The Tor Browser: comparison addon-sdk/source/lib/sdk/lang/functional.js

comparison: addon-sdk/source/lib/sdk/lang/functional.js

addon-sdk/source/lib/sdk/lang/functional.js

branch: TOR_BUG_3246
changeset 7: 129ffea94266

equal deleted inserted replaced

--1:000000000000
+:39408fb78dd4
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+// Disclaimer: Some of the functions in this module implement APIs from
+// Jeremy Ashkenas's http://underscorejs.org/ library and all credits for
+// those goes to him.
+"use strict";
+module.metadata = {
+"stability": "unstable"
+};
+const { deprecateFunction } = require("../util/deprecate");
+const { setImmediate, setTimeout, clearTimeout } = require("../timers");
+const arity = f => f.arity || f.length;
+const name = f => f.displayName || f.name;
+const derive = (f, source) => {
+f.displayName = name(source);
+f.arity = arity(source);
+return f;
+};
+/**
+* Takes variadic numeber of functions and returns composed one.
+* Returned function pushes `this` pseudo-variable to the head
+* of the passed arguments and invokes all the functions from
+* left to right passing same arguments to them. Composite function
+* returns return value of the right most funciton.
+*/
+const method = (...lambdas) => {
+return function method(...args) {
+args.unshift(this);
+return lambdas.reduce((_, lambda) => lambda.apply(this, args),
+void(0));
+};
+};
+exports.method = method;
+/**
+* Takes a function and returns a wrapped one instead, calling which will call
+* original function in the next turn of event loop. This is basically utility
+* to do `setImmediate(function() { ... })`, with a difference that returned
+* function is reused, instead of creating a new one each time. This also allows
+* to use this functions as event listeners.
+*/
+const defer = f => derive(function(...args) {
+setImmediate(invoke, f, args, this);
+}, f);
+exports.defer = defer;
+// Exporting `remit` alias as `defer` may conflict with promises.
+exports.remit = defer;
+/**
+* Invokes `callee` by passing `params` as an arguments and `self` as `this`
+* pseudo-variable. Returns value that is returned by a callee.
+* @param {Function} callee
+*    Function to invoke.
+* @param {Array} params
+*    Arguments to invoke function with.
+* @param {Object} self
+*    Object to be passed as a `this` pseudo variable.
+*/
+const invoke = (callee, params, self) => callee.apply(self, params);
+exports.invoke = invoke;
+/**
+* Takes a function and bind values to one or more arguments, returning a new
+* function of smaller arity.
+*
+* @param {Function} fn
+*    The function to partial
+*
+* @returns The new function with binded values
+*/
+const partial = (f, ...curried) => {
+if (typeof(f) !== "function")
+throw new TypeError(String(f) + " is not a function");
+let fn = derive(function(...args) {
+return f.apply(this, curried.concat(args));
+}, f);
+fn.arity = arity(f) - curried.length;
+return fn;
+};
+exports.partial = partial;
+/**
+* Returns function with implicit currying, which will continue currying until
+* expected number of argument is collected. Expected number of arguments is
+* determined by `fn.length`. Using this with variadic functions is stupid,
+* so don't do it.
+*
+* @examples
+*
+* var sum = curry(function(a, b) {
+*   return a + b
+* })
+* console.log(sum(2, 2)) // 4
+* console.log(sum(2)(4)) // 6
+*/
+const curry = new function() {
+const currier = (fn, arity, params) => {
+// Function either continues to curry arguments or executes function
+// if desired arguments have being collected.
+const curried = function(...input) {
+// Prepend all curried arguments to the given arguments.
+if (params) input.unshift.apply(input, params);
+// If expected number of arguments has being collected invoke fn,
+// othrewise return curried version Otherwise continue curried.
+return (input.length >= arity) ? fn.apply(this, input) :
+currier(fn, arity, input);
+};
+curried.arity = arity - (params ? params.length : 0);
+return curried;
+};
+return fn => currier(fn, arity(fn));
+};
+exports.curry = curry;
+/**
+* Returns the composition of a list of functions, where each function consumes
