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/*

 * 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

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 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

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package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 */

public abstract class Pattern extends Expression {

    /**

     * Returns the type of a pattern, which is always a <code>NodeType</code>.

     * A <code>NodeType</code> has a number of subtypes defined by

     * <code>NodeType._type</code> corresponding to each type of node.

     */

    public abstract Type typeCheck(SymbolTable stable) throws TypeCheckError;

    /**

     * Translate this node into JVM bytecodes. Patterns are translated as

     * boolean expressions with true/false lists. Before calling

     * <code>translate</code> on a pattern, make sure that the node being

     * matched is on top of the stack. After calling <code>translate</code>,

     * make sure to backpatch both true and false lists. True lists are the

     * default, in the sense that they always <em>"fall through"</em>. If this

     * is not the intended semantics (e.g., see

     * {@link com.sun.org.apache.xalan.internal.xsltc.compiler.AlternativePattern#translate})

     * then a GOTO must be appended to the instruction list after calling

     * <code>translate</code>.

     */

    public abstract void translate(ClassGenerator classGen,

                                   MethodGenerator methodGen);

    /**

     * Returns the priority of this pattern (section 5.5 in the XSLT spec).

     */

    public abstract double getPriority();

}