syntaxtreenode.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: SyntaxTreeNode.java,v 1.6 2006/06/06 22:34:33 spericas Exp $
 */

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

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import com.sun.org.apache.bcel.internal.generic.ANEWARRAY;
import com.sun.org.apache.bcel.internal.generic.BasicType;
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.DUP_X1;
import com.sun.org.apache.bcel.internal.generic.GETFIELD;
import com.sun.org.apache.bcel.internal.generic.ICONST;
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.InstructionList;
import com.sun.org.apache.bcel.internal.generic.NEW;
import com.sun.org.apache.bcel.internal.generic.NEWARRAY;
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.DOM;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AttributeList;

import org.xml.sax.Attributes;



/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author G. Todd Miller
 * @author Morten Jorensen
 * @author Erwin Bolwidt <[e-mail]>
 * @author John Howard <[e-mail]>
 */
public abstract class SyntaxTreeNode implements Constants {

    // Reference to the AST parser
    private Parser _parser;

    // AST navigation pointers
    protected SyntaxTreeNode _parent;          // Parent node
    private Stylesheet       _stylesheet;      // Stylesheet ancestor node
    private Template         _template;        // Template ancestor node
    private final Vector _contents = new Vector(2); // Child nodes

    // Element description data
    protected QName _qname;                    // The element QName
    private int _line;                         // Source file line number
    protected AttributeList _attributes = null;   // Attributes of this element
    private   Hashtable _prefixMapping = null; // Namespace declarations

    // Sentinel - used to denote unrecognised syntaxt tree nodes.
    protected static final SyntaxTreeNode Dummy = new AbsolutePathPattern(null);

    // These two are used for indenting nodes in the AST (debug output)
    protected static final int IndentIncrement = 4;
    private static final char[] _spaces = 
	"                                                       ".toCharArray();

    /**
     * Creates a new SyntaxTreeNode with a 'null' QName and no source file
     * line number reference.
     */
    public SyntaxTreeNode() {
	_line = 0;
	_qname = null;
    }

    /**
     * Creates a new SyntaxTreeNode with a 'null' QName.
     * @param line Source file line number reference
     */
    public SyntaxTreeNode(int line) {
	_line = line;
	_qname = null;
    }

    /**
     * Creates a new SyntaxTreeNode with no source file line number reference.
     * @param uri The element's namespace URI
     * @param prefix The element's namespace prefix
     * @param local The element's local name
     */
    public SyntaxTreeNode(String uri, String prefix, String local) {
	_line = 0;
	setQName(uri, prefix, local);
    }

    /**
     * Set the source file line number for this element
     * @param line The source file line number.
     */
    protected final void setLineNumber(int line) {
	_line = line;
    }

    /**
     * Get the source file line number for this element. If unavailable, lookup
     * in ancestors.
     *
     * @return The source file line number.
     */
    public final int getLineNumber() {
        if (_line > 0) return _line;
        SyntaxTreeNode parent = getParent();
        return (parent != null) ? parent.getLineNumber() : 0;
    }

    /**
     * Set the QName for the syntax tree node.
     * @param qname The QName for the syntax tree node
     */
    protected void setQName(QName qname) {
	_qname = qname;
    }

    /**
     * Set the QName for the SyntaxTreeNode
     * @param uri The element's namespace URI
     * @param prefix The element's namespace prefix
     * @param local The element's local name
     */
    protected void setQName(String uri, String prefix, String localname) {
	_qname = new QName(uri, prefix, localname);
    }

    /**
     * Set the QName for the SyntaxTreeNode
     * @param qname The QName for the syntax tree node
     */
    protected QName getQName() {
	return(_qname);
    }

    /**
     * Set the attributes for this SyntaxTreeNode.
     * @param attributes Attributes for the element. Must be passed in as an
     *                   implementation of org.xml.sax.Attributes.
     */
    protected void setAttributes(AttributeList attributes) {
	_attributes = attributes;
    }

    /**
     * Returns a value for an attribute from the source element.
     * @param qname The QName of the attribute to return.
     * @return The value of the attribute of name 'qname'.
     */
    protected String getAttribute(String qname) {
	if (_attributes == null) {
	    return EMPTYSTRING;
	}
	final String value = _attributes.getValue(qname);
	return (value == null || value.equals(EMPTYSTRING)) ? 
	    EMPTYSTRING : value;
    }
    
    protected String getAttribute(String prefix, String localName) {
        return getAttribute(prefix + ':' + localName);
    }

    protected boolean hasAttribute(String qname) {
	return (_attributes != null && _attributes.getValue(qname) != null);
    }
    
    protected void addAttribute(String qname, String value) {
        _attributes.add(qname, value);
    }

