coffee-script.coffee

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coffee-script.coffee
¶

CoffeeScript can be used both on the server, as a command-line compiler based on Node.js/V8, or to run CoffeeScript directly in the browser. This module contains the main entry functions for tokenizing, parsing, and compiling source CoffeeScript into JavaScript.
```
fs            = require 'fs'
vm            = require 'vm'
path          = require 'path'
{Lexer}       = require './lexer'
{parser}      = require './parser'
helpers       = require './helpers'
SourceMap     = require './sourcemap'
```
¶

Require package.json, which is two levels above this file, as this file is evaluated from lib/coffee-script.
```
packageJson   = require '../../package.json'
```

The current CoffeeScript version number.

exports.VERSION = packageJson.version

exports.FILE_EXTENSIONS = ['.coffee', '.litcoffee', '.coffee.md']

¶

Expose helpers for testing.
```
exports.helpers = helpers
```

Function that allows for btoa in both nodejs and the browser.

base64encode = (src) -> switch
  when typeof Buffer is 'function'
    new Buffer(src).toString('base64')
  when typeof btoa is 'function'

¶

The contents of a <script> block are encoded via UTF-16, so if any extended characters are used in the block, btoa will fail as it maxes out at UTF-8. See https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding#The_Unicode_Problem for the gory details, and for the solution implemented here.
```
    btoa encodeURIComponent(src).replace /%([0-9A-F]{2})/g, (match, p1) ->
      String.fromCharCode '0x' + p1
  else
    throw new Error('Unable to base64 encode inline sourcemap.')
```

Function wrapper to add source file information to SyntaxErrors thrown by the lexer/parser/compiler.

withPrettyErrors = (fn) ->
  (code, options = {}) ->
    try
      fn.call @, code, options
    catch err
      throw err if typeof code isnt 'string' # Support `CoffeeScript.nodes(tokens)`.
      throw helpers.updateSyntaxError err, code, options.filename

¶

For each compiled file, save its source in memory in case we need to recompile it later. We might need to recompile if the first compilation didn’t create a source map (faster) but something went wrong and we need a stack trace. Assuming that most of the time, code isn’t throwing exceptions, it’s probably more efficient to compile twice only when we need a stack trace, rather than always generating a source map even when it’s not likely to be used. Save in form of filename: (source)
```
sources = {}
```
¶

Also save source maps if generated, in form of filename: (source map).
```
sourceMaps = {}
```
¶

Compile CoffeeScript code to JavaScript, using the Coffee/Jison compiler.

If options.sourceMap is specified, then options.filename must also be specified. All options that can be passed to SourceMap#generate may also be passed here.

This returns a javascript string, unless options.sourceMap is passed, in which case this returns a {js, v3SourceMap, sourceMap} object, where sourceMap is a sourcemap.coffee#SourceMap object, handy for doing programmatic lookups.
```
exports.compile = compile = withPrettyErrors (code, options) ->
  {merge, extend} = helpers
  options = extend {}, options
```

Always generate a source map if no filename is passed in, since without a a filename we have no way to retrieve this source later in the event that we need to recompile it to get a source map for prepareStackTrace.

  generateSourceMap = options.sourceMap or options.inlineMap or not options.filename?
  filename = options.filename or '<anonymous>'

  sources[filename] = code
  map = new SourceMap if generateSourceMap

  tokens = lexer.tokenize code, options

Pass a list of referenced variables, so that generated variables won’t get the same name.

  options.referencedVars = (
    token[1] for token in tokens when token[0] is 'IDENTIFIER'
  )

Check for import or export; if found, force bare mode.

  unless options.bare? and options.bare is yes
    for token in tokens
      if token[0] in ['IMPORT', 'EXPORT']
        options.bare = yes
        break

  fragments = parser.parse(tokens).compileToFragments options

  currentLine = 0
  currentLine += 1 if options.header
  currentLine += 1 if options.shiftLine
  currentColumn = 0
  js = ""
  for fragment in fragments

¶

Update the sourcemap with data from each fragment.
```
    if generateSourceMap
```

Do not include empty, whitespace, or semicolon-only fragments.

      if fragment.locationData and not /^[;\s]*$/.test fragment.code
        map.add(
          [fragment.locationData.first_line, fragment.locationData.first_column]
          [currentLine, currentColumn]
          {noReplace: true})
      newLines = helpers.count fragment.code, "\n"
      currentLine += newLines
      if newLines
        currentColumn = fragment.code.length - (fragment.code.lastIndexOf("\n") + 1)
      else
        currentColumn += fragment.code.length

Copy the code from each fragment into the final JavaScript.

