Capture double/single-quoted atoms used as keys in keyword lists or maps (#93)

* Add captures for quoted atoms as keyword list keys.

Note: in this file Elixir atoms are refered to as 'symbols'
as in Ruby or other languages.
This might be better changed to 'atoms', but for now
I used 'symbols' in my hunks for consistency.

* Test tokenizations of atoms-as-keys

* Only matches for atoms without nested quotes;

Scrap the initial idea (matches for any letters inside quotes,
then warn for unescaped quotes) since it does not work properly
when there are multiple quoted-atom-key in a line.

Author: ymtszw

grammars/elixir.cson

@@ -1357,6 +1357,36 @@
       }
     ]
   }
+  {
+    'comment': """
+      symbols with single-quoted string, used as keys in Keyword lists.
+
+      In this case, `:` is suffixed to single-quoted string.
+      Leading letter `'` is exactly the same as in ordinary single-quoted string,
+      so this pattern is slightly difficult to capture.
+
+      This pattern only matches symbols when they do not have line breaks OR
+      (escaped or unescaped) single-quotes inside outermost single-quotes.
+      Thus, it will not match for patterns like `'foo\'bar':`.
+    """
+    'match': '(\')([^\']*)(\':)(?!:)'
+    'name': 'constant.other.symbol.single-quoted.elixir'
+    'captures': {
+      '1':
+        'name': 'punctuation.definition.constant.elixir'
+      '2':
+        'patterns': [
+          {
+            'include': '#interpolated_elixir'
+          }
+          {
+            'include': '#escaped_char'
+          }
+        ]
+      '3':
+        'name': 'punctuation.definition.constant.elixir'
+    }
+  }
   {
     'begin': ':"'
     'captures':
@@ -1433,6 +1463,26 @@
       }
     ]
   }
+  {
+    'comment': 'symbols defined by double-quoted string, used as keys in Keyword lists.'
+    'match': '(")([^"]*)(":)(?!:)'
+    'name': 'constant.other.symbol.double-quoted.elixir'
+    'captures': {
+      '1':
+        'name': 'punctuation.definition.constant.elixir'
+      '2':
+        'patterns': [
+          {
+            'include': '#interpolated_elixir'
+          }
+          {
+            'include': '#escaped_char'
+          }
+        ]
+      '3':
+        'name': 'punctuation.definition.constant.elixir'
+    }
+  }
   {
     'begin': '"'
     'beginCaptures':

spec/elixir-spec.coffee

@@ -152,6 +152,30 @@ describe "Elixir grammar", ->
     expect(tokens[0]).toEqual value: 'case', scopes: ['source.elixir', 'constant.other.symbol.elixir']
     expect(tokens[1]).toEqual value: ':', scopes: ['source.elixir', 'constant.other.symbol.elixir', 'punctuation.definition.constant.elixir']
 
+    {tokens} = grammar.tokenizeLine(':"symbol"')
+    expect(tokens[0]).toEqual value: ':"', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir', 'punctuation.definition.constant.elixir']
+    expect(tokens[1]).toEqual value: 'symbol', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir']
+    expect(tokens[2]).toEqual value: '"', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir', 'punctuation.definition.constant.elixir']
+
+    {tokens} = grammar.tokenizeLine('"symbol as key":')
+    expect(tokens[0]).toEqual value: '"', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir', 'punctuation.definition.constant.elixir']
+    expect(tokens[1]).toEqual value: 'symbol as key', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir']
+    expect(tokens[2]).toEqual value: '":', scopes: ['source.elixir', 'constant.other.symbol.double-quoted.elixir', 'punctuation.definition.constant.elixir']
+
+    {tokens} = grammar.tokenizeLine('"symbol as key with unescaped " inside":')
+    expect(tokens[0]).toEqual value: '"', scopes: ['source.elixir', 'string.quoted.double.elixir', 'punctuation.definition.string.begin.elixir']
+    expect(tokens[1]).toEqual value: 'symbol as key with unescaped ', scopes: ['source.elixir', 'string.quoted.double.elixir']
+    expect(tokens[2]).toEqual value: '"', scopes: ['source.elixir', 'string.quoted.double.elixir', 'punctuation.definition.string.end.elixir']
+    expect(tokens[3]).toEqual value: ' inside', scopes: ['source.elixir']
+    expect(tokens[4]).toEqual value: '"', scopes: ['source.elixir', 'string.quoted.double.elixir', 'punctuation.definition.string.begin.elixir']
+    expect(tokens[5]).toEqual value: ':', scopes: ['source.elixir', 'string.quoted.double.elixir']
+
+    {tokens} = grammar.tokenizeLine('"symbol as key with escaped \\" inside":')
+    expect(tokens[2]).toEqual value: '\\"', scopes: ['source.elixir', 'string.quoted.double.elixir', 'constant.character.escape.elixir']
+    expect(tokens[3]).toEqual value: ' inside', scopes: ['source.elixir', 'string.quoted.double.elixir']
+    expect(tokens[4]).toEqual value: '"', scopes: ['source.elixir', 'string.quoted.double.elixir', 'punctuation.definition.string.end.elixir']
+    expect(tokens[5]).toEqual value: ':', scopes: ['source.elixir', 'punctuation.separator.other.elixir']
+
   it "tokenizes comments", ->
     {tokens} = grammar.tokenizeLine("# TODO: stuff")
     expect(tokens[0]).toEqual value: '#', scopes: ['source.elixir', 'comment.line.number-sign.elixir', 'punctuation.definition.comment.elixir']