code: /*
   * 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
   *
   * 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.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.compiler.util;
  
  import org.apache.bcel.generic.BranchHandle;
  import org.apache.bcel.generic.BranchInstruction;
  import org.apache.bcel.generic.CHECKCAST;
  import org.apache.bcel.generic.ConstantPoolGen;
  import org.apache.bcel.generic.GOTO;
  import org.apache.bcel.generic.IFEQ;
  import org.apache.bcel.generic.IFGE;
  import org.apache.bcel.generic.IFGT;
  import org.apache.bcel.generic.IFLE;
  import org.apache.bcel.generic.IFLT;
  import org.apache.bcel.generic.IF_ICMPGE;
  import org.apache.bcel.generic.IF_ICMPGT;
  import org.apache.bcel.generic.IF_ICMPLE;
  import org.apache.bcel.generic.IF_ICMPLT;
  import org.apache.bcel.generic.ILOAD;
  import org.apache.bcel.generic.INVOKESPECIAL;
  import org.apache.bcel.generic.INVOKEVIRTUAL;
  import org.apache.bcel.generic.ISTORE;
  import org.apache.bcel.generic.Instruction;
  import org.apache.bcel.generic.InstructionList;
  import org.apache.bcel.generic.NEW;
  import org.apache.bcel.generic.PUSH;
  import org.apache.xalan.xsltc.compiler.Constants;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  public final class BooleanType extends Type {
      protected BooleanType() {}
  
      public String toString() {
  	return "boolean";
      }
  
      public boolean identicalTo(Type other) {
  	return this == other;
      }
  
      public String toSignature() {
  	return "Z";
      }
  
      public boolean isSimple() {
  	return true;
      }
  
      public org.apache.bcel.generic.Type toJCType() {
  	return org.apache.bcel.generic.Type.BOOLEAN;
      }
  
      /**
       * Translates a real into an object of internal type <code>type</code>. The
       * translation to int is undefined since booleans are always converted to
       * reals in arithmetic expressions.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    Type type) {
  	if (type == Type.String) {
  	    translateTo(classGen, methodGen, (StringType) type);
  	}
  	else if (type == Type.Real) {
  	    translateTo(classGen, methodGen, (RealType) type);
  	}
  	else if (type == Type.Reference) {
  	    translateTo(classGen, methodGen, (ReferenceType) type);
  	}
  	else {
  	    ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  					toString(), type.toString());
  	    classGen.getParser().reportError(Constants.FATAL, err);
  	}
      }
  
      /**
       * Expects a boolean on the stack and pushes a string. If the value on the
       * stack is zero, then the string 'false' is pushed. Otherwise, the string
       * 'true' is pushed.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    StringType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	final BranchHandle falsec = il.append(new IFEQ(null));
  	il.append(new PUSH(cpg, "true"));
  	final BranchHandle truec = il.append(new GOTO(null));
  	falsec.setTarget(il.append(new PUSH(cpg, "false")));
  	truec.setTarget(il.append(NOP));
      }
  
      /**
       * Expects a boolean on the stack and pushes a real. The value "true" is
       * converted to 1.0 and the value "false" to 0.0.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    RealType type) {
  	methodGen.getInstructionList().append(I2D);
      }
  
      /**
       * Expects a boolean on the stack and pushes a boxed boolean.
       * Boxed booleans are represented by an instance of
       * <code>java.lang.Boolean</code>.
       *
       * @see	org.apache.xalan.xsltc.compiler.util.Type#translateTo
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    ReferenceType type) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	il.append(new NEW(cpg.addClass(BOOLEAN_CLASS)));
  	il.append(DUP_X1);
  	il.append(SWAP);
  	il.append(new INVOKESPECIAL(cpg.addMethodref(BOOLEAN_CLASS,
  						     "<init>",
  						     "(Z)V")));
      }
  
      /**
       * Translates an internal boolean into an external (Java) boolean.
       */
      public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
  			    Class clazz) {
  	if (clazz == java.lang.Boolean.TYPE) {
  	    methodGen.getInstructionList().append(NOP);
  	}
          // Is Boolean <: clazz? I.e. clazz in { Boolean, Object }
          else if (clazz.isAssignableFrom(java.lang.Boolean.class)) {
              translateTo(classGen, methodGen, Type.Reference);
          }
  	else {
  	    ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
  					toString(), clazz.getName());
  	    classGen.getParser().reportError(Constants.FATAL, err);
  	}
      }
  
      /**
       * Translates an external (Java) boolean into internal boolean.
       */
      public void translateFrom(ClassGenerator classGen, MethodGenerator methodGen, 
  			      Class clazz) {
  	translateTo(classGen, methodGen, clazz);
      }
  
      /**
       * Translates an object of this type to its boxed representation.
       */ 
      public void translateBox(ClassGenerator classGen,
  			     MethodGenerator methodGen) {
  	translateTo(classGen, methodGen, Type.Reference);
      }
  
      /**
       * Translates an object of this type to its unboxed representation.
       */ 
      public void translateUnBox(ClassGenerator classGen,
  			       MethodGenerator methodGen) {
  	final ConstantPoolGen cpg = classGen.getConstantPool();
  	final InstructionList il = methodGen.getInstructionList();
  	il.append(new CHECKCAST(cpg.addClass(BOOLEAN_CLASS)));
  	il.append(new INVOKEVIRTUAL(cpg.addMethodref(BOOLEAN_CLASS,
  						     BOOLEAN_VALUE, 
  						     BOOLEAN_VALUE_SIG)));
      }
  
      public Instruction LOAD(int slot) {
  	return new ILOAD(slot);
      }
  	
      public Instruction STORE(int slot) {
  	return new ISTORE(slot);
      }
  
      public BranchInstruction GT(boolean tozero) {
  	return tozero ? (BranchInstruction) new IFGT(null) : 
  	    (BranchInstruction) new IF_ICMPGT(null);
      }
  
      public BranchInstruction GE(boolean tozero) {
  	return tozero ? (BranchInstruction) new IFGE(null) : 
  	    (BranchInstruction) new IF_ICMPGE(null);
      }
  
      public BranchInstruction LT(boolean tozero) {
  	return tozero ? (BranchInstruction) new IFLT(null) : 
  	    (BranchInstruction) new IF_ICMPLT(null);
      }
  
      public BranchInstruction LE(boolean tozero) {
  	return tozero ? (BranchInstruction) new IFLE(null) : 
  	    (BranchInstruction) new IF_ICMPLE(null);
      }
  }
  