/*

 */

/*

 * 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.

 */

package com.sun.org.apache.xpath.internal.operations;

import com.sun.org.apache.xalan.internal.res.XSLMessages;

import com.sun.org.apache.xml.internal.utils.QName;

import com.sun.org.apache.xpath.internal.Expression;

import com.sun.org.apache.xpath.internal.ExpressionOwner;

import com.sun.org.apache.xpath.internal.XPathContext;

import com.sun.org.apache.xpath.internal.XPathVisitor;

import com.sun.org.apache.xpath.internal.axes.PathComponent;

import com.sun.org.apache.xpath.internal.axes.WalkerFactory;

import com.sun.org.apache.xpath.internal.objects.XNodeSet;

import com.sun.org.apache.xpath.internal.objects.XObject;

import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;

/**

 * The variable reference expression executer.

 */

public class Variable extends Expression implements PathComponent

{

    static final long serialVersionUID = -4334975375609297049L;

  /** Tell if fixupVariables was called.

   *  @serial   */

  private boolean m_fixUpWasCalled = false;

  /** The qualified name of the variable.

   *  @serial   */

  protected QName m_qname;

  /**

   * The index of the variable, which is either an absolute index to a

   * global, or, if higher than the globals area, must be adjusted by adding

   * the offset to the current stack frame.

   */

  protected int m_index;

  /**

   * Set the index for the variable into the stack.  For advanced use only. You

   * must know what you are doing to use this.

   *

   * @param index a global or local index.

   */

  public void setIndex(int index)

  {

        m_index = index;

  }

  /**

   * Set the index for the variable into the stack.  For advanced use only.

   *

   * @return index a global or local index.

   */

  public int getIndex()

  {

        return m_index;

  }

  /**

   * Set whether or not this is a global reference.  For advanced use only.

   *

   * @param isGlobal true if this should be a global variable reference.

   */

  public void setIsGlobal(boolean isGlobal)

  {

        m_isGlobal = isGlobal;

  }

  /**

   * Set the index for the variable into the stack.  For advanced use only.

   *

   * @return true if this should be a global variable reference.

   */

  public boolean getGlobal()

  {

        return m_isGlobal;

  }

  protected boolean m_isGlobal = false;

  /**

   * This function is used to fixup variables from QNames to stack frame

   * indexes at stylesheet build time.

   * @param vars List of QNames that correspond to variables.  This list

   * should be searched backwards for the first qualified name that

   * corresponds to the variable reference qname.  The position of the

   * QName in the vector from the start of the vector will be its position

   * in the stack frame (but variables above the globalsTop value will need

   * to be offset to the current stack frame).

   */

  {

    m_fixUpWasCalled = true;

    int sz = vars.size();

    for (int i = vars.size()-1; i >= 0; i--)

    {

      // System.out.println("qn: "+qn);

      if(qn.equals(m_qname))

      {

        if(i < globalsSize)

        {

          m_isGlobal = true;

          m_index = i;

        }

        else

        {

          m_index = i-globalsSize;

        }

        return;

      }

    }

    java.lang.String msg = XSLMessages.createXPATHMessage(XPATHErrorResources.ER_COULD_NOT_FIND_VAR,

                                             new Object[]{m_qname.toString()});

    TransformerException te = new TransformerException(msg, this);

    throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(te);

  }

  /**

   * Set the qualified name of the variable.

   *

   * @param qname Must be a non-null reference to a qualified name.

   */

  public void setQName(QName qname)

  {

    m_qname = qname;

  }

  /**

   * Get the qualified name of the variable.

   *

   * @return A non-null reference to a qualified name.

   */

  public QName getQName()

  {

    return m_qname;

  }

  /**

   * Execute an expression in the XPath runtime context, and return the

   * result of the expression.

   *

   *

   * @param xctxt The XPath runtime context.

   *

   * @return The result of the expression in the form of a <code>XObject</code>.

   *

   * @throws javax.xml.transform.TransformerException if a runtime exception

   *         occurs.

   */

  public XObject execute(XPathContext xctxt)

    throws javax.xml.transform.TransformerException

  {

        return execute(xctxt, false);

  }

  /**

   * Dereference the variable, and return the reference value.  Note that lazy

   * evaluation will occur.  If a variable within scope is not found, a warning

   * will be sent to the error listener, and an empty nodeset will be returned.

   *

   *

   * @param xctxt The runtime execution context.

   *

   * @return The evaluated variable, or an empty nodeset if not found.

   *

   * @throws javax.xml.transform.TransformerException

   */

  public XObject execute(XPathContext xctxt, boolean destructiveOK) throws javax.xml.transform.TransformerException

  {

    com.sun.org.apache.xml.internal.utils.PrefixResolver xprefixResolver = xctxt.getNamespaceContext();

    XObject result;

    // Is the variable fetched always the same?

    // XObject result = xctxt.getVariable(m_qname);

    if(m_fixUpWasCalled)

    {

      if(m_isGlobal)

        result = xctxt.getVarStack().getGlobalVariable(xctxt, m_index, destructiveOK);

      else

        result = xctxt.getVarStack().getLocalVariable(xctxt, m_index, destructiveOK);

    }

    else {

        result = xctxt.getVarStack().getVariableOrParam(xctxt,m_qname);

    }

      if (null == result)

      {

        // This should now never happen...

        warn(xctxt, XPATHErrorResources.WG_ILLEGAL_VARIABLE_REFERENCE,

             new Object[]{ m_qname.getLocalPart() });  //"VariableReference given for variable out "+

  //      (new RuntimeException()).printStackTrace();

  //      error(xctxt, XPATHErrorResources.ER_COULDNOT_GET_VAR_NAMED,

  //            new Object[]{ m_qname.getLocalPart() });  //"Could not get variable named "+varName);

        result = new XNodeSet(xctxt.getDTMManager());

      }

      return result;

//    }

//    else

//    {

//      // Hack city... big time.  This is needed to evaluate xpaths from extensions,

//      // pending some bright light going off in my head.  Some sort of callback?

