// 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 a sequence of other patterns.
*/
goog.provide('goog.dom.pattern.Sequence');
goog.require('goog.dom.NodeType');
goog.require('goog.dom.pattern');
goog.require('goog.dom.pattern.AbstractPattern');
goog.require('goog.dom.pattern.MatchType');
/**
* Pattern object that matches a sequence of other patterns.
*
* @param {Array<goog.dom.pattern.AbstractPattern>} patterns Ordered array of
* patterns to match.
* @param {boolean=} opt_ignoreWhitespace Optional flag to ignore text nodes
* consisting entirely of whitespace. The default is to not ignore them.
* @constructor
* @extends {goog.dom.pattern.AbstractPattern}
* @final
*/
goog.dom.pattern.Sequence = function(patterns, opt_ignoreWhitespace) {
/**
* Ordered array of patterns to match.
*
* @type {Array<goog.dom.pattern.AbstractPattern>}
*/
this.patterns = patterns;
/**
* Whether or not to ignore whitespace only Text nodes.
*
* @private {boolean}
*/
this.ignoreWhitespace_ = !!opt_ignoreWhitespace;
/**
* Position in the patterns array we have reached by successful matches.
*
* @private {number}
*/
this.currentPosition_ = 0;
};
goog.inherits(goog.dom.pattern.Sequence, goog.dom.pattern.AbstractPattern);
/**
* Regular expression for breaking text nodes.
* @private {!RegExp}
*/
goog.dom.pattern.Sequence.BREAKING_TEXTNODE_RE_ = /^\s*$/;
/**
* Test whether the given token starts, continues, or finishes the sequence
* of patterns given in the constructor.
*
* @param {Node} token Token to match against.
* @param {goog.dom.TagWalkType} type The type of token.
* @return {goog.dom.pattern.MatchType} <code>MATCH</code> if the pattern
* matches, <code>MATCHING</code> if the pattern starts a match, and
* <code>NO_MATCH</code> if the pattern does not match.
* @override
*/
goog.dom.pattern.Sequence.prototype.matchToken = function(token, type) {
// If the option is set, ignore any whitespace only text nodes
if (this.ignoreWhitespace_ && token.nodeType == goog.dom.NodeType.TEXT &&
goog.dom.pattern.Sequence.BREAKING_TEXTNODE_RE_.test(token.nodeValue)) {
return goog.dom.pattern.MatchType.MATCHING;
}
switch (this.patterns[this.currentPosition_].matchToken(token, type)) {
case goog.dom.pattern.MatchType.MATCH:
// Record the first token we match.
if (this.currentPosition_ == 0) {
this.matchedNode = token;
}
// Move forward one position.
this.currentPosition_++;
// Check if this is the last position.
if (this.currentPosition_ == this.patterns.length) {
this.reset();
return goog.dom.pattern.MatchType.MATCH;
} else {
return goog.dom.pattern.MatchType.MATCHING;
}
case goog.dom.pattern.MatchType.MATCHING:
// This can happen when our child pattern is a sequence or a repetition.
return goog.dom.pattern.MatchType.MATCHING;
case goog.dom.pattern.MatchType.BACKTRACK_MATCH:
// This means a repetitive match succeeded 1 token ago.
// TODO(robbyw): Backtrack further if necessary.
this.currentPosition_++;
if (this.currentPosition_ == this.patterns.length) {
this.reset();
return goog.dom.pattern.MatchType.BACKTRACK_MATCH;
} else {
// Retry the same token on the next pattern.
return this.matchToken(token, type);
}
default:
this.reset();
return goog.dom.pattern.MatchType.NO_MATCH;
}
};
/**
* Reset any internal state this pattern keeps.
* @override
*/
goog.dom.pattern.Sequence.prototype.reset = function() {
if (this.patterns[this.currentPosition_]) {
this.patterns[this.currentPosition_].reset();
}
this.currentPosition_ = 0;
};