => void 0}, baz, decorator; //just to supress ReferenceErrors
+
+@decorator class Bizz {
+  @dec m1() {};
+  @bar @foo.bar(baz) m2() {};
+  @dec static [3 + 7] () {};
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
new file mode 100644
index 000000000000..c6acc0291e8a
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -0,0 +1,26 @@
+let decorate = () => void 0,
+    dec,
+    bar,
+    foo = {
+  bar: () => void 0
+},
+    baz,
+    decorator; //just to supress ReferenceErrors
+
+
+let _key;
+
+let Bizz = decorate(class Bizz {
+  m1() {
+    yo
+  }
+
+  m2() {
+    yo
+  }
+
+  static [(_key = 3 + 7)]() {
+    yo
+  }
+
+}, [["m1", [dec]], ["m2", [foo.bar(baz), bar]], [_key, [dec], true]], [decorator]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/index.js b/packages/babel-plugin-transform-decorators-2/test/index.js
new file mode 100644
index 000000000000..09cfbc31f54e
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/index.js
@@ -0,0 +1,3 @@
+import runner from "babel-helper-plugin-test-runner";
+
+runner(__dirname);

From f214d1dab25ed665bc66e65faa73b9a791799ae4 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Mon, 31 Jul 2017 06:02:31 +0530
Subject: [PATCH 03/21] wip commiting code before major changes

---
 .../src/index.js                              | 134 ++++++++++++++++++
 1 file changed, 134 insertions(+)

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 59598df8c930..deac82e2b8f8 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -1,7 +1,141 @@
+import template from 'babel-template';
 import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 
 //TODO: will have to check for dot (.) access to reserved keywords in decorator members
+//NOTE: convention is 'descriptor' is used for element descriptors, while 'propertyDescriptor' is used for property descriptor
+
+/** manual testing code
+class A { method() {console.log("method exec hua");} static estatic() {console.log("estatic hua");}}
+function methDec(descriptor) {console.log("methDec hua", arguments); return {descriptor, extras: [], finishers: []}}
+function methDec2(descriptor) {console.log("methDec2 hua", arguments); return {descriptor, extras: [], finishers: []}}
+function classDec(constructor, heritage, memberDescriptors) {console.log("class hua", arguments); return {constructor, elements: memberDescriptors, finishers: []}}
+decorate(A, [], [["method", [methDec, methDec2]], ["estatic", [methDec], true]])([classDec])
+**/
 export default function({ types: t }) {
+
+  // injected
+  function makeElementDescriptor(kind, key, isStatic, descriptor, finisher) {
+    return {kind, key, isStatic, descriptor, finisher};
+  }
+
+  // injected
+  function decorateElement(descriptor, decorators) { //spec uses the param "element" instead of "descriptor" and finds descriptor from it
+    let extras = [];
+    let finishers = [];
+
+    let previousDescriptor = descriptor;
+
+    for (let i = decorators.length - 1; i >= 0; i--) {
+      let decorator = decorators[i];
+      let result = decorator(previousDescriptor);
+      let currentDescriptor = result.descriptor;
+
+      if (result.finisher) {
+        finishers.push(current.finisher);
+        result.finisher = undefined;
+      }
+
+      previousDescriptor = currentDescriptor;
+
+      let extrasObject = result.extras;
+
+      if (extrasObject) {
+        for (let extra of extrasObject) {
+          extras.push(extra);
+        }
+      }
+    }
+
+    extras = mergeDuplicateElements(extras);
+
+    return {descriptor: previousDescriptor, extras, finishers}
+  }
+
+  // injected
+  function mergeDuplicateElements(elements) { return elements; /*TODO*/}
+
+  // injected
+  function decorateClass(constructor, decorators, heritage, elementDescriptors) {
+    let elements = [];
+    let finishers = [];
+
+    let previousConstructor = constructor;
+    let previousDescriptors = elementDescriptors;
+
+    for (let i = decorators.length - 1; i >= 0; i--) {
+      let decorator = decorators[i];
+      let result = decorator(previousConstructor, heritage, previousDescriptors);
+
+      previousConstructor = result.constructor;
+      if (result.finishers) {// result.finishers is called 'finisher' in the spec
+        finishers = finishers.concat(result.finishers);
+      }
+
+      if (result.elements) {
+        for (let element of result.elements) {
+          elements.push(element);
+        }
+      }
+
+      elements = mergeDuplicateElements(elements);
+    }
+
+    return {constructor: previousConstructor, elements, finishers};
+  }
+
+  function decorate(constructor, undecorated, memberDecorators, heritage) {
+    const prototype = constructor.prototype;
+    let finishers = [];
+    const elementDescriptors = {}; // elementDescriptors is meant to be an array, so this will be converted later
+    //TODO: merging of elementDescriptors
+
+    for (let [key, isStatic] of undecorated) {
+      const target = isStatic? constructor : prototype;
+      let propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
+      elementDescriptors[key] = makeElementDescriptor("property", key, isStatic, propertyDescriptor);
+    }
+
+    for (let [key, decorators, isStatic] of memberDecorators) {
+      let target = isStatic? constructor : prototype;
+      let propertyDescriptor = elementDescriptors[key] || Object.getOwnPropertyDescriptor(target, key);
+      let elementDescriptor = makeElementDescriptor("property", key, isStatic, propertyDescriptor);
+      let decorated = decorateElement(elementDescriptor, decorators);
+
+      elementDescriptors[key] = decorated.descriptor;
+
+      for (let extra of decorated.extras) { // extras is an array of element descriptors
+        elementDescriptors[extra.key] = extra;
+      }
+
+      finishers = finishers.concat(decorated.finishers);
+    }
+
+    return function (classDecorators) {
+      let result = decorateClass(constructor, classDecorators, heritage, Object.values(elementDescriptors));
+      finishers = finishers.concat(result.finishers);
+      //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
+      //TODO: step 38 and 39, what do they mean "initialize"?
+
+      for (let elementDescriptor of result.elements) {
+        let target = elementDescriptor.isStatic? constructor : prototype;  
+        Object.defineOwnProperty(target, elementDescriptor.key, elementDescriptor.descriptor);
+      }
+
+      return result.constructor;
+    }
+  }
+
+
+  function classDefintionEvaluation(path) {
+    // step 20, 21
+    for (const method of body) {
+      const { node } = method;
+      if (!method.isClassMethod()) continue;
+      if (!node.decorators || !method.node.decorators.length) continue;
+      if (node.kind === "constructor") continue;
+    }
+  }
+
   // goes over the methods of current class and prepares decorators
   // expects path of a ClassExpression
   function takeMethodDecorators(path) {

From edb7ff208ee7b83df3288cf921dac27d2694aaac Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Mon, 31 Jul 2017 19:41:32 +0530
Subject: [PATCH 04/21] Transform works great, move stuff to helpers

---
 packages/babel-helpers/src/helpers.js         | 148 ++++++++++++
 .../src/index.js                              | 213 ++++++------------
 .../test/fixtures/options.json                |   2 +-
 .../test/fixtures/wip/wip/actual.js           |   2 +
 .../test/fixtures/wip/wip/expected.js         |  20 +-
 5 files changed, 227 insertions(+), 158 deletions(-)

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 8ff523b25250..7d5b5d4fc27e 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -270,6 +270,141 @@ helpers.createClass = template(`
   })()
 `);
 
+helpers.decorate = template(`
+  (function (constructor, undecorated, memberDecorators, heritage) {
+    const prototype = constructor.prototype;
+    let finishers = [];
+    const elementDescriptors = {}; // elementDescriptors is meant to be an array, so this will be converted later
+    //TODO: merging of elementDescriptors
+
+    for (const [key, isStatic] of undecorated) {
+      const target = isStatic ? constructor : prototype;
+      const propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
+      elementDescriptors[key] = makeElementDescriptor(
+        "property",
+        key,
+        isStatic,
+        propertyDescriptor,
+      );
+    }
+
+    for (const [key, decorators, isStatic] of memberDecorators) {
+      const target = isStatic ? constructor : prototype;
+      const propertyDescriptor =
+        elementDescriptors[key] || Object.getOwnPropertyDescriptor(target, key);
+      const elementDescriptor = makeElementDescriptor(
+        "property",
+        key,
+        isStatic,
+        propertyDescriptor,
+      );
+      const decorated = decorateElement(elementDescriptor, decorators);
+
+      elementDescriptors[key] = decorated.descriptor;
+
+      for (const extra of decorated.extras) {
+        // extras is an array of element descriptors
+        elementDescriptors[extra.key] = extra;
+      }
+
+      finishers = finishers.concat(decorated.finishers);
+    }
+
+    return function(classDecorators) {
+      const result = decorateClass(
+        constructor,
+        classDecorators,
+        heritage,
+        Object.values(elementDescriptors),
+      );
+      finishers = finishers.concat(result.finishers);
+      //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
+      //TODO: step 38 and 39, what do they mean "initialize"?
+
+      for (const elementDescriptor of result.elements) {
+        const target = elementDescriptor.isStatic ? constructor : prototype;
+        Object.defineOwnProperty(
+          target,
+          elementDescriptor.key,
+          elementDescriptor.descriptor,
+        );
+      }
+
+      return result.constructor;
+    };
+  });
+`);
+
+helpers.decorateElement = template(`
+  (function (descriptor, decorators) {
+    //spec uses the param "element" instead of "descriptor" and finds descriptor from it
+    let extras = [];
+    const finishers = [];
+
+    let previousDescriptor = descriptor;
+
+    for (let i = decorators.length - 1; i >= 0; i--) {
+      const decorator = decorators[i];
+      const result = decorator(previousDescriptor);
+      const currentDescriptor = result.descriptor;
+
+      if (result.finisher) {
+        finishers.push(current.finisher);
+        result.finisher = undefined;
+      }
+
+      previousDescriptor = currentDescriptor;
+
+      const extrasObject = result.extras;
+
+      if (extrasObject) {
+        for (const extra of extrasObject) {
+          extras.push(extra);
+        }
+      }
+    }
+
+    extras = mergeDuplicateElements(extras);
+
+    return { descriptor: previousDescriptor, extras, finishers };
+  });
+`);
+
+helpers.decorateClass = template(`
+  (function (constructor, decorators, heritage, elementDescriptors) {
+    let elements = [];
+    let finishers = [];
+
+    let previousConstructor = constructor;
+    const previousDescriptors = elementDescriptors;
+
+    for (let i = decorators.length - 1; i >= 0; i--) {
+      const decorator = decorators[i];
+      const result = decorator(
+        previousConstructor,
+        heritage,
+        previousDescriptors,
+      );
+
+      previousConstructor = result.constructor;
+      if (result.finishers) {
+        // result.finishers is called 'finisher' in the spec
+        finishers = finishers.concat(result.finishers);
+      }
+
+      if (result.elements) {
+        for (const element of result.elements) {
+          elements.push(element);
+        }
+      }
+
+      elements = mergeDuplicateElements(elements);
+    }
+
+    return { constructor: previousConstructor, elements, finishers };
+  });
+`);
+
 helpers.defineEnumerableProperties = template(`
   (function (obj, descs) {
     for (var key in descs) {
@@ -417,6 +552,19 @@ helpers.interopRequireWildcard = template(`
   })
 `);
 
+helpers.makeElementDescriptor = template(`
+  (function (kind, key, isStatic, descriptor, finisher) {
+    return { kind, key, isStatic, descriptor, finisher };
+  });
+`);
+
+//TODO
+helpers.mergeDuplicateElements = template(`
+  (function (elements) {
+    return elements; 
+  });
+`);
+
 helpers.newArrowCheck = template(`
   (function (innerThis, boundThis) {
     if (innerThis !== boundThis) {
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index deac82e2b8f8..589ef67ed64f 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -1,8 +1,10 @@
-import template from 'babel-template';
+import template from "babel-template";
 import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 
 //TODO: will have to check for dot (.) access to reserved keywords in decorator members
 //NOTE: convention is 'descriptor' is used for element descriptors, while 'propertyDescriptor' is used for property descriptor
+//TODO: check if we need the 'define' + 'Property' and 'ke' + 'ys' hacks as seen in
+//https://github.com/loganfsmyth/babel-plugin-transform-decorators-legacy/blob/master/src/index.js#L69
 
 /** manual testing code
 class A { method() {console.log("method exec hua");} static estatic() {console.log("estatic hua");}}
@@ -12,127 +14,24 @@ function classDec(constructor, heritage, memberDescriptors) {console.log("class
 decorate(A, [], [["method", [methDec, methDec2]], ["estatic", [methDec], true]])([classDec])
 **/
 export default function({ types: t }) {
+  // converts [(expression)] to [(let key = (expression))] if expression is impure
+  // so as to avoid recomputation when the key is needed later
+  function addKeysToComputedMembers(path) {
+    const body = path.get("body.body");
 
