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. | helpers = exports.helpers = {} |
| Cross-browser indexOf, so that IE can join the party. | helpers.indexOf = indexOf = (array, item, from) ->
return array.indexOf item, from if array.indexOf
for other, index in array
if other is item and (not from or (from <= index))
return index
-1 |
| Does a list include a value? | helpers.include = include = (list, value) ->
indexOf(list, value) >= 0 |
| Peek at the beginning of a given string to see if it matches a sequence. | helpers.starts = starts = (string, literal, start) ->
string.substring(start, (start or 0) + literal.length) is literal |
| Peek at the end of a given string to see if it matches a sequence. | helpers.ends = ends = (string, literal, back) ->
start = string.length - literal.length - (back ? 0)
string.substring(start, start + literal.length) is literal |
| Trim out all falsy values from an array. | helpers.compact = compact = (array) -> item for item in array when item |
| Count the number of occurences of a character in a string. | helpers.count = count = (string, letter) ->
num = 0
pos = indexOf string, letter
while pos isnt -1
num += 1
pos = indexOf string, letter, pos + 1
num |
| Merge objects, returning a fresh copy with attributes from both sides.
Used every time | helpers.merge = merge = (options, overrides) ->
fresh = {}
(fresh[key] = val) for all key, val of options
(fresh[key] = val) for all key, val of overrides if overrides
fresh |
| Extend a source object with the properties of another object (shallow copy).
We use this to simulate Node's deprecated | helpers.extend = extend = (object, properties) ->
(object[key] = val) for all key, val of properties |
| Return a completely flattened version of an array. Handy for getting a
list of | helpers.flatten = flatten = (array) ->
memo = []
for item in array
if item instanceof Array then memo = memo.concat(item) else memo.push(item)
memo |
| Delete a key from an object, returning the value. Useful when a node is looking for a particular method in an options hash. | helpers.del = del = (obj, key) ->
val = obj[key]
delete obj[key]
val
|