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jashkenas--coffeescript/examples/underscore.coffee
Jeremy Ashkenas c067808b54 CoffeeScript 0.6.0 is on the books.
2010-04-03 20:43:50 -04:00

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# **Underscore.coffee
# (c) 2010 Jeremy Ashkenas, DocumentCloud Inc.**
# Underscore is freely distributable under the terms of the
# [MIT license](http://en.wikipedia.org/wiki/MIT_License).
# Portions of Underscore are inspired by or borrowed from
# [Prototype.js](http://prototypejs.org/api), Oliver Steele's
# [Functional](http://osteele.com), and John Resig's
# [Micro-Templating](http://ejohn.com).
# For all details and documentation:
# http://documentcloud.github.com/underscore/
# Baseline setup
# --------------
# Establish the root object, `window` in the browser, or `global` on the server.
root: this
# Save the previous value of the `_` variable.
previousUnderscore: root._
# Establish the object that gets thrown to break out of a loop iteration.
# `StopIteration` is SOP on Mozilla.
breaker: if typeof(StopIteration) is 'undefined' then '__break__' else StopIteration
# Helper function to escape **RegExp** contents, because JS doesn't have one.
escapeRegExp: (string) -> string.replace(/([.*+?^${}()|[\]\/\\])/g, '\\$1')
# Save bytes in the minified (but not gzipped) version:
ArrayProto: Array.prototype
ObjProto: Object.prototype
# Create quick reference variables for speed access to core prototypes.
slice: ArrayProto.slice
unshift: ArrayProto.unshift
toString: ObjProto.toString
hasOwnProperty: ObjProto.hasOwnProperty
propertyIsEnumerable: ObjProto.propertyIsEnumerable
# All **ECMA5** native implementations we hope to use are declared here.
nativeForEach: ArrayProto.forEach
nativeMap: ArrayProto.map
nativeReduce: ArrayProto.reduce
nativeReduceRight: ArrayProto.reduceRight
nativeFilter: ArrayProto.filter
nativeEvery: ArrayProto.every
nativeSome: ArrayProto.some
nativeIndexOf: ArrayProto.indexOf
nativeLastIndexOf: ArrayProto.lastIndexOf
nativeIsArray: Array.isArray
nativeKeys: Object.keys
# Create a safe reference to the Underscore object for use below.
_: (obj) -> new wrapper(obj)
# Export the Underscore object for **CommonJS**.
if typeof(exports) != 'undefined' then exports._: _
# Export Underscore to global scope.
root._: _
# Current version.
_.VERSION: '1.0.2'
# Collection Functions
# --------------------
# The cornerstone, an **each** implementation.
# Handles objects implementing **forEach**, arrays, and raw objects.
_.each: (obj, iterator, context) ->
try
if nativeForEach and obj.forEach is nativeForEach
obj.forEach iterator, context
else if _.isNumber obj.length
iterator.call(context, obj[i], i, obj) for i in [0...obj.length]
else
iterator.call(context, val, key, obj) for key, val of obj
catch e
throw e if e isnt breaker
obj
# Return the results of applying the iterator to each element. Use JavaScript
# 1.6's version of **map**, if possible.
_.map: (obj, iterator, context) ->
return obj.map(iterator, context) if nativeMap and obj.map is nativeMap
results: []
_.each obj, (value, index, list) ->
results.push iterator.call context, value, index, list
results
# **Reduce** builds up a single result from a list of values. Also known as
# **inject**, or **foldl**. Uses JavaScript 1.8's version of **reduce**, if possible.
_.reduce: (obj, memo, iterator, context) ->
return obj.reduce(_.bind(iterator, context), memo) if nativeReduce and obj.reduce is nativeReduce
