Unify and fix checkers for duplicate object literal properties.

src/scanner.h

Index: src/scanner.h
diff --git a/src/scanner.h b/src/scanner.h
index d7328085b79245d97b807ff6f7e248d7a6ed207d..3cefc833ac3323c536ca98015fdfbee1522060d5 100644
--- a/src/scanner.h
+++ b/src/scanner.h
@@ -34,6 +34,8 @@
 #include "char-predicates.h"
 #include "checks.h"
 #include "globals.h"
+#include "hashmap.h"
+#include "list.h"
 #include "token.h"
 #include "unicode-inl.h"
 #include "utils.h"
@@ -121,9 +123,10 @@ class Utf16CharacterStream {
 };
 
 
-class UnicodeCache {
 // ---------------------------------------------------------------------
 // Caching predicates used by scanners.
+
+class UnicodeCache {
  public:
   UnicodeCache() {}
   typedef unibrow::Utf8Decoder<512> Utf8Decoder;
@@ -148,6 +151,56 @@ class UnicodeCache {
 };
 
 
+// ---------------------------------------------------------------------
+// DuplicateFinder discovers duplicate symbols.
+
+class DuplicateFinder {
+ public:
+  explicit DuplicateFinder(UnicodeCache* constants)
+      : unicode_constants_(constants),
+        backing_store_(16),
+        map_(&Match) { }
+
+  int AddAsciiSymbol(Vector<const char> key, int value);
+  int AddUtf16Symbol(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(Vector<const char> key, int value);
+
+ private:
+  int AddSymbol(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(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(Vector<const byte> key, bool is_ascii);
+  // Checks whether a string containing a JS number is its canonical
+  // form.
+  static bool IsNumberCanonical(Vector<const char> key);
+
+  // Size of buffer. Sufficient for using it to call DoubleToCString in
+  // from conversions.h.
+  static const int kBufferSize = 100;
+
+  UnicodeCache* unicode_constants_;
+  // Backing store used to store strings used as hashmap keys.
+  SequenceCollector<unsigned char> backing_store_;
+  HashMap map_;
+  // Buffer used for string->number->canonical string conversions.
+  char number_buffer_[kBufferSize];
+};
+
+
 // ----------------------------------------------------------------------------
 // LiteralBuffer -  Collector of chars of literals.