castexpr.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: CastExpr.java,v 1.2.4.1 2005/09/12 10:06:35 pvedula Exp $
 */

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

import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.IF_ICMPNE;
import com.sun.org.apache.bcel.internal.generic.INVOKEINTERFACE;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.SIPUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MultiHashtable;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ResultTreeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import com.sun.org.apache.xml.internal.dtm.Axis;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 * @author Erwin Bolwidt <[e-mail]>
 */
final class CastExpr extends Expression {
    private final Expression _left;

    /**
     * Legal conversions between internal types.
     */
    static private MultiHashtable InternalTypeMap = new MultiHashtable();

    static {
	// Possible type conversions between internal types
	InternalTypeMap.put(Type.Boolean, Type.Boolean);
	InternalTypeMap.put(Type.Boolean, Type.Real);
	InternalTypeMap.put(Type.Boolean, Type.String);
	InternalTypeMap.put(Type.Boolean, Type.Reference);
        InternalTypeMap.put(Type.Boolean, Type.Object);

	InternalTypeMap.put(Type.Real, Type.Real);
	InternalTypeMap.put(Type.Real, Type.Int);
	InternalTypeMap.put(Type.Real, Type.Boolean);
	InternalTypeMap.put(Type.Real, Type.String);
	InternalTypeMap.put(Type.Real, Type.Reference);
        InternalTypeMap.put(Type.Real, Type.Object);

	InternalTypeMap.put(Type.Int, Type.Int);
	InternalTypeMap.put(Type.Int, Type.Real);
	InternalTypeMap.put(Type.Int, Type.Boolean);
	InternalTypeMap.put(Type.Int, Type.String);
	InternalTypeMap.put(Type.Int, Type.Reference);
        InternalTypeMap.put(Type.Int, Type.Object);

	InternalTypeMap.put(Type.String, Type.String);
	InternalTypeMap.put(Type.String, Type.Boolean);
	InternalTypeMap.put(Type.String, Type.Real);
	InternalTypeMap.put(Type.String, Type.Reference);
        InternalTypeMap.put(Type.String, Type.Object);

	InternalTypeMap.put(Type.NodeSet, Type.NodeSet);
	InternalTypeMap.put(Type.NodeSet, Type.Boolean);
	InternalTypeMap.put(Type.NodeSet, Type.Real);
	InternalTypeMap.put(Type.NodeSet, Type.String);
	InternalTypeMap.put(Type.NodeSet, Type.Node);
	InternalTypeMap.put(Type.NodeSet, Type.Reference);
	InternalTypeMap.put(Type.NodeSet, Type.Object);

	InternalTypeMap.put(Type.Node, Type.Node);
	InternalTypeMap.put(Type.Node, Type.Boolean);
	InternalTypeMap.put(Type.Node, Type.Real);
	InternalTypeMap.put(Type.Node, Type.String);
	InternalTypeMap.put(Type.Node, Type.NodeSet);
	InternalTypeMap.put(Type.Node, Type.Reference);
	InternalTypeMap.put(Type.Node, Type.Object);

	InternalTypeMap.put(Type.ResultTree, Type.ResultTree);
	InternalTypeMap.put(Type.ResultTree, Type.Boolean);
	InternalTypeMap.put(Type.ResultTree, Type.Real);
	InternalTypeMap.put(Type.ResultTree, Type.String);
	InternalTypeMap.put(Type.ResultTree, Type.NodeSet);
	InternalTypeMap.put(Type.ResultTree, Type.Reference);
	InternalTypeMap.put(Type.ResultTree, Type.Object);

	InternalTypeMap.put(Type.Reference, Type.Reference);
	InternalTypeMap.put(Type.Reference, Type.Boolean);
	InternalTypeMap.put(Type.Reference, Type.Int);
	InternalTypeMap.put(Type.Reference, Type.Real);
	InternalTypeMap.put(Type.Reference, Type.String);
	InternalTypeMap.put(Type.Reference, Type.Node);
	InternalTypeMap.put(Type.Reference, Type.NodeSet);
	InternalTypeMap.put(Type.Reference, Type.ResultTree);
	InternalTypeMap.put(Type.Reference, Type.Object);