_.each obj, (value, index, list) ->
memo: iterator.call context, memo, value, index, list
memo
# The right-associative version of **reduce**, also known as **foldr**. Uses
# JavaScript 1.8's version of **reduceRight**, if available.
_.reduceRight: (obj, memo, iterator, context) ->
return obj.reduceRight(_.bind(iterator, context), memo) if nativeReduceRight and obj.reduceRight is nativeReduceRight
_.each _.clone(_.toArray(obj)).reverse(), (value, index) ->
memo: iterator.call context, memo, value, index, obj
memo
# Return the first value which passes a truth test.
_.detect: (obj, iterator, context) ->
result: null
_.each obj, (value, index, list) ->
if iterator.call context, value, index, list
result: value
_.breakLoop()
result
# Return all the elements that pass a truth test. Use JavaScript 1.6's
# **filter**, if it exists.
_.filter: (obj, iterator, context) ->
return obj.filter iterator, context if nativeFilter and obj.filter is nativeFilter
results: []
_.each obj, (value, index, list) ->
results.push value if iterator.call context, value, index, list
results
# Return all the elements for which a truth test fails.
_.reject: (obj, iterator, context) ->
results: []
_.each obj, (value, index, list) ->
results.push value if not iterator.call context, value, index, list
results
# Determine whether all of the elements match a truth test. Delegate to
# JavaScript 1.6's **every**, if it is present.
_.every: (obj, iterator, context) ->
iterator ||= _.identity
return obj.every iterator, context if nativeEvery and obj.every is nativeEvery
result: true
_.each obj, (value, index, list) ->
_.breakLoop() unless (result: result and iterator.call(context, value, index, list))
result
# Determine if at least one element in the object matches a truth test. Use
# JavaScript 1.6's **some**, if it exists.
_.some: (obj, iterator, context) ->
iterator ||= _.identity
return obj.some iterator, context if nativeSome and obj.some is nativeSome
result: false
_.each obj, (value, index, list) ->
_.breakLoop() if (result: iterator.call(context, value, index, list))
result
# Determine if a given value is included in the array or object,
# based on `===`.
_.include: (obj, target) ->
return _.indexOf(obj, target) isnt -1 if nativeIndexOf and obj.indexOf is nativeIndexOf
for key, val of obj
return true if val is target
false
# Invoke a method with arguments on every item in a collection.
_.invoke: (obj, method) ->
args: _.rest arguments, 2
(if method then val[method] else val).apply(val, args) for val in obj
# Convenience version of a common use case of **map**: fetching a property.
_.pluck: (obj, key) ->
_.map(obj, (val) -> val[key])
# Return the maximum item or (item-based computation).
_.max: (obj, iterator, context) ->
return Math.max.apply(Math, obj) if not iterator and _.isArray(obj)
result: {computed: -Infinity}
_.each obj, (value, index, list) ->
computed: if iterator then iterator.call(context, value, index, list) else value
computed >= result.computed and (result: {value: value, computed: computed})
result.value
# Return the minimum element (or element-based computation).
_.min: (obj, iterator, context) ->
return Math.min.apply(Math, obj) if not iterator and _.isArray(obj)
result: {computed: Infinity}
_.each obj, (value, index, list) ->
computed: if iterator then iterator.call(context, value, index, list) else value
computed < result.computed and (result: {value: value, computed: computed})
result.value
# Sort the object's values by a criterion produced by an iterator.
_.sortBy: (obj, iterator, context) ->
_.pluck(((_.map obj, (value, index, list) ->
{value: value, criteria: iterator.call(context, value, index, list)}
).sort((left, right) ->
a: left.criteria; b: right.criteria
if a < b then -1 else if a > b then 1 else 0
)), 'value')
# Use a comparator function to figure out at what index an object should
# be inserted so as to maintain order. Uses binary search.
_.sortedIndex: (array, obj, iterator) ->
iterator ||= _.identity
low: 0
high: array.length
while low < high
mid: (low + high) >> 1
if iterator(array[mid]) < iterator(obj) then low: mid + 1 else high: mid
low
# Convert anything iterable into a real, live array.
_.toArray: (iterable) ->
return [] if (!iterable)
return iterable.toArray() if (iterable.toArray)
return iterable if (_.isArray(iterable))
return slice.call(iterable) if (_.isArguments(iterable))
_.values(iterable)
