/*
*
* 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.qpid.messaging.util;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Lexer
*
*/
public class Lexer
{
private List<Token.Type> types;
private Token.Type eof;
private Pattern rexp;
public Lexer(List<Token.Type> types, Token.Type eof, Pattern rexp)
{
this.types = types;
this.eof = eof;
this.rexp = rexp;
}
public List<Token> lex(final String st)
{
List<Token> tokens = new ArrayList<Token>();
int position = 0;
Matcher m = rexp.matcher(st);
OUTER: while (position < st.length())
{
m.region(position, st.length());
if (m.lookingAt())
{
for (int i = 1; i <= m.groupCount(); i++)
{
String value = m.group(i);
if (value != null)
{
tokens.add(new Token(types.get(i-1), value, st, m.start(i)));
position = m.end(i);
continue OUTER;
}
}
throw new RuntimeException("no group matched");
}
else
{
throw new LexError("unrecognized characters line:" + LineInfo.get(st, position));
}
}
tokens.add(new Token(eof, null, st, position));
return tokens;
}
}