+* the return value of the function that follows. In math terms, composing the
+* functions `f()`, `g()`, and `h()` produces `f(g(h()))`.
+* @example
+*
+*   var greet = function(name) { return "hi: " + name; };
+*   var exclaim = function(statement) { return statement + "!"; };
+*   var welcome = compose(exclaim, greet);
+*
+*   welcome('moe');    // => 'hi: moe!'
+*/
+function compose(...lambdas) {
+return function composed(...args) {
+let index = lambdas.length;
+while (0 <= --index)
+args = [lambdas[index].apply(this, args)];
+return args[0];
+};
+}
+exports.compose = compose;
+/*
+* 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.
+* @example
+*
+*  var hello = function(name) { return "hello: " + name; };
+*  hello = wrap(hello, function(f) {
+*    return "before, " + f("moe") + ", after";
+*  });
+*
+*  hello();    // => 'before, hello: moe, after'
+*/
+const wrap = (f, wrapper) => derive(function wrapped(...args) {
+return wrapper.apply(this, [f].concat(args));
+}, f);
+exports.wrap = wrap;
+/**
+* Returns the same value that is used as the argument. In math: f(x) = x
+*/
+const identity = value => value;
+exports.identity = identity;
+/**
+* Memoizes a given function by caching the computed result. Useful for
+* speeding up slow-running computations. If passed an optional hashFunction,
+* it will be used to compute the hash key for storing the result, based on
+* the arguments to the original function. The default hashFunction just uses
+* the first argument to the memoized function as the key.
+*/
+const memoize = (f, hasher) => {
+let memo = Object.create(null);
+let cache = new WeakMap();
+hasher = hasher || identity;
+return derive(function memoizer(...args) {
+const key = hasher.apply(this, args);
+const type = typeof(key);
+if (key && (type === "object" || type === "function")) {
+if (!cache.has(key))
+cache.set(key, f.apply(this, args));
+return cache.get(key);
+}
+else {
+if (!(key in memo))
+memo[key] = f.apply(this, args);
+return memo[key];
+}
+}, f);
+};
+exports.memoize = memoize;
+/**
+* Much like setTimeout, invokes function after wait milliseconds. If you pass
+* the optional arguments, they will be forwarded on to the function when it is
+* invoked.
+*/
+const delay = function delay(f, ms, ...args) {
+setTimeout(() => f.apply(this, args), ms);
+};
+exports.delay = delay;
+/**
+* Creates a version of the function that can only be called one time. Repeated
+* calls to the modified function will have no effect, returning the value from
+* the original call. Useful for initialization functions, instead of having to
+* set a boolean flag and then check it later.
+*/
+const once = f => {
+let ran = false, cache;
+return derive(function(...args) {
+return ran ? cache : (ran = true, cache = f.apply(this, args));
+}, f);
+};
+exports.once = once;
+// export cache as once will may be conflicting with event once a lot.
+exports.cache = once;
+// Takes a `f` function and returns a function that takes the same
+// arguments as `f`, has the same effects, if any, and returns the
+// opposite truth value.
+const complement = f => derive(function(...args) {
+return args.length < arity(f) ? complement(partial(f, ...args)) :
+!f.apply(this, args);
+}, f);
+exports.complement = complement;
+// Constructs function that returns `x` no matter what is it
+// invoked with.
+const constant = x => _ => x;
+exports.constant = constant;
+// Takes `p` predicate, `consequent` function and an optional
+// `alternate` function and composes function that returns
+// application of arguments over `consequent` if application over
+// `p` is `true` otherwise returns application over `alternate`.
+// If `alternate` is not a function returns `undefined`.
+const when = (p, consequent, alternate) => {
+if (typeof(alternate) !== "function" && alternate !== void(0))
+throw TypeError("alternate must be a function");
+if (typeof(consequent) !== "function")
+throw TypeError("consequent must be a function");
+return function(...args) {
+return p.apply(this, args) ?
+consequent.apply(this, args) :
+alternate && alternate.apply(this, args);
+};
+};
+exports.when = when;
