Add --space-before-function-paren option (#22)

* Add test demonstrating behavior on eslint space-before-function-paren sample code

* Add --space-before-function-paren option

This corresponds to ESLint's `space-before-function-paren` "always"
option: http://eslint.org/docs/rules/space-before-function-paren#always

See prettier#1139

* Document --space-before-function-paren option

README.md

@@ -295,6 +295,7 @@ Prettier ships with a handful of customizable format options, usable in both the
 | **JSX Brackets on Same Line** - Put the `>` of a multi-line JSX element at the end of the last line instead of being alone on the next line | `false` | CLI: `--jsx-bracket-same-line` <br />API: `jsxBracketSameLine: <bool>` |
 | **Align Object Properties** - Align colons in multiline object literals. Does nothing if object has computed property names. | `false` | CLI: `--align-object-properties` <br/>API: `alignObjectProperties: <bool>` |
 | **No Space in Empty Function** - Omit space before empty anonymous function body.<br /><br />Valid options: <br /> - `true` <br /> - `false` | `false` | CLI: `--no-space-empty-fn` <br/>API: `noSpaceEmptyFn: <bool>` |
+| **Space before Function Paren** - Put a [space before function parenthesis](http://eslint.org/docs/rules/space-before-function-paren#always).<br /><br />Valid options: <br /> - `true` <br /> - `false` | `false` | CLI: `--space-before-function-paren` <br/>API: `spaceBeforeFunctionParen: <bool>` |
 | **Cursor Offset** - Specify where the cursor is. This option only works with `prettier.formatWithCursor`, and cannot be used with `rangeStart` and `rangeEnd`. | `-1` | CLI: `--cursor-offset <int>` <br />API: `cursorOffset: <int>` |
 | **Range Start** - Format code starting at a given character offset. The range will extend backwards to the start of the first line containing the selected statement. This option cannot be used with `cursorOffset`. | `0` | CLI: `--range-start <int>` <br />API: `rangeStart: <int>` |
 | **Range End** - Format code ending at a given character offset (exclusive). The range will extend forwards to the end of the selected statement. This option cannot be used with `cursorOffset`. | `Infinity` | CLI: `--range-end <int>` <br />API: `rangeEnd: <int>` |

bin/prettier.js

@@ -29,6 +29,7 @@ const argv = minimist(process.argv.slice(2), {
     "jsx-bracket-same-line",
     "align-object-properties",
     "space-empty-fn",
+    "space-before-function-paren",
     // The supports-color package (a sub sub dependency) looks directly at
     // `process.argv` for `--no-color` and such-like options. The reason it is
     // listed here is to avoid "Ignored unknown option: --no-color" warnings.
@@ -167,6 +168,7 @@ const options = {
   jsxBracketSameLine: argv["jsx-bracket-same-line"],
   alignObjectProperties: argv["align-object-properties"],
   noSpaceEmptyFn: !argv["space-empty-fn"],
+  spaceBeforeFunctionParen: argv["space-before-function-paren"],
   filepath: argv["stdin-filepath"],
   trailingComma: getTrailingComma(),
   parser: getParserOption()
@@ -262,6 +264,8 @@ if (argv["help"] || (!filepatterns.length && !stdin)) {
       "  --align-object-properties\n" +
       "                           Align colons in multiline object literals. Does nothing if object has computed property names.\n" +
       "  --no-space-empty-fn      Omit space before empty function body. Defaults to false.\n" +
+      "  --space-before-function-paren\n" +
+      "                           Put a space before function parenthesis. Defaults to false.\n" +
       "  --parser <flow|babylon|typescript|postcss|json>\n" +
       "                           Specify which parse to use. Defaults to babylon.\n" +
       "  --cursor-offset <int>    Print (to stderr) where a cursor at the given position would move to after formatting.\n" +

src/options.js

@@ -47,6 +47,7 @@ const defaults = {
   noSpaceEmptyFn: false,
   parser: "babylon",
   semi: true,
+  spaceBeforeFunctionParen: false,
   __log: false
 };
 

src/printer.js

@@ -2848,6 +2848,7 @@ function printMethod(path, options, print) {
           printFunctionTypeParameters(valuePath, options, print),
           group(
             concat([
+              options.spaceBeforeFunctionParen ? " " : "",
               printFunctionParams(valuePath, print, options),
               printReturnType(valuePath, print)
             ])
@@ -3175,6 +3176,7 @@ function printFunctionDeclaration(path, print, options) {
     printFunctionTypeParameters(path, options, print),
     group(
       concat([
+        options.spaceBeforeFunctionParen ? " " : "",
         printFunctionParams(path, print, options),
         printReturnType(path, print)
       ])
@@ -3217,6 +3219,7 @@ function printObjectMethod(path, options, print) {
     printFunctionTypeParameters(path, options, print),
     group(
       concat([
+        options.spaceBeforeFunctionParen ? " " : "",
         printFunctionParams(path, print, options),
         printReturnType(path, print)
       ])

tests/space-before-function-paren/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,62 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`eslint.js 1`] = `
+/*eslint space-before-function-paren: "error"*/
+/*eslint-env es6*/
+
+function foo() {
+    // ...
+}
+
+var bar = function() {
+    // ...
+};
+
+var bar = function foo() {
+    // ...
+};
+
+class Foo {
+    constructor() {
+        // ...
+    }
+}
+
+var foo = {
+    bar() {
+        // ...
+    }
+};
+
+var foo = async() => 1
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+/*eslint space-before-function-paren: "error"*/
+/*eslint-env es6*/
+
+function foo () {
+  // ...
+}
+
+var bar = function () {
+  // ...
+};
+
+var bar = function foo () {
+  // ...
+};
+
+class Foo {
+  constructor () {
+    // ...
+  }
+}
+
+var foo = {
+  bar () {
+    // ...
+  }
+};
+
+var foo = async () => 1;
+
+`;

tests/space-before-function-paren/eslint.js

@@ -0,0 +1,28 @@
+/*eslint space-before-function-paren: "error"*/
+/*eslint-env es6*/
+
+function foo() {
+    // ...
+}
+
+var bar = function() {
+    // ...
+};
+
+var bar = function foo() {
+    // ...
+};
+
+class Foo {
+    constructor() {
+        // ...
+    }
+}
+
+var foo = {
+    bar() {
+        // ...
+    }
+};
+
+var foo = async() => 1

tests/space-before-function-paren/jsfmt.spec.js

@@ -0,0 +1,4 @@
+run_spec(__dirname, { spaceBeforeFunctionParen: true }, [
+  "babylon",
+  "typescript"
+]);