Move files in wtf/ to platform/wtf/ (Part 9).

third_party/WebKit/Source/wtf/text/StringHash.h

-/*
- * Copyright (C) 2006, 2007, 2008, 2012, 2013 Apple Inc. All rights reserved
- * Copyright (C) Research In Motion Limited 2009. All rights reserved.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public License
- * along with this library; see the file COPYING.LIB.  If not, write to
- * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- *
- */
+// Copyright 2017 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 StringHash_h
-#define StringHash_h
+#include "platform/wtf/text/StringHash.h"
 
-#include "wtf/Allocator.h"
-#include "wtf/HashTraits.h"
-#include "wtf/StringHasher.h"
-#include "wtf/text/AtomicString.h"
-
-namespace WTF {
-
-inline bool HashTraits<String>::isEmptyValue(const String& value) {
-  return value.isNull();
-}
-
-// The hash() functions on StringHash and CaseFoldingHash do not support null
-// strings. get(), contains(), and add() on HashMap<String,..., StringHash>
-// cause a null-pointer dereference when passed null strings.
-
-// FIXME: We should really figure out a way to put the computeHash function
-// that's currently a member function of StringImpl into this file so we can be
-// a little closer to having all the nearly-identical hash functions in one
-// place.
-
-struct StringHash {
-  STATIC_ONLY(StringHash);
-  static unsigned hash(StringImpl* key) { return key->hash(); }
-  static inline bool equal(const StringImpl* a, const StringImpl* b) {
-    return equalNonNull(a, b);
-  }
-
-  static unsigned hash(const RefPtr<StringImpl>& key) { return key->hash(); }
-  static bool equal(const RefPtr<StringImpl>& a, const RefPtr<StringImpl>& b) {
-    return equal(a.get(), b.get());
-  }
-
-  static unsigned hash(const String& key) { return key.impl()->hash(); }
-  static bool equal(const String& a, const String& b) {
-    return equal(a.impl(), b.impl());
-  }
-
-  static const bool safeToCompareToEmptyOrDeleted = false;
-};
-
-class CaseFoldingHash {
-  STATIC_ONLY(CaseFoldingHash);
-
- public:
-  static unsigned hash(const UChar* data, unsigned length) {
-    return StringHasher::computeHashAndMaskTop8Bits<UChar, foldCase<UChar>>(
-        data, length);
-  }
-
-  static unsigned hash(StringImpl* str) {
-    if (str->is8Bit())
-      return hash(str->characters8(), str->length());
-    return hash(str->characters16(), str->length());
-  }
-
-  static unsigned hash(const LChar* data, unsigned length) {
-    return StringHasher::computeHashAndMaskTop8Bits<LChar, foldCase<LChar>>(
-        data, length);
-  }
-
-  static inline unsigned hash(const char* data, unsigned length) {
-    return CaseFoldingHash::hash(reinterpret_cast<const LChar*>(data), length);
-  }
-
-  static inline unsigned hash(const char* data) {
-    return CaseFoldingHash::hash(reinterpret_cast<const LChar*>(data),
-                                 strlen(data));
-  }
-
-  static inline bool equal(const StringImpl* a, const StringImpl* b) {
-    DCHECK(a);
-    DCHECK(b);
-    // Save one branch inside each StringView by derefing the StringImpl,
-    // and another branch inside the compare function by skipping the null
-    // checks.
-    return equalIgnoringCaseAndNullity(*a, *b);
-  }
-
-  static unsigned hash(const RefPtr<StringImpl>& key) {
-    return hash(key.get());
-  }
-
-  static bool equal(const RefPtr<StringImpl>& a, const RefPtr<StringImpl>& b) {
-    return equal(a.get(), b.get());
-  }
-
-  static unsigned hash(const String& key) { return hash(key.impl()); }
-  static unsigned hash(const AtomicString& key) { return hash(key.impl()); }
-  static bool equal(const String& a, const String& b) {
-    return equal(a.impl(), b.impl());
-  }
-  static bool equal(const AtomicString& a, const AtomicString& b) {
-    return (a == b) || equal(a.impl(), b.impl());
-  }
-
-  static const bool safeToCompareToEmptyOrDeleted = false;
-
- private:
-  // Private so no one uses this in the belief that it will return the
-  // correctly-folded code point in all cases (see comment below).
-  template <typename T>
-  static inline UChar foldCase(T ch) {
-    if (std::is_same<T, LChar>::value)
-      return StringImpl::latin1CaseFoldTable[ch];
-    // It's possible for WTF::Unicode::foldCase() to return a 32-bit value
-    // that's not representable as a UChar.  However, since this is rare and
-    // deterministic, and the result of this is merely used for hashing, go
-    // ahead and clamp the value.
-    return static_cast<UChar>(WTF::Unicode::foldCase(ch));
-  }
-};
-
-// This hash can be used in cases where the key is a hash of a string, but we
-// don't want to store the string. It's not really specific to string hashing,
-// but all our current uses of it are for strings.
-struct AlreadyHashed : IntHash<unsigned> {
-  STATIC_ONLY(AlreadyHashed);
-  static unsigned hash(unsigned key) { return key; }
-
-  // To use a hash value as a key for a hash table, we need to eliminate the
-  // "deleted" value, which is negative one. That could be done by changing
-  // the string hash function to never generate negative one, but this works
-  // and is still relatively efficient.
-  static unsigned avoidDeletedValue(unsigned hash) {
-    DCHECK(hash);
-    unsigned newHash = hash | (!(hash + 1) << 31);
-    DCHECK(newHash);
-    DCHECK_NE(newHash, 0xFFFFFFFF);
-    return newHash;
-  }
-};
-
-}  // namespace WTF
-
-using WTF::AlreadyHashed;
-using WTF::CaseFoldingHash;
-using WTF::StringHash;
-
-#endif
+// The contents of this header was moved to platform/wtf as part of
+// WTF migration project. See the following post for details:
+// https://groups.google.com/a/chromium.org/d/msg/blink-dev/tLdAZCTlcAA/bYXVT8gYCAAJ