expr.java

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/*
 * Copyright (c) 1998-2008 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;

import com.caucho.util.CharBuffer;
import com.caucho.xml.XmlChar;
import com.caucho.xml.XmlUtil;
import com.caucho.xpath.expr.ObjectVar;
import com.caucho.xpath.expr.Var;
import com.caucho.xpath.pattern.AbstractPattern;
import com.caucho.xpath.pattern.FromExpr;
import com.caucho.xpath.pattern.NodeArrayListIterator;
import com.caucho.xpath.pattern.NodeIterator;
import com.caucho.xpath.pattern.NodeListIterator;
import com.caucho.xpath.pattern.SingleNodeIterator;

import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import java.util.ArrayList;
import java.util.Iterator;

/**
 * Compute values from nodes.  Because the expressions themselves are
 * untyped, the class provides methods for creating the type of the
 * desired result.
 */
abstract public class Expr {
  protected static final int CONST = 0;

  protected static final int NODE_SET = CONST + 1;
  protected static final int ID = NODE_SET + 1;

  protected static final int OR = ID + 1;
  protected static final int AND = OR + 1;

  protected static final int EQ = AND + 1;
  protected static final int NEQ = EQ + 1;
  protected static final int LT = NEQ + 1;
  protected static final int LE = LT + 1;
  protected static final int GT = LE + 1;
  protected static final int GE = GT + 1;
  
  protected static final int BOOLEAN_EQ = GE + 1;
  protected static final int BOOLEAN_NEQ = BOOLEAN_EQ + 1;
  
  protected static final int NUMBER_EQ = BOOLEAN_NEQ + 1;
  protected static final int NUMBER_NEQ = NUMBER_EQ + 1;
  protected static final int NUMBER_LT = NUMBER_NEQ + 1;
  protected static final int NUMBER_LE = NUMBER_LT + 1;
  protected static final int NUMBER_GT = NUMBER_LE + 1;
  protected static final int NUMBER_GE = NUMBER_GT + 1;
  
  protected static final int STRING_EQ = NUMBER_GE + 1;
  protected static final int STRING_NEQ = STRING_EQ + 1;

  protected static final int NEG = STRING_NEQ + 1;
  protected static final int ADD = NEG + 1;
  protected static final int SUB = ADD + 1;
  protected static final int MUL = SUB + 1;
  protected static final int DIV = MUL + 1;
  protected static final int QUO = DIV + 1;
  protected static final int MOD = QUO + 1;

  protected static final int TRUE = MOD + 1;
  protected static final int FALSE = TRUE + 1;
  protected static final int NOT = FALSE + 1;
  protected static final int BOOLEAN = NOT + 1;
  protected static final int LANG = BOOLEAN + 1;

  protected static final int NUMBER = LANG + 1;
  protected static final int SUM = NUMBER + 1;
  protected static final int FLOOR = SUM + 1;
  protected static final int CEILING = FLOOR + 1;
  protected static final int ROUND = CEILING + 1;
  public static final int POSITION = ROUND + 1;
  protected static final int COUNT = POSITION + 1;
  protected static final int LAST = COUNT + 1;

  protected static final int STRING = LAST + 1;
  protected static final int CONCAT = STRING + 1;
  protected static final int STARTS_WITH = CONCAT + 1;
  protected static final int CONTAINS = STARTS_WITH + 1;
  protected static final int SUBSTRING = CONTAINS + 1;
  protected static final int SUBSTRING_BEFORE = SUBSTRING + 1;
  protected static final int SUBSTRING_AFTER = SUBSTRING_BEFORE + 1;
  protected static final int STRING_LENGTH = SUBSTRING_AFTER + 1;
  protected static final int NORMALIZE = STRING_LENGTH + 1;
  protected static final int TRANSLATE = NORMALIZE + 1;
  protected static final int FORMAT_NUMBER = TRANSLATE + 1;

  protected static final int LOCAL_PART = FORMAT_NUMBER + 1;
  protected static final int NAMESPACE = LOCAL_PART + 1;
  protected static final int QNAME = NAMESPACE + 1;
  protected static final int GENERATE_ID = QNAME + 1;

  protected static final int FUNCTION_AVAILABLE = GENERATE_ID + 1;
  protected static final int SYSTEM_PROPERTY = FUNCTION_AVAILABLE + 1;

  protected static final int IF = SYSTEM_PROPERTY + 1;
  
  protected static final int SELF = IF + 1;
  protected static final int SELF_NAME = SELF + 1;
  protected static final int ATTRIBUTE = SELF_NAME + 1;
  protected static final int ELEMENT = ATTRIBUTE + 1;
  
  protected static final int BASE_URI = ELEMENT + 1;
  protected static final int LAST_FUN = BASE_URI + 1;

  private AbstractPattern listContext;
  
  protected Expr() {}

  public void setListContext(AbstractPattern listContext)
  {
    this.listContext = listContext;
  }

  public AbstractPattern getListContext()
  {
    return listContext;
  }
  
  /**
   * true if the expression prefers to return a number.
   */
  public boolean isNumber()
  {
    return false;
  }
  
