/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.wicket.util.parse.metapattern.parsers;
import java.util.regex.Matcher;
import org.apache.wicket.util.parse.metapattern.MetaPattern;
/**
* Base class for various MetaPattern based parsers.
*
* @author Jonathan Locke
*/
public abstract class MetaPatternParser
{
/** The input to parse */
private final CharSequence input;
/** The length of the input; no. of characters */
private final int length;
/**
* The position (index) behind the last pattern group matched while advancing from one pattern
* group to the next one.
*/
private int pos;
/** The object maintaining all the regex match details */
private Matcher matcher;
/**
* Construct the parser. You must call
*
* @see #advance(MetaPattern) to initialize the matcher with the pattern.
* @param input
* to parse
*/
public MetaPatternParser(final CharSequence input)
{
this.input = input;
length = input.length();
}
/**
* Construct the parser and initialize the matcher with the pattern given.
*
* @param pattern
* Meta pattern
* @param input
* Input to parse
*/
public MetaPatternParser(final MetaPattern pattern, final CharSequence input)
{
this(input);
setPattern(pattern);
}
/**
* @param pattern
* Pattern
*/
public void setPattern(final MetaPattern pattern)
{
matcher = pattern.matcher(input);
}
/**
* Advance parsing to the next element. The internal cursor will be moved to end of the string
* matched.
*
* @param pattern
* Meta pattern
* @return True if found, false otherwise
*/
protected final boolean advance(final MetaPattern pattern)
{
// get the remaining part of the input
final CharSequence s = input.subSequence(pos, length);
// does the pattern match?
matcher = pattern.matcher(s);
if (matcher.lookingAt())
{
// Yes, it does. Move the cursor to the end of the
// char sequence matched.
pos += matcher.end();
// Found the pattern
return true;
}
// Did not find the pattern.
return false;
}
/**
* Whether the matcher matches the pattern.
*
* @return whether the matcher matches
*/
public boolean matches()
{
return matcher.matches();
}
/**
* Gets the matcher.
*
* @return the matcher
*/
public final Matcher matcher()
{
return matcher;
}
/**
* Whether the internal cursor has advanced to the end of the input.
*
* @return whether the input is parsed
*/
public final boolean atEnd()
{
return pos == length;
}
}