    /**
     * Returns a list of all attributes declared for the element represented by
     * this syntax tree node.
     * @return Attributes for this syntax tree node
     */
    protected Attributes getAttributes() {
	return(_attributes);
    }

    /**
     * Sets the prefix mapping for the namespaces that were declared in this
     * element. This does not include all prefix mappings in scope, so one
     * may have to check ancestor elements to get all mappings that are in
     * in scope. The prefixes must be passed in as a Hashtable that maps
     * namespace prefixes (String objects) to namespace URIs (also String).
     * @param mapping The Hashtable containing the mappings.
     */
    protected void setPrefixMapping(Hashtable mapping) {
	_prefixMapping = mapping;
    }

    /**
     * Returns a Hashtable containing the prefix mappings that were declared
     * for this element. This does not include all prefix mappings in scope,
     * so one may have to check ancestor elements to get all mappings that are
     * in in scope. 
     * @return Prefix mappings (for this element only).
     */
    protected Hashtable getPrefixMapping() {
	return _prefixMapping;
    }

    /**
     * Adds a single prefix mapping to this syntax tree node.
     * @param prefix Namespace prefix.
     * @param uri Namespace URI.
     */
    protected void addPrefixMapping(String prefix, String uri) {
	if (_prefixMapping == null)
	    _prefixMapping = new Hashtable();
	_prefixMapping.put(prefix, uri);
    }

    /**
     * Returns any namespace URI that is in scope for a given prefix. This
     * method checks namespace mappings for this element, and if necessary
     * for ancestor elements as well (ie. if the prefix maps to an URI in this
     * scope then you'll definately get the URI from this method).
     * @param prefix Namespace prefix.
     * @return Namespace URI.
     */
    protected String lookupNamespace(String prefix) {
	// Initialise the output (default is 'null' for undefined)
	String uri = null;

	// First look up the prefix/uri mapping in our own hashtable...
	if (_prefixMapping != null)
	    uri = (String)_prefixMapping.get(prefix);
	// ... but if we can't find it there we ask our parent for the mapping
	if ((uri == null) && (_parent != null)) {
	    uri = _parent.lookupNamespace(prefix);
	    if ((prefix == Constants.EMPTYSTRING) && (uri == null))
		uri = Constants.EMPTYSTRING;
	}
	// ... and then we return whatever URI we've got.
	return(uri);
    }

    /**
     * Returns any namespace prefix that is mapped to a prefix in the current
     * scope. This method checks namespace mappings for this element, and if
     * necessary for ancestor elements as well (ie. if the URI is declared
     * within the current scope then you'll definately get the prefix from
     * this method). Note that this is a very slow method and consequentially
     * it should only be used strictly when needed.
     * @param uri Namespace URI.
     * @return Namespace prefix.
     */
    protected String lookupPrefix(String uri) {
	// Initialise the output (default is 'null' for undefined)
	String prefix = null;

	// First look up the prefix/uri mapping in our own hashtable...
	if ((_prefixMapping != null) &&
	    (_prefixMapping.contains(uri))) {
	    Enumeration prefixes = _prefixMapping.keys();
	    while (prefixes.hasMoreElements()) {
		prefix = (String)prefixes.nextElement();
		String mapsTo = (String)_prefixMapping.get(prefix);
		if (mapsTo.equals(uri)) return(prefix);
	    }
	}
	// ... but if we can't find it there we ask our parent for the mapping
	else if (_parent != null) {
	    prefix = _parent.lookupPrefix(uri);
	    if ((uri == Constants.EMPTYSTRING) && (prefix == null))
		prefix = Constants.EMPTYSTRING;
	}
	return(prefix);
    }

    /**
     * Set this node's parser. The parser (the XSLT parser) gives this
     * syntax tree node access to the symbol table and XPath parser.
     * @param parser The XSLT parser.
     */
    protected void setParser(Parser parser) {
	_parser = parser;
    }

    /**
     * Returns this node's XSLT parser.
     * @return The XSLT parser.
     */
    public final Parser getParser() {
	return _parser;
    }