+// Apply function that behaves as `apply` does in lisp:
+// apply(f, x, [y, z]) => f.apply(f, [x, y, z])
+// apply(f, x) => f.apply(f, [x])
+const apply = (f, ...rest) => f.apply(f, rest.concat(rest.pop()));
+exports.apply = apply;
+// Returns function identical to given `f` but with flipped order
+// of arguments.
+const flip = f => derive(function(...args) {
+return f.apply(this, args.reverse());
+}, f);
+exports.flip = flip;
+// Takes field `name` and `target` and returns value of that field.
+// If `target` is `null` or `undefined` it would be returned back
+// instead of attempt to access it's field. Function is implicitly
+// curried, this allows accessor function generation by calling it
+// with only `name` argument.
+const field = curry((name, target) =>
+// Note: Permisive `==` is intentional.
+target == null ? target : target[name]);
+exports.field = field;
+// Takes `.` delimited string representing `path` to a nested field
+// and a `target` to get it from. For convinience function is
+// implicitly curried, there for accessors can be created by invoking
+// it with just a `path` argument.
+const query = curry((path, target) => {
+const names = path.split(".");
+const count = names.length;
+let index = 0;
+let result = target;
+// Note: Permisive `!=` is intentional.
+while (result != null && index < count) {
+result = result[names[index]];
+index = index + 1;
+}
+return result;
+});
+exports.query = query;
+// Takes `Type` (constructor function) and a `value` and returns
+// `true` if `value` is instance of the given `Type`. Function is
+// implicitly curried this allows predicate generation by calling
+// function with just first argument.
+const isInstance = curry((Type, value) => value instanceof Type);
+exports.isInstance = isInstance;
+/*
+* Takes a funtion and returns a wrapped function that returns `this`
+*/
+const chainable = f => derive(function(...args) {
+f.apply(this, args);
+return this;
+}, f);
+exports.chainable = chainable;
+exports.chain =
+deprecateFunction(chainable, "Function `chain` was renamed to `chainable`");
+// Functions takes `expected` and `actual` values and returns `true` if
+// `expected === actual`. Returns curried function if called with less then
+// two arguments.
+//
+// [ 1, 0, 1, 0, 1 ].map(is(1)) // => [ true, false, true, false, true ]
+const is = curry((expected, actual) => actual === expected);
+exports.is = is;
+const isnt = complement(is);
+exports.isnt = isnt;
+/**
+* From underscore's `_.debounce`
+* http://underscorejs.org
+* (c) 2009-2014 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
+* Underscore may be freely distributed under the MIT license.
+*/
+const debounce = function debounce (fn, wait) {
+let timeout, args, context, timestamp, result;
+let later = function () {
+let last = Date.now() - timestamp;
+if (last < wait) {
+timeout = setTimeout(later, wait - last);
+} else {
+timeout = null;
+result = fn.apply(context, args);
+context = args = null;
+}
+};
+return function (...aArgs) {
+context = this;
+args = aArgs;
+timestamp  = Date.now();
+if (!timeout) {
+timeout = setTimeout(later, wait);
+}
+return result;
+};
+};
+exports.debounce = debounce;
+/**
+* From underscore's `_.throttle`
+* http://underscorejs.org
+* (c) 2009-2014 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
+* Underscore may be freely distributed under the MIT license.
+*/
+const throttle = function throttle (func, wait, options) {
+let context, args, result;
+let timeout = null;
+let previous = 0;
+options || (options = {});
+let later = function() {
+previous = options.leading === false ? 0 : Date.now();
+timeout = null;
+result = func.apply(context, args);
+context = args = null;
+};
+return function() {
+let now = Date.now();
+if (!previous && options.leading === false) previous = now;
+let remaining = wait - (now - previous);
+context = this;
+args = arguments;
+if (remaining <= 0) {
+clearTimeout(timeout);
+timeout = null;
+previous = now;
+result = func.apply(context, args);
+context = args = null;
+} else if (!timeout && options.trailing !== false) {
+timeout = setTimeout(later, remaining);
+}
+return result;
+};
+};
+exports.throttle = throttle;