-  // injected
-  function makeElementDescriptor(kind, key, isStatic, descriptor, finisher) {
-    return {kind, key, isStatic, descriptor, finisher};
-  }
-
-  // injected
-  function decorateElement(descriptor, decorators) { //spec uses the param "element" instead of "descriptor" and finds descriptor from it
-    let extras = [];
-    let finishers = [];
-
-    let previousDescriptor = descriptor;
-
-    for (let i = decorators.length - 1; i >= 0; i--) {
-      let decorator = decorators[i];
-      let result = decorator(previousDescriptor);
-      let currentDescriptor = result.descriptor;
-
-      if (result.finisher) {
-        finishers.push(current.finisher);
-        result.finisher = undefined;
-      }
-
-      previousDescriptor = currentDescriptor;
-
-      let extrasObject = result.extras;
-
-      if (extrasObject) {
-        for (let extra of extrasObject) {
-          extras.push(extra);
-        }
-      }
-    }
-
-    extras = mergeDuplicateElements(extras);
-
-    return {descriptor: previousDescriptor, extras, finishers}
-  }
-
-  // injected
-  function mergeDuplicateElements(elements) { return elements; /*TODO*/}
-
-  // injected
-  function decorateClass(constructor, decorators, heritage, elementDescriptors) {
-    let elements = [];
-    let finishers = [];
-
-    let previousConstructor = constructor;
-    let previousDescriptors = elementDescriptors;
-
-    for (let i = decorators.length - 1; i >= 0; i--) {
-      let decorator = decorators[i];
-      let result = decorator(previousConstructor, heritage, previousDescriptors);
-
-      previousConstructor = result.constructor;
-      if (result.finishers) {// result.finishers is called 'finisher' in the spec
-        finishers = finishers.concat(result.finishers);
-      }
-
-      if (result.elements) {
-        for (let element of result.elements) {
-          elements.push(element);
-        }
-      }
-
-      elements = mergeDuplicateElements(elements);
-    }
-
-    return {constructor: previousConstructor, elements, finishers};
-  }
-
-  function decorate(constructor, undecorated, memberDecorators, heritage) {
-    const prototype = constructor.prototype;
-    let finishers = [];
-    const elementDescriptors = {}; // elementDescriptors is meant to be an array, so this will be converted later
-    //TODO: merging of elementDescriptors
-
-    for (let [key, isStatic] of undecorated) {
-      const target = isStatic? constructor : prototype;
-      let propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
-      elementDescriptors[key] = makeElementDescriptor("property", key, isStatic, propertyDescriptor);
-    }
-
-    for (let [key, decorators, isStatic] of memberDecorators) {
-      let target = isStatic? constructor : prototype;
-      let propertyDescriptor = elementDescriptors[key] || Object.getOwnPropertyDescriptor(target, key);
-      let elementDescriptor = makeElementDescriptor("property", key, isStatic, propertyDescriptor);
-      let decorated = decorateElement(elementDescriptor, decorators);
-
-      elementDescriptors[key] = decorated.descriptor;
-
-      for (let extra of decorated.extras) { // extras is an array of element descriptors
-        elementDescriptors[extra.key] = extra;
-      }
-
-      finishers = finishers.concat(decorated.finishers);
-    }
-
-    return function (classDecorators) {
-      let result = decorateClass(constructor, classDecorators, heritage, Object.values(elementDescriptors));
-      finishers = finishers.concat(result.finishers);
-      //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
-      //TODO: step 38 and 39, what do they mean "initialize"?
-
-      for (let elementDescriptor of result.elements) {
-        let target = elementDescriptor.isStatic? constructor : prototype;  
-        Object.defineOwnProperty(target, elementDescriptor.key, elementDescriptor.descriptor);
+    for (const member of body) {
+      if (member.node.computed && member.get("key").isPure()) {
+        const parent = path.findParent(p => p.parentPath.isBlock());
+        const ref = member.scope.generateUidIdentifier("key");
+        parent.insertBefore(
+          t.variableDeclaration("let", [t.variableDeclarator(ref)]),
+        );
+        const replacement = t.sequenceExpression([
+          t.assignmentExpression("=", ref, member.node.key),
+        ]);
+        //member.get("key").replaceWith(replacement); FIXME: should work, but doesn't accept sequenceexpression type
+        member.node.key = replacement;
       }
-
-      return result.constructor;
-    }
-  }
-
-
-  function classDefintionEvaluation(path) {
-    // step 20, 21
-    for (const method of body) {
-      const { node } = method;
-      if (!method.isClassMethod()) continue;
-      if (!node.decorators || !method.node.decorators.length) continue;
-      if (node.kind === "constructor") continue;
     }
   }
 
@@ -156,22 +55,12 @@ export default function({ types: t }) {
 
       const entry = [];
       if (node.computed) {
-        // if it is computed, we need an identifier to refer to it later
-        // so we can avoid evaluating the expression twice
+        // if it is computed, it has been processed by addKeysToComputedMembers
         if (t.isAssignmentExpression(node.key)) {
           entry.push(node.key.left);
         } else {
-          const parent = path.findParent(p => p.parentPath.isBlock());
-          const ref = method.scope.generateUidIdentifier("key");
-          parent.insertBefore(
-            t.variableDeclaration("let", [t.variableDeclarator(ref)]),
-          );
-          const replacement = t.sequenceExpression([
-            t.assignmentExpression("=", ref, node.key),
-          ]);
-          //method.get("key").replaceWith(); FIXME: this should work
-          node.key = replacement;
-          entry.push(ref);
+          // it's pure
+          entry.push(node.key);
         }
       } else {
         entry.push(t.stringLiteral(node.key.name));
@@ -197,6 +86,25 @@ export default function({ types: t }) {
     return t.arrayExpression(decorators);
   }
 
+  function undecoratedMethods(path) {
+    const body = path.get("body.body");
+    const result = []; // shape: [[method1], [method2], [staticMethod1, true]]
+
+    for (const method of body) {
+      if (method.node.decorators && method.node.decorators.length > 0) continue;
+
+      if (method.node.static) {
+        result.push(
+          t.arrayExpression([method.node.key, t.booleanLiteral(true)]),
+        );
+      } else {
+        result.push(t.arrayExpression([method.node.key]));
+      }
+    }
+
+    return t.arrayExpression(result);
+  }
+
   return {
     inherits: syntaxDecorators2,
     visitor: {
@@ -230,30 +138,43 @@ export default function({ types: t }) {
         );
       },
 
-      ClassExpression(path) {
+      ClassExpression(path, file) {
+        file.addHelper("makeElementDescriptor");
+        file.addHelper("decorateElement");
+        file.addHelper("mergeDuplicateElements");
+        file.addHelper("decorateClass");
+        const decorateIdentifier = file.addHelper("decorate");
+
+        addKeysToComputedMembers(path);
+
+        const undecorated = undecoratedMethods(path);
         const methodDecorators = takeMethodDecorators(path);
         const classDecorators = takeClassDecorators(path);
+
         if (
           methodDecorators.elements.length == 0 &&
           classDecorators.elements.length == 0
         ) {
           return;
         }
+
+        const superClass =
+          path.node.superClass == null
+            ? path.scope.buildUndefinedNode()
+            : path.node.superClass;
+
         path.replaceWith(
-          t.callExpression(t.identifier("decorate"), [
-            path.node,
-            methodDecorators,
-            classDecorators,
-          ]),
+          t.callExpression(
+            t.callExpression(decorateIdentifier, [
+              path.node,
+              undecorated,
+              methodDecorators,
+              superClass,
+            ]),
+            [classDecorators],
+          ),
         );
       },
-
-      ClassMethod(path) {
-        if (path.get("decorators")) {
-          path.get("decorators").forEach(p => p.remove());
-          path.get("body").unshiftContainer("body", t.identifier("yo"));
-        }
-      },
     },
   };
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json b/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
index 46ff9f3d5227..1de0ea87cd38 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/options.json
@@ -1,3 +1,3 @@
 {
-  "plugins": ["transform-decorators-2"]
+  "plugins": ["transform-decorators-2", "external-helpers"]
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
index f3913b9db341..c486ba7c609e 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
@@ -4,4 +4,6 @@ let decorate = () => void 0, dec, bar, foo = {bar: () => void 0}, baz, decorator
   @dec m1() {};
   @bar @foo.bar(baz) m2() {};
   @dec static [3 + 7] () {};
+  andAnUndecoratedMethod () {};
+  [calculated + and + undecorated] () {};
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
index c6acc0291e8a..a91f67d7db82 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -10,17 +10,15 @@ let decorate = () => void 0,
 
 let _key;
 
-let Bizz = decorate(class Bizz {
-  m1() {
-    yo
-  }
+let Bizz = babelHelpers.decorate(class Bizz {
+  m1() {}
 
-  m2() {
-    yo
-  }
+  m2() {}
 
-  static [(_key = 3 + 7)]() {
-    yo
-  }
+  static [(_key = 3 + 7)]() {}
 
-}, [["m1", [dec]], ["m2", [foo.bar(baz), bar]], [_key, [dec], true]], [decorator]);
+  andAnUndecoratedMethod() {}
+
+  [calculated + and + undecorated]() {}
+
+}, [[andAnUndecoratedMethod], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [foo.bar(baz), bar]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file

From 10d763e3b98e18462e368de4424f52d861736baf Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Mon, 31 Jul 2017 20:09:49 +0530
Subject: [PATCH 05/21] Clean up code

---
 packages/babel-helpers/src/helpers.js         |  2 +
 .../src/index.js                              | 24 ++++++------
 .../test/fixtures/wip/wip2/actual.js          | 24 ++++++++++++
 .../test/fixtures/wip/wip2/expected.js        | 37 +++++++++++++++++++
 4 files changed, 74 insertions(+), 13 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 7d5b5d4fc27e..5a08989aa8e4 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -270,6 +270,8 @@ helpers.createClass = template(`
   })()
 `);
 
+//NOTE: convention is 'descriptor' is used for element descriptors, while 'propertyDescriptor' is used for
+//property descriptor in all helpers related to decorators-2
 helpers.decorate = template(`
   (function (constructor, undecorated, memberDecorators, heritage) {
     const prototype = constructor.prototype;
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 589ef67ed64f..86444afb624b 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -1,17 +1,10 @@
-import template from "babel-template";
 import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 
 //TODO: will have to check for dot (.) access to reserved keywords in decorator members
-//NOTE: convention is 'descriptor' is used for element descriptors, while 'propertyDescriptor' is used for property descriptor
 //TODO: check if we need the 'define' + 'Property' and 'ke' + 'ys' hacks as seen in
 //https://github.com/loganfsmyth/babel-plugin-transform-decorators-legacy/blob/master/src/index.js#L69
 
 /** manual testing code
-class A { method() {console.log("method exec hua");} static estatic() {console.log("estatic hua");}}
-function methDec(descriptor) {console.log("methDec hua", arguments); return {descriptor, extras: [], finishers: []}}
-function methDec2(descriptor) {console.log("methDec2 hua", arguments); return {descriptor, extras: [], finishers: []}}
-function classDec(constructor, heritage, memberDescriptors) {console.log("class hua", arguments); return {constructor, elements: memberDescriptors, finishers: []}}
-decorate(A, [], [["method", [methDec, methDec2]], ["estatic", [methDec], true]])([classDec])
 **/
 export default function({ types: t }) {
   // converts [(expression)] to [(let key = (expression))] if expression is impure
@@ -29,7 +22,8 @@ export default function({ types: t }) {
         const replacement = t.sequenceExpression([
           t.assignmentExpression("=", ref, member.node.key),
         ]);
-        //member.get("key").replaceWith(replacement); FIXME: should work, but doesn't accept sequenceexpression type
+        // FIXME: the following should work: member.get("key").replaceWith(replacement);
+        // but doesn't accept sequenceexpression type so we have to directly manipulate node
         member.node.key = replacement;
       }
     }
@@ -51,7 +45,7 @@ export default function({ types: t }) {
       const decorators = method.node.decorators
         .map(d => d.expression)
         .reverse(); // reverse for correct evaluation order
-      node.decorators = []; //TODO: should we remove from path? method.get("decorators") doesn't work
+      node.decorators = []; //TODO: should we remove using path methods? method.get("decorators") doesn't work
 
       const entry = [];
       if (node.computed) {
@@ -80,10 +74,14 @@ export default function({ types: t }) {
 
   // expects path of a ClassExpression
   function takeClassDecorators(path) {
-    // reverse for correct decorator evaluation order
-    const decorators = path.node.decorators.map(d => d.expression).reverse();
-    path.node.decorators = [];
-    return t.arrayExpression(decorators);
+    if (path.node.decorators && path.node.decorators.length) {
+      // reverse for correct decorator evaluation order
+      const decorators = path.node.decorators.map(d => d.expression).reverse();
+      path.node.decorators = [];
+      return t.arrayExpression(decorators);
+    } else {
+      return t.arrayExpression();
+    }
   }
 
   function undecoratedMethods(path) {
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
new file mode 100644
index 000000000000..8d6b41897bce
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
@@ -0,0 +1,24 @@
+class A { 
+  @methDec @methDec2 method() {
+    console.log("method executed");
+  } 
+  
+  @methDec static estatic() {
+    console.log("estatic executed");
+  }
+}
+
+function methDec(descriptor) {
+  console.log("methDec executed", arguments); 
+  return {descriptor, extras: [], finishers: []}
+}
+
+function methDec2(descriptor) {
+  console.log("methDec2 executed", arguments); 
+  return {descriptor, extras: [], finishers: []}
+}
+
+function classDec(constructor, heritage, memberDescriptors) {
+  console.log("class executed", arguments); 
+  return {constructor, elements: memberDescriptors, finishers: []}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js
new file mode 100644
index 000000000000..563ccba0b79b
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js
@@ -0,0 +1,37 @@
+let A = babelHelpers.decorate(class A {
+  method() {
+    console.log("method executed");
+  }
+
+  static estatic() {
+    console.log("estatic executed");
+  }
+
+}, [], [["method", [methDec2, methDec]], ["estatic", [methDec], true]], void 0)([]);
+
+function methDec(descriptor) {
+  console.log("methDec executed", arguments);
+  return {
+    descriptor,
+    extras: [],
+    finishers: []
+  };
+}
+
+function methDec2(descriptor) {
+  console.log("methDec2 executed", arguments);
+  return {
+    descriptor,
+    extras: [],
+    finishers: []
+  };
+}
+
+function classDec(constructor, heritage, memberDescriptors) {
+  console.log("class executed", arguments);
+  return {
+    constructor,
+    elements: memberDescriptors,
+    finishers: []
+  };
+}
\ No newline at end of file

From 358cf70cc7758cb5c2ed93bb52474450d8618018 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Tue, 1 Aug 2017 11:16:31 +0530
Subject: [PATCH 06/21] Add feature to pass array of deps to a helper

---
 .../src/transformation/file/index.js           | 18 +++++++++++++++---
 packages/babel-helpers/src/index.js            |  4 ++--
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/packages/babel-core/src/transformation/file/index.js b/packages/babel-core/src/transformation/file/index.js
index 3461647bc9a8..4eab4dbbdf4a 100644
--- a/packages/babel-core/src/transformation/file/index.js
+++ b/packages/babel-core/src/transformation/file/index.js
@@ -211,13 +211,12 @@ export default class File extends Store {
     return id;
   }
 
-  addHelper(name: string): Object {
+  addHelper(name: string, deps: Array<string>): Object {
     const declar = this.declarations[name];
     if (declar) return declar;
 
     if (!this.usedHelpers[name]) {
       this.metadata.usedHelpers.push(name);
-      this.usedHelpers[name] = true;
     }
 
     const generator = this.get("helperGenerator");
@@ -229,7 +228,18 @@ export default class File extends Store {
       return t.memberExpression(runtime, t.identifier(name));
     }
 
