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;
+}