com.caucho.xpath.pattern.AbstractPattern Maven / Gradle / Ivy
/*
* Copyright (c) 1998-2012 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.xpath.pattern;
import com.caucho.xpath.Env;
import com.caucho.xpath.ExprEnvironment;
import com.caucho.xpath.XPathException;
import org.w3c.dom.Node;
import java.util.logging.Logger;
/**
* A node selection pattern. AbstractPatterns represent compiled XPath node selectors.
* They can be used to find nodes, select nodes, and test if a node matches
* a pattern.
*
* There are two types of patterns: select patterns and match patterns.
*
Select patterns match a node relative to another node.
* find and select use select patterns.
*
Match patterns match a node in isolation. isMatch uses
* match patterns.
*/
abstract public class AbstractPattern {
protected static final Logger log
= Logger.getLogger(AbstractPattern.class.getName());
// This is the value Axis wants
public static final String XMLNS = "http://www.w3.org/2000/xmlns/";
protected AbstractPattern _parent;
protected AbstractPattern _child;
AbstractPattern(AbstractPattern parent)
{
_parent = parent;
if (parent != null && parent._child == null)
parent._child = this;
}
/**
* Returns the parent pattern.
*/
public AbstractPattern getParent()
{
return _parent;
}
/**
* Returns the pattern's default priority as defined by the XSLT draft.
*/
public double getPriority()
{
return 0.5;
}
/**
* Returns the name of the matching node or '*' if many nodes match.
*
*
The Xsl package uses this to speed template matching.
*/
public String getNodeName()
{
return "*";
}
/**
* Returns an iterator selecting nodes in document order.
*
* @param node the starting node.
* @param env the variable environment.
*
* @return an iterator selecting nodes in document order.
*/
public NodeIterator select(Node node, ExprEnvironment env)
throws XPathException
{
NodeIterator base = createNodeIterator(node, env, copyPosition());
if (isStrictlyAscending())
return base;
else
return new MergeIterator(env, base);
}
/**
* Returns an iterator selecting unique nodes. The nodes are not
* necessarily in document order.
*
* @param node the starting node.
* @param env the variable environment.
* @param context the context node.
*
* @return an iterator selecting unique nodes.
*/
public NodeIterator selectUnique(Node node, ExprEnvironment env)
throws XPathException
{
NodeIterator base = createNodeIterator(node, env, copyPosition());
if (isUnique())
return base;
else
return new UniqueIterator(env, base);
}
/**
* Find any node matching the pattern.
*
* @param node the current node
* @param env the xpath environment
*
* @return one of the matching nodes
*/
public Node findAny(Node node, ExprEnvironment env)
throws XPathException
{
NodeIterator base = createNodeIterator(node, env, copyPosition());
return base.nextNode();
}
/**
* Returns true if the pattern is strictly ascending.
*/
public boolean isStrictlyAscending()
{
if (_parent != null)
return _parent.isStrictlyAscending();
else
return false;
}
/**
* Returns true if the pattern's iterator returns unique nodes.
*/
public boolean isUnique()
{
if (_parent != null)
return _parent.isUnique();
else
return false;
}
/**
* Returns true if the pattern selects a single node
*/
boolean isSingleSelect()
{
if (_parent != null)
return _parent.isSingleSelect();
else
return false;
}
/**
* Returns true if the pattern returns nodes on a single level.
*/
boolean isSingleLevel()
{
return isSingleSelect();
}
/**
* Creates a new node iterator.
*
* @param node the starting node
* @param env the variable environment
* @param pattern the level pattern
*
* @return the node iterator
*/
public NodeIterator createNodeIterator(Node node, ExprEnvironment env,
AbstractPattern pattern)
throws XPathException
{
if (_parent == null)
throw new RuntimeException(String.valueOf(this) + " " + getClass());
else
return _parent.createNodeIterator(node, env, pattern);
}
/**
* Returns the first node in the selection order.
*
* @param node the current node
* @param variable environment
*
* @return the first node
*/
public Node firstNode(Node node, ExprEnvironment env)
throws XPathException
{
throw new UnsupportedOperationException(String.valueOf(this) + " " + getClass());
}
/**
* Returns the last node in the selection order.
*
* @param node the current node
*
* @return the last node
*/
public Node lastNode(Node node)
{
return null;
}
/**
* Returns the next node in the selection order.
*
* @param node the current node
* @param last the last node
*
* @return the next node
*/
public Node nextNode(Node node, Node last)
throws XPathException
{
throw new UnsupportedOperationException();
}
/**
* The core match function test if the pattern matches the node.
*
* @param node the node to test
* @param env the variable environment.
*
* @return true if the node matches the pattern.
*/
public abstract boolean match(Node node, ExprEnvironment env)
throws XPathException;
/**
* Return true if the iterator is in document-order.
*/
public boolean isAscending()
{
return true;
}
/**
* Returns the position of the node in its context for a match pattern.
*
* @param node the current node
* @param env the variable environment
* @param pattern the position pattern
*
* @return the node's position.
*/
public int position(Node node, Env env, AbstractPattern pattern)
throws XPathException
{
return _parent.position(node, env, pattern);
}
/**
* Returns the number of nodes in its context for a match pattern.
*
* @param node the current node
* @param env the variable environment
* @param pattern the position pattern
*
* @return the count of nodes in the match selection
*/
public int count(Node node, Env env, AbstractPattern pattern)
throws XPathException
{
return _parent.count(node, env, pattern);
}
/**
* Returns the owning axis for the pattern.
*/
public AbstractPattern copyAxis()
{
if (_parent != null)
return _parent.copyAxis();
else
return null;
}
/**
* Returns the position matching pattern.
*/
public AbstractPattern copyPosition()
{
return this;
}
/**
* For string conversion, returns the string prefix corresponding to
* the parents.
*/
protected String getPrefix()
{
if (_parent == null ||
_parent instanceof FromAny)
return "";
else if (_parent instanceof FromContext) { // check for in Filter?
FromContext context = (FromContext) _parent;
String name = "";
for (int i = 0; i < context.getCount(); i++) {
name += "../";
}
return name;
}
else if (_parent instanceof FromRoot)
return "/";
else
return _parent + "/";
}
public String toPatternString()
{
return toString();
}
}