Add flow, convert to ES6 module

If anyone was importing like `require("dedent")`, they'll now need to
use `require("dedent").default`.

.babelrc

@@ -3,5 +3,8 @@
     "es2015",
     "es2016",
     "es2017"
+  ],
+  "plugins": [
+    "transform-flow-strip-types"
   ]
 }

.eslintrc

@@ -4,6 +4,10 @@
     "node": true,
     "es6": true
   },
+  "parser": "babel-eslint",
+  "parserOptions": {
+    "sourceType": "module"
+  },
   "extends": "eslint:recommended",
   "rules": {
     "semi": [2, "always"],

.flowconfig

@@ -0,0 +1,8 @@
+[ignore]
+
+[include]
+
+[libs]
+
+[options]
+emoji=true

__tests__/.eslintrc

@@ -0,0 +1,5 @@
+{
+  "env": {
+    "jest": true
+  }
+}

__tests__/dedent-tests.js

@@ -1,36 +1,30 @@
-/*global jest, describe, it, expect */
+// @flow
 
-"use strict";
-
-jest.dontMock("../dedent");
+import dd from '../dedent';
 
 describe("dedent", () => {
   it("works without interpolation", () => {
-    const dd = require("../dedent");
     const result = dd`first
                       second
                       third`;
     expect(result).toBe("first\nsecond\nthird");
   });
 
   it("works with interpolation", () => {
-    const dd = require("../dedent");
     const result = dd`first ${"line"}
                       ${"second"}
                       third`;
     expect(result).toBe("first line\nsecond\nthird");
   });
 
   it("works with suppressed newlines", () => {
-    const dd = require("../dedent");
     const result = dd`first \
                       ${"second"}
                       third`;
     expect(result).toBe("first second\nthird");
   });
 
   it("works with blank first line", () => {
-    const dd = require("../dedent");
     const result = dd`
       Some text that I might want to indent:
         * reasons
@@ -46,7 +40,6 @@ describe("dedent", () => {
   });
 
   it("works with multiple blank first lines", () => {
-    const dd = require("../dedent");
     const result = dd`
 
                     first
@@ -56,7 +49,6 @@ describe("dedent", () => {
   });
 
   it("works with removing same number of spaces", () => {
-    const dd = require("../dedent");
     const result = dd`
                       first
                          second
@@ -69,50 +61,43 @@ describe("dedent", () => {
     const expected = "A single line of input.";
 
     it("works with single line input", () => {
-      const dd = require("../dedent");
       const result = dd`A single line of input.`;
       expect(result).toBe(expected);
     });
 
     it("works with single line and closing backtick on newline", () => {
-      const dd = require("../dedent");
       const result = dd`
         A single line of input.
       `;
       expect(result).toBe(expected);
     });
 
     it("works with single line and inline closing backtick", () => {
-      const dd = require("../dedent");
       const result = dd`
         A single line of input.`;
       expect(result).toBe(expected);
     });
   });
 
   it("can be used as a function", () => {
-    const dd = require("../dedent");
     const arg = `
       A test argument.
     `;
     expect(dd(arg)).toBe("A test argument.");
   });
 
   it("escapes backticks", () => {
-    const dd = require("../dedent");
     expect(dd`\``).toBe('`');
   });
 
   it("doesn't strip exlicit newlines", () => {
-    const dd = require("../dedent");
     const result = dd`
       <p>Hello world!</p>\n
     `;
     expect(result).toBe("<p>Hello world!</p>\n");
   });
 
   it("doesn't strip exlicit newlines with mindent", () => {
-    const dd = require("../dedent");
     const result = dd`
       <p>
         Hello world!

dedent.js

@@ -1,14 +1,11 @@
-"use strict";
+// @flow
 
-function dedent(strings, ...values) {
-
-  let raw;
-  if (typeof strings === "string") {
-    // dedent can be used as a plain function
-    raw = [strings];
-  } else {
-    raw = strings.raw;
-  }
+export default function dedent(
+  strings: string | Array<string>,
+  ...values: Array<string>
+) {
+  // $FlowFixMe: Flow doesn't undestand .raw
+  const raw = typeof strings === "string" ? [strings] : strings.raw;
 
   // first, perform interpolation
   let result = "";
@@ -27,7 +24,7 @@ function dedent(strings, ...values) {
 
   // now strip indentation
   const lines = result.split("\n");
-  let mindent = null;
+  let mindent: number | null = null;
   lines.forEach(l => {
     let m = l.match(/^(\s+)\S+/);
     if (m) {
@@ -42,16 +39,13 @@ function dedent(strings, ...values) {
   });
 
   if (mindent !== null) {
-    result = lines.map(l => l[0] === " " ? l.slice(mindent) : l).join("\n");
+    const m = mindent; // appease Flow
+    result = lines.map(l => l[0] === " " ? l.slice(m) : l).join("\n");
   }
 
-  // dedent eats leading and trailing whitespace too
-  result = result.trim();
-
-  // handle escaped newlines at the end to ensure they don't get stripped too
-  return result.replace(/\\n/g, "\n");
-}
-
-if (typeof module !== "undefined") {
-  module.exports = dedent;
+  return result.
+    // dedent eats leading and trailing whitespace too
+    trim().
+    // handle escaped newlines at the end to ensure they don't get stripped too
+    replace(/\\n/g, "\n");
 }

dist/dedent.js

@@ -1,14 +1,12 @@
 "use strict";
 
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = dedent;
 function dedent(strings) {
-
-  var raw = void 0;
-  if (typeof strings === "string") {
-    // dedent can be used as a plain function
-    raw = [strings];
-  } else {
-    raw = strings.raw;
-  }
+  // $FlowFixMe: Flow doesn't undestand .raw
+  var raw = typeof strings === "string" ? [strings] : strings.raw;
 
   // first, perform interpolation
   var result = "";
@@ -42,18 +40,17 @@ function dedent(strings) {
   });
 
   if (mindent !== null) {
-    result = lines.map(function (l) {
-      return l[0] === " " ? l.slice(mindent) : l;
-    }).join("\n");
+    (function () {
+      var m = mindent; // appease Flow
+      result = lines.map(function (l) {
+        return l[0] === " " ? l.slice(m) : l;
+      }).join("\n");
+    })();
   }
 
+  return result.
   // dedent eats leading and trailing whitespace too
-  result = result.trim();
-
+  trim().
   // handle escaped newlines at the end to ensure they don't get stripped too
-  return result.replace(/\\n/g, "\n");
-}
-
-if (typeof module !== "undefined") {
-  module.exports = dedent;
+  replace(/\\n/g, "\n");
 }