-    const ref = getHelper(name);
+    const opts = {};
+    if (deps) {
+      for (const dep in deps) {
+        if (!this.usedHelpers[name]) {
+          throw "Helper dependencies must be added to the file first";
+        } else {
+          opts["babelHelpers." + dep] = this.usedHelpers[name];
+        }
+      }
+    }
+
+    const ref = getHelper(name, opts);
     const uid = (this.declarations[name] = this.scope.generateUidIdentifier(
       name,
     ));
@@ -248,6 +258,8 @@ export default class File extends Store {
       });
     }
 
+    this.usedHelpers[name] = uid.name;
+
     return uid;
   }
 
diff --git a/packages/babel-helpers/src/index.js b/packages/babel-helpers/src/index.js
index 58dc5e85aa82..5e66edf70431 100644
--- a/packages/babel-helpers/src/index.js
+++ b/packages/babel-helpers/src/index.js
@@ -1,10 +1,10 @@
 import helpers from "./helpers";
 
-export function get(name) {
+export function get(name, opts) {
   const fn = helpers[name];
   if (!fn) throw new ReferenceError(`Unknown helper ${name}`);
 
-  return fn().expression;
+  return fn(opts).expression;
 }
 
 export const list = Object.keys(helpers)

From 626b92e3b11ec5a4a3191e594791b287c5c29bd5 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sun, 6 Aug 2017 23:29:16 +0530
Subject: [PATCH 07/21] Add exec tests

---
 packages/babel-helpers/src/helpers.js         | 14 ++++-----
 .../src/index.js                              |  9 ++++--
 .../test/fixtures/wip/wip2/exec.js            | 29 +++++++++++++++++++
 3 files changed, 42 insertions(+), 10 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 5a08989aa8e4..4d7d83689204 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -282,7 +282,7 @@ helpers.decorate = template(`
     for (const [key, isStatic] of undecorated) {
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
-      elementDescriptors[key] = makeElementDescriptor(
+      elementDescriptors[key] = babelHelpers.makeElementDescriptor(
         "property",
         key,
         isStatic,
@@ -294,13 +294,13 @@ helpers.decorate = template(`
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor =
         elementDescriptors[key] || Object.getOwnPropertyDescriptor(target, key);
-      const elementDescriptor = makeElementDescriptor(
+      const elementDescriptor = babelHelpers.makeElementDescriptor(
         "property",
         key,
         isStatic,
         propertyDescriptor,
-      );
-      const decorated = decorateElement(elementDescriptor, decorators);
+      )
+      const decorated = babelHelpers.decorateElement(elementDescriptor, decorators);
 
       elementDescriptors[key] = decorated.descriptor;
 
@@ -313,7 +313,7 @@ helpers.decorate = template(`
     }
 
     return function(classDecorators) {
-      const result = decorateClass(
+      const result = babelHelpers.decorateClass(
         constructor,
         classDecorators,
         heritage,
@@ -366,7 +366,7 @@ helpers.decorateElement = template(`
       }
     }
 
-    extras = mergeDuplicateElements(extras);
+    extras = babelHelpers.mergeDuplicateElements(extras);
 
     return { descriptor: previousDescriptor, extras, finishers };
   });
@@ -400,7 +400,7 @@ helpers.decorateClass = template(`
         }
       }
 
-      elements = mergeDuplicateElements(elements);
+      elements = babelHelpers.mergeDuplicateElements(elements);
     }
 
     return { constructor: previousConstructor, elements, finishers };
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 86444afb624b..d386696e0fbf 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -138,10 +138,13 @@ export default function({ types: t }) {
 
       ClassExpression(path, file) {
         file.addHelper("makeElementDescriptor");
-        file.addHelper("decorateElement");
         file.addHelper("mergeDuplicateElements");
-        file.addHelper("decorateClass");
-        const decorateIdentifier = file.addHelper("decorate");
+        file.addHelper("decorateClass", ["mergeDuplicateElements"]);
+        file.addHelper("decorateElement", ["mergeDuplicateElements"]);
+        const decorateIdentifier = file.addHelper("decorate", [
+          "decorateClass",
+          "decorateElement",
+        ]);
 
         addKeysToComputedMembers(path);
 
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js
new file mode 100644
index 000000000000..4f04e2893e65
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js
@@ -0,0 +1,29 @@
+var log = [];
+var console = {log: (...args) => log.push(args)};
+
+class A { 
+  @methDec @methDec2 method() {
+    console.log("method executed");
+  } 
+  
+  @methDec static estatic() {
+    console.log("estatic executed");
+  }
+}
+
+function methDec(descriptor) {
+  console.log("methDec executed", arguments); 
+  return {descriptor, extras: [], finishers: []}
+}
+
+function methDec2(descriptor) {
+  console.log("methDec2 executed", arguments); 
+  return {descriptor, extras: [], finishers: []}
+}
+
+function classDec(constructor, heritage, memberDescriptors) {
+  console.log("class executed", arguments); 
+  return {constructor, elements: memberDescriptors, finishers: []}
+}
+
+assert.deepEqual(log, []);

From d8cebbac0b21dd2d4e8a410cfa4cb7af43ebe658 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Mon, 7 Aug 2017 12:51:05 +0530
Subject: [PATCH 08/21] Add tests for evaluation order and fix transformation

---
 .../src/index.js                              |  8 ++--
 .../decorator-list-evaluation/exec.js         | 27 ++++++++++++++
 .../evalutation-order/execution/exec.js       | 28 ++++++++++++++
 .../test/fixtures/wip/wip/expected.js         |  2 +-
 .../test/fixtures/wip/wip2/actual.js          | 24 ------------
 .../test/fixtures/wip/wip2/exec.js            | 29 ---------------
 .../test/fixtures/wip/wip2/expected.js        | 37 -------------------
 7 files changed, 59 insertions(+), 96 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index d386696e0fbf..59722a4f865c 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -42,9 +42,8 @@ export default function({ types: t }) {
       if (!method.isClassMethod()) continue;
       if (!node.decorators || !method.node.decorators.length) continue;
 
-      const decorators = method.node.decorators
-        .map(d => d.expression)
-        .reverse(); // reverse for correct evaluation order
+      const decorators = method.node.decorators.map(d => d.expression);
+
       node.decorators = []; //TODO: should we remove using path methods? method.get("decorators") doesn't work
 
       const entry = [];
@@ -75,8 +74,7 @@ export default function({ types: t }) {
   // expects path of a ClassExpression
   function takeClassDecorators(path) {
     if (path.node.decorators && path.node.decorators.length) {
-      // reverse for correct decorator evaluation order
-      const decorators = path.node.decorators.map(d => d.expression).reverse();
+      const decorators = path.node.decorators.map(d => d.expression);
       path.node.decorators = [];
       return t.arrayExpression(decorators);
     } else {
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js
new file mode 100644
index 000000000000..b1978abda38c
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js
@@ -0,0 +1,27 @@
+const calls = [];
+
+function dec(id){
+  calls.push(id);
+  return function(descriptor) { return {descriptor, extras:[], finishers:[] };};
+}
+
+class Foo {
+  @dec(1)
+  @dec(2)
+  method1() {}
+
+  @dec(3)
+  @dec(4)
+  method2() {}
+
+  @dec(5)
+  @dec(6)
+  method3() {}
+
+  @dec(7)
+  @dec(8)
+  method4() {}
+}
+
+assert.deepEqual(calls, [1, 2, 3, 4, 5, 6, 7, 8]);
+
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js
new file mode 100644
index 000000000000..7f64b5fcb039
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js
@@ -0,0 +1,28 @@
+const calls = [];
+
+function dec(id){
+  return function(descriptor) { 
+    calls.push(id); 
+    return {descriptor, extras:[], finishers:[] };
+  };
+}
+
+class Foo {
+  @dec(2)
+  @dec(1)
+  method1() {}
+
+  @dec(4)
+  @dec(3)
+  method2() {}
+
+  @dec(6)
+  @dec(5)
+  method3() {}
+
+  @dec(8)
+  @dec(7)
+  method4() {}
+}
+
+assert.deepEqual(calls, [1, 2, 3, 4, 5, 6, 7, 8]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
index a91f67d7db82..e85c99bccd07 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -21,4 +21,4 @@ let Bizz = babelHelpers.decorate(class Bizz {
 
   [calculated + and + undecorated]() {}
 
-}, [[andAnUndecoratedMethod], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [foo.bar(baz), bar]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file
+}, [[andAnUndecoratedMethod], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [bar, foo.bar(baz)]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
deleted file mode 100644
index 8d6b41897bce..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/actual.js
+++ /dev/null
@@ -1,24 +0,0 @@
-class A { 
-  @methDec @methDec2 method() {
-    console.log("method executed");
-  } 
-  
-  @methDec static estatic() {
-    console.log("estatic executed");
-  }
-}
-
-function methDec(descriptor) {
-  console.log("methDec executed", arguments); 
-  return {descriptor, extras: [], finishers: []}
-}
-
-function methDec2(descriptor) {
-  console.log("methDec2 executed", arguments); 
-  return {descriptor, extras: [], finishers: []}
-}
-
-function classDec(constructor, heritage, memberDescriptors) {
-  console.log("class executed", arguments); 
-  return {constructor, elements: memberDescriptors, finishers: []}
-}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js
deleted file mode 100644
index 4f04e2893e65..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/exec.js
+++ /dev/null
@@ -1,29 +0,0 @@
-var log = [];
-var console = {log: (...args) => log.push(args)};
-
-class A { 
-  @methDec @methDec2 method() {
-    console.log("method executed");
-  } 
-  
-  @methDec static estatic() {
-    console.log("estatic executed");
-  }
-}
-
-function methDec(descriptor) {
-  console.log("methDec executed", arguments); 
-  return {descriptor, extras: [], finishers: []}
-}
-
-function methDec2(descriptor) {
-  console.log("methDec2 executed", arguments); 
-  return {descriptor, extras: [], finishers: []}
-}
-
-function classDec(constructor, heritage, memberDescriptors) {
-  console.log("class executed", arguments); 
-  return {constructor, elements: memberDescriptors, finishers: []}
-}
-
-assert.deepEqual(log, []);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js
deleted file mode 100644
index 563ccba0b79b..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip2/expected.js
+++ /dev/null
@@ -1,37 +0,0 @@
-let A = babelHelpers.decorate(class A {
-  method() {
-    console.log("method executed");
-  }
-
-  static estatic() {
-    console.log("estatic executed");
-  }
-
-}, [], [["method", [methDec2, methDec]], ["estatic", [methDec], true]], void 0)([]);
-
-function methDec(descriptor) {
-  console.log("methDec executed", arguments);
-  return {
-    descriptor,
-    extras: [],
-    finishers: []
-  };
-}
-
-function methDec2(descriptor) {
-  console.log("methDec2 executed", arguments);
-  return {
-    descriptor,
-    extras: [],
-    finishers: []
-  };
-}
-
-function classDec(constructor, heritage, memberDescriptors) {
-  console.log("class executed", arguments);
-  return {
-    constructor,
-    elements: memberDescriptors,
-    finishers: []
-  };
-}
\ No newline at end of file

From ef4eba5d7abd3d98890c60f7925ad48095057d7d Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Wed, 9 Aug 2017 17:47:48 +0530
Subject: [PATCH 09/21] Add tests for class decorators; minor fixes

---
 packages/babel-helpers/src/helpers.js         |  6 ++--
 .../src/index.js                              |  1 +
 .../class-and-method-decorators/actual.js     | 25 +++++++++++++++
 .../class-and-method-decorators/exec.js       | 25 +++++++++++++++
 .../class-and-method-decorators/expected.js   | 31 +++++++++++++++++++
 5 files changed, 85 insertions(+), 3 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 4d7d83689204..470402292151 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -317,7 +317,7 @@ helpers.decorate = template(`
         constructor,
         classDecorators,
         heritage,
-        Object.values(elementDescriptors),
+        Object.values(elementDescriptors)
       );
       finishers = finishers.concat(result.finishers);
       //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
@@ -325,10 +325,10 @@ helpers.decorate = template(`
 
       for (const elementDescriptor of result.elements) {
         const target = elementDescriptor.isStatic ? constructor : prototype;
-        Object.defineOwnProperty(
+        Object.defineProperty(
           target,
           elementDescriptor.key,
-          elementDescriptor.descriptor,
+          elementDescriptor.descriptor
         );
       }
 
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 59722a4f865c..9cb0c9f80f93 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -88,6 +88,7 @@ export default function({ types: t }) {
 
     for (const method of body) {
       if (method.node.decorators && method.node.decorators.length > 0) continue;
+      if (method.node.key.name == "constructor") continue;
 
       if (method.node.static) {
         result.push(
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
new file mode 100644
index 000000000000..be624a3a3587
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
@@ -0,0 +1,25 @@
+const calls = [];
+
+function classDec(constructor, heritage, elements) {
+  calls.push("classDec evaluated");
+  return {constructor, elements, finishers: []};
+}
+
+function methDec(descriptor){
+  calls.push("methDec evaluated");
+  return {descriptor, extras:[], finishers:[] };
+}
+
+
+
+@classDec class A {
+  constructor () {
+    calls.push("ctor called");
+  }
+
+  @methDec method1() {
+    calls.push("method1 called");
+  }
+}
+
+assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
new file mode 100644
index 000000000000..be624a3a3587
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
@@ -0,0 +1,25 @@
+const calls = [];
+
+function classDec(constructor, heritage, elements) {
+  calls.push("classDec evaluated");
+  return {constructor, elements, finishers: []};
+}
+
+function methDec(descriptor){
+  calls.push("methDec evaluated");
+  return {descriptor, extras:[], finishers:[] };
+}
+
+
+
+@classDec class A {
+  constructor () {
+    calls.push("ctor called");
+  }
+
+  @methDec method1() {
+    calls.push("method1 called");
+  }
+}
+
+assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js
new file mode 100644
index 000000000000..d3674151e402
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js
@@ -0,0 +1,31 @@
+const calls = [];
+
+function classDec(constructor, heritage, elements) {
+  calls.push("classDec evaluated");
+  return {
+    constructor,
+    elements,
+    finishers: []
+  };
+}
+
+function methDec(descriptor) {
+  calls.push("methDec evaluated");
+  return {
+    descriptor,
+    extras: [],
+    finishers: []
+  };
+}
+
+let A = babelHelpers.decorate(class A {
+  constructor() {
+    calls.push("ctor called");
+  }
+
+  method1() {
+    calls.push("method1 called");
+  }
+
+}, [], [["method1", [methDec]]], void 0)([classDec]);
+assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
\ No newline at end of file