# Return the number of elements in an object.
_.size: (obj) -> _.toArray(obj).length
# Array Functions
# ---------------
# Get the first element of an array. Passing `n` will return the first N
# values in the array. Aliased as **head**. The `guard` check allows it to work
# with **map**.
_.first: (array, n, guard) ->
if n and not guard then slice.call(array, 0, n) else array[0]
# Returns everything but the first entry of the array. Aliased as **tail**.
# Especially useful on the arguments object. Passing an `index` will return
# the rest of the values in the array from that index onward. The `guard`
# check allows it to work with **map**.
_.rest: (array, index, guard) ->
slice.call(array, if _.isUndefined(index) or guard then 1 else index)
# Get the last element of an array.
_.last: (array) -> array[array.length - 1]
# Trim out all falsy values from an array.
_.compact: (array) -> item for item in array when item
# Return a completely flattened version of an array.
_.flatten: (array) ->
_.reduce array, [], (memo, value) ->
return memo.concat(_.flatten(value)) if _.isArray value
memo.push value
memo
# Return a version of the array that does not contain the specified value(s).
_.without: (array) ->
values: _.rest arguments
val for val in _.toArray(array) when not _.include values, val
# Produce a duplicate-free version of the array. If the array has already
# been sorted, you have the option of using a faster algorithm.
_.uniq: (array, isSorted) ->
memo: []
for el, i in _.toArray array
memo.push el if i is 0 || (if isSorted is true then _.last(memo) isnt el else not _.include(memo, el))
memo
# Produce an array that contains every item shared between all the
# passed-in arrays.
_.intersect: (array) ->
rest: _.rest arguments
_.select _.uniq(array), (item) ->
_.all rest, (other) ->
_.indexOf(other, item) >= 0
# Zip together multiple lists into a single array -- elements that share
# an index go together.
_.zip: ->
length: _.max _.pluck arguments, 'length'
results: new Array length
for i in [0...length]
results[i]: _.pluck arguments, String i
results
# If the browser doesn't supply us with **indexOf** (I'm looking at you, MSIE),
# we need this function. Return the position of the first occurence of an
# item in an array, or -1 if the item is not included in the array.
_.indexOf: (array, item) ->
return array.indexOf item if nativeIndexOf and array.indexOf is nativeIndexOf
i: 0; l: array.length
while l - i
if array[i] is item then return i else i++
-1
# Provide JavaScript 1.6's **lastIndexOf**, delegating to the native function,
# if possible.
_.lastIndexOf: (array, item) ->
return array.lastIndexOf(item) if nativeLastIndexOf and array.lastIndexOf is nativeLastIndexOf
i: array.length
while i
if array[i] is item then return i else i--
-1
# Generate an integer Array containing an arithmetic progression. A port of
# [the native Python **range** function](http://docs.python.org/library/functions.html#range).
_.range: (start, stop, step) ->
a: arguments
solo: a.length <= 1
i: start: if solo then 0 else a[0]
stop: if solo then a[0] else a[1]
step: a[2] or 1
len: Math.ceil((stop - start) / step)
return [] if len <= 0
range: new Array len
idx: 0
while true
return range if (if step > 0 then i - stop else stop - i) >= 0
range[idx]: i
idx++
i+= step
# Function Functions
# ------------------
# Create a function bound to a given object (assigning `this`, and arguments,
# optionally). Binding with arguments is also known as **curry**.
_.bind: (func, obj) ->
args: _.rest arguments, 2
-> func.apply obj or root, args.concat arguments
# Bind all of an object's methods to that object. Useful for ensuring that
# all callbacks defined on an object belong to it.
_.bindAll: (obj) ->
funcs: if arguments.length > 1 then _.rest(arguments) else _.functions(obj)
_.each funcs, (f) -> obj[f]: _.bind obj[f], obj
obj
# Delays a function for the given number of milliseconds, and then calls
# it with the arguments supplied.
_.delay: (func, wait) ->
args: _.rest arguments, 2
setTimeout((-> func.apply(func, args)), wait)
