Reintroduce duplicate identifier detection in preparser.

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index cd0a530e8d0bba8b368510601e30ff566a00cb49..9dc36f18a3fbaca89ad4821ebedb76e8e9ebd08f 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -31,6 +31,8 @@
 namespace v8 {
 namespace preparser {
 
+typedef uint8_t byte;
+
 // Preparsing checks a JavaScript program and emits preparse-data that helps
 // a later parsing to be faster.
 // See preparse-data-format.h for the data format.
@@ -46,6 +48,57 @@ namespace preparser {
 
 namespace i = v8::internal;
 
+class DuplicateFinder {
+ public:
+  explicit DuplicateFinder(i::UnicodeCache* constants)
+      : unicode_constants_(constants),
+        backing_store_(16),
+        map_(new i::HashMap(&Match)) { }
+
+  ~DuplicateFinder() {
+    delete map_;
+  }
+
+  int AddAsciiSymbol(i::Vector<const char> key, int value);
+  int AddUC16Symbol(i::Vector<const uint16_t> key, int value);
+  // Add a a number literal by converting it (if necessary)
+  // to the string that ToString(ToNumber(literal)) would generate.
+  // and then adding that string with AddAsciiSymbol.
+  // This string is the actual value used as key in an object literal,
+  // and the one that must be different from the other keys.
+  int AddNumber(i::Vector<const char> key, int value);
+
+ private:
+  int AddSymbol(i::Vector<const byte> key, bool is_ascii, int value);
+  // Backs up the key and its length in the backing store.
+  // The backup is stored with a base 127 encoding of the
+  // length (plus a bit saying whether the string is ASCII),
+  // followed by the bytes of the key.
+  byte* BackupKey(i::Vector<const byte> key, bool is_ascii);
+
+  // Compare two encoded keys (both pointing into the backing store)
+  // for having the same base-127 encoded lengths and ASCII-ness,
+  // and then having the same 'length' bytes following.
+  static bool Match(void* first, void* second);
+  // Creates a hash from a sequence of bytes.
+  static uint32_t Hash(i::Vector<const byte> key, bool is_ascii);
+  // Checks whether a string containing a JS number is its canonical
+  // form.
+  static bool IsNumberCanonical(i::Vector<const char> key);
+
+  // Size of buffer. Sufficient for using it to call DoubleToCString in
+  // from conversions.h.
+  static const int kBufferSize = 100;
+
+  i::UnicodeCache* unicode_constants_;
+  // Backing store used to store strings used as hashmap keys.
+  i::SequenceCollector<unsigned char> backing_store_;
+  i::HashMap* map_;
+  // Buffer used for string->number->canonical string conversions.
+  char number_buffer_[kBufferSize];
+};
+
+
 class PreParser {
  public:
   enum PreParseResult {
@@ -67,6 +120,45 @@ class PreParser {
   }
 
  private:
+  // Used to detect duplicates in object literals. Each of the values
+  // kGetterProperty, kSetterProperty and kValueProperty represents
+  // a type of object literal property. When parsing a property, its
+  // type value is stored in the DuplicateFinder for the property name.
+  // Values are chosen so that having intersection bits means the there is
+  // an incompatibility.
+  // I.e., you can add a getter to a property that already has a setter, since
+  // kGetterProperty and kSetterProperty doesn't intersect, but not if it
+  // already has a getter or a value. Adding the getter to an existing
+  // setter will store the value (kGetterProperty | kSetterProperty), which
+  // is incompatible with adding any further properties.
+  enum PropertyType {
+    kNone = 0,
+    // Bit patterns representing different object literal property types.
+    kGetterProperty = 1,
+    kSetterProperty = 2,
+    kValueProperty = 7,
+    // Helper constants.
+    kValueFlag = 4
+  };
+
+  // Checks the type of conflict based on values coming from PropertyType.
+  bool HasConflict(int type1, int type2) { return (type1 & type2) != 0; }
+  bool IsDataDataConflict(int type1, int type2) {
+    return ((type1 & type2) & kValueFlag) != 0;
+  }
+  bool IsDataAccessorConflict(int type1, int type2) {
+    return ((type1 ^ type2) & kValueFlag) != 0;
+  }
+  bool IsAccessorAccessorConflict(int type1, int type2) {
+    return ((type1 | type2) & kValueFlag) == 0;
+  }
+
+
+  void CheckDuplicate(DuplicateFinder* finder,
+                      i::Token::Value property,
+                      int type,
+                      bool* ok);
+
   // These types form an algebra over syntactic categories that is just
   // rich enough to let us recognize and propagate the constructs that
   // are either being counted in the preparser data, or is important
@@ -371,6 +463,11 @@ class PreParser {
 
   // Report syntax error
   void ReportUnexpectedToken(i::Token::Value token);
+  void ReportMessageAt(i::Scanner::Location location,
+                       const char* type,
+                       const char* name_opt) {
+    log_->LogMessage(location.beg_pos, location.end_pos, type, name_opt);
+  }
   void ReportMessageAt(int start_pos,
                        int end_pos,
                        const char* type,