From b1092ca65ad87d292d97d12dcd202ac07f3cd441 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Fri, 11 Aug 2017 14:41:51 +0530
Subject: [PATCH 10/21] Add test for enumerability decorator

---
 packages/babel-helpers/src/helpers.js         | 27 +++++++-----
 .../src/index.js                              | 41 ++++++++++---------
 .../class-and-method-decorators-order/exec.js | 26 ++++++++++++
 .../decorator-execution-order}/exec.js        |  0
 .../decorator-list-evaluation-order}/exec.js  |  0
 .../class-and-method-decorators/actual.js     | 25 -----------
 .../class-and-method-decorators/exec.js       | 25 -----------
 .../class-and-method-decorators/expected.js   | 31 --------------
 .../examples/change-enumerability/exec.js     | 22 ++++++++++
 .../class-decorators/actual.js                |  7 ++++
 .../class-decorators/expected.js              |  8 ++++
 .../method-and-class-decorators/actual.js     |  4 ++
 .../method-and-class-decorators/expected.js   |  6 +++
 .../method-decorators/actual.js               |  6 +++
 .../method-decorators/expected.js             | 10 +++++
 .../test/fixtures/wip/wip/expected.js         |  2 +-
 16 files changed, 128 insertions(+), 112 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/class-and-method-decorators-order/exec.js
 rename packages/babel-plugin-transform-decorators-2/test/fixtures/{evalutation-order/execution => basic/decorator-execution-order}/exec.js (100%)
 rename packages/babel-plugin-transform-decorators-2/test/fixtures/{evalutation-order/decorator-list-evaluation => basic/decorator-list-evaluation-order}/exec.js (100%)
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
 delete mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/expected.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/expected.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 470402292151..3ff50b783ded 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -293,7 +293,9 @@ helpers.decorate = template(`
     for (const [key, decorators, isStatic] of memberDecorators) {
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor =
-        elementDescriptors[key] || Object.getOwnPropertyDescriptor(target, key);
+        elementDescriptors[key] && elementDescriptors[key].descriptor 
+        || Object.getOwnPropertyDescriptor(target, key);
+
       const elementDescriptor = babelHelpers.makeElementDescriptor(
         "property",
         key,
@@ -347,15 +349,14 @@ helpers.decorateElement = template(`
 
     for (let i = decorators.length - 1; i >= 0; i--) {
       const decorator = decorators[i];
-      const result = decorator(previousDescriptor);
-      const currentDescriptor = result.descriptor;
+      const result = decorator(previousDescriptor.descriptor);
 
       if (result.finisher) {
         finishers.push(current.finisher);
         result.finisher = undefined;
       }
 
-      previousDescriptor = currentDescriptor;
+      previousDescriptor.descriptor = result.descriptor; // just change the property descriptor
 
       const extrasObject = result.extras;
 
@@ -374,30 +375,28 @@ helpers.decorateElement = template(`
 
 helpers.decorateClass = template(`
   (function (constructor, decorators, heritage, elementDescriptors) {
-    let elements = [];
+    let elements = elementDescriptors;
     let finishers = [];
 
     let previousConstructor = constructor;
-    const previousDescriptors = elementDescriptors;
 
     for (let i = decorators.length - 1; i >= 0; i--) {
       const decorator = decorators[i];
       const result = decorator(
         previousConstructor,
         heritage,
-        previousDescriptors,
+        elements
       );
 
       previousConstructor = result.constructor;
+
       if (result.finishers) {
         // result.finishers is called 'finisher' in the spec
         finishers = finishers.concat(result.finishers);
       }
 
       if (result.elements) {
-        for (const element of result.elements) {
-          elements.push(element);
-        }
+        elements = elements.concat(result.elements); //FIXME: for some reason using for of exhausts heap here
       }
 
       elements = babelHelpers.mergeDuplicateElements(elements);
@@ -563,7 +562,13 @@ helpers.makeElementDescriptor = template(`
 //TODO
 helpers.mergeDuplicateElements = template(`
   (function (elements) {
-    return elements; 
+    let elementMap = {};
+
+    for (let elementDescriptor of elements) {
+      elementMap[elementDescriptor.key] = elementDescriptor;
+    }
+
+    return Object.values(elementMap); 
   });
 `);
 
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 9cb0c9f80f93..a6a4b948c02a 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -29,6 +29,21 @@ export default function({ types: t }) {
     }
   }
 
+  // expects a method node
+  function getKey(node) {
+    if (node.computed) {
+      // if it is computed, it has been processed by addKeysToComputedMembers
+      if (t.isAssignmentExpression(node.key)) {
+        return node.key.left;
+      } else {
+        // it's pure
+        return node.key;
+      }
+    } else {
+      return t.stringLiteral(node.key.name);
+    }
+  }
+
   // goes over the methods of current class and prepares decorators
   // expects path of a ClassExpression
   function takeMethodDecorators(path) {
@@ -46,20 +61,7 @@ export default function({ types: t }) {
 
       node.decorators = []; //TODO: should we remove using path methods? method.get("decorators") doesn't work
 
-      const entry = [];
-      if (node.computed) {
-        // if it is computed, it has been processed by addKeysToComputedMembers
-        if (t.isAssignmentExpression(node.key)) {
-          entry.push(node.key.left);
-        } else {
-          // it's pure
-          entry.push(node.key);
-        }
-      } else {
-        entry.push(t.stringLiteral(node.key.name));
-      }
-
-      entry.push(t.arrayExpression(decorators));
+      const entry = [getKey(node), t.arrayExpression(decorators)];
 
       if (node.static) {
         entry.push(t.booleanLiteral(true));
@@ -82,20 +84,21 @@ export default function({ types: t }) {
     }
   }
 
+  // assume:addKeysToComputedMembers has been executed
   function undecoratedMethods(path) {
     const body = path.get("body.body");
-    const result = []; // shape: [[method1], [method2], [staticMethod1, true]]
+    const result = []; // shape: [["method1"], ["method2"], ["staticMethod1", true]]
 
     for (const method of body) {
       if (method.node.decorators && method.node.decorators.length > 0) continue;
       if (method.node.key.name == "constructor") continue;
 
+      const key = getKey(method.node);
+
       if (method.node.static) {
-        result.push(
-          t.arrayExpression([method.node.key, t.booleanLiteral(true)]),
-        );
+        result.push(t.arrayExpression([key, t.booleanLiteral(true)]));
       } else {
-        result.push(t.arrayExpression([method.node.key]));
+        result.push(t.arrayExpression([key]));
       }
     }
 
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/class-and-method-decorators-order/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/class-and-method-decorators-order/exec.js
new file mode 100644
index 000000000000..ed3b5b3929f6
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/class-and-method-decorators-order/exec.js
@@ -0,0 +1,26 @@
+const calls = [];
+
+function classDec(arg) {
+  calls.push(3);
+  return function (constructor, heritage, elements) {
+    calls.push(4);
+    return {constructor, elements, finishers: []};
+  }
+}
+
+function methDec(arg) {
+  calls.push(1);
+  return function (descriptor){
+    calls.push(2);
+    return {descriptor, extras:[], finishers:[] };
+  }
+}
+
+
+
+@classDec("arg") class A {
+  constructor () {}
+  @methDec("arg") method1() {}
+}
+
+assert.deepEqual(calls, [1, 2, 3, 4]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/decorator-execution-order/exec.js
similarity index 100%
rename from packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/execution/exec.js
rename to packages/babel-plugin-transform-decorators-2/test/fixtures/basic/decorator-execution-order/exec.js
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/decorator-list-evaluation-order/exec.js
similarity index 100%
rename from packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/decorator-list-evaluation/exec.js
rename to packages/babel-plugin-transform-decorators-2/test/fixtures/basic/decorator-list-evaluation-order/exec.js
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
deleted file mode 100644
index be624a3a3587..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/actual.js
+++ /dev/null
@@ -1,25 +0,0 @@
-const calls = [];
-
-function classDec(constructor, heritage, elements) {
-  calls.push("classDec evaluated");
-  return {constructor, elements, finishers: []};
-}
-
-function methDec(descriptor){
-  calls.push("methDec evaluated");
-  return {descriptor, extras:[], finishers:[] };
-}
-
-
-
-@classDec class A {
-  constructor () {
-    calls.push("ctor called");
-  }
-
-  @methDec method1() {
-    calls.push("method1 called");
-  }
-}
-
-assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
deleted file mode 100644
index be624a3a3587..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/exec.js
+++ /dev/null
@@ -1,25 +0,0 @@
-const calls = [];
-
-function classDec(constructor, heritage, elements) {
-  calls.push("classDec evaluated");
-  return {constructor, elements, finishers: []};
-}
-
-function methDec(descriptor){
-  calls.push("methDec evaluated");
-  return {descriptor, extras:[], finishers:[] };
-}
-
-
-
-@classDec class A {
-  constructor () {
-    calls.push("ctor called");
-  }
-
-  @methDec method1() {
-    calls.push("method1 called");
-  }
-}
-
-assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js
deleted file mode 100644
index d3674151e402..000000000000
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/evalutation-order/class-and-method-decorators/expected.js
+++ /dev/null
@@ -1,31 +0,0 @@
-const calls = [];
-
-function classDec(constructor, heritage, elements) {
-  calls.push("classDec evaluated");
-  return {
-    constructor,
-    elements,
-    finishers: []
-  };
-}
-
-function methDec(descriptor) {
-  calls.push("methDec evaluated");
-  return {
-    descriptor,
-    extras: [],
-    finishers: []
-  };
-}
-
-let A = babelHelpers.decorate(class A {
-  constructor() {
-    calls.push("ctor called");
-  }
-
-  method1() {
-    calls.push("method1 called");
-  }
-
-}, [], [["method1", [methDec]]], void 0)([classDec]);
-assert.deepEqual(["methDec evaluated", "classDec evaluated"], calls);
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
new file mode 100644
index 000000000000..dbba987e4eab
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
@@ -0,0 +1,22 @@
+function enumerable(bool) {
+  return function(descriptor) {
+    descriptor.enumerable = bool;
+    return {descriptor, finishers: [], extras: []};
+  }
+}
+
+class Foo {
+  @enumerable(false) falsy() {}
+  @enumerable(true) @enumerable(false) truthy() {}
+  falsyByDefault() {}
+}
+
+//existence 
+assert(Foo.prototype.falsy);
+assert(Foo.prototype.truthy);
+
+//enumerability
+assert.equal(Foo.prototype.propertyIsEnumerable("falsyByDefault"), false);
+assert.equal(Foo.prototype.propertyIsEnumerable("falsy"), false);
+assert.equal(Foo.prototype.propertyIsEnumerable("truthy"), true);
+assert.deepEqual(Object.keys(Foo.prototype), ["truthy"]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/actual.js
new file mode 100644
index 000000000000..3674083d4a11
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/actual.js
@@ -0,0 +1,7 @@
+@classDecOuter("args") @classDecInner class Foo {
+  someMethod() {}
+}
+
+class Undecorated {
+  someMethod() {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
new file mode 100644
index 000000000000..79c6344892fe
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
@@ -0,0 +1,8 @@
+let Foo = babelHelpers.decorate(class Foo {
+  someMethod() {}
+
+}, [["someMethod"]], [], void 0)([classDecOuter("args"), classDecInner]);
+let Undecorated = class Undecorated {
+  someMethod() {}
+
+};
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/actual.js
new file mode 100644
index 000000000000..01cd5da8ab3b
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/actual.js
@@ -0,0 +1,4 @@
+@classDec class Foo {
+  @methDec method() {}
+  undecorated() {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/expected.js
new file mode 100644
index 000000000000..610da2991ef0
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-and-class-decorators/expected.js
@@ -0,0 +1,6 @@
+let Foo = babelHelpers.decorate(class Foo {
+  method() {}
+
+  undecorated() {}
+
+}, [["undecorated"]], [["method", [methDec]]], void 0)([classDec]);
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/actual.js
new file mode 100644
index 000000000000..5cff777a74eb
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/actual.js
@@ -0,0 +1,6 @@
+class Foo {
+  @dec1 method1() {}
+  @dec2(a, b, c) method2() {}
+  @dec3outer @dec3inner method3() {}
+  undecorated() {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/expected.js
new file mode 100644
index 000000000000..95d0b14d1b30
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/method-decorators/expected.js
@@ -0,0 +1,10 @@
+let Foo = babelHelpers.decorate(class Foo {
+  method1() {}
+
+  method2() {}
+
+  method3() {}
+
+  undecorated() {}
+
+}, [["undecorated"]], [["method1", [dec1]], ["method2", [dec2(a, b, c)]], ["method3", [dec3outer, dec3inner]]], void 0)([]);
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
index e85c99bccd07..14444812071a 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -21,4 +21,4 @@ let Bizz = babelHelpers.decorate(class Bizz {
 
   [calculated + and + undecorated]() {}
 
-}, [[andAnUndecoratedMethod], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [bar, foo.bar(baz)]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file
+}, [["andAnUndecoratedMethod"], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [bar, foo.bar(baz)]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file

From a55e374de78681f87ef791dd6868e1c3fdd16475 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Tue, 15 Aug 2017 18:54:19 +0530
Subject: [PATCH 11/21] Add examples, & tests for extras, finishers

---
 packages/babel-helpers/src/helpers.js         | 48 ++++++++++++-------
 .../test/fixtures/basic/extras/exec.js        | 37 ++++++++++++++
 .../test/fixtures/basic/finishers/exec.js     | 35 ++++++++++++++
 .../test/fixtures/examples/logger/exec.js     | 31 ++++++++++++
 .../test/fixtures/examples/overrider/exec.js  | 17 +++++++
 .../test/fixtures/examples/spare/exec.js      | 30 ++++++++++++
 6 files changed, 181 insertions(+), 17 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/extras/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 3ff50b783ded..31bc71772f18 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -276,24 +276,27 @@ helpers.decorate = template(`
   (function (constructor, undecorated, memberDecorators, heritage) {
     const prototype = constructor.prototype;
     let finishers = [];
-    const elementDescriptors = {}; // elementDescriptors is meant to be an array, so this will be converted later
-    //TODO: merging of elementDescriptors
+    const elementDescriptors = new Map(); // elementDescriptors is meant to be an array, so this will be converted later
 
     for (const [key, isStatic] of undecorated) {
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
-      elementDescriptors[key] = babelHelpers.makeElementDescriptor(
-        "property",
-        key,
-        isStatic,
-        propertyDescriptor,
+      elementDescriptors.set(
+        [key, isStatic], 
+        babelHelpers.makeElementDescriptor(
+          "property",
+          key,
+          isStatic,
+          propertyDescriptor,
+        )
       );
     }
 
