Experimental support for RegExp lookbehind.

src/ast.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast.h"
 
 #include <cmath>  // For isfinite.
 #include "src/builtins.h"
 #include "src/code-stubs.h"
 #include "src/contexts.h"
@@ skipping 832 matching lines @@
 Interval RegExpAlternative::CaptureRegisters() {
   return ListCaptureRegisters(nodes());
 }
 
 
 Interval RegExpDisjunction::CaptureRegisters() {
   return ListCaptureRegisters(alternatives());
 }
 
 
-Interval RegExpLookahead::CaptureRegisters() {
+Interval RegExpLookaround::CaptureRegisters() {
   return body()->CaptureRegisters();
 }
 
 
 Interval RegExpCapture::CaptureRegisters() {
   Interval self(StartRegister(index()), EndRegister(index()));
   return self.Union(body()->CaptureRegisters());
 }
 
 
@@ skipping 47 matching lines @@
 bool RegExpDisjunction::IsAnchoredAtEnd() {
   ZoneList<RegExpTree*>* alternatives = this->alternatives();
   for (int i = 0; i < alternatives->length(); i++) {
     if (!alternatives->at(i)->IsAnchoredAtEnd())
       return false;
   }
   return true;
 }
 
 
-bool RegExpLookahead::IsAnchoredAtStart() {
-  return is_positive() && body()->IsAnchoredAtStart();
+bool RegExpLookaround::IsAnchoredAtStart() {
+  return is_positive() && read_direction() == READ_FORWARD &&
+         body()->IsAnchoredAtStart();
 }
 
 
 bool RegExpCapture::IsAnchoredAtStart() {
   return body()->IsAnchoredAtStart();
 }
 
 
 bool RegExpCapture::IsAnchoredAtEnd() {
   return body()->IsAnchoredAtEnd();
@@ skipping 128 matching lines @@
 
 
 void* RegExpUnparser::VisitCapture(RegExpCapture* that, void* data) {
   os_ << "(^ ";
   that->body()->Accept(this, data);
   os_ << ")";
   return NULL;
 }
 
 
-void* RegExpUnparser::VisitLookahead(RegExpLookahead* that, void* data) {
-  os_ << "(-> " << (that->is_positive() ? "+ " : "- ");
+void* RegExpUnparser::VisitLookaround(RegExpLookaround* that, void* data) {
+  os_ << "(";
+  os_ << (that->read_direction() == RegExpTree::READ_FORWARD ? "->" : "<-");
+  os_ << (that->is_positive() ? " + " : " - ");
   that->body()->Accept(this, data);
   os_ << ")";
   return NULL;
 }
 
 
 void* RegExpUnparser::VisitBackReference(RegExpBackReference* that,
                                          void* data) {
   os_ << "(<- " << that->index() << ")";
   return NULL;
 }
 
 
 void* RegExpUnparser::VisitEmpty(RegExpEmpty* that, void* data) {
   os_ << '%';
   return NULL;
 }
 
 
 std::ostream& RegExpTree::Print(std::ostream& os, Zone* zone) {  // NOLINT
   RegExpUnparser unparser(os, zone);
   Accept(&unparser, NULL);
   return os;
 }
 
 
-RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
-    : alternatives_(alternatives) {
+RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives,
+                                     ReadDirection read_direction)
+    : RegExpTree(read_direction), alternatives_(alternatives) {
   DCHECK(alternatives->length() > 1);
   RegExpTree* first_alternative = alternatives->at(0);
   min_match_ = first_alternative->min_match();
   max_match_ = first_alternative->max_match();
   for (int i = 1; i < alternatives->length(); i++) {
     RegExpTree* alternative = alternatives->at(i);
     min_match_ = Min(min_match_, alternative->min_match());
     max_match_ = Max(max_match_, alternative->max_match());
   }
 }
 
 
 static int IncreaseBy(int previous, int increase) {
   if (RegExpTree::kInfinity - previous < increase) {
     return RegExpTree::kInfinity;
   } else {
     return previous + increase;
   }
 }
 
-RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes)
-    : nodes_(nodes) {
+RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes,
+                                     ReadDirection read_direction)
+    : RegExpTree(read_direction), nodes_(nodes) {
   DCHECK(nodes->length() > 1);
   min_match_ = 0;
   max_match_ = 0;
   for (int i = 0; i < nodes->length(); i++) {
     RegExpTree* node = nodes->at(i);
     int node_min_match = node->min_match();
     min_match_ = IncreaseBy(min_match_, node_min_match);
     int node_max_match = node->max_match();
     max_match_ = IncreaseBy(max_match_, node_max_match);
   }
@@ skipping 19 matching lines @@
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 
 }  // namespace internal
 }  // namespace v8