io.debezium.antlr.CaseChangingCharStream Maven / Gradle / Ivy
/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
*
* Licensed under the BSD 3-clause license, available at https://raw.githubusercontent.com/antlr/antlr4/master/LICENSE.txt
*/
package io.debezium.antlr;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.misc.Interval;
/**
* https://github.com/parrt/antlr4/blob/case-insensitivity-doc/doc/resources/CaseChangingCharStream.java
*
* This class supports case-insensitive lexing by wrapping an existing
* {@link CharStream} and forcing the lexer to see either upper or
* lowercase characters. Grammar literals should then be either upper or
* lower case such as 'BEGIN' or 'begin'. The text of the character
* stream is unaffected. Example: input 'BeGiN' would match lexer rule
* 'BEGIN' if constructor parameter upper=true but getText() would return
* 'BeGiN'.
*/
public class CaseChangingCharStream implements CharStream {
final CharStream stream;
final boolean upper;
/**
* Constructs a new CaseChangingCharStream wrapping the given {@link CharStream} forcing
* all characters to upper case or lower case.
*
* @param stream The stream to wrap.
* @param upper If true force each symbol to upper case, otherwise force to lower.
*/
public CaseChangingCharStream(CharStream stream, boolean upper) {
this.stream = stream;
this.upper = upper;
}
@Override
public String getText(Interval interval) {
return stream.getText(interval);
}
@Override
public void consume() {
stream.consume();
}
@Override
public int LA(int i) {
int c = stream.LA(i);
if (c <= 0) {
return c;
}
if (upper) {
return Character.toUpperCase(c);
}
return Character.toLowerCase(c);
}
@Override
public int mark() {
return stream.mark();
}
@Override
public void release(int marker) {
stream.release(marker);
}
@Override
public int index() {
return stream.index();
}
@Override
public void seek(int index) {
stream.seek(index);
}
@Override
public int size() {
return stream.size();
}
@Override
public String getSourceName() {
return stream.getSourceName();
}
}