Implement visited link coloring.

chrome/common/visitedlink_common.h

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_VISITEDLINK_COMMON_H__
 #define CHROME_COMMON_VISITEDLINK_COMMON_H__
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 37 matching lines @@
   // A hash value of a fingerprint
   typedef int32 Hash;
 
   // A fingerprint or hash value that does not exist
   static const Fingerprint null_fingerprint_;
   static const Hash null_hash_;
 
   VisitedLinkCommon();
   virtual ~VisitedLinkCommon();
 
-  // Computes the fingerprint of the key and looks it up in the table. We
-  // return true if found. Does not modify the hastable. The input should be
-  // the canonical 16-bit URL.
+  // Returns the fingerprint for the given URL.
+  Fingerprint ComputeURLFingerprint(const char* canonical_url,
+                                    size_t url_len) const {
+    return ComputeURLFingerprint(canonical_url, url_len, salt_);
+  }
+
+  // Looks up the given key in the table. The fingerprint for the URL is
+  // computed if you call one with the string argument. Returns true if found.
+  // Does not modify the hastable.
   bool IsVisited(const char* canonical_url, size_t url_len) const;
   bool IsVisited(const GURL& url) const {
     return IsVisited(url.spec().data(), url.spec().size());
   }
+  bool IsVisited(Fingerprint fingerprint) const;
 
 #ifdef UNIT_TEST
   // Returns statistics about DB usage
   void GetUsageStatistics(int32* table_size,
                           VisitedLinkCommon::Fingerprint** fingerprints) {
     *table_size = table_length_;
     *fingerprints = hash_table_;
   }
 #endif
 
@@ skipping 11 matching lines @@
   // Returns the fingerprint at the given index into the URL table. This
   // function should be called instead of accessing the table directly to contain
   // endian issues.
   Fingerprint FingerprintAt(int32 table_offset) const {
     DCHECK(hash_table_);
     if (!hash_table_)
       return 0;
     return hash_table_[table_offset];
   }
 
-  // Returns true if the given fingerprint is in the table.
-  bool IsVisited(Fingerprint fingerprint) const;
-
   // Computes the fingerprint of the given canonical URL. It is static so the
   // same algorithm can be re-used by the table rebuilder, so you will have to
-  // pass the salt as a parameter.
+  // pass the salt as a parameter. See the non-static version above if you
+  // want to use the current class' salt.
   static Fingerprint ComputeURLFingerprint(const char* canonical_url,
                                            size_t url_len,
                                            const uint8 salt[LINK_SALT_LENGTH]);
 
   // Computes the hash value of the given fingerprint, this is used as a lookup
   // into the hashtable.
   static Hash HashFingerprint(Fingerprint fingerprint, int32 table_length) {
     return static_cast<Hash>(fingerprint % table_length);
   }
   Hash HashFingerprint(Fingerprint fingerprint) const { // uses the current hashtable
     return HashFingerprint(fingerprint, table_length_);
   }
 
   // pointer to the first item
   VisitedLinkCommon::Fingerprint* hash_table_;
 
   // the number of items in the hash table
   int32 table_length_;
 
   // salt used for each URL when computing the fingerprint
   uint8 salt_[LINK_SALT_LENGTH];
 
  private:
   DISALLOW_EVIL_CONSTRUCTORS(VisitedLinkCommon);
 };
 
 #endif // WIN_COMMON_VISITEDLINK_COMMON_H__