booleantype.java

java1.6众多例子参考

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * 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.
 */
/*
 * $Id: BooleanType.java,v 1.2.4.1 2005/09/05 11:03:37 pvedula Exp $
 */

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

import com.sun.org.apache.bcel.internal.generic.BranchHandle;
import com.sun.org.apache.bcel.internal.generic.BranchInstruction;
import com.sun.org.apache.bcel.internal.generic.CHECKCAST;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.GOTO;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.IFGE;
import com.sun.org.apache.bcel.internal.generic.IFGT;
import com.sun.org.apache.bcel.internal.generic.IFLE;
import com.sun.org.apache.bcel.internal.generic.IFLT;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPGE;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPGT;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPLE;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPLT;
import com.sun.org.apache.bcel.internal.generic.ILOAD;
import com.sun.org.apache.bcel.internal.generic.INVOKESPECIAL;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
import com.sun.org.apache.bcel.internal.generic.ISTORE;
import com.sun.org.apache.bcel.internal.generic.Instruction;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.NEW;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.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 com.sun.org.apache.bcel.internal.generic.Type toJCType() {
	return com.sun.org.apache.bcel.internal.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	com.sun.org.apache.xalan.internal.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	com.sun.org.apache.xalan.internal.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	com.sun.org.apache.xalan.internal.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	com.sun.org.apache.xalan.internal.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);
    }
}