Each RegExtTree node can now report the min and max size of strings it can match.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@988 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ast.cc

@@ -332,7 +332,7 @@ void* RegExpUnparser::VisitText(RegExpText* that, void* data) {
 
 void* RegExpUnparser::VisitQuantifier(RegExpQuantifier* that, void* data) {
   stream()->Add("(# %i ", that->min());
-  if (that->max() == RegExpQuantifier::kInfinity) {
+  if (that->max() == RegExpTree::kInfinity) {
     stream()->Add("- ");
   } else {
     stream()->Add("%i ", that->max());
@@ -381,4 +381,34 @@ SmartPointer<const char> RegExpTree::ToString() {
 }
 
 
+RegExpDisjunction::RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
+    : alternatives_(alternatives) {
+  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());
+  }
+}
+
+
+RegExpAlternative::RegExpAlternative(ZoneList<RegExpTree*>* nodes)
+    : nodes_(nodes) {
+  min_match_ = 0;
+  max_match_ = 0;
+  for (int i = 0; i < nodes->length(); i++) {
+    RegExpTree* node = nodes->at(i);
+    min_match_ += node->min_match();
+    int node_max_match = node->max_match();
+    if (kInfinity - max_match_ < node_max_match) {
+      max_match_ = kInfinity;
+    } else {
+      max_match_ += node->max_match();
+    }
+  }
+}
+
+
 } }  // namespace v8::internal

src/ast.h

@@ -1213,11 +1213,14 @@ class ThisFunction: public Expression {
 
 class RegExpTree: public ZoneObject {
  public:
+  static const int kInfinity = (1<<31)-1;
   virtual ~RegExpTree() { }
   virtual void* Accept(RegExpVisitor* visitor, void* data) = 0;
   virtual RegExpNode* ToNode(RegExpCompiler* compiler,
                              RegExpNode* on_success) = 0;
   virtual bool IsTextElement() { return false; }
+  virtual int min_match() = 0;
+  virtual int max_match() = 0;
   virtual void AppendToText(RegExpText* text);
   SmartPointer<const char> ToString();
 #define MAKE_ASTYPE(Name)                                                  \
@@ -1230,47 +1233,37 @@ class RegExpTree: public ZoneObject {
 
 class RegExpDisjunction: public RegExpTree {
  public:
-  explicit RegExpDisjunction(ZoneList<RegExpTree*>* alternatives)
-      : alternatives_(alternatives) { }
+  explicit RegExpDisjunction(ZoneList<RegExpTree*>* alternatives);
   virtual void* Accept(RegExpVisitor* visitor, void* data);
   virtual RegExpNode* ToNode(RegExpCompiler* compiler,
                              RegExpNode* on_success);
   virtual RegExpDisjunction* AsDisjunction();
   virtual bool IsDisjunction();
+  virtual int min_match() { return min_match_; }
+  virtual int max_match() { return max_match_; }
   ZoneList<RegExpTree*>* alternatives() { return alternatives_; }
  private:
   ZoneList<RegExpTree*>* alternatives_;
+  int min_match_;
+  int max_match_;
 };
 
 
 class RegExpAlternative: public RegExpTree {
  public:
-  explicit RegExpAlternative(ZoneList<RegExpTree*>* nodes) : nodes_(nodes) { }
+  explicit RegExpAlternative(ZoneList<RegExpTree*>* nodes);
   virtual void* Accept(RegExpVisitor* visitor, void* data);
   virtual RegExpNode* ToNode(RegExpCompiler* compiler,
                              RegExpNode* on_success);
   virtual RegExpAlternative* AsAlternative();
   virtual bool IsAlternative();
+  virtual int min_match() { return min_match_; }
+  virtual int max_match() { return max_match_; }
   ZoneList<RegExpTree*>* nodes() { return nodes_; }
  private:
   ZoneList<RegExpTree*>* nodes_;
-};
-
-
-class RegExpText: public RegExpTree {
- public:
-  RegExpText() : elements_(2) { }
-  virtual void* Accept(RegExpVisitor* visitor, void* data);
-  virtual RegExpNode* ToNode(RegExpCompiler* compiler,
-                             RegExpNode* on_success);
-  virtual RegExpText* AsText();
-  virtual bool IsText();
-  virtual bool IsTextElement() { return true; }
-  virtual void AppendToText(RegExpText* text);
-  void AddElement(TextElement elm) { elements_.Add(elm); }
-  ZoneList<TextElement>* elements() { return &elements_; }
- private:
-  ZoneList<TextElement> elements_;
+  int min_match_;
+  int max_match_;
 };
 
