Componentize visitedlinks to src/components/visitedlink

chrome/common/visitedlink_common.cc

-// Copyright (c) 2011 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.
-
-#include "chrome/common/visitedlink_common.h"
-
-#include <string.h>  // for memset()
-
-#include "base/logging.h"
-#include "base/md5.h"
-#include "googleurl/src/gurl.h"
-
-const VisitedLinkCommon::Fingerprint VisitedLinkCommon::null_fingerprint_ = 0;
-const VisitedLinkCommon::Hash VisitedLinkCommon::null_hash_ = -1;
-
-VisitedLinkCommon::VisitedLinkCommon()
-    : hash_table_(NULL),
-      table_length_(0) {
-  memset(salt_, 0, sizeof(salt_));
-}
-
-VisitedLinkCommon::~VisitedLinkCommon() {
-}
-
-// FIXME: this uses linear probing, it should be replaced with quadratic
-// probing or something better. See VisitedLinkMaster::AddFingerprint
-bool VisitedLinkCommon::IsVisited(const char* canonical_url,
-                                  size_t url_len) const {
-  if (url_len == 0)
-    return false;
-  if (!hash_table_ || table_length_ == 0)
-    return false;
-  return IsVisited(ComputeURLFingerprint(canonical_url, url_len));
-}
-
-bool VisitedLinkCommon::IsVisited(const GURL& url) const {
-  return IsVisited(url.spec().data(), url.spec().size());
-}
-
-bool VisitedLinkCommon::IsVisited(Fingerprint fingerprint) const {
-  // Go through the table until we find the item or an empty spot (meaning it
-  // wasn't found). This loop will terminate as long as the table isn't full,
-  // which should be enforced by AddFingerprint.
-  Hash first_hash = HashFingerprint(fingerprint);
-  Hash cur_hash = first_hash;
-  while (true) {
-    Fingerprint cur_fingerprint = FingerprintAt(cur_hash);
-    if (cur_fingerprint == null_fingerprint_)
-      return false;  // End of probe sequence found.
-    if (cur_fingerprint == fingerprint)
-      return true;  // Found a match.
-
-    // This spot was taken, but not by the item we're looking for, search in
-    // the next position.
-    cur_hash++;
-    if (cur_hash == table_length_)
-      cur_hash = 0;
-    if (cur_hash == first_hash) {
-      // Wrapped around and didn't find an empty space, this means we're in an
-      // infinite loop because AddFingerprint didn't do its job resizing.
-      NOTREACHED();
-      return false;
-    }
-  }
-}
-
-// Uses the top 64 bits of the MD5 sum of the canonical URL as the fingerprint,
-// this is as random as any other subset of the MD5SUM.
-//
-// FIXME: this uses the MD5SUM of the 16-bit character version. For systems
-// where wchar_t is not 16 bits (Linux uses 32 bits, I think), this will not be
-// compatable. We should define explicitly what should happen here across
-// platforms, and convert if necessary (probably to UTF-16).
-
-// static
-VisitedLinkCommon::Fingerprint VisitedLinkCommon::ComputeURLFingerprint(
-    const char* canonical_url,
-    size_t url_len,
-    const uint8 salt[LINK_SALT_LENGTH]) {
-  DCHECK(url_len > 0) << "Canonical URLs should not be empty";
-
-  base::MD5Context ctx;
-  base::MD5Init(&ctx);
-  base::MD5Update(&ctx, base::StringPiece(reinterpret_cast<const char*>(salt),
-                                          LINK_SALT_LENGTH));
-  base::MD5Update(&ctx, base::StringPiece(canonical_url, url_len));
-
-  base::MD5Digest digest;
-  base::MD5Final(&digest, &ctx);
-
-  // This is the same as "return *(Fingerprint*)&digest.a;" but if we do that
-  // direct cast the alignment could be wrong, and we can't access a 64-bit int
-  // on arbitrary alignment on some processors. This reinterpret_casts it
-  // down to a char array of the same size as fingerprint, and then does the
-  // bit cast, which amounts to a memcpy. This does not handle endian issues.
-  return bit_cast<Fingerprint, uint8[8]>(
-      *reinterpret_cast<uint8(*)[8]>(&digest.a));
-}