//      synchronized(this)

//      {

//              com.sun.org.apache.xalan.internal.templates.ElemVariable vvar= getElemVariable();

//              if(null != vvar)

//              {

//          m_index = vvar.getIndex();

//          m_isGlobal = vvar.getIsTopLevel();

//          m_fixUpWasCalled = true;

//          return execute(xctxt);

//              }

//      }

//      throw new javax.xml.transform.TransformerException(XSLMessages.createXPATHMessage(XPATHErrorResources.ER_VAR_NOT_RESOLVABLE, new Object[]{m_qname.toString()})); //"Variable not resolvable: "+m_qname);

//    }

  }

  /**

   * Get the XSLT ElemVariable that this sub-expression references.  In order for

   * this to work, the SourceLocator must be the owning ElemTemplateElement.

   * @return The dereference to the ElemVariable, or null if not found.

   */

  // J2SE does not support Xalan interpretive

  /*

  public com.sun.org.apache.xalan.internal.templates.ElemVariable getElemVariable()

  {

    // Get the current ElemTemplateElement, and then walk backwards in

    // document order, searching

    // for an xsl:param element or xsl:variable element that matches our

    // qname.  If we reach the top level, use the StylesheetRoot's composed

    // list of top level variables and parameters.

    com.sun.org.apache.xalan.internal.templates.ElemVariable vvar = null;

    com.sun.org.apache.xpath.internal.ExpressionNode owner = getExpressionOwner();

    if (null != owner && owner instanceof com.sun.org.apache.xalan.internal.templates.ElemTemplateElement)

    {

      com.sun.org.apache.xalan.internal.templates.ElemTemplateElement prev =

        (com.sun.org.apache.xalan.internal.templates.ElemTemplateElement) owner;

      if (!(prev instanceof com.sun.org.apache.xalan.internal.templates.Stylesheet))

      {

        while ( prev != null && !(prev.getParentNode() instanceof com.sun.org.apache.xalan.internal.templates.Stylesheet) )

        {

          com.sun.org.apache.xalan.internal.templates.ElemTemplateElement savedprev = prev;

          while (null != (prev = prev.getPreviousSiblingElem()))

          {

            if(prev instanceof com.sun.org.apache.xalan.internal.templates.ElemVariable)

            {

              vvar = (com.sun.org.apache.xalan.internal.templates.ElemVariable) prev;

              if (vvar.getName().equals(m_qname))

              {

                return vvar;

              }

              vvar = null;

            }

          }

          prev = savedprev.getParentElem();

        }

      }

      if (prev != null)

        vvar = prev.getStylesheetRoot().getVariableOrParamComposed(m_qname);

    }

    return vvar;

  }

  */

  /**

   * Tell if this expression returns a stable number that will not change during

   * iterations within the expression.  This is used to determine if a proximity

   * position predicate can indicate that no more searching has to occur.

   *

   *

   * @return true if the expression represents a stable number.

   */

  public boolean isStableNumber()

  {

    return true;

  }

  /**

   * Get the analysis bits for this walker, as defined in the WalkerFactory.

   * @return One of WalkerFactory#BIT_DESCENDANT, etc.

   */

  public int getAnalysisBits()

  {

    // J2SE does not support Xalan interpretive

    /*

        com.sun.org.apache.xalan.internal.templates.ElemVariable vvar = getElemVariable();

        if(null != vvar)

        {

                XPath xpath = vvar.getSelect();

                if(null != xpath)

                {

                        Expression expr = xpath.getExpression();

                        if(null != expr && expr instanceof PathComponent)

                        {

                                return ((PathComponent)expr).getAnalysisBits();

                        }

                }

        }

    */

    return WalkerFactory.BIT_FILTER;

  }

  /**

   * @see com.sun.org.apache.xpath.internal.XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)

   */

  public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)

  {

        visitor.visitVariableRef(owner, this);

  }

  /**

   * @see Expression#deepEquals(Expression)

   */

  public boolean deepEquals(Expression expr)

  {

        if(!isSameClass(expr))

                return false;

        if(!m_qname.equals(((Variable)expr).m_qname))

                return false;

    // J2SE does not support Xalan interpretive

    /*

        // We have to make sure that the qname really references

        // the same variable element.

    if(getElemVariable() != ((Variable)expr).getElemVariable())

        return false;

        */

        return true;

  }

  static final java.lang.String PSUEDOVARNAMESPACE = "http://xml.apache.org/xalan/psuedovar";

  /**

   * Tell if this is a psuedo variable reference, declared by Xalan instead

   * of by the user.

   */

  public boolean isPsuedoVarRef()

  {

        java.lang.String ns = m_qname.getNamespaceURI();

        if((null != ns) && ns.equals(PSUEDOVARNAMESPACE))

        {

                if(m_qname.getLocalName().startsWith("#"))

                        return true;

        }

        return false;

  }

}