Add spellcheck and word suggestion to the prediction service

third_party/prediction/suggest/policyimpl/dictionary/utils/format_utils.cpp

+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "third_party/prediction/suggest/policyimpl/dictionary/utils/format_utils.h"
+#include "third_party/prediction/suggest/policyimpl/dictionary/utils/byte_array_utils.h"
+
+namespace latinime {
+
+const uint32_t FormatUtils::MAGIC_NUMBER = 0x9BC13AFE;
+
+// Magic number (4 bytes), version (2 bytes), flags (2 bytes), header size (4
+// bytes) = 12
+const int FormatUtils::DICTIONARY_MINIMUM_SIZE = 12;
+
+/* static */ FormatUtils::FORMAT_VERSION FormatUtils::getFormatVersion(
+    const int formatVersion) {
+  switch (formatVersion) {
+    case VERSION_2:
+      return VERSION_2;
+    case VERSION_4_ONLY_FOR_TESTING:
+      return VERSION_4_ONLY_FOR_TESTING;
+    case VERSION_4:
+      return VERSION_4;
+    case VERSION_4_DEV:
+      return VERSION_4_DEV;
+    default:
+      return UNKNOWN_VERSION;
+  }
+}
+/* static */ FormatUtils::FORMAT_VERSION FormatUtils::detectFormatVersion(
+    const uint8_t* const dict,
+    const int dictSize) {
+  // The magic number is stored big-endian.
+  // If the dictionary is less than 4 bytes, we can't even read the magic
+  // number, so we don't
+  // understand this format.
+  if (dictSize < DICTIONARY_MINIMUM_SIZE) {
+    return UNKNOWN_VERSION;
+  }
+  const uint32_t magicNumber = ByteArrayUtils::readUint32(dict, 0);
+  switch (magicNumber) {
+    case MAGIC_NUMBER:
+      // The layout of the header is as follows:
+      // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE
+      // Dictionary format version number (2 bytes)
+      // Options (2 bytes)
+      // Header size (4 bytes) : integer, big endian
+      // Conceptually this converts the hardcoded value of the bytes in the file
+      // into
+      // the symbolic value we use in the code. But we want the constants to be
+      // the
+      // same so we use them for both here.
+      return getFormatVersion(ByteArrayUtils::readUint16(dict, 4));
+    default:
+      return UNKNOWN_VERSION;
+  }
+}
+
+}  // namespace latinime