src/org/apache/xalan/xsltc/compiler/Param.java

/*
 * @(#)$Id$
 *
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xalan" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
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 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 2001, Sun
 * Microsystems., http://www.sun.com.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 * @author Erwin Bolwidt <ejb@klomp.org>
 * @author John Howard <JohnH@schemasoft.com>
 *
 */

package org.apache.xalan.xsltc.compiler;

import java.util.Vector;

import org.apache.xalan.xsltc.compiler.util.Type;
import org.apache.xalan.xsltc.compiler.util.ReferenceType;

import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.*;
import org.apache.bcel.classfile.Field;

import org.apache.xalan.xsltc.compiler.util.*;

final class Param extends VariableBase {

    /**
     * Display variable as single string
     */
    public String toString() {
	return("param("+_name+")");
    }

    /**
     * Display variable in a full AST dump
     */
    public void display(int indent) {
	indent(indent);
	System.out.println("param " + _name);
	if (_select != null) {
	    indent(indent + IndentIncrement);
	    System.out.println("select " + _select.toString());
	}
	displayContents(indent + IndentIncrement);
    }

    /**
     * Parse the contents of the <xsl:param> element. This method must read
     * the 'name' (required) and 'select' (optional) attributes.
     */
    public void parseContents(Parser parser) {

	// Parse 'name' and 'select' attributes plus parameter contents
	super.parseContents(parser);

	// Add a ref to this param to its enclosing construct
	final SyntaxTreeNode parent = getParent();
	if (parent instanceof Stylesheet) {
	    // Mark this as a global parameter
	    _isLocal = false;
	    // Check if a global variable with this name already exists...
	    Param param = parser.getSymbolTable().lookupParam(_name);
	    // ...and if it does we need to check import precedence
	    if (param != null) {
		final int us = this.getImportPrecedence();
		final int them = param.getImportPrecedence();
		// It is an error if the two have the same import precedence
		if (us == them) {
		    final String name = _name.toString();
		    reportError(this, parser, ErrorMsg.VARIABLE_REDEF_ERR,name);
		}
		// Ignore this if previous definition has higher precedence
		else if (them > us) {
		    _ignore = true;
		    return;
		}
		else {
		    param.disable();
		}
	    }
	    // Add this variable if we have higher precedence
	    ((Stylesheet)parent).addParam(this);
	    parser.getSymbolTable().addParam(this);
	}
	else if (parent instanceof Template) {
	    _isLocal = true;
	    ((Template)parent).hasParams(true);
	}
    }

    /**
     * Type-checks the parameter. The parameter type is determined by the
     * 'select' expression (if present) or is a result tree if the parameter
     * element has a body and no 'select' expression.
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	if (_select != null) {
	    _type = _select.typeCheck(stable); 
	    if (_type instanceof ReferenceType == false) {
		_select = new CastExpr(_select, Type.Reference);
	    }
	}
	else if (hasContents()) {
	    typeCheckContents(stable);
	}
	_type = Type.Reference;

	// This element has no type (the parameter does, but the parameter
	// element itself does not).
	return Type.Void;
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {

	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	if (_ignore) return;
	_ignore = true;

	final String name = getVariable();
	final String signature = _type.toSignature();
	final String className = _type.getClassName();

	if (isLocal()) {

	    il.append(classGen.loadTranslet());
	    il.append(new PUSH(cpg, name));
	    translateValue(classGen, methodGen);
	    il.append(new PUSH(cpg, true));

	    // Call addParameter() from this class
	    il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
							 ADD_PARAMETER,
							 ADD_PARAMETER_SIG)));
	    if (className != EMPTYSTRING) {
		il.append(new CHECKCAST(cpg.addClass(className)));
	    }

	    _type.translateUnBox(classGen, methodGen);

	    if (_refs.isEmpty()) { // nobody uses the value
		il.append(_type.POP());
		_local = null;
	    }
	    else {		// normal case
		_local = methodGen.addLocalVariable2(name,
						     _type.toJCType(),
						     il.getEnd());
		// Cache the result of addParameter() in a local variable
		il.append(_type.STORE(_local.getIndex()));
	    }
	}
	else {
	    if (classGen.containsField(name) == null) {
		classGen.addField(new Field(ACC_PUBLIC, cpg.addUtf8(name),
					    cpg.addUtf8(signature),
					    null, cpg.getConstantPool()));
		il.append(classGen.loadTranslet());
		il.append(DUP);
		il.append(new PUSH(cpg, name));
		translateValue(classGen, methodGen);
		il.append(new PUSH(cpg, true));

		// Call addParameter() from this class
		il.append(new INVOKEVIRTUAL(cpg.addMethodref(TRANSLET_CLASS,
						     ADD_PARAMETER,
						     ADD_PARAMETER_SIG)));

		_type.translateUnBox(classGen, methodGen);

		// Cache the result of addParameter() in a field
		if (className != EMPTYSTRING) {
		    il.append(new CHECKCAST(cpg.addClass(className)));
		}
		il.append(new PUTFIELD(cpg.addFieldref(classGen.getClassName(),
						       name, signature)));
	    }
	}
    }

}