# Defers a function, scheduling it to run after the current call stack has
# cleared.
_.defer: (func) ->
_.delay.apply _, [func, 1].concat _.rest arguments
# Returns the first function passed as an argument to the second,
# allowing you to adjust arguments, run code before and after, and
# conditionally execute the original function.
_.wrap: (func, wrapper) ->
-> wrapper.apply wrapper, [func].concat arguments
# Returns a function that is the composition of a list of functions, each
# consuming the return value of the function that follows.
_.compose: ->
funcs: arguments
->
args: arguments
for i in [(funcs.length - 1)..0]
args: [funcs[i].apply(this, args)]
args[0]
# Object Functions
# ----------------
# Retrieve the names of an object's properties.
_.keys: nativeKeys or (obj) ->
return _.range 0, obj.length if _.isArray(obj)
key for key, val of obj
# Retrieve the values of an object's properties.
_.values: (obj) ->
_.map obj, _.identity
# Return a sorted list of the function names available in Underscore.
_.functions: (obj) ->
_.filter(_.keys(obj), (key) -> _.isFunction(obj[key])).sort()
# Extend a given object with all of the properties in a source object.
_.extend: (obj) ->
for source in _.rest(arguments)
(obj[key]: val) for key, val of source
obj
# Create a (shallow-cloned) duplicate of an object.
_.clone: (obj) ->
return obj.slice 0 if _.isArray obj
_.extend {}, obj
# Invokes interceptor with the obj, and then returns obj.
# The primary purpose of this method is to "tap into" a method chain, in order to perform operations on intermediate results within the chain.
_.tap: (obj, interceptor) ->
interceptor obj
obj
# Perform a deep comparison to check if two objects are equal.
_.isEqual: (a, b) ->
# Check object identity.
return true if a is b
# Different types?
atype: typeof(a); btype: typeof(b)
return false if atype isnt btype
# Basic equality test (watch out for coercions).
return true if `a == b`
# One is falsy and the other truthy.
return false if (!a and b) or (a and !b)
# One of them implements an `isEqual()`?
return a.isEqual(b) if a.isEqual
# Check dates' integer values.
return a.getTime() is b.getTime() if _.isDate(a) and _.isDate(b)
# Both are NaN?
return true if _.isNaN(a) and _.isNaN(b)
# Compare regular expressions.
if _.isRegExp(a) and _.isRegExp(b)
return a.source is b.source and
a.global is b.global and
a.ignoreCase is b.ignoreCase and
a.multiline is b.multiline
# If a is not an object by this point, we can't handle it.
return false if atype isnt 'object'
# Check for different array lengths before comparing contents.
return false if a.length and (a.length isnt b.length)
# Nothing else worked, deep compare the contents.
aKeys: _.keys(a); bKeys: _.keys(b)
# Different object sizes?
return false if aKeys.length isnt bKeys.length
# Recursive comparison of contents.
(return false) for key, val of a when !(key in b) or !_.isEqual(val, b[key])
true
# Is a given array or object empty?
_.isEmpty: (obj) ->
return obj.length is 0 if _.isArray obj
(return false) for key of obj when hasOwnProperty.call(obj, key)
true
# Is a given value a DOM element?
_.isElement: (obj) -> obj and obj.nodeType is 1
# Is a given value an array?
_.isArray: nativeIsArray or (obj) -> !!(obj and obj.concat and obj.unshift and not obj.callee)
# Is a given variable an arguments object?
_.isArguments: (obj) -> obj and obj.callee
# Is the given value a function?
_.isFunction: (obj) -> !!(obj and obj.constructor and obj.call and obj.apply)
# Is the given value a string?
_.isString: (obj) -> !!(obj is '' or (obj and obj.charCodeAt and obj.substr))
# Is a given value a number?
_.isNumber: (obj) -> (obj is +obj) or toString.call(obj) is '[object Number]'
# Is a given value a boolean?
_.isBoolean: (obj) -> obj is true or obj is false
# Is a given value a Date?
_.isDate: (obj) -> !!(obj and obj.getTimezoneOffset and obj.setUTCFullYear)
