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/*
* grunt
* http://gruntjs.com/
*
* Copyright (c) 2013 "Cowboy" Ben Alman
* Licensed under the MIT license.
* https://github.com/gruntjs/grunt/blob/master/LICENSE-MIT
*/
(function(exports) {
'use strict';
// Construct-o-rama.
function Task() {
// Information about the currently-running task.
this.current = {};
// Tasks.
this._tasks = {};
// Task queue.
this._queue = [];
// Queue placeholder (for dealing with nested tasks).
this._placeholder = {placeholder: true};
// Queue marker (for clearing the queue programatically).
this._marker = {marker: true};
// Options.
this._options = {};
// Is the queue running?
this._running = false;
// Success status of completed tasks.
this._success = {};
}
// Expose the constructor function.
exports.Task = Task;
// Create a new Task instance.
exports.create = function() {
return new Task();
};
// If the task runner is running or an error handler is not defined, throw
// an exception. Otherwise, call the error handler directly.
Task.prototype._throwIfRunning = function(obj) {
if (this._running || !this._options.error) {
// Throw an exception that the task runner will catch.
throw obj;
} else {
// Not inside the task runner. Call the error handler and abort.
this._options.error.call({name: null}, obj);
}
};
// Register a new task.
Task.prototype.registerTask = function(name, info, fn) {
// If optional "info" string is omitted, shuffle arguments a bit.
if (fn == null) {
fn = info;
info = null;
}
// String or array of strings was passed instead of fn.
var tasks;
if (typeof fn !== 'function') {
// Array of task names.
tasks = this.parseArgs([fn]);
// This task function just runs the specified tasks.
fn = this.run.bind(this, fn);
fn.alias = true;
// Generate an info string if one wasn't explicitly passed.
if (!info) {
info = 'Alias for "' + tasks.join('", "') + '" task' +
(tasks.length === 1 ? '' : 's') + '.';
}
} else if (!info) {
info = 'Custom task.';
}
// Add task into cache.
this._tasks[name] = {name: name, info: info, fn: fn};
// Make chainable!
return this;
};
// Is the specified task an alias?
Task.prototype.isTaskAlias = function(name) {
return !!this._tasks[name].fn.alias;
};
// Rename a task. This might be useful if you want to override the default
// behavior of a task, while retaining the old name. This is a billion times
// easier to implement than some kind of in-task "super" functionality.
Task.prototype.renameTask = function(oldname, newname) {
// Rename task.
this._tasks[newname] = this._tasks[oldname];
// Update name property of task.
this._tasks[newname].name = newname;
// Remove old name.
delete this._tasks[oldname];
// Make chainable!
return this;
};
// Argument parsing helper. Supports these signatures:
// fn('foo') // ['foo']
// fn('foo', 'bar', 'baz') // ['foo', 'bar', 'baz']
// fn(['foo', 'bar', 'baz']) // ['foo', 'bar', 'baz']
Task.prototype.parseArgs = function(args) {
// Return the first argument if it's an array, otherwise return an array
// of all arguments.
return Array.isArray(args[0]) ? args[0] : [].slice.call(args);
};
// Split a colon-delimited string into an array, unescaping (but not
// splitting on) any \: escaped colons.
Task.prototype.splitArgs = function(str) {
if (!str) { return []; }
// Store placeholder for \\ followed by \:
str = str.replace(/\\\\/g, '\uFFFF').replace(/\\:/g, '\uFFFE');
// Split on :
return str.split(':').map(function(s) {
// Restore place-held : followed by \\
return s.replace(/\uFFFE/g, ':').replace(/\uFFFF/g, '\\');
});
};
// Given a task name, determine which actual task will be called, and what
// arguments will be passed into the task callback. "foo" -> task "foo", no
// args. "foo:bar:baz" -> task "foo:bar:baz" with no args (if "foo:bar:baz"
// task exists), otherwise task "foo:bar" with arg "baz" (if "foo:bar" task
// exists), otherwise task "foo" with args "bar" and "baz".
Task.prototype._taskPlusArgs = function(name) {
// Get task name / argument parts.
var parts = this.splitArgs(name);
// Start from the end, not the beginning!
var i = parts.length;
var task;
do {
// Get a task.
task = this._tasks[parts.slice(0, i).join(':')];
// If the task doesn't exist, decrement `i`, and if `i` is greater than
// 0, repeat.
} while (!task && --i > 0);
// Just the args.
var args = parts.slice(i);
// Maybe you want to use them as flags instead of as positional args?
var flags = {};
args.forEach(function(arg) { flags[arg] = true; });
// The task to run and the args to run it with.
return {task: task, nameArgs: name, args: args, flags: flags};
};
// Append things to queue in the correct spot.
