Speedup by caching parsed tokens when checking for syntax error

src/coffeelint.coffee

@@ -222,13 +222,12 @@ coffeelint.registerRule require './rules/no_this.coffee'
 coffeelint.registerRule require './rules/eol_last.coffee'
 coffeelint.registerRule require './rules/no_private_function_fat_arrows.coffee'
 
-hasSyntaxError = (source) ->
+getTokens = (source) ->
     try
         # If there are syntax errors this will abort the lexical and line
         # linters.
-        CoffeeScript.tokens(source)
-        return false
-    return true
+        return CoffeeScript.tokens(source)
+    return null
 
 ErrorReport = require('./error_report.coffee')
 coffeelint.getErrorReport = ->
@@ -310,9 +309,10 @@ coffeelint.lint = (source, userConfig = {}, literate = false) ->
 
     # only do further checks if the syntax is okay, otherwise they just fail
     # with syntax error exceptions
-    unless hasSyntaxError(source)
+    tokens = getTokens(source)
+    if tokens
         # Do lexical linting.
-        lexicalLinter = new LexicalLinter(source, config, _rules, CoffeeScript)
+        lexicalLinter = new LexicalLinter(source, config, _rules, CoffeeScript, tokens)
         lexErrors = lexicalLinter.lint()
         errors = errors.concat(lexErrors)
 

src/lexical_linter.coffee

@@ -1,7 +1,7 @@
 class TokenApi
 
-    constructor: (CoffeeScript, source, @config, @tokensByLine) ->
-        @tokens = CoffeeScript.tokens(source)
+    constructor: (CoffeeScript, source, @config, @tokensByLine, @tokens) ->
+        @tokens ?= CoffeeScript.tokens(source)
         @lines = source.split('\n')
         @tokensByLine = {}  # A map of tokens by line.
 
@@ -18,10 +18,10 @@ BaseLinter = require './base_linter.coffee'
 #
 module.exports = class LexicalLinter extends BaseLinter
 
-    constructor: (source, config, rules, CoffeeScript) ->
+    constructor: (source, config, rules, CoffeeScript, tokens) ->
         super source, config, rules
 
-        @tokenApi = new TokenApi CoffeeScript, source, @config, @tokensByLine
+        @tokenApi = new TokenApi CoffeeScript, source, @config, @tokensByLine, tokens
         # This needs to be available on the LexicalLinter so it can be passed
         # to the LineLinter when this finishes running.
         @tokensByLine = @tokenApi.tokensByLine