001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 /*
019 * $Id: If.java 468650 2006-10-28 07:03:30Z minchau $
020 */
021
022 package org.apache.xalan.xsltc.compiler;
023
024 import org.apache.bcel.generic.InstructionHandle;
025 import org.apache.bcel.generic.InstructionList;
026 import org.apache.xalan.xsltc.compiler.util.BooleanType;
027 import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
028 import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
029 import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
030 import org.apache.xalan.xsltc.compiler.util.Type;
031 import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
032 import org.apache.xalan.xsltc.compiler.util.Util;
033
034 /**
035 * @author Jacek Ambroziak
036 * @author Santiago Pericas-Geertsen
037 * @author Morten Jorgensen
038 */
039 final class If extends Instruction {
040
041 private Expression _test;
042 private boolean _ignore = false;
043
044 /**
045 * Display the contents of this element
046 */
047 public void display(int indent) {
048 indent(indent);
049 Util.println("If");
050 indent(indent + IndentIncrement);
051 System.out.print("test ");
052 Util.println(_test.toString());
053 displayContents(indent + IndentIncrement);
054 }
055
056 /**
057 * Parse the "test" expression and contents of this element.
058 */
059 public void parseContents(Parser parser) {
060 // Parse the "test" expression
061 _test = parser.parseExpression(this, "test", null);
062
063 // Make sure required attribute(s) have been set
064 if (_test.isDummy()) {
065 reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "test");
066 return;
067 }
068
069 // Ignore xsl:if when test is false (function-available() and
070 // element-available())
071 Object result = _test.evaluateAtCompileTime();
072 if (result != null && result instanceof Boolean) {
073 _ignore = !((Boolean) result).booleanValue();
074 }
075
076 parseChildren(parser);
077 }
078
079 /**
080 * Type-check the "test" expression and contents of this element.
081 * The contents will be ignored if we know the test will always fail.
082 */
083 public Type typeCheck(SymbolTable stable) throws TypeCheckError {
084 // Type-check the "test" expression
085 if (_test.typeCheck(stable) instanceof BooleanType == false) {
086 _test = new CastExpr(_test, Type.Boolean);
087 }
088 // Type check the element contents
089 if (!_ignore) {
090 typeCheckContents(stable);
091 }
092 return Type.Void;
093 }
094
095 /**
096 * Translate the "test" expression and contents of this element.
097 * The contents will be ignored if we know the test will always fail.
098 */
099 public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
100 final InstructionList il = methodGen.getInstructionList();
101 _test.translateDesynthesized(classGen, methodGen);
102 // remember end of condition
103 final InstructionHandle truec = il.getEnd();
104 if (!_ignore) {
105 translateContents(classGen, methodGen);
106 }
107 _test.backPatchFalseList(il.append(NOP));
108 _test.backPatchTrueList(truec.getNext());
109 }
110 }