big refactor -- pulled all helper functions into helpers.coffee to facilitate sharing.

src/lexer.coffee

@@ -10,9 +10,9 @@
 # Set up the Lexer for both Node.js and the browser, depending on where we are.
 if process?
   Rewriter: require('./rewriter').Rewriter
+  process.mixin require './helpers'
 else
   this.exports: this
-  Rewriter: this.Rewriter
 
 # The Lexer Class
 # ---------------
@@ -146,7 +146,7 @@ exports.Lexer: class Lexer
   # Matches a token in which which the passed delimiter pairs must be correctly
   # balanced (ie. strings, JS literals).
   balanced_token: (delimited...) ->
-    @balanced_string @chunk, delimited
+    balanced_string @chunk, delimited
 
   # Matches and conumes comments. We pass through comments into JavaScript,
   # so they're treated as real tokens, like any other part of the language.
@@ -304,36 +304,6 @@ exports.Lexer: class Lexer
   assignment_error: ->
     throw new Error "SyntaxError: Reserved word \"${@value()}\" on line ${@line + 1} can't be assigned"
 
-  # Matches a balanced group such as a single or double-quoted string. Pass in
-  # a series of delimiters, all of which must be nested correctly within the
-  # contents of the string. This method allows us to have strings within
-  # interpolations within strings etc...
-  balanced_string: (str, delimited) ->
-    slash: delimited[0][0] is '/'
-    levels: []
-    i: 0
-    while i < str.length
-      if levels.length and starts str, '\\', i
-        i += 1
-      else
-        for pair in delimited
-          [open, close]: pair
-          if levels.length and starts(str, close, i) and levels[levels.length - 1] is pair
-            levels.pop()
-            i += close.length - 1
-            i += 1 unless levels.length
-            break
-          else if starts str, open, i
-            levels.push(pair)
-            i += open.length - 1
-            break
-      break if not levels.length or slash and starts str, '\n', i
-      i += 1
-    if levels.length
-      return false if slash
-      throw new Error "SyntaxError: Unterminated ${levels.pop()[0]} starting on line ${@line + 1}"
-    if not i then false else str.substring(0, i)
-
   # Expand variables and expressions inside double-quoted strings using
   # [ECMA Harmony's interpolation syntax](http://wiki.ecmascript.org/doku.php?id=strawman:string_interpolation)
   # for substitution of bare variables as well as arbitrary expressions.
@@ -362,7 +332,7 @@ exports.Lexer: class Lexer
           tokens.push ['IDENTIFIER', interp]
           i += group.length - 1
           pi: i + 1
-        else if (expr: @balanced_string str.substring(i), [['${', '}']])
+        else if (expr: balanced_string str.substring(i), [['${', '}']])
           tokens.push ['STRING', "$quote${ str.substring(pi, i) }$quote"] if pi < i
           inner: expr.substring(2, expr.length - 1)
           if inner.length
@@ -509,26 +479,3 @@ ACCESSORS: ['PROPERTY_ACCESS', 'PROTOTYPE_ACCESS', 'SOAK_ACCESS', '@']
 # occurs at the start of a line. We disambiguate these from trailing whens to
 # avoid an ambiguity in the grammar.
 BEFORE_WHEN: ['INDENT', 'OUTDENT', 'TERMINATOR']
-
-# Utility Functions
-# -----------------
-
-# Does a list include a value?
-include: (list, value) ->
-  list.indexOf(value) >= 0
-
-# Peek at the beginning of a given string to see if it matches a sequence.
-starts: (string, literal, start) ->
-  string.substring(start, (start or 0) + literal.length) is literal
-
-# Trim out all falsy values from an array.
-compact: (array) -> item for item in array when item
-
-# Count the number of occurences of a character in a string.
-count: (string, letter) ->
-  num: 0
-  pos: string.indexOf(letter)
-  while pos isnt -1
-    num += 1
-    pos: string.indexOf(letter, pos + 1)
-  num