xslelement.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: XslElement.java,v 1.2.4.1 2005/09/12 11:39:55 pvedula Exp $
 */

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

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.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.ICONST;
import com.sun.org.apache.bcel.internal.generic.INVOKESTATIC;
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.PUSH;
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.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Util;
import com.sun.org.apache.xml.internal.utils.XML11Char;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class XslElement extends Instruction {

    private String  _prefix;
    private boolean _ignore = false;
    private boolean _isLiteralName = true;
    private AttributeValueTemplate _name; 
    private AttributeValueTemplate _namespace;

    /**
     * Displays the contents of the element
     */
    public void display(int indent) {
	indent(indent);
	Util.println("Element " + _name);
	displayContents(indent + IndentIncrement);
    }

    /**
     * This method is now deprecated. The new implemation of this class
     * never declares the default NS.
     */
    public boolean declaresDefaultNS() {
	return false;
    }

    public void parseContents(Parser parser) {
	final SymbolTable stable = parser.getSymbolTable();

	// Handle the 'name' attribute
	String name = getAttribute("name");
	if (name == EMPTYSTRING) {
	    ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_ELEM_NAME_ERR,
					name, this);
	    parser.reportError(WARNING, msg);
	    parseChildren(parser);
	    _ignore = true; 	// Ignore the element if the QName is invalid
	    return;
	}

	// Get namespace attribute
	String namespace = getAttribute("namespace");

	// Optimize compilation when name is known at compile time
        _isLiteralName = Util.isLiteral(name);
	if (_isLiteralName) {
            if (!XML11Char.isXML11ValidQName(name)) {
		ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_ELEM_NAME_ERR,
					    name, this);
		parser.reportError(WARNING, msg);
		parseChildren(parser);
		_ignore = true; 	// Ignore the element if the QName is invalid
		return;
	    }

	    final QName qname = parser.getQNameSafe(name);
	    String prefix = qname.getPrefix();
	    String local = qname.getLocalPart();
	    
	    if (prefix == null) {
		prefix = EMPTYSTRING;
	    }

	    if (!hasAttribute("namespace")) {
		namespace = lookupNamespace(prefix); 
		if (namespace == null) {
		    ErrorMsg err = new ErrorMsg(ErrorMsg.NAMESPACE_UNDEF_ERR,
						prefix, this);
		    parser.reportError(WARNING, err);
		    parseChildren(parser);
		    _ignore = true; 	// Ignore the element if prefix is undeclared
		    return;
		}
		_prefix = prefix;
		_namespace = new AttributeValueTemplate(namespace, parser, this);
	    }
	    else {
		if (prefix == EMPTYSTRING) {
        	    if (Util.isLiteral(namespace)) {
			prefix = lookupPrefix(namespace);
			if (prefix == null) {
			    prefix = stable.generateNamespacePrefix();
			}
		    }

		    // Prepend prefix to local name
		    final StringBuffer newName = new StringBuffer(prefix);
		    if (prefix != EMPTYSTRING) {
			newName.append(':');
		    }
		    name = newName.append(local).toString();
		}
		_prefix = prefix;
		_namespace = new AttributeValueTemplate(namespace, parser, this);
	    }
	}
	else {
	    _namespace = (namespace == EMPTYSTRING) ? null :
			 new AttributeValueTemplate(namespace, parser, this);
	}

	_name = new AttributeValueTemplate(name, parser, this);

	final String useSets = getAttribute("use-attribute-sets");
	if (useSets.length() > 0) {
            if (!Util.isValidQNames(useSets)) {
                ErrorMsg err = new ErrorMsg(ErrorMsg.INVALID_QNAME_ERR, useSets, this);
                parser.reportError(Constants.ERROR, err);	
            }
	    setFirstElement(new UseAttributeSets(useSets, parser));
	}

	parseChildren(parser);
    }

    /**
     * Run type check on element name & contents
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	if (!_ignore) {
	    _name.typeCheck(stable);
	    if (_namespace != null) {
		_namespace.typeCheck(stable);
	    }
	}
	typeCheckContents(stable);
	return Type.Void;
    }

