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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 'use strict'; | |
6 | |
7 /** | |
8 * @class FunctionSequence to invoke steps in sequence | |
9 * | |
10 * @param {string} name // TODO(JSDOC). | |
11 * @param {Array} steps array of functions to invoke in sequence. | |
12 * @param {Object} logger logger. | |
13 * @param {function} callback callback to invoke on success. | |
14 * @param {function} failureCallback callback to invoke on failure. | |
15 * @constructor | |
16 */ | |
17 function FunctionSequence(name, steps, logger, callback, failureCallback) { | |
18 // Private variables hidden in closure | |
19 this.currentStepIdx_ = -1; | |
20 this.failed_ = false; | |
21 this.steps_ = steps; | |
22 this.callback_ = callback; | |
23 this.failureCallback_ = failureCallback; | |
24 this.logger = logger; | |
25 this.name = name; | |
26 | |
27 this.onError = this.onError_.bind(this); | |
28 this.finish = this.finish_.bind(this); | |
29 this.nextStep = this.nextStep_.bind(this); | |
30 this.apply = this.apply_.bind(this); | |
31 } | |
32 | |
33 /** | |
34 * Sets new callback | |
35 * | |
36 * @param {function} callback new callback to call on succeed. | |
37 */ | |
38 FunctionSequence.prototype.setCallback = function(callback) { | |
39 this.callback_ = callback; | |
40 }; | |
41 | |
42 /** | |
43 * Sets new error callback | |
44 * | |
45 * @param {function} failureCallback new callback to call on failure. | |
46 */ | |
47 FunctionSequence.prototype.setFailureCallback = function(failureCallback) { | |
48 this.failureCallback_ = failureCallback; | |
49 }; | |
50 | |
51 | |
52 /** | |
53 * Error handling function, which traces current error step, stops sequence | |
54 * advancing and fires error callback. | |
55 * | |
56 * @param {string} err Error message. | |
57 * @private | |
58 */ | |
59 FunctionSequence.prototype.onError_ = function(err) { | |
60 this.logger.vlog('Failed step: ' + this.steps_[this.currentStepIdx_].name + | |
61 ': ' + err); | |
62 if (!this.failed_) { | |
63 this.failed_ = true; | |
64 this.failureCallback_(err); | |
65 } | |
66 }; | |
67 | |
68 /** | |
69 * Finishes sequence processing and jumps to the last step. | |
70 * This method should not be used externally. In external | |
71 * cases should be used finish function, which is defined in closure and thus | |
72 * has access to internal variables of functionsequence. | |
73 * @private | |
74 */ | |
75 FunctionSequence.prototype.finish_ = function() { | |
76 if (!this.failed_ && this.currentStepIdx_ < this.steps_.length) { | |
77 this.currentStepIdx_ = this.steps_.length; | |
78 this.callback_(); | |
79 } | |
80 }; | |
81 | |
82 /** | |
83 * Advances to next step. | |
84 * This method should not be used externally. In external | |
85 * cases should be used nextStep function, which is defined in closure and thus | |
86 * has access to internal variables of functionsequence. | |
87 * @private | |
88 * @param {...} var_args // TODO(JSDOC). | |
89 */ | |
90 FunctionSequence.prototype.nextStep_ = function(var_args) { | |
91 if (this.failed_) { | |
92 return; | |
93 } | |
94 | |
95 if (++this.currentStepIdx_ >= this.steps_.length) { | |
96 this.logger.vlog('Sequence ended'); | |
97 this.callback_.apply(this, arguments); | |
98 } else { | |
99 this.logger.vlog('Attempting to start step [' + | |
100 this.steps_[this.currentStepIdx_].name + | |
101 ']'); | |
102 try { | |
103 this.steps_[this.currentStepIdx_].apply(this, arguments); | |
104 } catch (e) { | |
105 this.onError(e.toString()); | |
106 } | |
107 } | |
108 }; | |
109 | |
110 /** | |
111 * This function should be called only once on start, so start sequence pipeline | |
112 * @param {...} var_args // TODO(JSDOC). | |
113 */ | |
114 FunctionSequence.prototype.start = function(var_args) { | |
115 if (this.started) { | |
116 throw new Error('"Start" method of FunctionSequence was called twice'); | |
117 } | |
118 | |
119 this.logger.log('Starting sequence with ' + arguments.length + ' arguments'); | |
120 | |
121 this.started = true; | |
122 this.nextStep.apply(this, arguments); | |
123 }; | |
124 | |
125 /** | |
126 * Add Function object mimics to FunctionSequence | |
127 * @private | |
128 * @param {*} obj // TODO(JSDOC). | |
129 * @param {Array.*} args // TODO(JSDOC). | |
130 */ | |
131 FunctionSequence.prototype.apply_ = function(obj, args) { | |
132 this.start.apply(this, args); | |
133 }; | |
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