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// Copyright 2017 the V8 project 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 V8_STRING_HASHER_INL_H_
#define V8_STRING_HASHER_INL_H_
#include "src/string-hasher.h"
#include "src/char-predicates-inl.h"
#include "src/objects.h"
#include "src/objects/string-inl.h"
namespace v8 {
namespace internal {
StringHasher::StringHasher(int length, uint64_t seed)
: length_(length),
raw_running_hash_(static_cast<uint32_t>(seed)),
array_index_(0),
is_array_index_(0 < length_ && length_ <= String::kMaxArrayIndexSize),
is_first_char_(true) {
DCHECK(FLAG_randomize_hashes || raw_running_hash_ == 0);
}
bool StringHasher::has_trivial_hash() {
return length_ > String::kMaxHashCalcLength;
}
uint32_t StringHasher::AddCharacterCore(uint32_t running_hash, uint16_t c) {
running_hash += c;
running_hash += (running_hash << 10);
running_hash ^= (running_hash >> 6);
return running_hash;
}
uint32_t StringHasher::GetHashCore(uint32_t running_hash) {
running_hash += (running_hash << 3);
running_hash ^= (running_hash >> 11);
running_hash += (running_hash << 15);
if ((running_hash & String::kHashBitMask) == 0) {
return kZeroHash;
}
return running_hash;
}
uint32_t StringHasher::ComputeRunningHash(uint32_t running_hash,
const uc16* chars, int length) {
DCHECK_NOT_NULL(chars);
DCHECK_GE(length, 0);
for (int i = 0; i < length; ++i) {
running_hash = AddCharacterCore(running_hash, *chars++);
}
return running_hash;
}
uint32_t StringHasher::ComputeRunningHashOneByte(uint32_t running_hash,
const char* chars,
int length) {
DCHECK_NOT_NULL(chars);
DCHECK_GE(length, 0);
for (int i = 0; i < length; ++i) {
uint16_t c = static_cast<uint16_t>(*chars++);
running_hash = AddCharacterCore(running_hash, c);
}
return running_hash;
}
void StringHasher::AddCharacter(uint16_t c) {
// Use the Jenkins one-at-a-time hash function to update the hash
// for the given character.
raw_running_hash_ = AddCharacterCore(raw_running_hash_, c);
}
bool StringHasher::UpdateIndex(uint16_t c) {
DCHECK(is_array_index_);
if (!IsDecimalDigit(c)) {
is_array_index_ = false;
return false;
}
int d = c - '0';
if (is_first_char_) {
is_first_char_ = false;
if (d == 0 && length_ > 1) {
is_array_index_ = false;
return false;
}
}
if (array_index_ > 429496729U - ((d + 3) >> 3)) {
is_array_index_ = false;
return false;
}
array_index_ = array_index_ * 10 + d;
return true;
}
template <typename Char>
inline void StringHasher::AddCharacters(const Char* chars, int length) {
DCHECK(sizeof(Char) == 1 || sizeof(Char) == 2);
int i = 0;
if (is_array_index_) {
for (; i < length; i++) {
AddCharacter(chars[i]);
if (!UpdateIndex(chars[i])) {
i++;
break;
}
}
}
for (; i < length; i++) {
DCHECK(!is_array_index_);
AddCharacter(chars[i]);
}
}
template <typename schar>
uint32_t StringHasher::HashSequentialString(const schar* chars, int length,
uint64_t seed) {
StringHasher hasher(length, seed);
if (!hasher.has_trivial_hash()) hasher.AddCharacters(chars, length);
return hasher.GetHashField();
}
IteratingStringHasher::IteratingStringHasher(int len, uint64_t seed)
: StringHasher(len, seed) {}
uint32_t IteratingStringHasher::Hash(String* string, uint64_t seed) {
IteratingStringHasher hasher(string->length(), seed);
// Nothing to do.
if (hasher.has_trivial_hash()) return hasher.GetHashField();
ConsString* cons_string = String::VisitFlat(&hasher, string);
if (cons_string == nullptr) return hasher.GetHashField();
hasher.VisitConsString(cons_string);
return hasher.GetHashField();
}
void IteratingStringHasher::VisitOneByteString(const uint8_t* chars,
int length) {
AddCharacters(chars, length);
}
void IteratingStringHasher::VisitTwoByteString(const uint16_t* chars,
int length) {
AddCharacters(chars, length);
}
std::size_t SeededStringHasher::operator()(const char* name) const {
return StringHasher::HashSequentialString(
name, static_cast<int>(strlen(name)), hashseed_);
}
} // namespace internal
} // namespace v8
#endif // V8_STRING_HASHER_INL_H_
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