Line data    Source code

       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #include "txPatternOptimizer.h"
       7             : #include "txXSLTPatterns.h"
       8             : 
       9             : nsresult
      10           0 : txPatternOptimizer::optimize(txPattern* aInPattern, txPattern** aOutPattern)
      11             : {
      12           0 :     *aOutPattern = nullptr;
      13           0 :     nsresult rv = NS_OK;
      14             : 
      15             :     // First optimize sub expressions
      16           0 :     uint32_t i = 0;
      17             :     Expr* subExpr;
      18           0 :     while ((subExpr = aInPattern->getSubExprAt(i))) {
      19           0 :         Expr* newExpr = nullptr;
      20           0 :         rv = mXPathOptimizer.optimize(subExpr, &newExpr);
      21           0 :         NS_ENSURE_SUCCESS(rv, rv);
      22           0 :         if (newExpr) {
      23           0 :             delete subExpr;
      24           0 :             aInPattern->setSubExprAt(i, newExpr);
      25             :         }
      26             : 
      27           0 :         ++i;
      28             :     }
      29             : 
      30             :     // Then optimize sub patterns
      31             :     txPattern* subPattern;
      32           0 :     i = 0;
      33           0 :     while ((subPattern = aInPattern->getSubPatternAt(i))) {
      34           0 :         txPattern* newPattern = nullptr;
      35           0 :         rv = optimize(subPattern, &newPattern);
      36           0 :         NS_ENSURE_SUCCESS(rv, rv);
      37           0 :         if (newPattern) {
      38           0 :             delete subPattern;
      39           0 :             aInPattern->setSubPatternAt(i, newPattern);
      40             :         }
      41             : 
      42           0 :         ++i;
      43             :     }
      44             : 
      45             :     // Finally see if current pattern can be optimized
      46           0 :     switch (aInPattern->getType()) {
      47             :         case txPattern::STEP_PATTERN:
      48           0 :             return optimizeStep(aInPattern, aOutPattern);
      49             : 
      50             :         default:
      51           0 :             break;
      52             :     }
      53             : 
      54           0 :     return NS_OK;
      55             : }
      56             : 
      57             : 
      58             : nsresult
      59           0 : txPatternOptimizer::optimizeStep(txPattern* aInPattern,
      60             :                                  txPattern** aOutPattern)
      61             : {
      62           0 :     txStepPattern* step = static_cast<txStepPattern*>(aInPattern);
      63             : 
      64             :     // Test for predicates that can be combined into the nodetest
      65             :     Expr* pred;
      66           0 :     while ((pred = step->getSubExprAt(0)) &&
      67           0 :            !pred->canReturnType(Expr::NUMBER_RESULT) &&
      68           0 :            !pred->isSensitiveTo(Expr::NODESET_CONTEXT)) {
      69           0 :         txNodeTest* predTest = new txPredicatedNodeTest(step->getNodeTest(),
      70           0 :                                                         pred);
      71           0 :         step->dropFirst();
      72           0 :         step->setNodeTest(predTest);
      73             :     }
      74             : 
      75           0 :     return NS_OK;
      76             : }