1. /*

  2.  * Copyright 2001-2004 The Apache Software Foundation.

  3.  *

  4.  * Licensed under the Apache License, Version 2.0 (the "License");

  5.  * you may not use this file except in compliance with the License.

  6.  * You may obtain a copy of the License at

  7.  *

  8.  *     http://www.apache.org/licenses/LICENSE-2.0

  9.  *

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

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

  12.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  13.  * See the License for the specific language governing permissions and

  14.  * limitations under the License.

  15.  */

  16. /*

  17.  * $Id: Pattern.java,v 1.4 2004/02/16 22:24:29 minchau Exp $

  18.  */

  19. 

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

  21. 

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

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

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

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

  26. 

  27. /**

  28.  * @author Jacek Ambroziak

  29.  * @author Santiago Pericas-Geertsen

  30.  */

  31. public abstract class Pattern extends Expression {

  32.     /**

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

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

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

  36.      */

  37.     public abstract Type typeCheck(SymbolTable stable) throws TypeCheckError;

  38. 

  39.     /**

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

  41.      * boolean expressions with true/false lists. Before calling 

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

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

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

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

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

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

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

  49.      * <code>translate</code>. 

  50.      */

  51.     public abstract void translate(ClassGenerator classGen,

  52. 				   MethodGenerator methodGen);

  53. 

  54.     /**

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

  56.      */

  57.     public abstract double getPriority();

  58. }