+    // decorate and store in elementDescriptors
     for (const [key, decorators, isStatic] of memberDecorators) {
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor =
-        elementDescriptors[key] && elementDescriptors[key].descriptor 
+        elementDescriptors.has([key, isStatic]) && elementDescriptors.get([key, isStatic]).descriptor 
         || Object.getOwnPropertyDescriptor(target, key);
 
       const elementDescriptor = babelHelpers.makeElementDescriptor(
@@ -304,11 +307,11 @@ helpers.decorate = template(`
       )
       const decorated = babelHelpers.decorateElement(elementDescriptor, decorators);
 
-      elementDescriptors[key] = decorated.descriptor;
+      elementDescriptors.set([key, isStatic], decorated.descriptor);
 
       for (const extra of decorated.extras) {
         // extras is an array of element descriptors
-        elementDescriptors[extra.key] = extra;
+        elementDescriptors.set([extra.key, extra.isStatic], extra);
       }
 
       finishers = finishers.concat(decorated.finishers);
@@ -319,8 +322,9 @@ helpers.decorate = template(`
         constructor,
         classDecorators,
         heritage,
-        Object.values(elementDescriptors)
+        Array.from(elementDescriptors.values())
       );
+
       finishers = finishers.concat(result.finishers);
       //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
       //TODO: step 38 and 39, what do they mean "initialize"?
@@ -334,6 +338,10 @@ helpers.decorate = template(`
         );
       }
 
+      for (let finisher of finishers) {
+        finisher.call(undefined, result.constructor);
+      }
+
       return result.constructor;
     };
   });
@@ -343,7 +351,7 @@ helpers.decorateElement = template(`
   (function (descriptor, decorators) {
     //spec uses the param "element" instead of "descriptor" and finds descriptor from it
     let extras = [];
-    const finishers = [];
+    let finishers = [];
 
     let previousDescriptor = descriptor;
 
@@ -351,9 +359,10 @@ helpers.decorateElement = template(`
       const decorator = decorators[i];
       const result = decorator(previousDescriptor.descriptor);
 
-      if (result.finisher) {
-        finishers.push(current.finisher);
-        result.finisher = undefined;
+      //TODO: why does .finisher exist on an elementDescriptor? the following conditional deviates from 
+      //the spec because it uses result.finishers rather than result.descriptor.finisher
+      if (result.finishers) {
+        finishers = finishers.concat(result.finishers);
       }
 
       previousDescriptor.descriptor = result.descriptor; // just change the property descriptor
@@ -563,12 +572,17 @@ helpers.makeElementDescriptor = template(`
 helpers.mergeDuplicateElements = template(`
   (function (elements) {
     let elementMap = {};
+    let staticElementMap = {};
 
     for (let elementDescriptor of elements) {
-      elementMap[elementDescriptor.key] = elementDescriptor;
+      if (elementDescriptor.isStatic) {
+        staticElementMap[elementDescriptor.key] = elementDescriptor;
+      } else {
+        elementMap[elementDescriptor.key] = elementDescriptor;
+      }
     }
 
-    return Object.values(elementMap); 
+    return Object.values(elementMap).concat(Object.values(staticElementMap)); 
   });
 `);
 
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/extras/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/extras/exec.js
new file mode 100644
index 000000000000..b0dcbcbb6ffa
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/extras/exec.js
@@ -0,0 +1,37 @@
+function dec(descriptor) {
+  const extra = {
+    kind: "property",
+    key: "magic",
+    isStatic: false,
+    descriptor: {
+      enumerable: true,
+      configurable: true,
+      writable: true,
+      value: function () {return "extra"}
+    }
+  }
+  
+  const extraStatic = {
+    kind: "property",
+    key: "magic",
+    isStatic: true,
+    descriptor: {
+      enumerable: true,
+      configurable: true,
+      writable: true,
+      value: function () {return "extraStatic"}
+    }
+  }
+
+  return {descriptor, extras: [extra, extraStatic], finishers: []}
+}
+
+class Foo {
+  @dec method() {return "method"}
+}
+
+var x = new Foo();
+
+assert.equal(x.method(), "method");
+assert.equal(x.magic(), "extra");
+assert.equal(Foo.magic(), "extraStatic");
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
new file mode 100644
index 000000000000..04ea5cf47646
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
@@ -0,0 +1,35 @@
+const logs = [];
+
+function overrider(fn) {
+  return function(descriptor) {
+    descriptor.value = fn;
+    return {descriptor, extras: [], finishers: []};
+  }
+}
+
+function dec(log) {
+  return function (descriptor) {
+    const finisher = function (ctor) {
+      const x = new ctor(); 
+      assert(x.method1);
+      assert(x.method2);
+      assert.equal(x.method1(), "method1");
+      // making sure that ctor passed to the finisher has all the decorators applied
+      assert.equal(x.method2(), "method2 overridden");
+      logs.push("finisher called " + log);
+    }
+
+    return {descriptor, extras: [], finishers: [finisher]}
+  }
+}
+
+function classDec(constructor, heritage, elements) {
+  return {constructor, elements, finishers: [() => logs.push("finisher called classDec")]};
+}
+
+@classDec class Foo {
+  @dec(1) method1() {return "method1"}
+  @dec(2) @overrider(() => "method2 overridden") method2() {return "method2"};
+}
+
+assert.deepEqual(logs, ["finisher called 1", "finisher called 2", "finisher called classDec"]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
new file mode 100644
index 000000000000..2df2d3ceda54
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
@@ -0,0 +1,31 @@
+const calls = [];
+
+function log(message) {
+  return function (descriptor) {
+    let oldFunc = descriptor.value;
+    descriptor.value = function(...args) {
+      calls.push(message + " entered");
+      let result = oldFunc.apply(this, args);
+      calls.push(message + " exited");
+      return result;
+    }
+    return {descriptor, extras: [], finishers: []};
+  }
+}
+
+class Foo {
+  @log("method1") method1() {
+    assert.equal(this.method2(), 6);
+    return 4;
+  }
+  @log("method2") method2() {return 6;}
+  @log("method3") method3() {return 8;}
+}
+
+let foo = new Foo();
+
+assert.equal(foo.method1(), 4);
+assert.equal(foo.method3(), 8);
+assert.deepEqual(calls, ["method1 entered", "method2 entered", "method2 exited", "method1 exited", "method3 entered", "method3 exited"]);
+
+
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
new file mode 100644
index 000000000000..ff279de23059
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
@@ -0,0 +1,17 @@
+function overrider(fn) {
+  return function(descriptor) {
+    descriptor.value = fn;
+    return {descriptor, extras: [], finishers: []};
+  }
+}
+
+class Foo {
+  @overrider(() => 3) method() {
+    return 2;
+  }
+}
+
+const x = new Foo();
+assert.equal(x.method(), 3);
+
+
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js
new file mode 100644
index 000000000000..a82ea40e1875
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js
@@ -0,0 +1,30 @@
+// makes an undecorated copy of the method
+function spare(name, isStatic) {
+  return function(descriptor) {
+    const clone = {
+      kind: "property",
+      isStatic: !!isStatic,
+      key: name,
+      descriptor: Object.assign({}, descriptor)
+    }
+    return {descriptor, extras: [clone], finishers: []};
+  }
+}
+
+function overrider(fn) {
+  return function(descriptor) {
+    descriptor.value = fn;
+    return {descriptor, extras: [], finishers: []};
+  }
+}
+
+class Foo {
+  @overrider(() => 3) @spare("spared") method() {
+    return 2; 
+  }
+}
+
+const x = new Foo();
+
+assert.equal(x.spared(), 2);
+assert.equal(x.method(), 3);

From 8707f4e45762db1a5465aa82dac0aa3c044133a1 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Wed, 16 Aug 2017 20:47:52 +0530
Subject: [PATCH 12/21] Update versions to make tests pass

---
 .../package.json                              |   2 +-
 .../package.json                              |   8 +-
 .../expected.js                               |   2 +-
 yarn.lock                                     | 178 +++++++++++++++++-
 4 files changed, 182 insertions(+), 8 deletions(-)

diff --git a/packages/babel-plugin-syntax-decorators-2/package.json b/packages/babel-plugin-syntax-decorators-2/package.json
index 005833819675..2ae9d9b30c28 100644
--- a/packages/babel-plugin-syntax-decorators-2/package.json
+++ b/packages/babel-plugin-syntax-decorators-2/package.json
@@ -1,6 +1,6 @@
 {
   "name": "babel-plugin-syntax-decorators-2",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.19",
   "description": "Updated parsing of decorators",
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-syntax-decorators-2",
   "license": "MIT",
diff --git a/packages/babel-plugin-transform-decorators-2/package.json b/packages/babel-plugin-transform-decorators-2/package.json
index e42296272eec..2bb9fc28d48d 100644
--- a/packages/babel-plugin-transform-decorators-2/package.json
+++ b/packages/babel-plugin-transform-decorators-2/package.json
@@ -1,6 +1,6 @@
 {
   "name": "babel-plugin-transform-decorators-2",
-  "version": "7.0.0-alpha.15",
+  "version": "7.0.0-alpha.19",
   "author": "Peeyush Kushwaha <peeyush.p97@gmail.com>",
   "license": "MIT",
   "description": "Transformer for stage-2 decorators",
@@ -12,9 +12,11 @@
     "decorators"
   ],
   "dependencies": {
-    "babel-plugin-syntax-decorators-2": "7.0.0-alpha.15"
+    "babel-plugin-syntax-decorators-2": "7.0.0-alpha.19"
   },
   "devDependencies": {
-    "babel-helper-plugin-test-runner": "7.0.0-alpha.15"
+    "babel-helper-plugin-test-runner": "7.0.0-alpha.19",
+    "babel-helper-transform-fixture-test-runner": "7.0.0-alpha.19",
+    "babel-plugin-transform-decorators-2": "7.0.0-alpha.19"
   }
 }
diff --git a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js
index 62aab77ce7ff..736437e2edf7 100644
--- a/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js
+++ b/packages/babel-plugin-transform-es2015-parameters/test/fixtures/parameters/rest-member-expression-optimisation/expected.js
@@ -21,6 +21,6 @@ function t() {
 
 function t() {
   for (var i = 0; i < arguments.length; i++) {
-    return arguments.length <= i ? undefined : arguments[i];
+    return i < 0 || arguments.length <= i ? undefined : arguments[i];
   }
 }
diff --git a/yarn.lock b/yarn.lock
index 7f28248b3c69..ab39b20c7603 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -389,6 +389,26 @@ babel-code-frame@^6.16.0, babel-code-frame@^6.22.0:
     esutils "^2.0.2"
     js-tokens "^3.0.0"
 
+babel-core@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-7.0.0-alpha.15.tgz#4c5e608b3de921dbfea68f7ca196d297931acb23"
+  dependencies:
+    babel-code-frame "7.0.0-alpha.15"
+    babel-generator "7.0.0-alpha.15"
+    babel-helpers "7.0.0-alpha.15"
+    babel-messages "7.0.0-alpha.15"
+    babel-template "7.0.0-alpha.15"
+    babel-traverse "7.0.0-alpha.15"
+    babel-types "7.0.0-alpha.15"
+    babylon "7.0.0-beta.15"
+    convert-source-map "^1.1.0"
+    debug "^2.1.1"
+    json5 "^0.5.0"
+    lodash "^4.2.0"
+    micromatch "^2.3.11"
+    resolve "^1.3.2"
+    source-map "^0.5.0"
+
 babel-core@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-7.0.0-alpha.18.tgz#416cb65ac7c95b59c9230a65c4c595b6d5e30b4a"
@@ -409,6 +429,30 @@ babel-core@7.0.0-alpha.18:
     resolve "^1.3.2"
     source-map "^0.5.0"
 
+babel-core@^6.24.1:
+  version "6.25.0"
+  resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-6.25.0.tgz#7dd42b0463c742e9d5296deb3ec67a9322dad729"
+  dependencies:
+    babel-code-frame "^6.22.0"
+    babel-generator "^6.25.0"
+    babel-helpers "^6.24.1"
+    babel-messages "^6.23.0"
+    babel-register "^6.24.1"
+    babel-runtime "^6.22.0"
+    babel-template "^6.25.0"
+    babel-traverse "^6.25.0"
+    babel-types "^6.25.0"
+    babylon "^6.17.2"
+    convert-source-map "^1.1.0"
+    debug "^2.1.1"
+    json5 "^0.5.0"
+    lodash "^4.2.0"
+    minimatch "^3.0.2"
+    path-is-absolute "^1.0.0"
+    private "^0.1.6"
+    slash "^1.0.0"
+    source-map "^0.5.0"
+
 babel-eslint@8.0.0-alpha.15:
   version "8.0.0-alpha.15"
   resolved "https://registry.yarnpkg.com/babel-eslint/-/babel-eslint-8.0.0-alpha.15.tgz#7cf5c1c81eaf40662d40aef51b0b488dfd199b2d"
@@ -418,6 +462,17 @@ babel-eslint@8.0.0-alpha.15:
     babel-types "7.0.0-alpha.15"
     babylon "7.0.0-beta.16"
 
+babel-generator@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-7.0.0-alpha.15.tgz#27884018a9cc8300e20497cad17c4bc1f416a9fc"
+  dependencies:
+    babel-messages "7.0.0-alpha.15"
+    babel-types "7.0.0-alpha.15"
+    jsesc "^1.3.0"
+    lodash "^4.2.0"
+    source-map "^0.5.0"
+    trim-right "^1.0.1"
+
 babel-generator@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-7.0.0-alpha.18.tgz#107566ad9824b1e5192bee3185a1c2f6c7437cee"
@@ -429,7 +484,7 @@ babel-generator@7.0.0-alpha.18:
     source-map "^0.5.0"
     trim-right "^1.0.1"
 
-babel-generator@^6.18.0:
+babel-generator@^6.18.0, babel-generator@^6.25.0:
   version "6.25.0"
   resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-6.25.0.tgz#33a1af70d5f2890aeb465a4a7793c1df6a9ea9fc"
   dependencies:
@@ -472,6 +527,22 @@ babel-helper-explode-assignable-expression@7.0.0-alpha.18:
     babel-traverse "7.0.0-alpha.18"
     babel-types "7.0.0-alpha.18"
 
