Support for NumericLiteralSeparator, Stage 1 feature (#5793)

* Support for NumericLiteralSeparator, Stage 1 feature

commit cd8f6e062876261a334d968f875e477a48927b6d
Author: Sven SAULEAU <xtuc@users.noreply.github.com>
Date:   Wed May 31 16:14:15 2017 +0200

    docs: update README [skip ci]

commit cf013e3382bf73cdf9224026c1ec0b1a368cfef2
Author: Rick Waldron <waldron.rick@gmail.com>
Date:   Tue May 30 14:51:20 2017 -0400

    Support for NumericLiteralSeparator, Stage 1 feature

    Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

* add note about presets [skip ci]

packages/babel-plugin-transform-numeric-separator/.npmignore

@@ -0,0 +1,3 @@
+src
+test
+*.log

packages/babel-plugin-transform-numeric-separator/README.md

@@ -0,0 +1,114 @@
+# babel-plugin-transform-numeric-separator
+
+> This plugin allows Babel to transform Decimal, Binary, Hex and Octal literals containing Numeric Literal Separator to their non-separated form.
+
+## Example
+
+### Decimal Literals
+
+```js
+let budget = 1_000_000_000_000;
+
+// What is the value of `budget`? It's 1 trillion!
+// 
+// Let's confirm:
+console.log(budget === 10 ** 12); // true
+```
+
+### Binary Literals
+
+```js
+let nibbles = 0b1010_0001_1000_0101;
+
+// Is bit 7 on? It sure is!
+// 0b1010_0001_1000_0101
+//             ^
+//             
+// We can double check: 
+console.log(!!(nibbles & (1 << 7))); // true
+```
+
+### Hex Literal
+
+```js
+// Messages are sent as 24 bit values, but should be 
+// treated as 3 distinct bytes:
+let message = 0xA0_B0_C0;
+
+// What's the value of the upper most byte? It's A0, or 160.
+// We can confirm that:
+let a = (message >> 16) & 0xFF; 
+console.log(a.toString(16), a); // a0, 160
+
+// What's the value of the middle byte? It's B0, or 176.
+// Let's just make sure...
+let b = (message >> 8) & 0xFF;
+console.log(b.toString(16), b); // b0, 176
+
+// What's the value of the lower most byte? It's C0, or 192.
+// Again, let's prove that:
+let c = message & 0xFF;
+console.log(c.toString(16), b); // c0, 192
+```
+
+### Octal Literal
+
+*hand wave emoji*
+
+Octals are great for permissions, but also look better when represented in `0o0000` form. No real benefit with separators here. 
+
+## Installation
+
+```sh
+npm install --save-dev babel-plugin-transform-numeric-separator
+```
+
+## Usage
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "plugins": ["transform-numeric-separator"]
+}
+```
+
+### Via CLI
+
+```sh
+babel --plugins transform-numeric-separator script.js
+```
+
+### Via Node API
+
+```javascript
+require("babel-core").transform("code", {
+  plugins: ["transform-numeric-separator"]
+});
+```
+
+## Additional Information 
+
+If you need to further compile ES2015 Decimal, Binary, Hex and Octal number representations to their pre-ES2015 numeric literal form, add the [`"transform-es2015-literals"`](http://babeljs.io/docs/plugins/transform-es2015-literals/) plugin:
+
+> `transform-es2015-literals` is already included in [babel-preset-env](https://github.com/babel/babel-preset-env) and babel-preset-es2015.
+
+### Via `.babelrc` (Recommended)
+
+**.babelrc**
+
+```json
+{
+  "presets": ["env"],
+  "plugins": ["transform-numeric-separator"]
+}
+{
+  "plugins": ["transform-numeric-separator", "transform-es2015-literals"]
+}
+```
+
+## References
+
+* [Proposal: Numeric Separators](https://github.com/samuelgoto/proposal-numeric-separator)

