Add duplicate parameter detection to preparser.

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 3d72c97e2691862349b16416591314641ee4695a..863a2c70ba4785ec28bf6e591b675a30a24f6a8b 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 +48,51 @@ namespace preparser {
 
 namespace i = v8::internal;
 
+class DuplicateFinder {
+ public:
+  DuplicateFinder()
+      : 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);
+
+  static const int kBufferSize = 100;
+  // Buffer used for string->number->canonical string conversions.
+  char number_buffer_[kBufferSize];
+  // Backing store used to store strings used as hashmap keys.
+  i::SequenceCollector<unsigned char> backing_store_;
+  i::HashMap* map_;
+};
+
+
 class PreParser {
  public:
   enum PreParseResult {
@@ -67,6 +114,22 @@ class PreParser {
   }
 
  private:
+  // Used to detect duplicates in object literals.
+  enum PropertyType {
+    kNone = 0,
+    // Bit patterns representing different object literal property types.
+    kGetterProperty = 1,
+    kSetterProperty = 2,
+    kValueProperty = 7,
+    // Helper constants.
+    kValueFlag = 4
+  };
+
+  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
@@ -364,6 +427,11 @@ 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,