+babel-helper-fixtures@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-helper-fixtures/-/babel-helper-fixtures-7.0.0-alpha.15.tgz#f6014b506c98cb6c706bb38b2fb5264f004ba438"
+  dependencies:
+    lodash "^4.2.0"
+    semver "^5.3.0"
+    try-resolve "^1.0.0"
+
+babel-helper-fixtures@^6.22.0:
+  version "6.22.0"
+  resolved "https://registry.yarnpkg.com/babel-helper-fixtures/-/babel-helper-fixtures-6.22.0.tgz#3cb9eaf5feae29f001d2754ab43b14a9dfa304ff"
+  dependencies:
+    babel-runtime "^6.22.0"
+    lodash "^4.2.0"
+    try-resolve "^1.0.0"
+
 babel-helper-function-name@7.0.0-alpha.15:
   version "7.0.0-alpha.15"
   resolved "https://registry.yarnpkg.com/babel-helper-function-name/-/babel-helper-function-name-7.0.0-alpha.15.tgz#087bb6bb6677acde36b3c19f6bc1afedb3d12e30"
@@ -514,6 +585,12 @@ babel-helper-optimise-call-expression@7.0.0-alpha.18:
   dependencies:
     babel-types "7.0.0-alpha.18"
 
+babel-helper-plugin-test-runner@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-helper-plugin-test-runner/-/babel-helper-plugin-test-runner-7.0.0-alpha.15.tgz#2a318588f35f25ef8b278b8946e56544f1dce121"
+  dependencies:
+    babel-helper-transform-fixture-test-runner "7.0.0-alpha.15"
+
 babel-helper-regex@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-helper-regex/-/babel-helper-regex-7.0.0-alpha.18.tgz#c54f5cc91a10deef88924381e5a8bf4157cd480d"
@@ -548,6 +625,32 @@ babel-helper-replace-supers@7.0.0-alpha.18:
     babel-traverse "7.0.0-alpha.18"
     babel-types "7.0.0-alpha.18"
 
+babel-helper-transform-fixture-test-runner@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-helper-transform-fixture-test-runner/-/babel-helper-transform-fixture-test-runner-7.0.0-alpha.15.tgz#45cdb7d4e1094c93b151779906d65dae7f6b24a4"
+  dependencies:
+    babel-code-frame "7.0.0-alpha.15"
+    babel-core "7.0.0-alpha.15"
+    babel-helper-fixtures "7.0.0-alpha.15"
+    babel-polyfill "7.0.0-alpha.15"
+    chai "^3.0.0"
+    lodash "^4.2.0"
+    resolve "^1.3.2"
+    source-map "^0.5.0"
+
+babel-helper-transform-fixture-test-runner@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-transform-fixture-test-runner/-/babel-helper-transform-fixture-test-runner-6.24.1.tgz#47eaa699acbe98a25c0f868e2d5666de8d33b4e5"
+  dependencies:
+    babel-code-frame "^6.22.0"
+    babel-core "^6.24.1"
+    babel-helper-fixtures "^6.22.0"
+    babel-polyfill "^6.23.0"
+    babel-runtime "^6.22.0"
+    chai "^3.0.0"
+    lodash "^4.2.0"
+    source-map "^0.5.0"
+
 babel-helper-wrap-function@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-helper-wrap-function/-/babel-helper-wrap-function-7.0.0-alpha.18.tgz#47d194f19d0fab899a60e768214b7e1fc71471b0"
@@ -557,12 +660,25 @@ babel-helper-wrap-function@7.0.0-alpha.18:
     babel-traverse "7.0.0-alpha.18"
     babel-types "7.0.0-alpha.18"
 
+babel-helpers@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-helpers/-/babel-helpers-7.0.0-alpha.15.tgz#60e08a396d7ce79104dd2da4651a61e625468ebe"
+  dependencies:
+    babel-template "7.0.0-alpha.15"
+
 babel-helpers@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-helpers/-/babel-helpers-7.0.0-alpha.18.tgz#22e466d3f48e8ea777d47b50fdc2c98befc801e0"
   dependencies:
     babel-template "7.0.0-alpha.18"
 
+babel-helpers@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helpers/-/babel-helpers-6.24.1.tgz#3471de9caec388e5c850e597e58a26ddf37602b2"
+  dependencies:
+    babel-runtime "^6.22.0"
+    babel-template "^6.24.1"
+
 babel-loader@7.1.1, babel-loader@^7.1.1:
   version "7.1.1"
   resolved "https://registry.yarnpkg.com/babel-loader/-/babel-loader-7.1.1.tgz#b87134c8b12e3e4c2a94e0546085bc680a2b8488"
@@ -916,6 +1032,13 @@ babel-plugin-transform-unicode-property-regex@^2.0.2:
     babel-runtime "^6.23.0"
     regexpu-core "^4.1.1"
 
+babel-polyfill@7.0.0-alpha.15:
+  version "7.0.0-alpha.15"
+  resolved "https://registry.yarnpkg.com/babel-polyfill/-/babel-polyfill-7.0.0-alpha.15.tgz#4d1c8e3c86b4189591a6818bae90d1ab7eaab584"
+  dependencies:
+    core-js "^2.4.0"
+    regenerator-runtime "^0.10.0"
+
 babel-polyfill@7.0.0-alpha.18:
   version "7.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-polyfill/-/babel-polyfill-7.0.0-alpha.18.tgz#e5673adef75bf3c9014e9b7d0cb23520e58bd94a"
@@ -923,6 +1046,14 @@ babel-polyfill@7.0.0-alpha.18:
     core-js "^2.4.0"
     regenerator-runtime "^0.10.0"
 
+babel-polyfill@^6.23.0:
+  version "6.23.0"
+  resolved "https://registry.yarnpkg.com/babel-polyfill/-/babel-polyfill-6.23.0.tgz#8364ca62df8eafb830499f699177466c3b03499d"
+  dependencies:
+    babel-runtime "^6.22.0"
+    core-js "^2.4.0"
+    regenerator-runtime "^0.10.0"
+
 babel-preset-env@2.0.0-alpha.18:
   version "2.0.0-alpha.18"
   resolved "https://registry.yarnpkg.com/babel-preset-env/-/babel-preset-env-2.0.0-alpha.18.tgz#1ff927011521e9bc97819d921700ccd3faa6c676"
@@ -1048,6 +1179,18 @@ babel-register@7.0.0-alpha.18:
     pirates "^3.0.1"
     source-map-support "^0.4.2"
 
+babel-register@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-register/-/babel-register-6.24.1.tgz#7e10e13a2f71065bdfad5a1787ba45bca6ded75f"
+  dependencies:
+    babel-core "^6.24.1"
+    babel-runtime "^6.22.0"
+    core-js "^2.4.0"
+    home-or-tmp "^2.0.0"
+    lodash "^4.2.0"
+    mkdirp "^0.5.1"
+    source-map-support "^0.4.2"
+
 babel-runtime@^6.18.0, babel-runtime@^6.22.0, babel-runtime@^6.23.0:
   version "6.25.0"
   resolved "https://registry.yarnpkg.com/babel-runtime/-/babel-runtime-6.25.0.tgz#33b98eaa5d482bb01a8d1aa6b437ad2b01aec41c"
@@ -1073,7 +1216,7 @@ babel-template@7.0.0-alpha.18:
     babylon "7.0.0-beta.18"
     lodash "^4.2.0"
 
-babel-template@^6.16.0:
+babel-template@^6.16.0, babel-template@^6.24.1, babel-template@^6.25.0:
   version "6.25.0"
   resolved "https://registry.yarnpkg.com/babel-template/-/babel-template-6.25.0.tgz#665241166b7c2aa4c619d71e192969552b10c071"
   dependencies:
@@ -1490,6 +1633,14 @@ center-align@^0.1.1:
     align-text "^0.1.3"
     lazy-cache "^1.0.3"
 
+chai@^3.0.0:
+  version "3.5.0"
+  resolved "https://registry.yarnpkg.com/chai/-/chai-3.5.0.tgz#4d02637b067fe958bdbfdd3a40ec56fef7373247"
+  dependencies:
+    assertion-error "^1.0.1"
+    deep-eql "^0.1.3"
+    type-detect "^1.0.0"
+
 chai@^4.1.0:
   version "4.1.1"
   resolved "https://registry.yarnpkg.com/chai/-/chai-4.1.1.tgz#66e21279e6f3c6415ff8231878227900e2171b39"
@@ -2089,6 +2240,12 @@ dedent@^0.7.0:
   version "0.7.0"
   resolved "https://registry.yarnpkg.com/dedent/-/dedent-0.7.0.tgz#2495ddbaf6eb874abb0e1be9df22d2e5a544326c"
 
+deep-eql@^0.1.3:
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-0.1.3.tgz#ef558acab8de25206cd713906d74e56930eb69f2"
+  dependencies:
+    type-detect "0.1.1"
+
 deep-eql@^2.0.1:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-2.0.2.tgz#b1bac06e56f0a76777686d50c9feb75c2ed7679a"
@@ -3344,6 +3501,13 @@ hoek@2.x.x:
   version "2.16.3"
   resolved "https://registry.yarnpkg.com/hoek/-/hoek-2.16.3.tgz#20bb7403d3cea398e91dc4710a8ff1b8274a25ed"
 
+home-or-tmp@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/home-or-tmp/-/home-or-tmp-2.0.0.tgz#e36c3f2d2cae7d746a857e38d18d5f32a7882db8"
+  dependencies:
+    os-homedir "^1.0.0"
+    os-tmpdir "^1.0.1"
+
 home-or-tmp@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/home-or-tmp/-/home-or-tmp-3.0.0.tgz#57a8fe24cf33cdd524860a15821ddc25c86671fb"
@@ -4880,7 +5044,7 @@ os-locale@^2.0.0:
     lcid "^1.0.0"
     mem "^1.1.0"
 
-os-tmpdir@^1.0.0, os-tmpdir@~1.0.1:
+os-tmpdir@^1.0.0, os-tmpdir@^1.0.1, os-tmpdir@~1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/os-tmpdir/-/os-tmpdir-1.0.2.tgz#bbe67406c79aa85c5cfec766fe5734555dfa1274"
 
@@ -6121,6 +6285,14 @@ type-check@~0.3.2:
   dependencies:
     prelude-ls "~1.1.2"
 
+type-detect@0.1.1:
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-0.1.1.tgz#0ba5ec2a885640e470ea4e8505971900dac58822"
+
+type-detect@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-1.0.0.tgz#762217cc06db258ec48908a1298e8b95121e8ea2"
+
 type-detect@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-3.0.0.tgz#46d0cc8553abb7b13a352b0d6dea2fd58f2d9b55"

From 6ec36a1428f47d8082148526b360be8031faf0b3 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sun, 20 Aug 2017 15:42:11 +0530
Subject: [PATCH 13/21] Improvements in handling of computed keys  - don't use
 sequenceExpressions  - use single declaration  - use keys based on the node

---
 .../src/index.js                              | 37 +++++++++++++------
 .../transformations/computed-keys/actual.js   |  7 ++++
 .../transformations/computed-keys/expected.js | 12 ++++++
 .../test/fixtures/wip/wip/actual.js           |  3 +-
 .../test/fixtures/wip/wip/expected.js         | 20 +++-------
 5 files changed, 51 insertions(+), 28 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index a6a4b948c02a..d03c5ad66da2 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -7,24 +7,35 @@ import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 /** manual testing code
 **/
 export default function({ types: t }) {
+  // a class expression with decorators is wrapped in a `decorate(..)` call. The following is to avoid
+  // processing the same class node again
+  const processedClassNodes = [];
+
   // converts [(expression)] to [(let key = (expression))] if expression is impure
   // so as to avoid recomputation when the key is needed later
+  let injectedKeyDeclaration;
   function addKeysToComputedMembers(path) {
     const body = path.get("body.body");
 
     for (const member of body) {
-      if (member.node.computed && member.get("key").isPure()) {
-        const parent = path.findParent(p => p.parentPath.isBlock());
-        const ref = member.scope.generateUidIdentifier("key");
-        parent.insertBefore(
-          t.variableDeclaration("let", [t.variableDeclarator(ref)]),
+      if (member.node.computed && !member.get("key").isPure()) {
+        const ref = member.scope.generateUidIdentifierBasedOnNode(
+          member.node.key,
         );
-        const replacement = t.sequenceExpression([
-          t.assignmentExpression("=", ref, member.node.key),
-        ]);
-        // FIXME: the following should work: member.get("key").replaceWith(replacement);
-        // but doesn't accept sequenceexpression type so we have to directly manipulate node
-        member.node.key = replacement;
+
+        if (!injectedKeyDeclaration) {
+          const parent = path.getStatementParent();
+          parent.insertBefore(t.variableDeclaration("let", []));
+          injectedKeyDeclaration = parent.getSibling(parent.key - 1);
+        }
+
+        injectedKeyDeclaration.pushContainer(
+          "declarations",
+          t.variableDeclarator(ref),
+        );
+
+        const replacement = t.assignmentExpression("=", ref, member.node.key);
+        member.get("key").replaceWith(replacement);
       }
     }
   }
@@ -139,6 +150,8 @@ export default function({ types: t }) {
       },
 
       ClassExpression(path, file) {
+        if (processedClassNodes.indexOf(path.node) > -1) return;
+
         file.addHelper("makeElementDescriptor");
         file.addHelper("mergeDuplicateElements");
         file.addHelper("decorateClass", ["mergeDuplicateElements"]);
@@ -166,6 +179,8 @@ export default function({ types: t }) {
             ? path.scope.buildUndefinedNode()
             : path.node.superClass;
 
