🚀 Flatten Literals in TemplateLiterals

build-system/babel-plugins/babel-plugin-transform-function-declarations/index.js

@@ -77,7 +77,7 @@ module.exports = function ({types: t}) {
   function containsThisExpression(path) {
     let containsThis = false;
     path.traverse({
-      ThisExpression() {
+      ThisExpression(path) {
         containsThis = true;
         path.stop();
       },

build-system/babel-plugins/babel-plugin-transform-stringish-literals/index.js

@@ -0,0 +1,148 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const MERGEABLE_TYPES = ['StringLiteral', 'NumericLiteral', 'TemplateLiteral'];
+
+module.exports = function ({types: t}) {
+  const cloneNodes = (nodes) => nodes.map((node) => t.cloneNode(node));
+  const escapeStringForTemplateLiteral = (value) =>
+    String(value).replace(/\x60/g, '\\`');
+  const canMergeBinaryExpression = (binaryExpression) =>
+    MERGEABLE_TYPES.includes(binaryExpression.left.type) &&
+    MERGEABLE_TYPES.includes(binaryExpression.right.type) &&
+    binaryExpression.operator === '+';
+
+  function whichCloneQuasi(clonedQuasis, index) {
+    for (let i = index; i >= 0; i--) {
+      const quasi = clonedQuasis[i];
+      if (quasi !== null) {
+        return index;
+      }
+    }
+  }
+
+  return {
+    name: 'flatten-stringish-literals',
+    visitor: {
+      BinaryExpression: {
+        exit(path) {
+          if (!canMergeBinaryExpression(path.node)) {
+            return;
+          }
+
+          const {left, right} = path.node;
+          if (t.isTemplateLiteral(right)) {
+            const rightQuasis = cloneNodes(right.quasis);
+
+            if (t.isTemplateLiteral(left)) {
+              const leftQuasis = cloneNodes(left.quasis);
+              const finalLeftQuasi = leftQuasis[leftQuasis.length - 1];
+              leftQuasis[leftQuasis.length - 1].value = {
+                raw: finalLeftQuasi.value.raw + rightQuasis[0].value.raw,
+                cooked: finalLeftQuasi.value.cooked + rightQuasis[0].value.raw,
+              };
+              rightQuasis[0] = null;
+
+              path.replaceWith(
+                t.templateLiteral(
+                  [...leftQuasis, ...rightQuasis.filter(Boolean)],
+                  [
+                    ...cloneNodes(left.expressions),
+                    ...cloneNodes(right.expressions),
+                  ]
+                )
+              );
+              return;
+            }
+
+            // Left is a literal, containing a value to merge into the right.
+            const leftValue = escapeStringForTemplateLiteral(left.value);
+            rightQuasis[0].value = {
+              raw: leftValue + rightQuasis[0].value.raw,
+              cooked: leftValue + rightQuasis[0].value.cooked,
+            };
+            path.replaceWith(
+              t.templateLiteral(rightQuasis, cloneNodes(right.expressions))
+            );
+          }
+
+          // Right is a literal containing a value to merge into the left.
+          if (t.isTemplateLiteral(left)) {
+            const rightValue = escapeStringForTemplateLiteral(right.value);
+            const leftQuasis = cloneNodes(left.quasis);
+            const finalLeftQuasi = leftQuasis[leftQuasis.length - 1];
+            leftQuasis[leftQuasis.length - 1].value = {
+              raw: finalLeftQuasi.value.raw + rightValue,
+              cooked: finalLeftQuasi.value.cooked + rightValue,
+            };
+
+            path.replaceWith(
+              t.templateLiteral(leftQuasis, cloneNodes(left.expressions))
+            );
+            return;
+          }
+
+          // Merge two string literals
+          if (t.isStringLiteral(left) && t.isStringLiteral(right)) {
+            const newLiteral = t.cloneNode(left);
+            newLiteral.value = left.value + String(right.value);
+            path.replaceWith(newLiteral);
+          }
+        },
+      },
+      TemplateLiteral(path) {
+        const {expressions, quasis} = path.node;
+        const newQuasis = cloneNodes(quasis);
+        const newExpressions = cloneNodes(expressions);
+        let conversions = 0;
+
+        for (let index = expressions.length; index >= 0; index--) {
+          const expression = expressions[index];
+          if (
+            t.isStringLiteral(expression) ||
+            t.isNumericLiteral(expression) ||
+            t.isBooleanLiteral(expression)
+          ) {
+            const {value} = expression;
+            const readIndex = whichCloneQuasi(newQuasis, index + 1);
+            const modifyIndex = whichCloneQuasi(newQuasis, index);
+            const {value: changedValue} = newQuasis[readIndex];
+            const {value: previousValue} = newQuasis[modifyIndex];
+
+            newQuasis[modifyIndex] = t.templateElement({
+              raw: previousValue.raw + value + changedValue.raw,
+              cooked: previousValue.cooked + value + changedValue.cooked,
+            });
+            newQuasis[index + 1] = null;
+            newExpressions[index] = null;
+            conversions++;
+          }
+        }
+
+        if (conversions === 0) {
+          return;
+        }
+
+        path.replaceWith(
+          t.templateLiteral(
+            newQuasis.filter(Boolean),
+            newExpressions.filter(Boolean)
+          )
+        );
+      },
+    },
+  };
+};