    js += fragment.code

  if options.header
    header = "Generated by CoffeeScript #{@VERSION}"
    js = "// #{header}\n#{js}"

  if generateSourceMap
    v3SourceMap = map.generate(options, code)
    sourceMaps[filename] = map

  if options.inlineMap
    encoded = base64encode JSON.stringify v3SourceMap
    sourceMapDataURI = "//# sourceMappingURL=data:application/json;base64,#{encoded}"
    sourceURL = "//# sourceURL=#{options.filename ? 'coffeescript'}"
    js = "#{js}\n#{sourceMapDataURI}\n#{sourceURL}"

  if options.sourceMap
    {
      js
      sourceMap: map
      v3SourceMap: JSON.stringify v3SourceMap, null, 2
    }
  else
    js

Tokenize a string of CoffeeScript code, and return the array of tokens.

exports.tokens = withPrettyErrors (code, options) ->
  lexer.tokenize code, options

¶

Parse a string of CoffeeScript code or an array of lexed tokens, and return the AST. You can then compile it by calling .compile() on the root, or traverse it by using .traverseChildren() with a callback.
```
exports.nodes = withPrettyErrors (source, options) ->
  if typeof source is 'string'
    parser.parse lexer.tokenize source, options
  else
    parser.parse source
```
¶

Compile and execute a string of CoffeeScript (on the server), correctly setting __filename, __dirname, and relative require().
```
exports.run = (code, options = {}) ->
  mainModule = require.main
```

Set the filename.

  mainModule.filename = process.argv[1] =
    if options.filename then fs.realpathSync(options.filename) else '<anonymous>'

¶

Clear the module cache.
```
  mainModule.moduleCache and= {}
```

Assign paths for node_modules loading

  dir = if options.filename?
    path.dirname fs.realpathSync options.filename
  else
    fs.realpathSync '.'
  mainModule.paths = require('module')._nodeModulePaths dir

Compile.

  if not helpers.isCoffee(mainModule.filename) or require.extensions
    answer = compile code, options
    code = answer.js ? answer

  mainModule._compile code, mainModule.filename

Compile and evaluate a string of CoffeeScript (in a Node.js-like environment). The CoffeeScript REPL uses this to run the input.

exports.eval = (code, options = {}) ->
  return unless code = code.trim()
  createContext = vm.Script.createContext ? vm.createContext

  isContext = vm.isContext ? (ctx) ->
    options.sandbox instanceof createContext().constructor

  if createContext
    if options.sandbox?
      if isContext options.sandbox
        sandbox = options.sandbox
      else
        sandbox = createContext()
        sandbox[k] = v for own k, v of options.sandbox
      sandbox.global = sandbox.root = sandbox.GLOBAL = sandbox
    else
      sandbox = global
    sandbox.__filename = options.filename || 'eval'
    sandbox.__dirname  = path.dirname sandbox.__filename

define module/require only if they chose not to specify their own

    unless sandbox isnt global or sandbox.module or sandbox.require
      Module = require 'module'
      sandbox.module  = _module  = new Module(options.modulename || 'eval')
      sandbox.require = _require = (path) ->  Module._load path, _module, true
      _module.filename = sandbox.__filename
      for r in Object.getOwnPropertyNames require when r not in ['paths', 'arguments', 'caller']
        _require[r] = require[r]

use the same hack node currently uses for their own REPL

      _require.paths = _module.paths = Module._nodeModulePaths process.cwd()
      _require.resolve = (request) -> Module._resolveFilename request, _module
  o = {}
  o[k] = v for own k, v of options
  o.bare = on # ensure return value
  js = compile code, o
  if sandbox is global
    vm.runInThisContext js
  else
    vm.runInContext js, sandbox

exports.register = -> require './register'

Throw error with deprecation warning when depending upon implicit require.extensions registration

if require.extensions
  for ext in @FILE_EXTENSIONS then do (ext) ->
    require.extensions[ext] ?= ->
      throw new Error """
      Use CoffeeScript.register() or require the coffee-script/register module to require #{ext} files.
      """

exports._compileFile = (filename, sourceMap = no, inlineMap = no) ->
  raw = fs.readFileSync filename, 'utf8'

Strip the Unicode byte order mark, if this file begins with one.

  stripped = if raw.charCodeAt(0) is 0xFEFF then raw.substring 1 else raw

  try
    answer = compile stripped, {
      filename, sourceMap, inlineMap
      sourceFiles: [filename]
      literate: helpers.isLiterate filename
    }
  catch err

¶

As the filename and code of a dynamically loaded file will be different from the original file compiled with CoffeeScript.run, add that information to error so it can be pretty-printed later.
```
    throw helpers.updateSyntaxError err, stripped, filename

  answer
```
¶