+        processedClassNodes.push(path.node);
+
         path.replaceWith(
           t.callExpression(
             t.callExpression(decorateIdentifier, [
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/actual.js
new file mode 100644
index 000000000000..ca10ce4a4472
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/actual.js
@@ -0,0 +1,7 @@
+class Bizz {
+  @dec uncomputed() {};
+  @dec static [3 + 7] () {};
+  @dec [foo()] () {}
+  [computed + and + undecorated] () {};
+}
+
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js
new file mode 100644
index 000000000000..f5368ccb0423
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js
@@ -0,0 +1,12 @@
+let _foo, _ref;
+
+let Bizz = babelHelpers.decorate(class Bizz {
+  uncomputed() {}
+
+  static [3 + 7]() {}
+
+  [_foo = foo()]() {}
+
+  [_ref = computed + and + undecorated]() {}
+
+}, [[_ref]], [["uncomputed", [dec]], [3 + 7, [dec], true], [_foo, [dec]]], void 0)([]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
index c486ba7c609e..bada88422a88 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/actual.js
@@ -1,9 +1,8 @@
-let decorate = () => void 0, dec, bar, foo = {bar: () => void 0}, baz, decorator; //just to supress ReferenceErrors
-
 @decorator class Bizz {
   @dec m1() {};
   @bar @foo.bar(baz) m2() {};
   @dec static [3 + 7] () {};
   andAnUndecoratedMethod () {};
   [calculated + and + undecorated] () {};
+  @dec [foo()] () {}
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
index 14444812071a..0a639295d20b 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -1,24 +1,14 @@
-let decorate = () => void 0,
-    dec,
-    bar,
-    foo = {
-  bar: () => void 0
-},
-    baz,
-    decorator; //just to supress ReferenceErrors
-
-
-let _key;
-
 let Bizz = babelHelpers.decorate(class Bizz {
   m1() {}
 
   m2() {}
 
-  static [(_key = 3 + 7)]() {}
+  static [3 + 7]() {}
 
   andAnUndecoratedMethod() {}
 
-  [calculated + and + undecorated]() {}
+  [_ref = calculated + and + undecorated]() {}
+
+  [_foo = foo()]() {}
 
-}, [["andAnUndecoratedMethod"], [calculated + and + undecorated]], [["m1", [dec]], ["m2", [bar, foo.bar(baz)]], [(_key = 3 + 7), [dec], true]], void 0)([decorator]);
\ No newline at end of file
+}, [["andAnUndecoratedMethod"], [_ref]], [["m1", [dec]], ["m2", [bar, foo.bar(baz)]], [3 + 7, [dec], true], [_foo, [dec]]], void 0)([decorator]);

From 2e7c6a14cf7d91add1516fb0f0cfd840f59dc83c Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sun, 20 Aug 2017 21:24:15 +0530
Subject: [PATCH 14/21] Add predicate hasDecorators (for early exit)

---
 .../src/index.js                              | 28 ++++++++++++++-----
 .../class-decorators/expected.js              |  5 ++--
 .../transformations/no-decorators/actual.js   |  5 ++++
 .../transformations/no-decorators/expected.js |  8 ++++++
 4 files changed, 37 insertions(+), 9 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/expected.js

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index d03c5ad66da2..9f898ac1ccf2 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -7,10 +7,6 @@ import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 /** manual testing code
 **/
 export default function({ types: t }) {
-  // a class expression with decorators is wrapped in a `decorate(..)` call. The following is to avoid
-  // processing the same class node again
-  const processedClassNodes = [];
-
   // converts [(expression)] to [(let key = (expression))] if expression is impure
   // so as to avoid recomputation when the key is needed later
   let injectedKeyDeclaration;
@@ -40,6 +36,22 @@ export default function({ types: t }) {
     }
   }
 
+  //a predicate which tells if a path has any decorators at all or not.
+  function hasDecorators(path) {
+    if (path.node.decorators && path.node.decorators.length > 0) return true;
+
+    const body = path.node.body.body;
+    for (let i = 0; i < body.length; i++) {
+      const method = body[i];
+      if (!t.isClassMethod(method)) continue;
+      if (method.decorators && method.decorators.length > 0) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
   // expects a method node
   function getKey(node) {
     if (node.computed) {
@@ -121,6 +133,8 @@ export default function({ types: t }) {
     visitor: {
       // export default is a special case since it expects and expression rather than a declaration
       ExportDefaultDeclaration(path) {
+        if (!hasDecorators(path)) return;
+
         const classPath = path.get("declaration");
         if (!classPath.isClassDeclaration()) return;
 
@@ -139,6 +153,8 @@ export default function({ types: t }) {
 
       // replace declaration with a let declaration
       ClassDeclaration(path) {
+        if (!hasDecorators(path)) return;
+
         const { node } = path;
         const ref = node.id || path.scope.generateUidIdentifier("class");
 
@@ -150,7 +166,7 @@ export default function({ types: t }) {
       },
 
       ClassExpression(path, file) {
-        if (processedClassNodes.indexOf(path.node) > -1) return;
+        if (!hasDecorators(path)) return;
 
         file.addHelper("makeElementDescriptor");
         file.addHelper("mergeDuplicateElements");
@@ -179,8 +195,6 @@ export default function({ types: t }) {
             ? path.scope.buildUndefinedNode()
             : path.node.superClass;
 
-        processedClassNodes.push(path.node);
-
         path.replaceWith(
           t.callExpression(
             t.callExpression(decorateIdentifier, [
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
index 79c6344892fe..f18518c4a98d 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/class-decorators/expected.js
@@ -2,7 +2,8 @@ let Foo = babelHelpers.decorate(class Foo {
   someMethod() {}
 
 }, [["someMethod"]], [], void 0)([classDecOuter("args"), classDecInner]);
-let Undecorated = class Undecorated {
+
+class Undecorated {
   someMethod() {}
 
-};
\ No newline at end of file
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/actual.js
new file mode 100644
index 000000000000..2389fa0a8474
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/actual.js
@@ -0,0 +1,5 @@
+class Foo {
+  method() {}
+  [3 + 7] () {}
+  static method() {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/expected.js
new file mode 100644
index 000000000000..ccbddf1010e5
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/no-decorators/expected.js
@@ -0,0 +1,8 @@
+class Foo {
+  method() {}
+
+  [3 + 7]() {}
+
+  static method() {}
+
+}

From 8e28ca7e49240644d913190661710cd009c2db38 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sun, 20 Aug 2017 22:14:48 +0530
Subject: [PATCH 15/21] use path.scope.parent.push & other review suggestions

---
 .../src/index.js                                 | 16 +++-------------
 .../transformations/computed-keys/expected.js    |  2 +-
 .../transformations/literal-keys/actual.js       |  4 ++++
 .../transformations/literal-keys/expected.js     |  6 ++++++
 .../test/fixtures/wip/wip/expected.js            |  2 ++
 5 files changed, 16 insertions(+), 14 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/expected.js

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 9f898ac1ccf2..0d937b41c66c 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -9,7 +9,6 @@ import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
 export default function({ types: t }) {
   // converts [(expression)] to [(let key = (expression))] if expression is impure
   // so as to avoid recomputation when the key is needed later
-  let injectedKeyDeclaration;
   function addKeysToComputedMembers(path) {
     const body = path.get("body.body");
 
@@ -19,17 +18,7 @@ export default function({ types: t }) {
           member.node.key,
         );
 
-        if (!injectedKeyDeclaration) {
-          const parent = path.getStatementParent();
-          parent.insertBefore(t.variableDeclaration("let", []));
-          injectedKeyDeclaration = parent.getSibling(parent.key - 1);
-        }
-
-        injectedKeyDeclaration.pushContainer(
-          "declarations",
-          t.variableDeclarator(ref),
-        );
-
+        path.scope.parent.push({ id: ref });
         const replacement = t.assignmentExpression("=", ref, member.node.key);
         member.get("key").replaceWith(replacement);
       }
@@ -63,7 +52,7 @@ export default function({ types: t }) {
         return node.key;
       }
     } else {
-      return t.stringLiteral(node.key.name);
+      return t.stringLiteral(node.key.name || String(node.key.value));
     }
   }
 
@@ -175,6 +164,7 @@ export default function({ types: t }) {
         const decorateIdentifier = file.addHelper("decorate", [
           "decorateClass",
           "decorateElement",
+          "makeElementDescriptor",
         ]);
 
         addKeysToComputedMembers(path);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js
index f5368ccb0423..bb8aac7c4f42 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/computed-keys/expected.js
@@ -1,4 +1,4 @@
-let _foo, _ref;
+var _foo, _ref;
 
 let Bizz = babelHelpers.decorate(class Bizz {
   uncomputed() {}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/actual.js
new file mode 100644
index 000000000000..bb1c981d9ea3
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/actual.js
@@ -0,0 +1,4 @@
+@dec class Foo {
+  3 () {}
+  "yo" () {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/expected.js
new file mode 100644
index 000000000000..77e3c148d42c
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/literal-keys/expected.js
@@ -0,0 +1,6 @@
+let Foo = babelHelpers.decorate(class Foo {
+  3() {}
+
+  "yo"() {}
+
+}, [["3"], ["yo"]], [], void 0)([dec]);
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
index 0a639295d20b..31ca54bd0493 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/wip/wip/expected.js
@@ -1,3 +1,5 @@
+var _ref, _foo;
+
 let Bizz = babelHelpers.decorate(class Bizz {
   m1() {}
 

From 1776e2474493ecf06b5b16e9206683f49f3eb90d Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Thu, 24 Aug 2017 20:23:38 +0530
Subject: [PATCH 16/21] Account for getters and setters

---
 .../src/index.js                              | 12 +++++++
 .../transformations/accessors/actual.js       | 24 +++++++++++++
 .../transformations/accessors/expected.js     | 34 +++++++++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/actual.js
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/expected.js

diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 0d937b41c66c..5fc24be40e10 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -1,4 +1,5 @@
 import syntaxDecorators2 from "babel-plugin-syntax-decorators-2";
+import _ from "lodash";
 
 //TODO: will have to check for dot (.) access to reserved keywords in decorator members
 //TODO: check if we need the 'define' + 'Property' and 'ke' + 'ys' hacks as seen in
@@ -100,6 +101,7 @@ export default function({ types: t }) {
   function undecoratedMethods(path) {
     const body = path.get("body.body");
     const result = []; // shape: [["method1"], ["method2"], ["staticMethod1", true]]
+    const avoidDuplicates = []; // to avoid duplicates when both a getter and a setter are involved
 
     for (const method of body) {
       if (method.node.decorators && method.node.decorators.length > 0) continue;
@@ -107,6 +109,16 @@ export default function({ types: t }) {
 
       const key = getKey(method.node);
 
+      if (method.node.kind == "get" || method.node.kind == "set") {
+        const record = [key.value, method.node.static];
+
+        if (_.find(avoidDuplicates, r => _.isEqual(record, r))) {
+          continue;
+        } else {
+          avoidDuplicates.push(record);
+        }
+      }
+
       if (method.node.static) {
         result.push(t.arrayExpression([key, t.booleanLiteral(true)]));
       } else {
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/actual.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/actual.js
new file mode 100644
index 000000000000..398085bdb57a
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/actual.js
@@ -0,0 +1,24 @@
+class Foo {
+  @decorated method() {}
+  get bar() {}
+  get baz() {}
+  set baz(val) {}
+}
+
+class Bar {
+  @decorated method() {}
+  get 3() {}
+  set 3(val) {}
+}
+
+class Baz {
+  @decorated method() {}
+  get 3() {}
+  set "3"(val) {}
+}
+
+class Bam {
+  @decorated method() {}
+  get yo() {}
+  set "yo"(val) {}
+}
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/expected.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/expected.js
new file mode 100644
index 000000000000..0eb940e3bd88
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/transformations/accessors/expected.js
@@ -0,0 +1,34 @@
+let Foo = babelHelpers.decorate(class Foo {
+  method() {}
+
+  get bar() {}
+
+  get baz() {}
+
+  set baz(val) {}
+
+}, [["bar"], ["baz"]], [["method", [decorated]]], void 0)([]);
+let Bar = babelHelpers.decorate(class Bar {
+  method() {}
+
+  get 3() {}
+
+  set 3(val) {}
+
+}, [["3"]], [["method", [decorated]]], void 0)([]);
+let Baz = babelHelpers.decorate(class Baz {
+  method() {}
+
+  get 3() {}
+
+  set "3"(val) {}
+
+}, [["3"]], [["method", [decorated]]], void 0)([]);
+let Bam = babelHelpers.decorate(class Bam {
+  method() {}
+
+  get yo() {}
+
+  set "yo"(val) {}
+
+}, [["yo"]], [["method", [decorated]]], void 0)([]);

From 4e527a334cfbe205b0a94df6e382a4685114d5d2 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Thu, 24 Aug 2017 23:48:17 +0530
Subject: [PATCH 17/21] Pass elementDescriptor to decorators not
 propertyDescriptor

---
 packages/babel-helpers/src/helpers.js                    | 4 ++--
 .../test/fixtures/basic/finishers/exec.js                | 2 +-
 .../test/fixtures/examples/change-enumerability/exec.js  | 2 +-
 .../test/fixtures/examples/logger/exec.js                | 5 +++--
 .../test/fixtures/examples/overrider/exec.js             | 2 +-
 .../test/fixtures/examples/spare/exec.js                 | 9 +++++----
 6 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 97b1027824ba..f040424d56f4 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -357,7 +357,7 @@ helpers.decorateElement = template(`
 
     for (let i = decorators.length - 1; i >= 0; i--) {
       const decorator = decorators[i];
-      const result = decorator(previousDescriptor.descriptor);
+      const result = decorator(previousDescriptor);
 
       //TODO: why does .finisher exist on an elementDescriptor? the following conditional deviates from 
       //the spec because it uses result.finishers rather than result.descriptor.finisher
@@ -365,7 +365,7 @@ helpers.decorateElement = template(`
         finishers = finishers.concat(result.finishers);
       }
 
-      previousDescriptor.descriptor = result.descriptor; // just change the property descriptor
+      previousDescriptor = result.descriptor;
 
       const extrasObject = result.extras;
 