 
@@ -1290,6 +1283,8 @@ class RegExpAssertion: public RegExpTree {
                              RegExpNode* on_success);
   virtual RegExpAssertion* AsAssertion();
   virtual bool IsAssertion();
+  virtual int min_match() { return 0; }
+  virtual int max_match() { return 0; }
   Type type() { return type_; }
  private:
   Type type_;
@@ -1312,6 +1307,8 @@ class RegExpCharacterClass: public RegExpTree {
   virtual RegExpCharacterClass* AsCharacterClass();
   virtual bool IsCharacterClass();
   virtual bool IsTextElement() { return true; }
+  virtual int min_match() { return 1; }
+  virtual int max_match() { return 1; }
   virtual void AppendToText(RegExpText* text);
   ZoneList<CharacterRange>* ranges() { return ranges_; }
   bool is_negated() { return is_negated_; }
@@ -1330,20 +1327,53 @@ class RegExpAtom: public RegExpTree {
   virtual RegExpAtom* AsAtom();
   virtual bool IsAtom();
   virtual bool IsTextElement() { return true; }
+  virtual int min_match() { return data_.length(); }
+  virtual int max_match() { return data_.length(); }
   virtual void AppendToText(RegExpText* text);
   Vector<const uc16> data() { return data_; }
+  int length() { return data_.length(); }
  private:
   Vector<const uc16> data_;
 };
 
 
+class RegExpText: public RegExpTree {
+ public:
+  RegExpText() : elements_(2), length_(0) {}
+  virtual void* Accept(RegExpVisitor* visitor, void* data);
+  virtual RegExpNode* ToNode(RegExpCompiler* compiler,
+                             RegExpNode* on_success);
+  virtual RegExpText* AsText();
+  virtual bool IsText();
+  virtual bool IsTextElement() { return true; }
+  virtual int min_match() { return length_; }
+  virtual int max_match() { return length_; }
+  virtual void AppendToText(RegExpText* text);
+  void AddElement(TextElement elm)  {
+    elements_.Add(elm);
+    length_ += elm.length();
+  };
+  ZoneList<TextElement>* elements() { return &elements_; }
+ private:
+  ZoneList<TextElement> elements_;
+  int length_;
+};
+
+
 class RegExpQuantifier: public RegExpTree {
  public:
   RegExpQuantifier(int min, int max, bool is_greedy, RegExpTree* body)
       : min_(min),
         max_(max),
         is_greedy_(is_greedy),
-        body_(body) { }
+        body_(body),
+        min_match_(min * body->min_match()) {
+    if (max > 0 && body->max_match() > kInfinity / max) {
+      max_match_ = kInfinity;
+    } else {
+      max_match_ = max * body->max_match();
+    }
+  }
   virtual void* Accept(RegExpVisitor* visitor, void* data);
   virtual RegExpNode* ToNode(RegExpCompiler* compiler,
                              RegExpNode* on_success);
@@ -1355,18 +1385,19 @@ class RegExpQuantifier: public RegExpTree {
                             RegExpNode* on_success);
   virtual RegExpQuantifier* AsQuantifier();
   virtual bool IsQuantifier();
+  virtual int min_match() { return min_match_; }
+  virtual int max_match() { return max_match_; }
   int min() { return min_; }
   int max() { return max_; }
   bool is_greedy() { return is_greedy_; }
   RegExpTree* body() { return body_; }
-  // We just use a very large integer value as infinity because 2^30
-  // is infinite in practice.
-  static const int kInfinity = (1 << 30);
  private:
   int min_;
   int max_;
   bool is_greedy_;
   RegExpTree* body_;
+  int min_match_;
+  int max_match_;
 };
 
