/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */
/*
 * $Id$
 */

package org.apache.xalan.xsltc.compiler;

import java.util.Hashtable;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.Vector;

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

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class SymbolTable {

    // These hashtables are used for all stylesheets
    private final Hashtable _stylesheets = new Hashtable();
    private final Hashtable _primops     = new Hashtable();

    // These hashtables are used for some stylesheets
    private Hashtable _variables = null;
    private Hashtable _templates = null;
    private Hashtable _attributeSets = null;
    private Hashtable _aliases = null;
    private Hashtable _excludedURI = null;
    private Stack     _excludedURIStack = null;
    private Hashtable _decimalFormats = null;
    private Hashtable _keys = null;

    public DecimalFormatting getDecimalFormatting(QName name) {
	if (_decimalFormats == null) return null;
	return((DecimalFormatting)_decimalFormats.get(name));
    }

    public void addDecimalFormatting(QName name, DecimalFormatting symbols) {
	if (_decimalFormats == null) _decimalFormats = new Hashtable();
	_decimalFormats.put(name, symbols);
    }

    public Key getKey(QName name) {
	if (_keys == null) return null;
	return (Key) _keys.get(name);
    }

    public void addKey(QName name, Key key) {
	if (_keys == null) _keys = new Hashtable();
	_keys.put(name, key);
    }
    
    public Stylesheet addStylesheet(QName name, Stylesheet node) {
	return (Stylesheet)_stylesheets.put(name, node);
    }
	
    public Stylesheet lookupStylesheet(QName name) {
	return (Stylesheet)_stylesheets.get(name);
    }

    public Template addTemplate(Template template) {
	final QName name = template.getName();
	if (_templates == null) _templates = new Hashtable();
	return (Template)_templates.put(name, template);
    }
	
    public Template lookupTemplate(QName name) {
	if (_templates == null) return null;
	return (Template)_templates.get(name);
    }

    public Variable addVariable(Variable variable) {
	if (_variables == null) _variables = new Hashtable();
	final String name = variable.getName().getStringRep();
	return (Variable)_variables.put(name, variable);
    }
	
    public Param addParam(Param parameter) {
	if (_variables == null) _variables = new Hashtable();
	final String name = parameter.getName().getStringRep();
	return (Param)_variables.put(name, parameter);
    }
	
    public Variable lookupVariable(QName qname) {
	if (_variables == null) return null;
	final String name = qname.getStringRep();
	final Object obj = _variables.get(name);
	return obj instanceof Variable ? (Variable)obj : null;
    }

    public Param lookupParam(QName qname) {
	if (_variables == null) return null;
	final String name = qname.getStringRep();
	final Object obj = _variables.get(name);
	return obj instanceof Param ? (Param)obj : null;
    }
	
    public SyntaxTreeNode lookupName(QName qname) {
	if (_variables == null) return null;
	final String name = qname.getStringRep();
	return (SyntaxTreeNode)_variables.get(name);
    }

    public AttributeSet addAttributeSet(AttributeSet atts) {
	if (_attributeSets == null) _attributeSets = new Hashtable();
	return (AttributeSet)_attributeSets.put(atts.getName(), atts);
    }

    public AttributeSet lookupAttributeSet(QName name) {
	if (_attributeSets == null) return null;
	return (AttributeSet)_attributeSets.get(name);
    }

    /**
     * Add a primitive operator or function to the symbol table. To avoid
     * name clashes with user-defined names, the prefix <tt>PrimopPrefix</tt>
     * is prepended.
     */
    public void addPrimop(String name, MethodType mtype) {
	Vector methods = (Vector)_primops.get(name);
	if (methods == null) {
	    _primops.put(name, methods = new Vector());
	}
	methods.addElement(mtype);
    }
	
    /**
     * Lookup a primitive operator or function in the symbol table by
     * prepending the prefix <tt>PrimopPrefix</tt>.
     */
    public Vector lookupPrimop(String name) {
	return (Vector)_primops.get(name);
    }