    /**
     * This method is called when the name of the element is known at compile time.
     * In this case, there is no need to inspect the element name at runtime to
     * determine if a prefix exists, needs to be generated, etc.
     */
    public void translateLiteral(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	if (!_ignore) {
	    il.append(methodGen.loadHandler());
	    _name.translate(classGen, methodGen);
	    il.append(DUP2);
	    il.append(methodGen.startElement());

	    if (_namespace != null) {
		il.append(methodGen.loadHandler());
		il.append(new PUSH(cpg, _prefix));
		_namespace.translate(classGen,methodGen);
		il.append(methodGen.namespace());
	    }
	}

	translateContents(classGen, methodGen);

	if (!_ignore) {
	    il.append(methodGen.endElement());
	}
    }

    /**
     * At runtime the compilation of xsl:element results in code that: (i)
     * evaluates the avt for the name, (ii) checks for a prefix in the name
     * (iii) generates a new prefix and create a new qname when necessary
     * (iv) calls startElement() on the handler (v) looks up a uri in the XML
     * when the prefix is not known at compile time (vi) calls namespace() 
     * on the handler (vii) evaluates the contents (viii) calls endElement().
     */
    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	LocalVariableGen local = null;
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();

	// Optimize translation if element name is a literal
	if (_isLiteralName) {
	    translateLiteral(classGen, methodGen);
	    return;
	}

	if (!_ignore) {
       
            // if the qname is an AVT, then the qname has to be checked at runtime if it is a valid qname
            LocalVariableGen nameValue = methodGen.addLocalVariable2("nameValue",
                    Util.getJCRefType(STRING_SIG),
                    il.getEnd());
                    
            // store the name into a variable first so _name.translate only needs to be called once  
            _name.translate(classGen, methodGen);
            il.append(new ASTORE(nameValue.getIndex()));
            il.append(new ALOAD(nameValue.getIndex()));
            
            // call checkQName if the name is an AVT
            final int check = cpg.addMethodref(BASIS_LIBRARY_CLASS, "checkQName",
                            "("
                            +STRING_SIG
                            +")V");                 
            il.append(new INVOKESTATIC(check));
            
            // Push handler for call to endElement()
            il.append(methodGen.loadHandler());         
            
            // load name value again    
            il.append(new ALOAD(nameValue.getIndex()));  
                    
	    if (_namespace != null) {
		_namespace.translate(classGen, methodGen);
	    }
	    else {
		il.append(ACONST_NULL);
	    }

	    // Push additional arguments
	    il.append(methodGen.loadHandler());
	    il.append(methodGen.loadDOM());
	    il.append(methodGen.loadCurrentNode());
        
            // Invoke BasisLibrary.startXslElemCheckQName()
            il.append(new INVOKESTATIC(
            cpg.addMethodref(BASIS_LIBRARY_CLASS, "startXslElement",
                    "(" + STRING_SIG 
                    + STRING_SIG 
                    + TRANSLET_OUTPUT_SIG 
                    + DOM_INTF_SIG + "I)" + STRING_SIG)));                


	}

	translateContents(classGen, methodGen);

	if (!_ignore) {
	    il.append(methodGen.endElement());
	}
    }

    /**
     * Override this method to make sure that xsl:attributes are not
     * copied to output if this xsl:element is to be ignored
     */
    public void translateContents(ClassGenerator classGen,
				  MethodGenerator methodGen) {
	final int n = elementCount();
	for (int i = 0; i < n; i++) {
	    final SyntaxTreeNode item =
		(SyntaxTreeNode)getContents().elementAt(i);
	    if (_ignore && item instanceof XslAttribute) continue;
	    item.translate(classGen, methodGen);
	}
    }

}