/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * 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.compiler.util.Util;

import org.xml.sax.Attributes;

import org.xml.sax.helpers.AttributesImpl;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 * @author G. Todd Miller

 * @author Morten Jorensen

 * @author Erwin Bolwidt <ejb@klomp.org>

 * @author John Howard <JohnH@schemasoft.com>

 */

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 AttributesImpl _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(AttributesImpl 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) {

        int index = _attributes.getIndex(qname);

        if (index != -1) {

            _attributes.setAttribute(index, "", Util.getLocalName(qname),

                    qname, "CDATA", value);

        }

        else {

            _attributes.addAttribute("", Util.getLocalName(qname), qname,

                    "CDATA", 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);

            return var.getName();

        }

        else if (node instanceof Param) {

            final Param param = (Param)node;

            parser.addParameter(param);

            return param.getName();

        }

        else {

            return null;

        }

    }

    /**

     * Type check the children of this node. The type check phase may add

     * coercions (CastExpr) to the AST.

     * @param stable The compiler/parser's symbol table

     */

    public abstract Type typeCheck(SymbolTable stable) throws TypeCheckError;

    /**

     * Call typeCheck() on all child syntax tree nodes.

     * @param stable The compiler/parser's symbol table

     */

    protected Type typeCheckContents(SymbolTable stable) throws TypeCheckError {

        final int n = elementCount();

        for (int i = 0; i < n; i++) {

            SyntaxTreeNode item = (SyntaxTreeNode)_contents.elementAt(i);

            item.typeCheck(stable);

        }

        return Type.Void;

    }

    /**

     * Translate this abstract syntax tree node into JVM bytecodes.

     * @param classGen BCEL Java class generator

     * @param methodGen BCEL Java method generator

     */

    public abstract void translate(ClassGenerator classGen,

                                   MethodGenerator methodGen);

    /**

     * Call translate() on all child syntax tree nodes.

     * @param classGen BCEL Java class generator

     * @param methodGen BCEL Java method generator

     */

    protected void translateContents(ClassGenerator classGen,

                                     MethodGenerator methodGen) {

        // Call translate() on all child nodes

        final int n = elementCount();

        for (int i = 0; i < n; i++) {

            final SyntaxTreeNode item = (SyntaxTreeNode)_contents.elementAt(i);

            item.translate(classGen, methodGen);

        }

        // After translation, unmap any registers for any variables/parameters

        // that were declared in this scope. Performing this unmapping in the

        // same AST scope as the declaration deals with the problems of

        // references falling out-of-scope inside the for-each element.

        // (the cause of which being 'lazy' register allocation for references)

        for (int i = 0; i < n; i++) {