helpers.coffee

Jump To … +

browser.coffee cake.coffee coffeescript.coffee command.coffee grammar.coffee helpers.coffee index.coffee lexer.coffee nodes.coffee optparse.coffee register.coffee repl.coffee rewriter.coffee scope.litcoffee sourcemap.litcoffee

helpers.coffee
¶

This file contains the common helper functions that we’d like to share among the Lexer, Rewriter, and the Nodes. Merge objects, flatten arrays, count characters, that sort of thing.
```
md = require('markdown-it')()
```

Peek at the beginning of a given string to see if it matches a sequence.

exports.starts = (string, literal, start) ->
  literal is string.substr start, literal.length

Peek at the end of a given string to see if it matches a sequence.

exports.ends = (string, literal, back) ->
  len = literal.length
  literal is string.substr string.length - len - (back or 0), len

¶

Repeat a string n times.
```
exports.repeat = repeat = (str, n) ->
```

Use clever algorithm to have O(log(n)) string concatenation operations.

  res = ''
  while n > 0
    res += str if n & 1
    n >>>= 1
    str += str
  res

Trim out all falsy values from an array.

exports.compact = (array) ->
  item for item in array when item

Count the number of occurrences of a string in a string.

exports.count = (string, substr) ->
  num = pos = 0
  return 1/0 unless substr.length
  num++ while pos = 1 + string.indexOf substr, pos
  num

¶

Merge objects, returning a fresh copy with attributes from both sides. Used every time Base#compile is called, to allow properties in the options hash to propagate down the tree without polluting other branches.
```
exports.merge = (options, overrides) ->
  extend (extend {}, options), overrides
```

Extend a source object with the properties of another object (shallow copy).

extend = exports.extend = (object, properties) ->
  for key, val of properties
    object[key] = val
  object

Return a flattened version of an array. Handy for getting a list of children from the nodes.

exports.flatten = flatten = (array) ->
  flattened = []
  for element in array
    if '[object Array]' is Object::toString.call element
      flattened = flattened.concat flatten element
    else
      flattened.push element
  flattened

¶

Delete a key from an object, returning the value. Useful when a node is looking for a particular method in an options hash.
```
exports.del = (obj, key) ->
  val =  obj[key]
  delete obj[key]
  val
```

Typical Array::some

exports.some = Array::some ? (fn) ->
  return true for e in this when fn e
  false

¶

Simple function for extracting code from Literate CoffeeScript by stripping out all non-code blocks, producing a string of CoffeeScript code that can be compiled “normally.” Uses MarkdownIt to tell the difference between Markdown and code blocks.
```
exports.invertLiterate = (code) ->
  out = []
  md.renderer.rules =
```

Delete all other rules, since all we want are the code blocks.

    code_block: (tokens, idx, options, env, slf) ->
      startLine = tokens[idx].map[0]
      lines = tokens[idx].content.split '\n'
      for line, i in lines
        out[startLine + i] = line
  md.render code
  out.join '\n'

Merge two jison-style location data objects together. If last is not provided, this will simply return first.

buildLocationData = (first, last) ->
  if not last
    first
  else
    first_line: first.first_line
    first_column: first.first_column
    last_line: last.last_line
    last_column: last.last_column

This returns a function which takes an object as a parameter, and if that object is an AST node, updates that object’s locationData. The object is returned either way.

exports.addLocationDataFn = (first, last) ->
  (obj) ->
    if ((typeof obj) is 'object') and (!!obj['updateLocationDataIfMissing'])
      obj.updateLocationDataIfMissing buildLocationData(first, last)

    return obj

Convert jison location data to a string. obj can be a token, or a locationData.

exports.locationDataToString = (obj) ->
  if ("2" of obj) and ("first_line" of obj[2]) then locationData = obj[2]
  else if "first_line" of obj then locationData = obj

  if locationData
    "#{locationData.first_line + 1}:#{locationData.first_column + 1}-" +
    "#{locationData.last_line + 1}:#{locationData.last_column + 1}"
  else
    "No location data"

A .coffee.md compatible version of basename, that returns the file sans-extension.

exports.baseFileName = (file, stripExt = no, useWinPathSep = no) ->
  pathSep = if useWinPathSep then /\\|\// else /\//
  parts = file.split(pathSep)
  file = parts[parts.length - 1]
  return file unless stripExt and file.indexOf('.') >= 0
  parts = file.split('.')
  parts.pop()
  parts.pop() if parts[parts.length - 1] is 'coffee' and parts.length > 1
  parts.join('.')

Determine if a filename represents a CoffeeScript file.

exports.isCoffee = (file) -> /\.((lit)?coffee|coffee\.md)$/.test file

Determine if a filename represents a Literate CoffeeScript file.

exports.isLiterate = (file) -> /\.(litcoffee|coffee\.md)$/.test file

¶

Throws a SyntaxError from a given location. The error’s toString will return an error message following the “standard” format <filename>:<line>:<col>: <message> plus the line with the error and a marker showing where the error is.
```
exports.throwSyntaxError = (message, location) ->
  error = new SyntaxError message
  error.location = location
  error.toString = syntaxErrorToString
```
¶

Instead of showing the compiler’s stacktrace, show our custom error message (this is useful when the error bubbles up in Node.js applications that compile CoffeeScript for example).
```
  error.stack = error.toString()

  throw error
```
¶

Update a compiler SyntaxError with source code information if it didn’t have it already.
```
exports.updateSyntaxError = (error, code, filename) ->
```

Avoid screwing up the stack property of other errors (i.e. possible bugs).

  if error.toString is syntaxErrorToString
    error.code or= code
    error.filename or= filename
    error.stack = error.toString()
  error

syntaxErrorToString = ->
  return Error::toString.call @ unless @code and @location

  {first_line, first_column, last_line, last_column} = @location
  last_line ?= first_line
  last_column ?= first_column

  filename = @filename or '[stdin]'
  codeLine = @code.split('\n')[first_line]
  start    = first_column

Show only the first line on multi-line errors.

  end      = if first_line is last_line then last_column + 1 else codeLine.length
  marker   = codeLine[...start].replace(/[^\s]/g, ' ') + repeat('^', end - start)

Check to see if we’re running on a color-enabled TTY.

  if process?
    colorsEnabled = process.stdout?.isTTY and not process.env?.NODE_DISABLE_COLORS

  if @colorful ? colorsEnabled
    colorize = (str) -> "\x1B[1;31m#{str}\x1B[0m"
    codeLine = codeLine[...start] + colorize(codeLine[start...end]) + codeLine[end..]
    marker   = colorize marker

  """
    #{filename}:#{first_line + 1}:#{first_column + 1}: error: #{@message}
    #{codeLine}
    #{marker}
  """

exports.nameWhitespaceCharacter = (string) ->
  switch string
    when ' ' then 'space'
    when '\n' then 'newline'
    when '\r' then 'carriage return'
    when '\t' then 'tab'
    else string