Task.prototype._push = function(things) {
// Get current placeholder index.
var index = this._queue.indexOf(this._placeholder);
if (index === -1) {
// No placeholder, add task+args objects to end of queue.
this._queue = this._queue.concat(things);
} else {
// Placeholder exists, add task+args objects just before placeholder.
[].splice.apply(this._queue, [index, 0].concat(things));
}
};
// Enqueue a task.
Task.prototype.run = function() {
// Parse arguments into an array, returning an array of task+args objects.
var things = this.parseArgs(arguments).map(this._taskPlusArgs, this);
// Throw an exception if any tasks weren't found.
var fails = things.filter(function(thing) { return !thing.task; });
if (fails.length > 0) {
this._throwIfRunning(new Error('Task "' + fails[0].nameArgs + '" not found.'));
return this;
}
// Append things to queue in the correct spot.
this._push(things);
// Make chainable!
return this;
};
// Add a marker to the queue to facilitate clearing it programatically.
Task.prototype.mark = function() {
this._push(this._marker);
// Make chainable!
return this;
};
// Run a task function, handling this.async / return value.
Task.prototype.runTaskFn = function(context, fn, done) {
// Async flag.
var async = false;
// Update the internal status object and run the next task.
var complete = function(success) {
var err = null;
if (success === false) {
// Since false was passed, the task failed generically.
err = new Error('Task "' + context.nameArgs + '" failed.');
} else if (success instanceof Error || {}.toString.call(success) === '[object Error]') {
// An error object was passed, so the task failed specifically.
err = success;
success = false;
} else {
// The task succeeded.
success = true;
}
// The task has ended, reset the current task object.
this.current = {};
// A task has "failed" only if it returns false (async) or if the
// function returned by .async is passed false.
this._success[context.nameArgs] = success;
// If task failed, call error handler.
if (!success && this._options.error) {
this._options.error.call({name: context.name, nameArgs: context.nameArgs}, err);
}
done(err, success);
}.bind(this);
// When called, sets the async flag and returns a function that can
// be used to continue processing the queue.
context.async = function() {
async = true;
// The returned function should execute asynchronously in case
// someone tries to do this.async()(); inside a task (WTF).
return function(success) {
setTimeout(function() { complete(success); }, 1);
};
};
// Expose some information about the currently-running task.
this.current = context;
try {
// Get the current task and run it, setting `this` inside the task
// function to be something useful.
var success = fn.call(context);
// If the async flag wasn't set, process the next task in the queue.
if (!async) {
complete(success);
}
} catch (err) {
complete(err);
}
};
// Begin task queue processing. Ie. run all tasks.
Task.prototype.start = function() {
// Abort if already running.
if (this._running) { return false; }
// Actually process the next task.
var nextTask = function() {
// Get next task+args object from queue.
var thing;
// Skip any placeholders or markers.
do {
thing = this._queue.shift();
} while (thing === this._placeholder || thing === this._marker);
// If queue was empty, we're all done.
if (!thing) {
this._running = false;
if (this._options.done) {
this._options.done();
}
return;
}
// Add a placeholder to the front of the queue.
this._queue.unshift(this._placeholder);
// Expose some information about the currently-running task.
var context = {
// The current task name plus args, as-passed.
nameArgs: thing.nameArgs,
// The current task name.
name: thing.task.name,
// The current task arguments.
args: thing.args,
// The current arguments, available as named flags.
flags: thing.flags
};
// Actually run the task function (handling this.async, etc)
this.runTaskFn(context, function() {
return thing.task.fn.apply(this, this.args);
}, nextTask);
}.bind(this);
// Update flag.
this._running = true;
// Process the next task.
nextTask();
};
// Clear remaining tasks from the queue.
Task.prototype.clearQueue = function(options) {
if (!options) { options = {}; }
if (options.untilMarker) {
this._queue.splice(0, this._queue.indexOf(this._marker) + 1);
} else {
this._queue = [];
}
// Make chainable!
return this;
};
// Test to see if all of the given tasks have succeeded.
Task.prototype.requires = function() {
this.parseArgs(arguments).forEach(function(name) {
var success = this._success[name];
if (!success) {
throw new Error('Required task "' + name +
'" ' + (success === false ? 'failed' : 'must be run first') + '.');
}
}.bind(this));
};
// Override default options.
Task.prototype.options = function(options) {
Object.keys(options).forEach(function(name) {
this._options[name] = options[name];
}.bind(this));
};
}(typeof exports === 'object' && exports || this));