    /**
     * Set this syntax tree node's parent node, if unset. For
     * re-parenting just use <code>node._parent = newparent</code>.
     *
     * @param parent The parent node.
     */
    protected void setParent(SyntaxTreeNode parent) {
        if (_parent == null) _parent = parent;
    }

    /**
     * Returns this syntax tree node's parent node.
     * @return The parent syntax tree node.
     */
    protected final SyntaxTreeNode getParent() {
	return _parent;
    }

    /**
     * Returns 'true' if this syntax tree node is the Sentinal node.
     * @return 'true' if this syntax tree node is the Sentinal node.
     */
    protected final boolean isDummy() {
        return this == Dummy;
    }

    /**
     * Get the import precedence of this element. The import precedence equals
     * the import precedence of the stylesheet in which this element occured.
     * @return The import precedence of this syntax tree node.
     */
    protected int getImportPrecedence() {
	Stylesheet stylesheet = getStylesheet();
	if (stylesheet == null) return Integer.MIN_VALUE;
	return stylesheet.getImportPrecedence();
    }

    /**
     * Get the Stylesheet node that represents the <xsl:stylesheet/> element
     * that this node occured under.
     * @return The Stylesheet ancestor node of this node.
     */
    public Stylesheet getStylesheet() {
	if (_stylesheet == null) {
	    SyntaxTreeNode parent = this;
	    while (parent != null) {
		if (parent instanceof Stylesheet)
		    return((Stylesheet)parent);
		parent = parent.getParent();
	    }
	    _stylesheet = (Stylesheet)parent;
	}
	return(_stylesheet);
    }

    /**
     * Get the Template node that represents the <xsl:template/> element
     * that this node occured under. Note that this method will return 'null'
     * for nodes that represent top-level elements.
     * @return The Template ancestor node of this node or 'null'.
     */
    protected Template getTemplate() {
	if (_template == null) {
	    SyntaxTreeNode parent = this;
	    while ((parent != null) && (!(parent instanceof Template)))
		parent = parent.getParent();
	    _template = (Template)parent;
	}
	return(_template);
    }

    /**
     * Returns a reference to the XSLTC (XSLT compiler) in use.
     * @return XSLTC - XSLT compiler.
     */
    protected final XSLTC getXSLTC() {
	return _parser.getXSLTC();
    }

    /**
     * Returns the XSLT parser's symbol table.
     * @return Symbol table.
     */
    protected final SymbolTable getSymbolTable() {
	return (_parser == null) ? null : _parser.getSymbolTable();
    }

    /**
     * Parse the contents of this syntax tree nodes (child nodes, XPath
     * expressions, patterns and functions). The default behaviour is to parser
     * the syntax tree node's children (since there are no common expressions,
     * patterns, etc. that can be handled in this base class.
     * @param parser reference to the XSLT parser
     */
    public void parseContents(Parser parser) {
	parseChildren(parser);
    }

    /**
     * Parse all children of this syntax tree node. This method is normally
     * called by the parseContents() method.
     * @param parser reference to the XSLT parser
     */
    protected final void parseChildren(Parser parser) {

	Vector locals = null;	// only create when needed
	
	final int count = _contents.size();
	for (int i=0; i<count; i++) {
	    SyntaxTreeNode child = (SyntaxTreeNode)_contents.elementAt(i);
	    parser.getSymbolTable().setCurrentNode(child);
	    child.parseContents(parser);
	    // if variable or parameter, add it to scope
	    final QName varOrParamName = updateScope(parser, child);
	    if (varOrParamName != null) {
		if (locals == null) {
		    locals = new Vector(2);
		}
		locals.addElement(varOrParamName);
	    }
	}

	parser.getSymbolTable().setCurrentNode(this);

	// after the last element, remove any locals from scope
	if (locals != null) {
	    final int nLocals = locals.size();
	    for (int i = 0; i < nLocals; i++) {
		parser.removeVariable((QName)locals.elementAt(i));
	    }
	}
    }
   
    /**
     * Add a node to the current scope and return name of a variable or
     * parameter if the node represents a variable or a parameter.
     */
    protected QName updateScope(Parser parser, SyntaxTreeNode node) {
	if (node instanceof Variable) {
	    final Variable var = (Variable)node;
	    parser.addVariable(var);