 
@@ -1389,6 +1420,8 @@ class RegExpCapture: public RegExpTree {
                             RegExpNode* on_success);
   virtual RegExpCapture* AsCapture();
   virtual bool IsCapture();
+  virtual int min_match() { return body_->min_match(); }
+  virtual int max_match() { return body_->max_match(); }
   RegExpTree* body() { return body_; }
   int index() { return index_; }
   inline CaptureAvailability available() { return available_; }
@@ -1414,6 +1447,8 @@ class RegExpLookahead: public RegExpTree {
                              RegExpNode* on_success);
   virtual RegExpLookahead* AsLookahead();
   virtual bool IsLookahead();
+  virtual int min_match() { return 0; }
+  virtual int max_match() { return 0; }
   RegExpTree* body() { return body_; }
   bool is_positive() { return is_positive_; }
  private:
@@ -1431,6 +1466,8 @@ class RegExpBackReference: public RegExpTree {
                              RegExpNode* on_success);
   virtual RegExpBackReference* AsBackReference();
   virtual bool IsBackReference();
+  virtual int min_match() { return capture_->min_match(); }
+  virtual int max_match() { return capture_->max_match(); }
   int index() { return capture_->index(); }
   RegExpCapture* capture() { return capture_; }
  private:
@@ -1446,6 +1483,8 @@ class RegExpEmpty: public RegExpTree {
                              RegExpNode* on_success);
   virtual RegExpEmpty* AsEmpty();
   virtual bool IsEmpty();
+  virtual int min_match() { return 0; }
+  virtual int max_match() { return 0; }
   static RegExpEmpty* GetInstance() { return &kInstance; }
  private:
   static RegExpEmpty kInstance;

src/jsregexp.cc

@@ -1193,6 +1193,16 @@ TextElement TextElement::CharClass(
 }
 
 
+int TextElement::length() {
+  if (type == ATOM) {
+    return data.u_atom->length();
+  } else {
+    ASSERT(type == CHAR_CLASS);
+    return 1;
+  }
+}
+
+
 DispatchTable* ChoiceNode::GetTable(bool ignore_case) {
   if (table_ == NULL) {
     table_ = new DispatchTable();
@@ -2667,7 +2677,7 @@ RegExpNode* RegExpQuantifier::ToNode(int min,
   // TODO(someone): clear captures on repetition and handle empty
   //   matches.
   bool has_min = min > 0;
-  bool has_max = max < RegExpQuantifier::kInfinity;
+  bool has_max = max < RegExpTree::kInfinity;
   bool needs_counter = has_min || has_max;
   int reg_ctr = needs_counter ? compiler->AllocateRegister() : -1;
   ChoiceNode* center = new LoopChoiceNode(2);
@@ -3784,7 +3794,7 @@ Handle<FixedArray> RegExpEngine::Compile(RegExpCompileData* data,
   //   since we don't even handle ^ yet I'm saving that optimization for
   //   later.
   RegExpNode* node = RegExpQuantifier::ToNode(0,
-                                              RegExpQuantifier::kInfinity,
+                                              RegExpTree::kInfinity,
                                               false,
                                               new RegExpCharacterClass('*'),
                                               &compiler,

src/jsregexp.h

@@ -439,6 +439,7 @@ class TextElement {
   explicit TextElement(Type t) : type(t), cp_offset(-1) { }
   static TextElement Atom(RegExpAtom* atom);
   static TextElement CharClass(RegExpCharacterClass* char_class);
+  int length();
   Type type;
   union {
     RegExpAtom* u_atom;

src/parser.cc

@@ -470,9 +470,8 @@ void RegExpBuilder::AddQuantifierToAtom(int min, int max, bool is_greedy) {
   } else if (terms_.length() > 0) {
     ASSERT(last_added_ == ADD_ATOM);
     atom = terms_.RemoveLast();
-    if (atom->IsLookahead() || atom->IsAssertion()) {
-      // Guaranteed not to match a non-empty string.
-      // Assertion as an atom can happen as, e.g., (?:\b)
+    if (atom->max_match() == 0) {
+      // Guaranteed to only match an empty string.
       LAST(ADD_TERM);
       if (min == 0) {
         return;
@@ -3797,12 +3796,12 @@ RegExpTree* RegExpParser::ParseDisjunction() {
     //   {
     case '*':
       min = 0;
-      max = RegExpQuantifier::kInfinity;
+      max = RegExpTree::kInfinity;
       Advance();
       break;
     case '+':
       min = 1;
-      max = RegExpQuantifier::kInfinity;
+      max = RegExpTree::kInfinity;
       Advance();
       break;
     case '?':
@@ -3968,7 +3967,7 @@ bool RegExpParser::ParseIntervalQuantifier(int* min_out, int* max_out) {
   } else if (current() == ',') {
     Advance();
     if (current() == '}') {
-      max = RegExpQuantifier::kInfinity;
+      max = RegExpTree::kInfinity;
       Advance();
     } else {
       while (IsDecimalDigit(current())) {

test/cctest/test-regexp.cc

@@ -76,9 +76,36 @@ static bool CheckSimple(const char* input) {
   return result.simple;
 }
 