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
index 04ea5cf47646..d3cc91439472 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/finishers/exec.js
@@ -2,7 +2,7 @@ const logs = [];
 
 function overrider(fn) {
   return function(descriptor) {
-    descriptor.value = fn;
+    descriptor.descriptor.value = fn;
     return {descriptor, extras: [], finishers: []};
   }
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
index dbba987e4eab..6d338d262825 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/change-enumerability/exec.js
@@ -1,6 +1,6 @@
 function enumerable(bool) {
   return function(descriptor) {
-    descriptor.enumerable = bool;
+    descriptor.descriptor.enumerable = bool;
     return {descriptor, finishers: [], extras: []};
   }
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
index 2df2d3ceda54..823903c8d6ea 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/logger/exec.js
@@ -2,8 +2,9 @@ const calls = [];
 
 function log(message) {
   return function (descriptor) {
-    let oldFunc = descriptor.value;
-    descriptor.value = function(...args) {
+    let propertyDescriptor = descriptor.descriptor;
+    let oldFunc = propertyDescriptor.value;
+    propertyDescriptor.value = function(...args) {
       calls.push(message + " entered");
       let result = oldFunc.apply(this, args);
       calls.push(message + " exited");
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
index ff279de23059..1c916ebaaed4 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/overrider/exec.js
@@ -1,6 +1,6 @@
 function overrider(fn) {
   return function(descriptor) {
-    descriptor.value = fn;
+    descriptor.descriptor.value = fn;
     return {descriptor, extras: [], finishers: []};
   }
 }
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js
index a82ea40e1875..0bea3dab3fa6 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/examples/spare/exec.js
@@ -1,11 +1,12 @@
 // makes an undecorated copy of the method
 function spare(name, isStatic) {
   return function(descriptor) {
+    name = name || descriptor.key + "_spare";
     const clone = {
       kind: "property",
       isStatic: !!isStatic,
       key: name,
-      descriptor: Object.assign({}, descriptor)
+      descriptor: Object.assign({}, descriptor.descriptor)
     }
     return {descriptor, extras: [clone], finishers: []};
   }
@@ -13,18 +14,18 @@ function spare(name, isStatic) {
 
 function overrider(fn) {
   return function(descriptor) {
-    descriptor.value = fn;
+    descriptor.descriptor.value = fn;
     return {descriptor, extras: [], finishers: []};
   }
 }
 
 class Foo {
-  @overrider(() => 3) @spare("spared") method() {
+  @overrider(() => 3) @spare() method() {
     return 2; 
   }
 }
 
 const x = new Foo();
 
-assert.equal(x.spared(), 2);
+assert.equal(x.method_spare(), 2);
 assert.equal(x.method(), 3);

From 44465f2fcbc38bca77b9583ab9dff23369bf8471 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Tue, 29 Aug 2017 20:05:16 +0530
Subject: [PATCH 18/21] configurability checks

---
 packages/babel-helpers/src/helpers.js         | 19 +++++++++
 .../fixtures/basic/configurability/exec.js    | 40 +++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/configurability/exec.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index f040424d56f4..9e5476cae496 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -357,8 +357,27 @@ helpers.decorateElement = template(`
 
     for (let i = decorators.length - 1; i >= 0; i--) {
       const decorator = decorators[i];
+      const shallowClone = {
+        configurable: previousDescriptor.descriptor.configurable,
+        enumerable: previousDescriptor.descriptor.enumerable,
+        writable: previousDescriptor.descriptor.writable,
+        value: previousDescriptor.descriptor.value
+      }
+
       const result = decorator(previousDescriptor);
 
+      if (!shallowClone.configurable) {
+        let check = 
+          result.descriptor.configurable === shallowClone.configurable &&
+          result.descriptor.enumerable === shallowClone.enumerable &&
+          result.descriptor.writable === shallowClone.writable &&
+          result.descriptor.value === shallowClone.value;
+
+        if (!check) {
+          throw new Error("Decorator tried to change unconfigurable property descriptor");
+        }
+      }
+
       //TODO: why does .finisher exist on an elementDescriptor? the following conditional deviates from 
       //the spec because it uses result.finishers rather than result.descriptor.finisher
       if (result.finishers) {
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/configurability/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/configurability/exec.js
new file mode 100644
index 000000000000..d8ebb1246a40
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/configurability/exec.js
@@ -0,0 +1,40 @@
+function set(prop, value) {
+  return function(descriptor) {
+    descriptor.descriptor[prop] = value;
+    return {descriptor, extras: [], finishers: []};
+  }
+}
+
+const msg = "Decorator tried to change unconfigurable property descriptor";
+
+assert.throws(() => {
+  class Foo {
+    @set('configurable', true) @set('configurable', false) method() {}
+  }
+}, msg);
+
+assert.throws(() => {
+  class Foo {
+    @set('writable', false) @set('configurable', false) method() {}
+  }
+}, msg);
+
+assert.throws(() => {
+  class Foo {
+    @set('enumerable', true) @set('configurable', false) method() {}
+  }
+}, msg);
+
+assert.throws(() => {
+  class Foo {
+    @set('value', (x) => x) @set('configurable', false) method() {}
+  }
+}, msg);
+
+assert.doesNotThrow(() => {
+  class Foo {
+    @set('configurable', true) method1() {}
+    @set('writable', true) method2() {}
+    @set('enumerable', false) method3() {}
+  }
+}, msg);

From f86b327d913d00f6fdc19db027842ec65a9aef2c Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sat, 16 Sep 2017 15:19:31 +0530
Subject: [PATCH 19/21] Merge getters and setters; Map->object in decorate And
 other review suggestions

---
 packages/babel-helpers/src/helpers.js         | 74 +++++++++++++------
 .../src/index.js                              |  7 --
 .../test/fixtures/basic/merging/exec.js       | 57 ++++++++++++++
 3 files changed, 108 insertions(+), 30 deletions(-)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/merging/exec.js

diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 9e5476cae496..89355b004a01 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -276,42 +276,44 @@ helpers.decorate = template(`
   (function (constructor, undecorated, memberDecorators, heritage) {
     const prototype = constructor.prototype;
     let finishers = [];
-    const elementDescriptors = new Map(); // elementDescriptors is meant to be an array, so this will be converted later
+    const elementDescriptors = {}; // elementDescriptors is meant to be an array, so this will be converted later
+    const staticElementDescriptors = {};
 
     for (const [key, isStatic] of undecorated) {
+      const map = isStatic? staticElementDescriptors : elementDescriptors;
       const target = isStatic ? constructor : prototype;
       const propertyDescriptor = Object.getOwnPropertyDescriptor(target, key);
-      elementDescriptors.set(
-        [key, isStatic], 
-        babelHelpers.makeElementDescriptor(
-          "property",
-          key,
-          isStatic,
-          propertyDescriptor,
-        )
+      map[key] = babelHelpers.makeElementDescriptor(
+        "property",
+        key,
+        isStatic,
+        propertyDescriptor,
       );
     }
 
-    // decorate and store in elementDescriptors
+    // decorate and store in elementDescriptors or staticElementDescriptors
     for (const [key, decorators, isStatic] of memberDecorators) {
+      const map = isStatic ? staticElementDescriptors : elementDescriptors;
       const target = isStatic ? constructor : prototype;
-      const propertyDescriptor =
-        elementDescriptors.has([key, isStatic]) && elementDescriptors.get([key, isStatic]).descriptor 
-        || Object.getOwnPropertyDescriptor(target, key);
+      const propertyDescriptor = 
+        map[key] && map[key].descriptor || Object.getOwnPropertyDescriptor(target, key);
 
       const elementDescriptor = babelHelpers.makeElementDescriptor(
         "property",
         key,
         isStatic,
         propertyDescriptor,
-      )
+      );
+
       const decorated = babelHelpers.decorateElement(elementDescriptor, decorators);
 
-      elementDescriptors.set([key, isStatic], decorated.descriptor);
+      map[key] = decorated.descriptor;
 
       for (const extra of decorated.extras) {
         // extras is an array of element descriptors
-        elementDescriptors.set([extra.key, extra.isStatic], extra);
+        const map = extra.isStatic? staticElementDescriptors : elementDescriptors;
+        // TODO: refactor to use proper merging logic here. currently it's just overriding
+        map[extra.key] = extra;
       }
 
       finishers = finishers.concat(decorated.finishers);
@@ -322,12 +324,13 @@ helpers.decorate = template(`
         constructor,
         classDecorators,
         heritage,
-        Array.from(elementDescriptors.values())
+        Object.values(elementDescriptors).concat(Object.values(staticElementDescriptors))
       );
 
       finishers = finishers.concat(result.finishers);
       //TODO: heritage hacks so result.constructor has the correct prototype and instanceof results
-      //TODO: step 38 and 39, what do they mean "initialize"?
+      //NOTE: step 38 and 39 in spec, refer to some "initialize" state which hasn't been implemented,
+      //because it's unlikely to stay in future versions of the spec
 
       for (const elementDescriptor of result.elements) {
         const target = elementDescriptor.isStatic ? constructor : prototype;
@@ -347,6 +350,7 @@ helpers.decorate = template(`
   });
 `);
 
+//TODO guarding against malformed descriptors returned by decorators
 helpers.decorateElement = template(`
   (function (descriptor, decorators) {
     //spec uses the param "element" instead of "descriptor" and finds descriptor from it
@@ -583,21 +587,45 @@ helpers.interopRequireWildcard = template(`
 
 helpers.makeElementDescriptor = template(`
   (function (kind, key, isStatic, descriptor, finisher) {
-    return { kind, key, isStatic, descriptor, finisher };
+    var elementDescriptor = { kind, key, isStatic, descriptor};
+    if (finisher) {
+      elementDescriptor.finisher = finisher;
+    }
+    return elementDescriptor;
   });
 `);
 
-//TODO
+/** 
+ * NOTE: Details for merging haven't been decided on by TC39.
+ * The following function implements a reasonable merging strategy - which 
+ * is to merge getters and setters, and to override everything else 
+ **/
 helpers.mergeDuplicateElements = template(`
   (function (elements) {
     let elementMap = {};
     let staticElementMap = {};
 
     for (let elementDescriptor of elements) {
-      if (elementDescriptor.isStatic) {
-        staticElementMap[elementDescriptor.key] = elementDescriptor;
+      let map = elementDescriptor.isStatic? staticElementMap : elementMap;
+
+      if (!map[elementDescriptor.key]) {
+        map[elementDescriptor.key] = elementDescriptor;
       } else {
-        elementMap[elementDescriptor.key] = elementDescriptor;
+        let prev = map[elementDescriptor.key];
+        let isDataDescriptor = !!prev.descriptor.value;
+        let newIsDataDescriptor = !!elementDescriptor.descriptor.value;
+
+        if (!newIsDataDescriptor && !isDataDescriptor) {
+          // if both are accessor descriptors, merge getters and setters
+          let get = elementDescriptor.descriptor.get || prev.descriptor.get;
+          let set = elementDescriptor.descriptor.set || prev.descriptor.set;
+
+          let descriptor = Object.assign({}, elementDescriptor.descriptor, {get, set});
+
+          map[elementDescriptor.key] = Object.assign({}, elementDescriptor, {descriptor});
+        } else {
+          map[elementDescriptor.key] = elementDescriptor; // overrideprevious descriptor
+        }
       }
     }
 
diff --git a/packages/babel-plugin-transform-decorators-2/src/index.js b/packages/babel-plugin-transform-decorators-2/src/index.js
index 5fc24be40e10..9eb2f61bd8b3 100644
--- a/packages/babel-plugin-transform-decorators-2/src/index.js
+++ b/packages/babel-plugin-transform-decorators-2/src/index.js
@@ -185,13 +185,6 @@ export default function({ types: t }) {
         const methodDecorators = takeMethodDecorators(path);
         const classDecorators = takeClassDecorators(path);
 
-        if (
-          methodDecorators.elements.length == 0 &&
-          classDecorators.elements.length == 0
-        ) {
-          return;
-        }
-
         const superClass =
           path.node.superClass == null
             ? path.scope.buildUndefinedNode()
diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/merging/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/merging/exec.js
new file mode 100644
index 000000000000..03e8e5826fe1
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/merging/exec.js
@@ -0,0 +1,57 @@
+let calls = [];
+
+function getter(name) {
+  return function (descriptor) {
+    const extra = {
+      kind: "property",
+      key: name,
+      isStatic: false,
+      descriptor: {
+        enumerable: true,
+        configurable: true,
+        get: function () {
+          calls.push("getter called for " + name);
+        }
+      }
+    }
+    
+    return {descriptor, extras: [extra], finishers: []}
+  }
+}
+
+function setter(name) {
+  return function (descriptor) {
+    const extra = {
+      kind: "property",
+      key: name,
+      isStatic: false,
+      descriptor: {
+        enumerable: true,
+        configurable: true,
+        set: function (value) {
+          calls.push("setter called for " + name);
+        }
+      }
+    }
+
+    return {descriptor, extras: [extra], finishers: []}
+  }
+}
+
+class Foo {
+  @setter("sets") @getter("gets") @getter("both") @setter("both") bar () {return "hello"}
+}
+
+let x = new Foo();
+assert.equal(x.bar(), "hello");
+
+x.both;
+x.both = 3;
+x.sets;
+x.sets = 5;
+x.gets;
+x.gets = 7;
+
+// getters and setters are merged
+assert.deepEqual(calls, ["getter called for both", "setter called for both", "setter called for sets", "getter called for gets"]);
+

From 96f51aad229eae0f817d7e436e50b330c5d97dae Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Sat, 16 Sep 2017 15:21:50 +0530
Subject: [PATCH 20/21] Add failing test for instanceof

---
 .../test/fixtures/basic/parentage/exec.js     | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js

diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js
new file mode 100644
index 000000000000..4ff6cf658a51
--- /dev/null
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js
@@ -0,0 +1,20 @@
+function noopClassDec(constructor, heritage, elements) {
+  return {constructor, elements, finishers: []}
+}
+
+function noopMethodDec(descriptor) {
+  return {descriptor, extras: [], finishers: []}
+}
+
+@noopClassDec class Bar {
+  @noopMethodDec foo() {}
+}
+
+@noopClassDec class Foo {
+  @noopMethodDec bar() {}
+}
+
+let x = new Foo();
+
+assert.ok(x instanceof Foo);
+assert.ok(x instanceof Bar);

From 76f5d3cca8d00e23bed36c418246fdec1ef0ba04 Mon Sep 17 00:00:00 2001
From: Peeyush Kushwaha <peeyush.p97@gmail.com>
Date: Wed, 20 Sep 2017 23:51:58 +0530
Subject: [PATCH 21/21] Fix parentage tests. It's not an issue I had missed
 extends in the test case but the asserts were expecting it. I thought that
 tests were failing for more sinister reasons, but thankfully it isn't so

---
 .../test/fixtures/basic/parentage/exec.js                   | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js
index 4ff6cf658a51..1d8c896bd355 100644
--- a/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js
+++ b/packages/babel-plugin-transform-decorators-2/test/fixtures/basic/parentage/exec.js
@@ -10,11 +10,15 @@ function noopMethodDec(descriptor) {
   @noopMethodDec foo() {}
 }
 
-@noopClassDec class Foo {
+@noopClassDec class Foo extends Bar {
   @noopMethodDec bar() {}
 }
 
 let x = new Foo();
+let y = new Bar();
 
 assert.ok(x instanceof Foo);
 assert.ok(x instanceof Bar);
+
+assert.ok(y instanceof Bar);
+assert.equal(y instanceof Foo, false);