packages/babel-plugin-transform-numeric-separator/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "babel-plugin-transform-numeric-separator",
+  "version": "7.0.0-alpha.12",
+  "description": "Remove numeric separators from Decimal, Binary, Hex and Octal literals",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-plugin-transform-numeric-separator",
+  "license": "MIT",
+  "main": "lib/index.js",
+  "keywords": [
+    "babel-plugin"
+  ],
+  "dependencies": {
+    "babel-plugin-syntax-numeric-separator": "7.0.0-alpha.12"
+  },
+  "devDependencies": {
+    "babel-helper-plugin-test-runner": "7.0.0-alpha.10"
+  }
+}

packages/babel-plugin-transform-numeric-separator/src/index.js

@@ -0,0 +1,31 @@
+import syntaxNumericSeparator from "babel-plugin-syntax-numeric-separator";
+
+export default function () {
+
+  function replacer(value) {
+    return value.replace(/_/g, "");
+  }
+
+  function replaceNumberArg({ node }) {
+    if (node.callee.name === "Number") {
+      node.arguments[0].value = replacer(node.arguments[0].value);
+    }
+  }
+
+  const CallExpression = replaceNumberArg;
+  const NewExpression = replaceNumberArg;
+
+  return {
+    inherits: syntaxNumericSeparator,
+
+    visitor: {
+      CallExpression,
+      NewExpression,
+      NumericLiteral({ node }) {
+        if (node.extra && /_/.test(node.extra.raw)) {
+          node.value = replacer(node.extra.raw);
+        }
+      },
+    },
+  };
+}

packages/babel-plugin-transform-numeric-separator/test/fixtures/number/exec.js

@@ -0,0 +1,9 @@
+assert.equal(Number("1_000"), Number("1000"));
+assert.equal(Number("0xAE_BE_CE"), Number("0xAEBECE"));
+assert.equal(Number("0b1010_0001_1000_0101"), Number("0b1010000110000101"));
+assert.equal(Number("0o0_6_6_6"), Number("0o0666"));
+
+assert.equal(new Number("1_000").valueOf(), new Number("1000").valueOf());
+assert.equal(new Number("0xAE_BE_CE").valueOf(), new Number("0xAEBECE").valueOf());
+assert.equal(new Number("0b1010_0001_1000_0101").valueOf(), new Number("0b1010000110000101").valueOf());
+assert.equal(new Number("0o0_6_6_6").valueOf(), new Number("0o0666").valueOf());

packages/babel-plugin-transform-numeric-separator/test/fixtures/number/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-numeric-separator"]
+}

packages/babel-plugin-transform-numeric-separator/test/fixtures/removal/exec.js

@@ -0,0 +1,4 @@
+assert.equal(1_000, 1000);
+assert.equal(0xAE_BE_CE, 0xAEBECE);
+assert.equal(0b1010_0001_1000_0101, 0b1010000110000101);
+assert.equal(0o0_6_6_6, 0o0666);

packages/babel-plugin-transform-numeric-separator/test/fixtures/removal/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-numeric-separator"]
+}

packages/babel-plugin-transform-numeric-separator/test/fixtures/used-with-transform-es2015-literals/actual.js

@@ -0,0 +1,4 @@
+1_000;
+0xA0_B0_C0;
+0b1010_0001_1000_0101;
+0o0_6_6_6;

packages/babel-plugin-transform-numeric-separator/test/fixtures/used-with-transform-es2015-literals/exec.js

@@ -0,0 +1,4 @@
+assert.equal(1_000, 1000);
+assert.equal(0xAE_BE_CE, 11452110);
+assert.equal(0b1010_0001_1000_0101, 41349);
+assert.equal(0o0_6_6_6, 438);

packages/babel-plugin-transform-numeric-separator/test/fixtures/used-with-transform-es2015-literals/expected.js

@@ -0,0 +1,4 @@
+1000;
+10531008;
+41349;
+438;

packages/babel-plugin-transform-numeric-separator/test/fixtures/used-with-transform-es2015-literals/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-numeric-separator", "transform-es2015-literals"]
+}

packages/babel-plugin-transform-numeric-separator/test/index.js

@@ -0,0 +1,3 @@
+import runner from "babel-helper-plugin-test-runner";
+
+runner(__dirname);