+struct MinMaxPair {
+  int min_match;
+  int max_match;
+};
+
+static MinMaxPair CheckMinMaxMatch(const char* input) {
+  V8::Initialize(NULL);
+  v8::HandleScope scope;
+  unibrow::Utf8InputBuffer<> buffer(input, strlen(input));
+  ZoneScope zone_scope(DELETE_ON_EXIT);
+  FlatStringReader reader(CStrVector(input));
+  RegExpCompileData result;
+  CHECK(v8::internal::ParseRegExp(&reader, false, &result));
+  CHECK(result.tree != NULL);
+  CHECK(result.error.is_null());
+  int min_match = result.tree->min_match();
+  int max_match = result.tree->max_match();
+  MinMaxPair pair = { min_match, max_match };
+  return pair;
+}
+
+
 
 #define CHECK_PARSE_EQ(input, expected) CHECK_EQ(expected, *Parse(input))
 #define CHECK_SIMPLE(input, simple) CHECK_EQ(simple, CheckSimple(input));
+#define CHECK_MIN_MAX(input, min, max)                                         \
+  { MinMaxPair min_max = CheckMinMaxMatch(input);                              \
+    CHECK_EQ(min, min_max.min_match);                                          \
+    CHECK_EQ(max, min_max.max_match);                                          \
+  }
 
 TEST(Parser) {
   V8::Initialize(NULL);
@@ -251,6 +278,55 @@ TEST(Parser) {
   CHECK_PARSE_EQ("{12z}", "'{12z}'");
   CHECK_PARSE_EQ("{12,", "'{12,'");
   CHECK_PARSE_EQ("{12,3b", "'{12,3b'");
+
+  CHECK_MIN_MAX("a", 1, 1);
+  CHECK_MIN_MAX("abc", 3, 3);
+  CHECK_MIN_MAX("a[bc]d", 3, 3);
+  CHECK_MIN_MAX("a|bc", 1, 2);
+  CHECK_MIN_MAX("ab|c", 1, 2);
+  CHECK_MIN_MAX("a||bc", 0, 2);
+  CHECK_MIN_MAX("|", 0, 0);
+  CHECK_MIN_MAX("(?:ab)", 2, 2);
+  CHECK_MIN_MAX("(?:ab|cde)", 2, 3);
+  CHECK_MIN_MAX("(?:ab)|cde", 2, 3);
+  CHECK_MIN_MAX("(ab)", 2, 2);
+  CHECK_MIN_MAX("(ab|cde)", 2, 3);
+  CHECK_MIN_MAX("(ab)\\1", 4, 4);
+  CHECK_MIN_MAX("(ab|cde)\\1", 4, 6);
+  CHECK_MIN_MAX("(?:ab)?", 0, 2);
+  CHECK_MIN_MAX("(?:ab)*", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:ab)+", 2, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a?", 0, 1);
+  CHECK_MIN_MAX("a*", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a+", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a??", 0, 1);
+  CHECK_MIN_MAX("a*?", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a+?", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a?)?", 0, 1);
+  CHECK_MIN_MAX("(?:a*)?", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a+)?", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a?)+", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a*)+", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a+)+", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a?)*", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a*)*", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a+)*", 0, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a{0}", 0, 0);
+  CHECK_MIN_MAX("(?:a+){0}", 0, 0);
+  CHECK_MIN_MAX("(?:a+){0,0}", 0, 0);
+  CHECK_MIN_MAX("a*b", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a+b", 2, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a*b|c", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("a+b|c", 1, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:a{5,1000000}){3,1000000}", 15, RegExpTree::kInfinity);
+  CHECK_MIN_MAX("(?:ab){4,7}", 8, 14);
+  CHECK_MIN_MAX("a\\bc", 2, 2);
+  CHECK_MIN_MAX("a\\Bc", 2, 2);
+  CHECK_MIN_MAX("a\\sc", 3, 3);
+  CHECK_MIN_MAX("a\\Sc", 3, 3);
+  CHECK_MIN_MAX("a(?=b)c", 2, 2);
+  CHECK_MIN_MAX("a(?=bbb|bb)c", 2, 2);
+  CHECK_MIN_MAX("a(?!bbb|bb)c", 2, 2);
 }
 
 TEST(ParserRegression) {