	InternalTypeMap.put(Type.Object, Type.String);

	InternalTypeMap.put(Type.Void, Type.String);
    }

    private boolean _typeTest = false;

    /**
     * Construct a cast expression and check that the conversion is 
     * valid by calling typeCheck().
     */
    public CastExpr(Expression left, Type type) throws TypeCheckError {
	_left = left;
	_type = type;		// use inherited field

	if ((_left instanceof Step) && (_type == Type.Boolean)) {
	    Step step = (Step)_left;
	    if ((step.getAxis() == Axis.SELF) && (step.getNodeType() != -1)) 
		_typeTest = true;
	}
	
	// check if conversion is valid
	setParser(left.getParser());
	setParent(left.getParent());
	left.setParent(this);
	typeCheck(left.getParser().getSymbolTable());
    }
		
    public Expression getExpr() {
	return _left;
    }

    /**
     * Returns true if this expressions contains a call to position(). This is
     * needed for context changes in node steps containing multiple predicates.
     */
    public boolean hasPositionCall() {
	return(_left.hasPositionCall());
    }

    public boolean hasLastCall() {
	return(_left.hasLastCall());
    }

    public String toString() {
	return "cast(" + _left + ", " + _type + ")";
    }

    /**
     * Type checking a cast expression amounts to verifying that the  
     * type conversion is legal. Cast expressions are created during 
     * type checking, but typeCheck() is usually not called on them. 
     * As a result, this method is called from the constructor.
     */	
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	Type tleft = _left.getType();
	if (tleft == null) {
	    tleft = _left.typeCheck(stable);
	}
	if (tleft instanceof NodeType) {
	    tleft = Type.Node;	// multiple instances
	}
	else if (tleft instanceof ResultTreeType) {
	    tleft = Type.ResultTree; // multiple instances
	}
	if (InternalTypeMap.maps(tleft, _type) != null) {
	    return _type;
	}
	// throw new TypeCheckError(this);	
	throw new TypeCheckError(new ErrorMsg(
	    ErrorMsg.DATA_CONVERSION_ERR, tleft.toString(), _type.toString()));
    }

    public void translateDesynthesized(ClassGenerator classGen, 
				       MethodGenerator methodGen) {
	FlowList fl;
	final Type ltype = _left.getType();

	// This is a special case for the self:: axis. Instead of letting
	// the Step object create and iterator that we cast back to a single
	// node, we simply ask the DOM for the node type.
	if (_typeTest) {
	    final ConstantPoolGen cpg = classGen.getConstantPool();
	    final InstructionList il = methodGen.getInstructionList();

	    final int idx = cpg.addInterfaceMethodref(DOM_INTF,
						      "getExpandedTypeID",
                                                      "(I)I");
	    il.append(new SIPUSH((short)((Step)_left).getNodeType()));
	    il.append(methodGen.loadDOM());
	    il.append(methodGen.loadContextNode());
	    il.append(new INVOKEINTERFACE(idx, 2));
	    _falseList.add(il.append(new IF_ICMPNE(null)));
	}
	else {

	    _left.translate(classGen, methodGen);
	    if (_type != ltype) {
		_left.startIterator(classGen, methodGen);
		if (_type instanceof BooleanType) {
		    fl = ltype.translateToDesynthesized(classGen, methodGen,
							_type);
		    if (fl != null) {
			_falseList.append(fl);
		    }
		}
		else {
		    ltype.translateTo(classGen, methodGen, _type);	
		}
	    }
	}
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final Type ltype = _left.getType();
	_left.translate(classGen, methodGen);
	if (_type.identicalTo(ltype) == false) {
	    _left.startIterator(classGen, methodGen);
	    ltype.translateTo(classGen, methodGen, _type);
	}
    }
}