Add spellcheck and word suggestion to the prediction service

third_party/prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp

Index: third_party/prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
diff --git a/third_party/prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp b/third_party/prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..95d9af6cdb1928632d0939aba03da66018d1935c
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+++ b/third_party/prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
@@ -0,0 +1,108 @@
+/*
+ * 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/structure/pt_common/bigram/bigram_list_read_write_utils.h"
+
+#include "third_party/prediction/suggest/policyimpl/dictionary/utils/byte_array_utils.h"
+#include "third_party/prediction/suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
+
+namespace latinime {
+
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::MASK_ATTRIBUTE_ADDRESS_TYPE = 0x30;
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE = 0x10;
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES = 0x20;
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES = 0x30;
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::FLAG_ATTRIBUTE_OFFSET_NEGATIVE = 0x40;
+// Flag for presence of more attributes
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::FLAG_ATTRIBUTE_HAS_NEXT = 0x80;
+// Mask for attribute probability, stored on 4 bits inside the flags byte.
+const BigramListReadWriteUtils::BigramFlags
+    BigramListReadWriteUtils::MASK_ATTRIBUTE_PROBABILITY = 0x0F;
+
+/* static */ bool
+BigramListReadWriteUtils::getBigramEntryPropertiesAndAdvancePosition(
+    const uint8_t* const bigramsBuf,
+    const int bufSize,
+    BigramFlags* const outBigramFlags,
+    int* const outTargetPtNodePos,
+    int* const bigramEntryPos) {
+  if (bufSize <= *bigramEntryPos) {
+    AKLOGE(
+        "Read invalid pos in getBigramEntryPropertiesAndAdvancePosition(). "
+        "bufSize: %d, "
+        "bigramEntryPos: %d.",
+        bufSize, *bigramEntryPos);
+    return false;
+  }
+  const BigramFlags bigramFlags =
+      ByteArrayUtils::readUint8AndAdvancePosition(bigramsBuf, bigramEntryPos);
+  if (outBigramFlags) {
+    *outBigramFlags = bigramFlags;
+  }
+  const int targetPos = getBigramAddressAndAdvancePosition(
+      bigramsBuf, bigramFlags, bigramEntryPos);
+  if (outTargetPtNodePos) {
+    *outTargetPtNodePos = targetPos;
+  }
+  return true;
+}
+
+/* static */ bool BigramListReadWriteUtils::skipExistingBigrams(
+    const uint8_t* const bigramsBuf,
+    const int bufSize,
+    int* const bigramListPos) {
+  BigramFlags flags;
+  do {
+    if (!getBigramEntryPropertiesAndAdvancePosition(bigramsBuf, bufSize, &flags,
+                                                    0 /* outTargetPtNodePos */,
+                                                    bigramListPos)) {
+      return false;
+    }
+  } while (hasNext(flags));
+  return true;
+}
+
+/* static */ int BigramListReadWriteUtils::getBigramAddressAndAdvancePosition(
+    const uint8_t* const bigramsBuf,
+    const BigramFlags flags,
+    int* const pos) {
+  int offset = 0;
+  const int origin = *pos;
+  switch (MASK_ATTRIBUTE_ADDRESS_TYPE & flags) {
+    case FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE:
+      offset = ByteArrayUtils::readUint8AndAdvancePosition(bigramsBuf, pos);
+      break;
+    case FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES:
+      offset = ByteArrayUtils::readUint16AndAdvancePosition(bigramsBuf, pos);
+      break;
+    case FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES:
+      offset = ByteArrayUtils::readUint24AndAdvancePosition(bigramsBuf, pos);
+      break;
+  }
+  if (isOffsetNegative(flags)) {
+    return origin - offset;
+  } else {
+    return origin + offset;
+  }
+}
+
+}  // namespace latinime