    /**
     * This is used for xsl:attribute elements that have a "namespace"
     * attribute that is currently not defined using xmlns:
     */
    private int _nsCounter = 0;

    public String generateNamespacePrefix() {
	return("ns"+(_nsCounter++));
    }

    /**
     * Use a namespace prefix to lookup a namespace URI
     */
    private SyntaxTreeNode _current = null;

    public void setCurrentNode(SyntaxTreeNode node) {
	_current = node;
    }

    public String lookupNamespace(String prefix) {
	if (_current == null) return(Constants.EMPTYSTRING);
	return(_current.lookupNamespace(prefix));
    }

    /**
     * Adds an alias for a namespace prefix
     */ 
    public void addPrefixAlias(String prefix, String alias) {
	if (_aliases == null) _aliases = new Hashtable();
	_aliases.put(prefix,alias);
    }

    /**
     * Retrieves any alias for a given namespace prefix
     */ 
    public String lookupPrefixAlias(String prefix) {
	if (_aliases == null) return null;
	return (String)_aliases.get(prefix);
    }

    /**
     * Register a namespace URI so that it will not be declared in the output
     * unless it is actually referenced in the output.
     */
    public void excludeURI(String uri) {
	// The null-namespace cannot be excluded
	if (uri == null) return;

	// Create new hashtable of exlcuded URIs if none exists
	if (_excludedURI == null) _excludedURI = new Hashtable();

	// Register the namespace URI
	Integer refcnt = (Integer)_excludedURI.get(uri);
	if (refcnt == null)
	    refcnt = new Integer(1);
	else
	    refcnt = new Integer(refcnt.intValue() + 1);
	_excludedURI.put(uri,refcnt);
    }

    /**
     * Exclude a series of namespaces given by a list of whitespace
     * separated namespace prefixes.
     */
    public void excludeNamespaces(String prefixes) {
	if (prefixes != null) {
	    StringTokenizer tokens = new StringTokenizer(prefixes);
	    while (tokens.hasMoreTokens()) {
		final String prefix = tokens.nextToken();
		final String uri;
		if (prefix.equals("#default"))
		    uri = lookupNamespace(Constants.EMPTYSTRING);
		else
		    uri = lookupNamespace(prefix);
		if (uri != null) excludeURI(uri);
	    }
	}
    }

    /**
     * Check if a namespace should not be declared in the output (unless used)
     */
    public boolean isExcludedNamespace(String uri) {
	if (uri != null && _excludedURI != null) {
	    final Integer refcnt = (Integer)_excludedURI.get(uri);
	    return (refcnt != null && refcnt.intValue() > 0);
	}
	return false;
    }

    /**
     * Turn of namespace declaration exclusion
     */
    public void unExcludeNamespaces(String prefixes) {
	if (_excludedURI == null) return;
	if (prefixes != null) {
	    StringTokenizer tokens = new StringTokenizer(prefixes);
	    while (tokens.hasMoreTokens()) {
		final String prefix = tokens.nextToken();
		final String uri;
		if (prefix.equals("#default"))
		    uri = lookupNamespace(Constants.EMPTYSTRING);
		else
		    uri = lookupNamespace(prefix);
		Integer refcnt = (Integer)_excludedURI.get(uri);
		if (refcnt != null)
		    _excludedURI.put(uri, new Integer(refcnt.intValue() - 1));
	    }
	}	
    }

    /**
     * Exclusion of namespaces by a stylesheet does not extend to any stylesheet
     * imported or included by the stylesheet.  Upon entering the context of a
     * new stylesheet, a call to this method is needed to clear the current set
     * of excluded namespaces temporarily.  Every call to this method requires
     * a corresponding call to {@link #popExcludedNamespacesContext()}.
     */
    public void pushExcludedNamespacesContext() {
        if (_excludedURIStack == null) {
            _excludedURIStack = new Stack();
        }
        _excludedURIStack.push(_excludedURI);
        _excludedURI = null;
    }
    
    /**
     * Exclusion of namespaces by a stylesheet does not extend to any stylesheet
     * imported or included by the stylesheet.  Upon exiting the context of a
     * stylesheet, a call to this method is needed to restore the set of
     * excluded namespaces that was in effect prior to entering the context of
     * the current stylesheet.
     */
    public void popExcludedNamespacesContext() {
        _excludedURI = (Hashtable) _excludedURIStack.pop();
        if (_excludedURIStack.isEmpty()) {
            _excludedURIStack = null;
        }
    }

}