Instantiate a Lexer for our use here.
```
lexer = new Lexer
```

The real Lexer produces a generic stream of tokens. This object provides a thin wrapper around it, compatible with the Jison API. We can then pass it directly as a “Jison lexer”.

parser.lexer =
  lex: ->
    token = parser.tokens[@pos++]
    if token
      [tag, @yytext, @yylloc] = token
      parser.errorToken = token.origin or token
      @yylineno = @yylloc.first_line
    else
      tag = ''

    tag
  setInput: (tokens) ->
    parser.tokens = tokens
    @pos = 0
  upcomingInput: ->
    ""

¶

Make all the AST nodes visible to the parser.
```
parser.yy = require './nodes'
```
¶

Override Jison’s default error handling function.
```
parser.yy.parseError = (message, {token}) ->
```

Disregard Jison’s message, it contains redundant line number information. Disregard the token, we take its value directly from the lexer in case the error is caused by a generated token which might refer to its origin.

  {errorToken, tokens} = parser
  [errorTag, errorText, errorLoc] = errorToken

  errorText = switch
    when errorToken is tokens[tokens.length - 1]
      'end of input'
    when errorTag in ['INDENT', 'OUTDENT']
      'indentation'
    when errorTag in ['IDENTIFIER', 'NUMBER', 'INFINITY', 'STRING', 'STRING_START', 'REGEX', 'REGEX_START']
      errorTag.replace(/_START$/, '').toLowerCase()
    else
      helpers.nameWhitespaceCharacter errorText

¶

The second argument has a loc property, which should have the location data for this token. Unfortunately, Jison seems to send an outdated loc (from the previous token), so we take the location information directly from the lexer.
```
  helpers.throwSyntaxError "unexpected #{errorText}", errorLoc
```

Based on http://v8.googlecode.com/svn/branches/bleeding_edge/src/messages.js Modified to handle sourceMap

formatSourcePosition = (frame, getSourceMapping) ->
  filename = undefined
  fileLocation = ''

  if frame.isNative()
    fileLocation = "native"
  else
    if frame.isEval()
      filename = frame.getScriptNameOrSourceURL()
      fileLocation = "#{frame.getEvalOrigin()}, " unless filename
    else
      filename = frame.getFileName()

    filename or= "<anonymous>"

    line = frame.getLineNumber()
    column = frame.getColumnNumber()

Check for a sourceMap position

    source = getSourceMapping filename, line, column
    fileLocation =
      if source
        "#{filename}:#{source[0]}:#{source[1]}"
      else
        "#{filename}:#{line}:#{column}"

  functionName = frame.getFunctionName()
  isConstructor = frame.isConstructor()
  isMethodCall = not (frame.isToplevel() or isConstructor)

  if isMethodCall
    methodName = frame.getMethodName()
    typeName = frame.getTypeName()

    if functionName
      tp = as = ''
      if typeName and functionName.indexOf typeName
        tp = "#{typeName}."
      if methodName and functionName.indexOf(".#{methodName}") isnt functionName.length - methodName.length - 1
        as = " [as #{methodName}]"

      "#{tp}#{functionName}#{as} (#{fileLocation})"
    else
      "#{typeName}.#{methodName or '<anonymous>'} (#{fileLocation})"
  else if isConstructor
    "new #{functionName or '<anonymous>'} (#{fileLocation})"
  else if functionName
    "#{functionName} (#{fileLocation})"
  else
    fileLocation

getSourceMap = (filename) ->
  if sourceMaps[filename]?
    sourceMaps[filename]

CoffeeScript compiled in a browser may get compiled with options.filename of <anonymous>, but the browser may request the stack trace with the filename of the script file.

  else if sourceMaps['<anonymous>']?
    sourceMaps['<anonymous>']
  else if sources[filename]?
    answer = compile sources[filename],
      filename: filename
      sourceMap: yes
      literate: helpers.isLiterate filename
    answer.sourceMap
  else
    null

Based on michaelficarra/CoffeeScriptRedux NodeJS / V8 have no support for transforming positions in stack traces using sourceMap, so we must monkey-patch Error to display CoffeeScript source positions.

Error.prepareStackTrace = (err, stack) ->
  getSourceMapping = (filename, line, column) ->
    sourceMap = getSourceMap filename
    answer = sourceMap.sourceLocation [line - 1, column - 1] if sourceMap?
    if answer? then [answer[0] + 1, answer[1] + 1] else null

  frames = for frame in stack
    break if frame.getFunction() is exports.run
    "    at #{formatSourcePosition frame, getSourceMapping}"

  "#{err.toString()}\n#{frames.join '\n'}\n"