[CS2] Destructuring object spreads (#4493)

* Don’t confuse the syntax highlighter

* Comment Assign::compilePatternMatch a bit

* Assignment expressions in conditionals are a bad practice

* Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[`

* Correct comment

* object destructuring

* Allow custom position of the rest element.

* Output simple array destructuring assignments to ES2015

* Output simple object destructured assignments to ES2015

* Compile shorthand object properties to ES2015 shorthand properties

This dramatically improves the appearance of destructured imports.

* Don’t confuse the syntax highlighter

* Comment Assign::compilePatternMatch a bit

* Assignment expressions in conditionals are a bad practice

* Rename `wrapInBraces` to `wrapInParentheses`, to set the stage for future `wrapInBraces` that uses `{` and `wrapInBrackets` that uses `[`

* object destructuring

* Allow custom position of the rest element.

* rest element in object destructuring

* rest element in object destructuring

* fix string interpolation

* merging

* fixing splats in object literal

* Rest element in parameter destructuring

* merging with CS2

* merged with CS2

* Add support for the object spread initializer. https://github.com/tc39/proposal-object-rest-spread/blob/master/Spread.md

* Fix misspellings, trailing whitespace, other minor details

* merging with beta2

* refactor object spread properties

* small fix

* - Fixed object spread function parameters.
- Clean up "Assign" and moved all logic for object rest properties in single method (compileObjectDestruct).
- Add helper function "objectWithoutKeys" to the "UTILITIES" for use with object rest properties,
  e.g. {a, b, r...} = obj => {a, b} = obj, r = objectWithoutKeys(...)
- Clean up "Obj" and moved all logic for object spread properties in single method (compileSpread).
- Clean up "Code".
- Add method "hasSplat" to "Obj" and "Value" for checking if Obj contains the splat.
- Enable placing spread syntax triple dots on either right or left, per #85 (coffeescript6/discuss#85)

* Fixed typos

* Remove unused code

* Removed dots (e.g. splat) on the left side from the grammar

* Initial release for deep spread properties, e.g. obj2 = {obj.b..., a: 1} or {obj[b][c]..., d: 7}
Tests need to be prepared!

* 1. Object literal spread properties

Object literals:
- obj = { {b:{c:{d:1}}}..., a:1 }

Parenthetical:
- obj = { ( body ), a:1 }
- obj = { ( body )..., a:1 }

Invocation:
- obj = { ( (args) -> ... )(params), a:1 }
- obj = { ( (args) -> ... )(params)..., a:1 }
- obj = { foo(), a:1 }
- obj = { foo()..., a:1 }

2. Refactor, cleanup & other optimizations.

* Merged with 2.0

* Cleanup

* Some more cleanup.

* Fixed error with freeVariable and object destructuring.

* Fixed errors with object spread properties.

* Improvements, fixed errors.

* Minor improvement.

* Minor improvements.

* Typo.

* Remove unnecessary whitespace.

* Remove unnecessary whitespace.

* Changed few "assertErrorFormat" tests since parentheses are now allowed in the Obj.

* Whitespace cleanup

* Comments cleanup

* fix destructured obj param declarations

* refine fix; add test

* Refactor function args ({a, b...})

* Additional tests for object destructuring in function argument.

* Minor improvement for object destructuring variable declaration.

* refactor function args ({a, b...}) and ({a, b...} = {}); Obj And Param cleanup

* fix comment

* Fix object destructuring variable declaration.

* more tests with default values

* fix typo

* Fixed default values in object destructuring.

* small fix

* Babel’s tests for object rest spread

* Style: spaces after colons in object declarations

* Cleanup comments

* Simplify Babel tests

* Fix comments

* Fix destructuring with splats in multiple objects

* Add test for default values in detsructuring assignment with splats

* Handle default values when assigning to object splats

* Rewrite traverseRest to fix handling of dynamic keys

* Fix double parens around destructuring with splats

* Update compileObjectDestruct comments

* Improve formatting of top-level destructures with splats and tidy parens

* Added a bigger destructuring-with-defaults test and fixed a bug

* Refactor destructuring grammar to allow additional forms

* Add a missing case to ObjSpreadExpr

* These tests shouldn’t run in the browser

* Fix test.html

.gitignore

@@ -8,3 +8,4 @@ test/*.js
 parser.output
 /node_modules
 npm-debug.log*
+yarn.lock

documentation/test.html

@@ -39,6 +39,7 @@ <h1>CoffeeScript Test Suite</h1>
 <script type="text/coffeescript">
 @testingBrowser = yes
 @global = window
+bold = red = green = reset = ''
 stdout = document.getElementById 'stdout'
 start = new Date
 @currentFile = ''