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// Copyright 2012 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview A SimpleResult object that implements goog.result.Result.
* See below for a more detailed description.
*/
goog.provide('goog.result.SimpleResult');
goog.provide('goog.result.SimpleResult.StateError');
goog.require('goog.debug.Error');
goog.require('goog.result.Result');
/**
* A SimpleResult object is a basic implementation of the
* goog.result.Result interface. This could be subclassed(e.g. XHRResult)
* or instantiated and returned by another class as a form of result. The caller
* receiving the result could then attach handlers to be called when the result
* is resolved(success or error).
*
* @constructor
* @implements {goog.result.Result}
*/
goog.result.SimpleResult = function() {
/**
* The current state of this Result.
* @type {goog.result.Result.State}
* @private
*/
this.state_ = goog.result.Result.State.PENDING;
/**
* The list of handlers to call when this Result is resolved.
* @type {!Array.<!function(goog.result.SimpleResult)>}
* @private
*/
this.handlers_ = [];
};
/**
* The 'value' of this Result.
* @type {*}
* @private
*/
goog.result.SimpleResult.prototype.value_;
/**
* The error slug for this Result.
* @type {*}
* @private
*/
goog.result.SimpleResult.prototype.error_;
/**
* Error thrown if there is an attempt to set the value or error for this result
* more than once.
*
* @constructor
* @extends {goog.debug.Error}
*/
goog.result.SimpleResult.StateError = function() {
goog.base(this, 'Multiple attempts to set the state of this Result');
};
goog.inherits(goog.result.SimpleResult.StateError, goog.debug.Error);
/** @override */
goog.result.SimpleResult.prototype.getState = function() {
return this.state_;
};
/** @override */
goog.result.SimpleResult.prototype.getValue = function() {
return this.value_;
};
/** @override */
goog.result.SimpleResult.prototype.getError = function() {
return this.error_;
};
/**
* Attaches handlers to be called when the value of this Result is available.
*
* @param {!function(!goog.result.SimpleResult)} handler The function
* called when the value is available. The function is passed the Result
* object as the only argument.
* @override
*/
goog.result.SimpleResult.prototype.wait = function(handler) {
if (this.isPending_()) {
this.handlers_.push(handler);
} else {
handler(this);
}
};
/**
* Sets the value of this Result, changing the state.
*
* @param {*} value The value to set for this Result.
*/
goog.result.SimpleResult.prototype.setValue = function(value) {
if (this.isPending_()) {
this.value_ = value;
this.state_ = goog.result.Result.State.SUCCESS;
this.callHandlers_();
} else if (!this.isCanceled()) {
// setValue is a no-op if this Result has been canceled.
throw new goog.result.SimpleResult.StateError();
}
};
/**
* Sets the Result to be an error Result.
*
* @param {*=} opt_error Optional error slug to set for this Result.
*/
goog.result.SimpleResult.prototype.setError = function(opt_error) {
if (this.isPending_()) {
this.error_ = opt_error;
this.state_ = goog.result.Result.State.ERROR;
this.callHandlers_();
} else if (!this.isCanceled()) {
// setError is a no-op if this Result has been canceled.
throw new goog.result.SimpleResult.StateError();
}
};
/**
* Calls the handlers registered for this Result.
*
* @private
*/
goog.result.SimpleResult.prototype.callHandlers_ = function() {
while (this.handlers_.length) {
var callback = this.handlers_.shift();
callback(this);
}
};
/**
* @return {boolean} Whether the Result is pending.
* @private
*/
goog.result.SimpleResult.prototype.isPending_ = function() {
return this.state_ == goog.result.Result.State.PENDING;
};
/**
* Cancels the Result.
*
* @return {boolean} Whether the result was canceled. It will not be canceled if
* the result was already canceled or has already resolved.
* @override
*/
goog.result.SimpleResult.prototype.cancel = function() {
// cancel is a no-op if the result has been resolved.
if (this.isPending_()) {
this.setError(new goog.result.Result.CancelError());
return true;
}
return false;
};
/** @override */
goog.result.SimpleResult.prototype.isCanceled = function() {
return this.state_ == goog.result.Result.State.ERROR &&
this.error_ instanceof goog.result.Result.CancelError;
};
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