#include "qhashedstring_p.h"
-inline unsigned stringHash(const QChar* data, unsigned length)
+// This is a reimplementation of V8's string hash algorithm. It is significantly
+// faster to do it here than call into V8, but it adds the maintainence burden of
+// ensuring that the two hashes are identical. We Q_ASSERT() that the two return
+// the same value. If these asserts start to fail, the hash code needs to be
+// synced with V8.
+namespace String {
+ static const int kMaxArrayIndexSize = 10;
+ static const int kMaxHashCalcLength = 16383;
+ static const int kNofHashBitFields = 2;
+ static const int kHashShift = kNofHashBitFields;
+ static const int kIsNotArrayIndexMask = 1 << 1;
+ static const int kArrayIndexValueBits = 24;
+ static const int kArrayIndexHashLengthShift = kArrayIndexValueBits + kNofHashBitFields;
+ static const int kMaxCachedArrayIndexLength = 7;
+};
+
+template <typename schar>
+uint32_t calculateHash(const schar* chars, int length) {
+ if (length > String::kMaxHashCalcLength) {
+ // V8 trivial hash
+ return (length << String::kHashShift) | String::kIsNotArrayIndexMask;
+ }
+
+ uint32_t raw_running_hash = 0;
+ uint32_t array_index = 0;
+ bool is_array_index = (0 < length && length <= String::kMaxArrayIndexSize);
+ bool is_first_char = true;
+
+ int ii = 0;
+ for (;is_array_index && ii < length; ++ii) {
+ quint32 c = *chars++;
+
+ raw_running_hash += c;
+ raw_running_hash += (raw_running_hash << 10);
+ raw_running_hash ^= (raw_running_hash >> 6);
+
+ if (c < '0' || c > '9') {
+ is_array_index = false;
+ } else {
+ int d = c - '0';
+ if (is_first_char) {
+ is_first_char = false;
+ if (c = '0' && length > 1) {
+ is_array_index = false;
+ continue;
+ }
+ }
+ if (array_index > 429496729U - ((d + 2) >> 3)) {
+ is_array_index = false;
+ } else {
+ array_index = array_index * 10 + d;
+ }
+ }
+ }
+
+ for (;ii < length; ++ii) {
+ raw_running_hash += *chars++;
+ raw_running_hash += (raw_running_hash << 10);
+ raw_running_hash ^= (raw_running_hash >> 6);
+ }
+
+ if (is_array_index) {
+ array_index <<= String::kHashShift;
+ array_index |= length << String::kArrayIndexHashLengthShift;
+ return array_index;
+ } else {
+ raw_running_hash += (raw_running_hash << 3);
+ raw_running_hash ^= (raw_running_hash >> 11);
+ raw_running_hash += (raw_running_hash << 15);
+ if (raw_running_hash == 0) {
+ raw_running_hash = 27;
+ }
+
+ return (raw_running_hash << String::kHashShift) | String::kIsNotArrayIndexMask;
+ }
+}
+
+inline quint32 stringHash(const QChar* data, int length)
{
- return v8::String::ComputeHash((uint16_t *)data, length);
+ quint32 rv = calculateHash<quint16>((quint16*)data, length) >> String::kHashShift;
+ Q_ASSERT(rv == v8::String::ComputeHash((uint16_t*)data, length));
+ return rv;
+}
+
+inline quint32 stringHash(const char *data, int length)
+{
+ quint32 rv = calculateHash<quint8>((quint8*)data, length) >> String::kHashShift;
+ Q_ASSERT(rv == v8::String::ComputeHash((char *)data, length));
+ return rv;
}
void QHashedString::computeHash() const
void QHashedCStringRef::computeHash() const
{
- m_hash = v8::String::ComputeHash((char *)m_data, m_length);
+ m_hash = stringHash(m_data, m_length);
}
/*