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-rw-r--r--dom/xslt/xslt/txPatternOptimizer.cpp76
1 files changed, 76 insertions, 0 deletions
diff --git a/dom/xslt/xslt/txPatternOptimizer.cpp b/dom/xslt/xslt/txPatternOptimizer.cpp
new file mode 100644
index 000000000..633676ba4
--- /dev/null
+++ b/dom/xslt/xslt/txPatternOptimizer.cpp
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "txPatternOptimizer.h"
+#include "txXSLTPatterns.h"
+
+nsresult
+txPatternOptimizer::optimize(txPattern* aInPattern, txPattern** aOutPattern)
+{
+ *aOutPattern = nullptr;
+ nsresult rv = NS_OK;
+
+ // First optimize sub expressions
+ uint32_t i = 0;
+ Expr* subExpr;
+ while ((subExpr = aInPattern->getSubExprAt(i))) {
+ Expr* newExpr = nullptr;
+ rv = mXPathOptimizer.optimize(subExpr, &newExpr);
+ NS_ENSURE_SUCCESS(rv, rv);
+ if (newExpr) {
+ delete subExpr;
+ aInPattern->setSubExprAt(i, newExpr);
+ }
+
+ ++i;
+ }
+
+ // Then optimize sub patterns
+ txPattern* subPattern;
+ i = 0;
+ while ((subPattern = aInPattern->getSubPatternAt(i))) {
+ txPattern* newPattern = nullptr;
+ rv = optimize(subPattern, &newPattern);
+ NS_ENSURE_SUCCESS(rv, rv);
+ if (newPattern) {
+ delete subPattern;
+ aInPattern->setSubPatternAt(i, newPattern);
+ }
+
+ ++i;
+ }
+
+ // Finally see if current pattern can be optimized
+ switch (aInPattern->getType()) {
+ case txPattern::STEP_PATTERN:
+ return optimizeStep(aInPattern, aOutPattern);
+
+ default:
+ break;
+ }
+
+ return NS_OK;
+}
+
+
+nsresult
+txPatternOptimizer::optimizeStep(txPattern* aInPattern,
+ txPattern** aOutPattern)
+{
+ txStepPattern* step = static_cast<txStepPattern*>(aInPattern);
+
+ // Test for predicates that can be combined into the nodetest
+ Expr* pred;
+ while ((pred = step->getSubExprAt(0)) &&
+ !pred->canReturnType(Expr::NUMBER_RESULT) &&
+ !pred->isSensitiveTo(Expr::NODESET_CONTEXT)) {
+ txNodeTest* predTest = new txPredicatedNodeTest(step->getNodeTest(),
+ pred);
+ step->dropFirst();
+ step->setNodeTest(predTest);
+ }
+
+ return NS_OK;
+}