platform/lang-impl/src/com/intellij/lang/pratt/ReducingParser.java

/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * 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.
 */
package com.intellij.lang.pratt;

import com.intellij.psi.tree.IElementType;
import org.jetbrains.annotations.Nullable;

/**
 * @author peter
 */
public abstract class ReducingParser extends TokenParser{
  @Override
  public final boolean parseToken(final PrattBuilder builder) {
    builder.advance();
    final IElementType type = parseFurther(builder);
    if (type == null) return false;

    builder.reduce(type);
    return true;
  }

  @Nullable public abstract IElementType parseFurther(final PrattBuilder builder);
}