Add spellcheck and word suggestion to the prediction service

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

Index: third_party/android_prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
diff --git a/third_party/android_prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp b/third_party/android_prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..acc5a234f549e428e6f944769aa48924f1c5c593
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+++ b/third_party/android_prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.cpp
@@ -0,0 +1,96 @@
+/*
+ * 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/android_prediction/suggest/policyimpl/dictionary/structure/pt_common/bigram/bigram_list_read_write_utils.h"
+
+#include "third_party/android_prediction/suggest/policyimpl/dictionary/utils/byte_array_utils.h"
+#include "third_party/android_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