# Is the given value a regular expression?
_.isRegExp: (obj) -> !!(obj and obj.exec and (obj.ignoreCase or obj.ignoreCase is false))
# Is the given value NaN -- this one is interesting. `NaN != NaN`, and
# `isNaN(undefined) == true`, so we make sure it's a number first.
_.isNaN: (obj) -> _.isNumber(obj) and window.isNaN(obj)
# Is a given value equal to null?
_.isNull: (obj) -> obj is null
# Is a given variable undefined?
_.isUndefined: (obj) -> typeof obj is 'undefined'
# Utility Functions
# -----------------
# Run Underscore.js in noConflict mode, returning the `_` variable to its
# previous owner. Returns a reference to the Underscore object.
_.noConflict: ->
root._: previousUnderscore
this
# Keep the identity function around for default iterators.
_.identity: (value) -> value
# Run a function `n` times.
_.times: (n, iterator, context) ->
iterator.call(context, i) for i in [0...n]
# Break out of the middle of an iteration.
_.breakLoop: -> throw breaker
# Add your own custom functions to the Underscore object, ensuring that
# they're correctly added to the OOP wrapper as well.
_.mixin: (obj) ->
for name in _.functions(obj)
addToWrapper name, _[name]: obj[name]
# Generate a unique integer id (unique within the entire client session).
# Useful for temporary DOM ids.
idCounter: 0
_.uniqueId: (prefix) ->
(prefix or '') + idCounter++
# By default, Underscore uses **ERB**-style template delimiters, change the
# following template settings to use alternative delimiters.
_.templateSettings: {
start: '<%'
end: '%>'
interpolate: /<%=(.+?)%>/g
}
# JavaScript templating a-la **ERB**, pilfered from John Resig's
# *Secrets of the JavaScript Ninja*, page 83.
# Single-quote fix from Rick Strahl.
_.template: (str, data) ->
c: _.templateSettings
endMatch: new RegExp("'(?=[^"+c.end.substr(0, 1)+"]*"+escapeRegExp(c.end)+")","g")
fn: new Function 'obj',
'var p=[],print=function(){p.push.apply(p,arguments);};' +
'with(obj){p.push(\'' +
str.replace(/[\r\t\n]/g, " ")
.replace(endMatch,"\t")
.split("'").join("\\'")
.split("\t").join("'")
.replace(c.interpolate, "',$1,'")
.split(c.start).join("');")
.split(c.end).join("p.push('") +
"');}return p.join('');"
if data then fn(data) else fn
# Aliases
# -------
_.forEach: _.each
_.foldl: _.inject: _.reduce
_.foldr: _.reduceRight
_.select: _.filter
_.all: _.every
_.any: _.some
_.head: _.first
_.tail: _.rest
_.methods: _.functions
# Setup the OOP Wrapper
# ---------------------
# If Underscore is called as a function, it returns a wrapped object that
# can be used OO-style. This wrapper holds altered versions of all the
# underscore functions. Wrapped objects may be chained.
wrapper: (obj) ->
this._wrapped: obj
this
# Helper function to continue chaining intermediate results.
result: (obj, chain) ->
if chain then _(obj).chain() else obj
# A method to easily add functions to the OOP wrapper.
addToWrapper: (name, func) ->
wrapper.prototype[name]: ->
args: _.toArray arguments
unshift.call args, this._wrapped
result func.apply(_, args), this._chain
# Add all of the Underscore functions to the wrapper object.
_.mixin _
# Add all mutator Array functions to the wrapper.
_.each ['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], (name) ->
method: Array.prototype[name]
wrapper.prototype[name]: ->
method.apply(this._wrapped, arguments)
result(this._wrapped, this._chain)
# Add all accessor Array functions to the wrapper.
_.each ['concat', 'join', 'slice'], (name) ->
method: Array.prototype[name]
wrapper.prototype[name]: ->
result(method.apply(this._wrapped, arguments), this._chain)
# Start chaining a wrapped Underscore object.
wrapper::chain: ->
this._chain: true
this
# Extracts the result from a wrapped and chained object.
wrapper::value: -> this._wrapped
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