WebCore/xpath/impl/XPathStep.cpp

/*
 * Copyright 2005 Frerich Raabe <raabe@kde.org>
 * Copyright (C) 2006 Apple Computer, Inc.
 *
 * 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.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR 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 USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 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.
 */

#include "config.h"
#include "XPathStep.h"

#ifdef XPATH_SUPPORT

#include "NamedAttrMap.h"
#include "XPathNSResolver.h"
#include "XPathParser.h"

namespace WebCore {
namespace XPath {

Step::Step(Axis axis, const String& nodeTest, const Vector<Predicate*>& predicates)
    : m_axis(axis), m_nodeTest(nodeTest), m_predicates(predicates)
{
    Parser* parser = Parser::current();
    ASSERT(parser);
    m_namespaceURI = parser->m_currentNamespaceURI;
    parser->m_currentNamespaceURI = String();
}

Step::~Step()
{
    deleteAllValues(m_predicates);
}

NodeVector Step::evaluate(Node* context) const
{
    NodeVector inNodes = nodesInAxis(context), outNodes;
    inNodes = nodeTestMatches(inNodes);
    
    outNodes = inNodes;
    for (unsigned i = 0; i < m_predicates.size(); i++) {
        Predicate* predicate = m_predicates[i];

        outNodes.clear();
        Expression::evaluationContext().size = inNodes.size();
        Expression::evaluationContext().position = 1;
        for (unsigned j = 0; j < inNodes.size(); j++) {
            Node* node = inNodes[j].get();

            Expression::evaluationContext().node = node;
            EvaluationContext backupCtx = Expression::evaluationContext();
            if (predicate->evaluate())
                outNodes.append(node);

            Expression::evaluationContext() = backupCtx;
            ++Expression::evaluationContext().position;
        }

        inNodes = outNodes;
    }
    return outNodes;
}

NodeVector Step::nodesInAxis(Node* context) const
{
    NodeVector nodes;
    switch (m_axis) {
        case ChildAxis:
            for (Node* n = context->firstChild(); n; n = n->nextSibling())
                nodes.append(n);
            return nodes;
        case DescendantAxis: 
            for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context))
                nodes.append(n);
            return nodes;
        case ParentAxis:
            nodes.append(context->parentNode());
            return nodes;
        case AncestorAxis:
            for (Node* n = context->parentNode(); n; n = n->parentNode())
                nodes.append(n);
            return nodes;
        case FollowingSiblingAxis:
            if (context->nodeType() == Node::ATTRIBUTE_NODE ||
                 context->nodeType() == Node::XPATH_NAMESPACE_NODE) 
                return NodeVector();
            
            for (Node* n = context->nextSibling(); n; n = n->nextSibling())
                nodes.append(n);
            return nodes;
        case PrecedingSiblingAxis:
            if (context->nodeType() == Node::ATTRIBUTE_NODE ||
                 context->nodeType() == Node::XPATH_NAMESPACE_NODE)
                return NodeVector();
            
            for (Node* n = context->previousSibling(); n; n = n->previousSibling())
                nodes.append(n);
            return nodes;
        case FollowingAxis: 
            for (Node *p = context; !isRootDomNode(p); p = p->parentNode()) {
                for (Node* n = p->nextSibling(); n; n = n->nextSibling()) {
                    nodes.append(n);
                    for (Node* c = n->firstChild(); c; c = c->traverseNextNode(n))
                        nodes.append(c);
                }
            }
            return nodes;
        case PrecedingAxis:
            for (Node* p = context; !isRootDomNode(p); p = p->parentNode()) {
                for (Node* n = p->previousSibling(); n ; n = n->previousSibling()) {
                    nodes.append(n);
                    for (Node* c = n->firstChild(); c; c = c->traverseNextNode(n))
                        nodes.append(c);
                }
            }
            return nodes;
        case AttributeAxis: {
            if (context->nodeType() != Node::ELEMENT_NODE)
                return NodeVector();