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/binary-expression/input.js

@@ -0,0 +1,33 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+let add = `/rtv` + `/bar`;
+let multipleAdd = `/rtv` + `/bar` + `/`;
+let subtract = `/rtv` - `r`;
+let multiply = `/rtv` * `r`;
+let divide = `/rtv` / `r`;
+
+let numberStart = 1 + `/foo`;
+let stringStart = '1' + `/foo`;
+let numberEnd = `foo/` + 1;
+let stringEnd = `foo/` + '1';
+let illegalCharacter = `Invalid share providers configuration for in bookend. ` + 'Value must be `true` or a params object.';
+
+let stringLiterals = '1' + '2';
+let numberLiterals = 1 + 2;
+let booleanLiterals = false + true;
+
+let identifiers = `${foo}` + `${bar}`;

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/binary-expression/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["../../../../../babel-plugin-transform-stringish-literals"]
+}

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/binary-expression/output.js

@@ -0,0 +1,29 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+let add = `/rtv/bar`;
+let multipleAdd = `/rtv/bar/`;
+let subtract = `/rtv` - `r`;
+let multiply = `/rtv` * `r`;
+let divide = `/rtv` / `r`;
+let numberStart = `1/foo`;
+let stringStart = `1/foo`;
+let numberEnd = `foo/1`;
+let stringEnd = `foo/1`;
+let illegalCharacter = `Invalid share providers configuration for in bookend. Value must be \`true\` or a params object.`;
+let stringLiterals = "12";
+let numberLiterals = 1 + 2;
+let booleanLiterals = false + true;
+let identifiers = `${foo}${bar}`;

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/literals/input.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+let none = `/rtv/100/log-messages.simple.json`;
+let start = `${'123'}/foo`;
+let middle = `/rtv/${'012003312116250'}/log-messages.simple.json`;
+let end = `rtv/${'123'}`;
+let number = `${123}/foo`;
+let boolean = `${true}/foo`;

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/literals/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["../../../../../babel-plugin-transform-stringish-literals"]
+}

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/fixtures/transform/literals/output.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+let none = `/rtv/100/log-messages.simple.json`;
+let start = `123/foo`;
+let middle = `/rtv/012003312116250/log-messages.simple.json`;
+let end = `rtv/123`;
+let number = `123/foo`;
+let boolean = `true/foo`;

build-system/babel-plugins/babel-plugin-transform-stringish-literals/test/index.js

@@ -0,0 +1,19 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const runner = require('@babel/helper-plugin-test-runner').default;
+
+runner(__dirname);

build-system/compile/build.conf.js

@@ -46,6 +46,7 @@ const postCompilationPlugins = (isEsmBuild) =>
     ? [
         localPlugin('transform-minified-comments'),
         localPlugin('transform-function-declarations'),
+        localPlugin('transform-stringish-literals'),
       ]
     : [];
 

yarn.lock

@@ -16700,4 +16700,4 @@ yeast@0.1.2:
 zeparser@0.0.5:
   version "0.0.5"
   resolved "https://registry.yarnpkg.com/zeparser/-/zeparser-0.0.5.tgz#03726561bc268f2e5444f54c665b7fd4a8c029e2"
-  integrity sha1-A3JlYbwmjy5URPVMZlt/1KjAKeI=
+  integrity sha1-A3JlYbwmjy5URPVMZlt/1KjAKeI=