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// Copyright 2007 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 DOM pattern to match any children of a tag, and
* specifically collect those that match a child pattern.
*
* @author robbyw@google.com (Robby Walker)
*/
goog.provide('goog.dom.pattern.ChildMatches');
goog.require('goog.dom.pattern.AllChildren');
goog.require('goog.dom.pattern.MatchType');
/**
* Pattern object that matches any nodes at or below the current tree depth.
*
* @param {goog.dom.pattern.AbstractPattern} childPattern Pattern to collect
* child matches of.
* @param {number=} opt_minimumMatches Enforce a minimum nuber of matches.
* Defaults to 0.
* @constructor
* @extends {goog.dom.pattern.AllChildren}
*/
goog.dom.pattern.ChildMatches = function(childPattern, opt_minimumMatches) {
this.childPattern_ = childPattern;
this.matches = [];
this.minimumMatches_ = opt_minimumMatches || 0;
goog.dom.pattern.AllChildren.call(this);
};
goog.inherits(goog.dom.pattern.ChildMatches, goog.dom.pattern.AllChildren);
/**
* Array of matched child nodes.
*
* @type {Array.<Node>}
*/
goog.dom.pattern.ChildMatches.prototype.matches;
/**
* Minimum number of matches.
*
* @type {number}
* @private
*/
goog.dom.pattern.ChildMatches.prototype.minimumMatches_ = 0;
/**
* The child pattern to collect matches from.
*
* @type {goog.dom.pattern.AbstractPattern}
* @private
*/
goog.dom.pattern.ChildMatches.prototype.childPattern_;
/**
* Whether the pattern has recently matched or failed to match and will need to
* be reset when starting a new round of matches.
*
* @type {boolean}
* @private
*/
goog.dom.pattern.ChildMatches.prototype.needsReset_ = false;
/**
* Test whether the given token is on the same level.
*
* @param {Node} token Token to match against.
* @param {goog.dom.TagWalkType} type The type of token.
* @return {goog.dom.pattern.MatchType} {@code MATCHING} if the token is on the
* same level or deeper and {@code BACKTRACK_MATCH} if not.
* @override
*/
goog.dom.pattern.ChildMatches.prototype.matchToken = function(token, type) {
// Defer resets so we maintain our matches array until the last possible time.
if (this.needsReset_) {
this.reset();
}
// Call the super-method to ensure we stay in the child tree.
var status =
goog.dom.pattern.AllChildren.prototype.matchToken.apply(this, arguments);
switch (status) {
case goog.dom.pattern.MatchType.MATCHING:
var backtrack = false;
switch (this.childPattern_.matchToken(token, type)) {
case goog.dom.pattern.MatchType.BACKTRACK_MATCH:
backtrack = true;
case goog.dom.pattern.MatchType.MATCH:
// Collect the match.
this.matches.push(this.childPattern_.matchedNode);
break;
default:
// Keep trying if we haven't hit a terminal state.
break;
}
if (backtrack) {
// The only interesting result is a MATCH, since BACKTRACK_MATCH means
// we are hitting an infinite loop on something like a Repeat(0).
if (this.childPattern_.matchToken(token, type) ==
goog.dom.pattern.MatchType.MATCH) {
this.matches.push(this.childPattern_.matchedNode);
}
}
return goog.dom.pattern.MatchType.MATCHING;
case goog.dom.pattern.MatchType.BACKTRACK_MATCH:
// TODO(robbyw): this should return something like BACKTRACK_NO_MATCH
// when we don't meet our minimum.
this.needsReset_ = true;
return (this.matches.length >= this.minimumMatches_) ?
goog.dom.pattern.MatchType.BACKTRACK_MATCH :
goog.dom.pattern.MatchType.NO_MATCH;
default:
this.needsReset_ = true;
return status;
}
};
/**
* Reset any internal state this pattern keeps.
* @override
*/
goog.dom.pattern.ChildMatches.prototype.reset = function() {
this.needsReset_ = false;
this.matches.length = 0;
this.childPattern_.reset();
goog.dom.pattern.AllChildren.prototype.reset.call(this);
};
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