Separate DuplicateFinder from Scanner.

src/parsing/duplicate-finder.cc

+// Copyright 2011 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.
+
+#include "src/parsing/duplicate-finder.h"
+
+#include "src/conversions.h"
+#include "src/unicode-cache.h"
+
+namespace v8 {
+namespace internal {
+
+int DuplicateFinder::AddOneByteSymbol(Vector<const uint8_t> key, int value) {
+  return AddSymbol(key, true, value);
+}
+
+int DuplicateFinder::AddTwoByteSymbol(Vector<const uint16_t> key, int value) {
+  return AddSymbol(Vector<const uint8_t>::cast(key), false, value);
+}
+
+int DuplicateFinder::AddSymbol(Vector<const uint8_t> key, bool is_one_byte,
+                               int value) {
+  uint32_t hash = Hash(key, is_one_byte);
+  byte* encoding = BackupKey(key, is_one_byte);
+  base::HashMap::Entry* entry = map_.LookupOrInsert(encoding, hash);
+  int old_value = static_cast<int>(reinterpret_cast<intptr_t>(entry->value));
+  entry->value =
+      reinterpret_cast<void*>(static_cast<intptr_t>(value | old_value));
+  return old_value;
+}
+
+int DuplicateFinder::AddNumber(Vector<const uint8_t> key, int value) {
+  DCHECK(key.length() > 0);
+  // Quick check for already being in canonical form.
+  if (IsNumberCanonical(key)) {
+    return AddOneByteSymbol(key, value);
+  }
+
+  int flags = ALLOW_HEX | ALLOW_OCTAL | ALLOW_IMPLICIT_OCTAL | ALLOW_BINARY;
+  double double_value = StringToDouble(unicode_constants_, key, flags, 0.0);
+  int length;
+  const char* string;
+  if (!std::isfinite(double_value)) {
+    string = "Infinity";
+    length = 8;  // strlen("Infinity");
+  } else {
+    string = DoubleToCString(double_value,
+                             Vector<char>(number_buffer_, kBufferSize));
+    length = StrLength(string);
+  }
+  return AddSymbol(
+      Vector<const byte>(reinterpret_cast<const byte*>(string), length), true,
+      value);
+}
+
+bool DuplicateFinder::IsNumberCanonical(Vector<const uint8_t> number) {
+  // Test for a safe approximation of number literals that are already
+  // in canonical form: max 15 digits, no leading zeroes, except an
+  // integer part that is a single zero, and no trailing zeros below
+  // the decimal point.
+  int pos = 0;
+  int length = number.length();
+  if (number.length() > 15) return false;
+  if (number[pos] == '0') {
+    pos++;
+  } else {
+    while (pos < length &&
+           static_cast<unsigned>(number[pos] - '0') <= ('9' - '0'))
+      pos++;
+  }
+  if (length == pos) return true;
+  if (number[pos] != '.') return false;
+  pos++;
+  bool invalid_last_digit = true;
+  while (pos < length) {
+    uint8_t digit = number[pos] - '0';
+    if (digit > '9' - '0') return false;
+    invalid_last_digit = (digit == 0);
+    pos++;
+  }
+  return !invalid_last_digit;
+}
+
+uint32_t DuplicateFinder::Hash(Vector<const uint8_t> key, bool is_one_byte) {
+  // Primitive hash function, almost identical to the one used
+  // for strings (except that it's seeded by the length and representation).
+  int length = key.length();
+  uint32_t hash = (length << 1) | (is_one_byte ? 1 : 0);
+  for (int i = 0; i < length; i++) {
+    uint32_t c = key[i];
+    hash = (hash + c) * 1025;
+    hash ^= (hash >> 6);
+  }
+  return hash;
+}
+
+bool DuplicateFinder::Match(void* first, void* second) {
+  // Decode lengths.
+  // Length + representation is encoded as base 128, most significant heptet
+  // first, with a 8th bit being non-zero while there are more heptets.
+  // The value encodes the number of bytes following, and whether the original
+  // was Latin1.
+  byte* s1 = reinterpret_cast<byte*>(first);
+  byte* s2 = reinterpret_cast<byte*>(second);
+  uint32_t length_one_byte_field = 0;
+  byte c1;
+  do {
+    c1 = *s1;
+    if (c1 != *s2) return false;
+    length_one_byte_field = (length_one_byte_field << 7) | (c1 & 0x7f);
+    s1++;
+    s2++;
+  } while ((c1 & 0x80) != 0);
+  int length = static_cast<int>(length_one_byte_field >> 1);
+  return memcmp(s1, s2, length) == 0;
+}
+
+byte* DuplicateFinder::BackupKey(Vector<const uint8_t> bytes,
+                                 bool is_one_byte) {
+  uint32_t one_byte_length = (bytes.length() << 1) | (is_one_byte ? 1 : 0);
+  backing_store_.StartSequence();
+  // Emit one_byte_length as base-128 encoded number, with the 7th bit set
+  // on the byte of every heptet except the last, least significant, one.
+  if (one_byte_length >= (1 << 7)) {
+    if (one_byte_length >= (1 << 14)) {
+      if (one_byte_length >= (1 << 21)) {
+        if (one_byte_length >= (1 << 28)) {
+          backing_store_.Add(
+              static_cast<uint8_t>((one_byte_length >> 28) | 0x80));
+        }
+        backing_store_.Add(
+            static_cast<uint8_t>((one_byte_length >> 21) | 0x80u));
+      }
+      backing_store_.Add(static_cast<uint8_t>((one_byte_length >> 14) | 0x80u));
+    }
+    backing_store_.Add(static_cast<uint8_t>((one_byte_length >> 7) | 0x80u));
+  }
+  backing_store_.Add(static_cast<uint8_t>(one_byte_length & 0x7f));
+
+  backing_store_.AddBlock(bytes);
+  return backing_store_.EndSequence().start();
+}
+
+}  // namespace internal
+}  // namespace v8