  /**
   * Evaluates the expression as a double using the node as a context.
   *
   * @param node the node to evaluate and use as a context
   *
   * @return the numeric value.
   */
  public double evalNumber(Node node)
    throws XPathException
  {
    Env env = XPath.createEnv();
    env.setCurrentNode(node);
    env.setContextNode(node);

    double result = evalNumber(node, env);

    XPath.freeEnv(env);

    return result;
  }

  /**
   * Evaluates the expression as a number.
   *
   * @param node the current node.
   * @param env variable environment.
   *
   * @return the numeric value.
   */
  public abstract double evalNumber(Node node, ExprEnvironment env)
    throws XPathException;

  /**
   * true if the expression prefers to return a boolean.
   */
  public boolean isBoolean()
  {
    return false;
  }

  /**
   * Returns the boolean value of the node.
   *
   * @param node the node to evaluate and use as a context
   *
   * @return the boolean value
   */
  public boolean evalBoolean(Node node)
    throws XPathException
  {
    Env env = XPath.createEnv();
    env.setCurrentNode(node);
    env.setContextNode(node);

    boolean result = evalBoolean(node, env);

    XPath.freeEnv(env);

    return result;
  }

  /**
   * Returns the boolean value of the node.
   *
   * @param node the node to evaluate and use as a context
   * @param env variable environment.
   *
   * @return the boolean value.
   */
  public abstract boolean evalBoolean(Node node, ExprEnvironment env)
    throws XPathException;

  /**
   * Returns the expression evaluated as a string.
   *
   * @param node the node to evaluate and use as a context
   *
   * @return the string value of the expression.
   */
  public String evalString(Node node)
    throws XPathException
  {
    Env env = XPath.createEnv();
    env.setCurrentNode(node);
    env.setContextNode(node);

    String result = evalString(node, env);

    XPath.freeEnv(env);

    return result;
  }

  /**
   * true if the expression prefers to return a string.
   */
  public boolean isString()
  {
    return false;
  }

  /**
   * Returns the string value of the node.
   *
   * @param node the node to evaluate and use as a context
   * @param env variable environment.
   */
  public abstract String evalString(Node node, ExprEnvironment env)
    throws XPathException;
  
  /**
   * Fills a char buffer with the evaluated string results.
   *
   * @param cb the buffer containing the results.
   * @param node the node to evaluate and use as a context
   */
  public void evalString(CharBuffer cb, Node node)
    throws XPathException
  {
    Env env = XPath.createEnv();
    env.setCurrentNode(node);
    env.setContextNode(node);

    evalString(cb, node, env);

    XPath.freeEnv(env);
  }
  
  /**
   * Fills a char buffer with the evaluated string results.
   *
   * @param cb the buffer containing the results.
   * @param node the node to evaluate and use as a context
   * @param env the variable environment
   */
  public void evalString(CharBuffer cb, Node node, ExprEnvironment env)
    throws XPathException
  {
    cb.append(evalString(node, env));
  }

  /**
   * true if the expression prefers to return a node set.
   */
  public boolean isNodeSet()
  {
    return false;
  }

  /**
   * Returns an iterator of matching nodes
   *
   * @param node the node to evaluate and use as a context
   *
   * @return the value as a node iterator.
   */
  public NodeIterator evalNodeSet(Node node)
    throws XPathException
  {
    Env env = XPath.createEnv();
    env.setCurrentNode(node);
    env.setContextNode(node);

    NodeIterator result = evalNodeSet(node, env);

    XPath.freeEnv(env);

    return result;
  }

  /**
   * Returns an iterator of matching nodes
   *
   * @param node the node to evaluate and use as a context
   * @param env variable environment.
   *
   * @return the value as a node iterator.
   */
  public NodeIterator evalNodeSet(Node node, ExprEnvironment env)
    throws XPathException
  {
    Object obj = evalObject(node, env);

    if (obj instanceof Node)
      return new SingleNodeIterator(env, (Node) obj);

    else if (obj instanceof NodeList)
      return new NodeListIterator(env, (NodeList) obj);