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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * Licensed 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. See accompanying
 * LICENSE file.
 */

package com.gemstone.gemfire.cache.query.internal;

import java.util.*;

import com.gemstone.gemfire.cache.query.*;
import com.gemstone.gemfire.cache.EntryDestroyedException;
import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.internal.cache.PartitionedRegion;


/**
 * Represents an identifier that follows a dot operator.
 *
 * @version     $Revision: 1.1 $
 * @author      ericz
 */



public class CompiledPath extends AbstractCompiledValue {
  private CompiledValue _receiver;  // the value represented by the expression before the dot
  private String _tailID;           // the identifier after the dot.
  
  public CompiledPath(CompiledValue rcvr, String id) {
    _receiver = rcvr;
    _tailID = id;
  }
  
  @Override
  public List getChildren() {
    return Collections.singletonList(this._receiver);
  }
  
  public int getType() {
    return PATH;
  }
  
  @Override
  public Set computeDependencies(ExecutionContext context)
  throws TypeMismatchException, AmbiguousNameException, NameResolutionException {
    return context.addDependencies(this, this._receiver.computeDependencies(context));
  }
  
  
  
  @Override
  public List getPathOnIterator(RuntimeIterator itr, ExecutionContext context)
  throws TypeMismatchException, AmbiguousNameException {
    if (!isDependentOnIterator(itr, context))
      return null;
    
    List list = new ArrayList();
    list.add(getTailID());
    CompiledValue v = getReceiver();
    int type = v.getType();
    while (type == PATH) {
      CompiledPath p = (CompiledPath)v;
      list.add(0, p.getTailID());
      v = p.getReceiver();
      type = v.getType();
    };
    
    if (type == Identifier) {
      List path = v.getPathOnIterator(itr, context);
      if (path == null)
        return null;
      list.addAll(0, path);
      return list;
    }
    
    return null;
  }
  
  
  public Object evaluate(ExecutionContext context)
  throws FunctionDomainException, TypeMismatchException, NameResolutionException,
          QueryInvocationTargetException {
    CompiledValue rcvr = getReceiver();
    Object evalRcvr = rcvr.evaluate(context);

    if (context.isCqQueryContext()
        && (evalRcvr instanceof Region.Entry || evalRcvr instanceof CqEntry)) {
      try {
        if (evalRcvr instanceof Region.Entry) {
          Region.Entry re = (Region.Entry) evalRcvr;
          if (re.isDestroyed()) {
            return QueryService.UNDEFINED;
          }
          evalRcvr = re.getValue();
        } else if (evalRcvr instanceof CqEntry) {
          CqEntry re = (CqEntry) evalRcvr;
          evalRcvr = re.getValue();
        }
      } catch (EntryDestroyedException ede){
        // Even though isDestory() check is made, the entry could 
        // throw EntryDestroyedException if the value becomes null.
        return QueryService.UNDEFINED;
      }

    }

    // if the receiver is an iterator, then use the contrained type
    // for attribute evaluation instead of the runtime type
    
    //         RuntimeIterator cmpItr = null;
    
    //         if (rcvr.getType() == ID)
    //         {
    //             CompiledValue resolvedRcvr = context.resolve(((CompiledID)rcvr).getId());
    
    //             if (resolvedRcvr != null && resolvedRcvr.getType() == ITERATOR)
    //                 cmpItr = ((RuntimeIterator)resolvedRcvr);
    //         }
    
    //         if (rcvr.getType() == ITERATOR)
    //             cmpItr = (RuntimeIterator)rcvr;
    
    //         if (cmpItr != null)
    //         {
    //             Class constraint = cmpItr.getBaseCollection().getConstraint();
    //             return PathUtils.evaluateAttribute(evalRcvr,
    //                                                constraint,
    //                                                getTailID());
    //         }
    
    Object obj =  PathUtils.evaluateAttribute(evalRcvr, getTailID());
    // check for BucketRegion substitution
    PartitionedRegion pr = context.getPartitionedRegion();
    if (pr != null && (obj instanceof Region)) {
      if (pr.getFullPath().equals(((Region)obj).getFullPath())) {
        obj = context.getBucketRegion();
      }
    }
    return obj;
  }
  
  public String getTailID() {
    return _tailID;
  }
  
  public CompiledValue getReceiver() {
    return _receiver;
  }
  
  @Override
  public void generateCanonicalizedExpression(StringBuffer clauseBuffer, ExecutionContext context)
  throws AmbiguousNameException, TypeMismatchException, NameResolutionException {
    //Asif: Canonicalize the tail ID. If the tail ID contains
    // something like getX ,convert it into x.
    int len;
    if (_tailID.startsWith("get") && (len =_tailID.length()) > 3) {
      clauseBuffer.insert(0, len > 4 ? _tailID.substring(4) : "" );
      clauseBuffer.insert(0, Character.toLowerCase(_tailID.charAt(3)));
    } else {
      clauseBuffer.insert(0, _tailID);
    }
    clauseBuffer.insert(0, '.');
    _receiver. generateCanonicalizedExpression(clauseBuffer, context);
  }
}