            NamedAttrMap* attrs = context->attributes();
            if (!attrs)
                return nodes;

            for (unsigned long i = 0; i < attrs->length(); ++i) 
                nodes.append (attrs->item(i));
            return nodes;
        }
        case NamespaceAxis: {
            if (context->nodeType() != Node::ELEMENT_NODE)
                return NodeVector();

            bool foundXmlNsNode = false;
            for (Node* node = context; node; node = node->parentNode()) {
                NamedAttrMap* attrs = node->attributes();
                if (!attrs)
                    continue;

                for (unsigned long i = 0; i < attrs->length(); ++i) {
                    Node* n = attrs->item(i).get();
                    if (n->nodeName().startsWith("xmlns:")) {
                        nodes.append(n);
                    } else if (n->nodeName() == "xmlns" &&
                               !foundXmlNsNode) {
                        foundXmlNsNode = true;
                        if (!n->nodeValue().isEmpty())
                            nodes.append(n);
                    }
                }
            }
            return nodes;
        }
        case SelfAxis:
            nodes.append(context);
            return nodes;
        case DescendantOrSelfAxis:
            nodes.append(context);
            for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context))
                nodes.append(n);
            return nodes;
        case AncestorOrSelfAxis:
            nodes.append(context);
            for (Node* n = context->parentNode(); n; n = n->parentNode())
                nodes.append(n);
            return nodes;
    }

    return NodeVector();
}


NodeVector Step::nodeTestMatches(const NodeVector& nodes) const
{
    NodeVector matches;

    if (m_nodeTest == "*") {
        for (unsigned i = 0; i < nodes.size(); i++) {
            Node* node = nodes[i].get();
            if (node->nodeType() == primaryNodeType(m_axis) &&
                (m_namespaceURI.isEmpty() || m_namespaceURI == node->namespaceURI()))
                matches.append(node);
        }
        return nodes;
    } else if (m_nodeTest == "text()") {
        for (unsigned i = 0; i < nodes.size(); i++) {
            Node* node = nodes[i].get();
            if (node->nodeType() == Node::TEXT_NODE ||
                node->nodeType() == Node::CDATA_SECTION_NODE) 
                matches.append(node);
        }
        return matches;
    } else if (m_nodeTest == "comment()") {
        for (unsigned i = 0; i < nodes.size(); i++) {
            Node* node = nodes[i].get();
            if (node->nodeType() == Node::COMMENT_NODE)
                matches.append(node);
        }
        return matches;
    } else if (m_nodeTest.startsWith("processing-instruction")) {
        String param;

        const int space = m_nodeTest.find(' ');
        if (space > -1)
            param = m_nodeTest.deprecatedString().mid(space + 1);

        for (unsigned i = 0; i < nodes.size(); i++) {
            Node* node = nodes[i].get();

            if (node->nodeType() == Node::PROCESSING_INSTRUCTION_NODE &&
                (param.isEmpty() || node->nodeName() == param))
                    matches.append(node);
        }    
        return matches;
    } else if (m_nodeTest == "node()")
        return nodes;
    else {
        if (m_axis == AttributeAxis) {
            // In XPath land, namespace nodes are not accessible
            // on the attribute axis.
            if (m_nodeTest == "xmlns")
                return matches;

            for (unsigned i = 0; i < nodes.size(); i++) {
                Node* node = nodes[i].get();
                
                if (node->nodeName() == m_nodeTest) {
                    matches.append(node);
                    break; // There can only be one.
                }
            }

            return matches;
        } else if (m_axis == NamespaceAxis) {
            // Node test on the namespace axis is not implemented yet
        } else {
            for (unsigned i = 0; i < nodes.size(); i++) {
                Node* node = nodes[i].get();

                // We use tagQName here because we don't want the element name in uppercase 
                // like we get with HTML elements.
                if (node->nodeType() == Node::ELEMENT_NODE &&
                    static_cast<Element*>(node)->tagQName().localName() == m_nodeTest &&
                    (m_namespaceURI.isNull() || m_namespaceURI == node->namespaceURI()))
                    matches.append(node);
            }

            return matches;
        }
    }

    return matches;
}

void Step::optimize()
{
    for (unsigned i = 0; i < m_predicates.size(); i++)
        m_predicates[i]->optimize();
}

Node::NodeType Step::primaryNodeType(Axis axis) const
{
    switch (axis) {
        case AttributeAxis:
            return Node::ATTRIBUTE_NODE;
        case NamespaceAxis:
            return Node::XPATH_NAMESPACE_NODE;
        default:
            return Node::ELEMENT_NODE;
    }
}

}
}

#endif // XPATH_SUPPORT