resulttreetype.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: ResultTreeType.java,v 1.2.4.1 2005/09/05 11:30:01 pvedula Exp $
 */

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

import com.sun.org.apache.bcel.internal.generic.ALOAD;
import com.sun.org.apache.bcel.internal.generic.ASTORE;
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.GETFIELD;
import com.sun.org.apache.bcel.internal.generic.IFEQ;
import com.sun.org.apache.bcel.internal.generic.INVOKEINTERFACE;
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.Instruction;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.LocalVariableGen;
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;
import com.sun.org.apache.xalan.internal.xsltc.compiler.FlowList;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
public final class ResultTreeType extends Type {
    private final String _methodName;

    protected ResultTreeType() {
	_methodName = null;
    }

    public ResultTreeType(String methodName) {
	_methodName = methodName;
    }

    public String toString() {
	return "result-tree";
    }

    public boolean identicalTo(Type other) {
	return (other instanceof ResultTreeType);
    }

    public String toSignature() {
	return DOM_INTF_SIG;
    }

    public com.sun.org.apache.bcel.internal.generic.Type toJCType() {
	return Util.getJCRefType(toSignature());
    }

    public String getMethodName() {
	return _methodName;
    }

    public boolean implementedAsMethod() {
	return _methodName != null;
    }

    /**
     * Translates a result tree to object of internal type <code>type</code>. 
     * The translation to int is undefined since result trees
     * are always converted to reals in arithmetic expressions.
     *
     * @param classGen A BCEL class generator
     * @param methodGen A BCEL method generator
     * @param type An instance of the type to translate the result tree to
     * @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.Boolean) {
	    translateTo(classGen, methodGen, (BooleanType)type);
	}
	else if (type == Type.Real) {
	    translateTo(classGen, methodGen, (RealType)type);
	}
	else if (type == Type.NodeSet) {
	    translateTo(classGen, methodGen, (NodeSetType)type);
	}
	else if (type == Type.Reference) {
	    translateTo(classGen, methodGen, (ReferenceType)type);
	}
	else if (type == Type.Object) {
	    translateTo(classGen, methodGen, (ObjectType) type);
	}
	else {
	    ErrorMsg err = new ErrorMsg(ErrorMsg.DATA_CONVERSION_ERR,
					toString(), type.toString());
	    classGen.getParser().reportError(Constants.FATAL, err);
	}
    }

    /**
     * Expects an result tree on the stack and pushes a boolean.
     * Translates a result tree to a boolean by first converting it to string.
     *
     * @param classGen A BCEL class generator
     * @param methodGen A BCEL method generator
     * @param type An instance of BooleanType (any)
     * @see com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
			    BooleanType type) {
	// A result tree is always 'true' when converted to a boolean value,
	// since the tree always has at least one node (the root).
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();
	il.append(POP);      // don't need the DOM reference
	il.append(ICONST_1); // push 'true' on the stack
    }

    /**
     * Expects an result tree on the stack and pushes a string.
     *
     * @param classGen A BCEL class generator
     * @param methodGen A BCEL method generator
     * @param type An instance of StringType (any)
     * @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();
	
	if (_methodName == null) {
	    int index = cpg.addInterfaceMethodref(DOM_INTF,
						  "getStringValue", 
						  "()"+STRING_SIG);
	    il.append(new INVOKEINTERFACE(index, 1));
	}
	else {
	    final String className = classGen.getClassName();
	    final int current = methodGen.getLocalIndex("current");
	    
	    // Push required parameters 
	    il.append(classGen.loadTranslet());
	    if (classGen.isExternal()) {
		il.append(new CHECKCAST(cpg.addClass(className)));
	    }
	    il.append(DUP);
	    il.append(new GETFIELD(cpg.addFieldref(className, "_dom",
						   DOM_INTF_SIG)));

	    // Create a new instance of a StringValueHandler
	    int index = cpg.addMethodref(STRING_VALUE_HANDLER, "<init>", "()V");
	    il.append(new NEW(cpg.addClass(STRING_VALUE_HANDLER)));
	    il.append(DUP);
	    il.append(DUP);
	    il.append(new INVOKESPECIAL(index));
	    
	    // Store new Handler into a local variable
	    final LocalVariableGen handler =
		methodGen.addLocalVariable("rt_to_string_handler", 
					   Util.getJCRefType(STRING_VALUE_HANDLER_SIG),
					   null, null);
	    il.append(new ASTORE(handler.getIndex()));

	    // Call the method that implements this result tree
	    index = cpg.addMethodref(className, _methodName,
				     "("+DOM_INTF_SIG+TRANSLET_OUTPUT_SIG+")V");
	    il.append(new INVOKEVIRTUAL(index));
	    
	    // Restore new handler and call getValue()
	    il.append(new ALOAD(handler.getIndex()));
	    index = cpg.addMethodref(STRING_VALUE_HANDLER,
				     "getValue",
				     "()" + STRING_SIG);
	    il.append(new INVOKEVIRTUAL(index));
	}
    }

    /**
     * Expects an result tree on the stack and pushes a real.
     * Translates a result tree into a real by first converting it to string.
     *
     * @param classGen A BCEL class generator
     * @param methodGen A BCEL method generator
     * @param type An instance of RealType (any)
     * @see com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type#translateTo
     */
    public void translateTo(ClassGenerator classGen, MethodGenerator methodGen, 
			    RealType type) {
	translateTo(classGen, methodGen, Type.String);
	Type.String.translateTo(classGen, methodGen, Type.Real);	
    }

    /**
     * Expects a result tree on the stack and pushes a boxed result tree.
     * Result trees are already boxed so the translation is just a NOP.
     *
     * @param classGen A BCEL class generator
     * @param methodGen A BCEL method generator
     * @param type An instance of ReferenceType (any)
     * @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();

	if (_methodName == null) {
	    il.append(NOP);
	}
	else {
	    LocalVariableGen domBuilder, newDom;
	    final String className = classGen.getClassName();
	    final int current = methodGen.getLocalIndex("current");