dictionary/header/header_read_write_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 "suggest/policyimpl/dictionary/header/header_read_write_utils.h"

#include <cctype>
#include <cstdio>
#include <vector>

#include "defines.h"
#include "suggest/policyimpl/dictionary/utils/buffer_with_extendable_buffer.h"
#include "suggest/policyimpl/dictionary/utils/byte_array_utils.h"

namespace latinime {

// Number of base-10 digits in the largest integer + 1 to leave room for a zero terminator.
// As such, this is the maximum number of characters will be needed to represent an int as a
// string, including the terminator; this is used as the size of a string buffer large enough to
// hold any value that is intended to fit in an integer, e.g. in the code that reads the header
// of the binary dictionary where a {key,value} string pair scheme is used.
const int HeaderReadWriteUtils::LARGEST_INT_DIGIT_COUNT = 11;

const int HeaderReadWriteUtils::MAX_ATTRIBUTE_KEY_LENGTH = 256;
const int HeaderReadWriteUtils::MAX_ATTRIBUTE_VALUE_LENGTH = 256;

const int HeaderReadWriteUtils::HEADER_MAGIC_NUMBER_SIZE = 4;
const int HeaderReadWriteUtils::HEADER_DICTIONARY_VERSION_SIZE = 2;
const int HeaderReadWriteUtils::HEADER_FLAG_SIZE = 2;
const int HeaderReadWriteUtils::HEADER_SIZE_FIELD_SIZE = 4;

const HeaderReadWriteUtils::DictionaryFlags HeaderReadWriteUtils::NO_FLAGS = 0;

typedef DictionaryHeaderStructurePolicy::AttributeMap AttributeMap;

/* static */ int HeaderReadWriteUtils::getHeaderSize(const uint8_t *const dictBuf) {
    // See the format of the header in the comment in
    // BinaryDictionaryFormatUtils::detectFormatVersion()
    return ByteArrayUtils::readUint32(dictBuf, HEADER_MAGIC_NUMBER_SIZE
            + HEADER_DICTIONARY_VERSION_SIZE + HEADER_FLAG_SIZE);
}

/* static */ HeaderReadWriteUtils::DictionaryFlags
        HeaderReadWriteUtils::getFlags(const uint8_t *const dictBuf) {
    return ByteArrayUtils::readUint16(dictBuf,
            HEADER_MAGIC_NUMBER_SIZE + HEADER_DICTIONARY_VERSION_SIZE);
}

/* static */ HeaderReadWriteUtils::DictionaryFlags
        HeaderReadWriteUtils::createAndGetDictionaryFlagsUsingAttributeMap(
                const AttributeMap *const attributeMap) {
    return NO_FLAGS;
}

/* static */ void HeaderReadWriteUtils::fetchAllHeaderAttributes(const uint8_t *const dictBuf,
        AttributeMap *const headerAttributes) {
    const int headerSize = getHeaderSize(dictBuf);
    int pos = getHeaderOptionsPosition();
    if (pos == NOT_A_DICT_POS) {
        // The header doesn't have header options.
        return;
    }
    int keyBuffer[MAX_ATTRIBUTE_KEY_LENGTH];
    int valueBuffer[MAX_ATTRIBUTE_VALUE_LENGTH];
    while (pos < headerSize) {
        const int keyLength = ByteArrayUtils::readStringAndAdvancePosition(dictBuf,
                MAX_ATTRIBUTE_KEY_LENGTH, keyBuffer, &pos);
        std::vector<int> key;
        key.insert(key.end(), keyBuffer, keyBuffer + keyLength);
        const int valueLength = ByteArrayUtils::readStringAndAdvancePosition(dictBuf,
                MAX_ATTRIBUTE_VALUE_LENGTH, valueBuffer, &pos);
        std::vector<int> value;
        value.insert(value.end(), valueBuffer, valueBuffer + valueLength);
        headerAttributes->insert(AttributeMap::value_type(key, value));
    }
}

/* static */ bool HeaderReadWriteUtils::writeDictionaryVersion(
        BufferWithExtendableBuffer *const buffer, const FormatUtils::FORMAT_VERSION version,
        int *const writingPos) {
    if (!buffer->writeUintAndAdvancePosition(FormatUtils::MAGIC_NUMBER, HEADER_MAGIC_NUMBER_SIZE,
            writingPos)) {
        return false;
    }
    switch (version) {
        case FormatUtils::VERSION_2:
            // Version 2 dictionary writing is not supported.
            return false;
        case FormatUtils::VERSION_4_ONLY_FOR_TESTING:
        case FormatUtils::VERSION_4:
        case FormatUtils::VERSION_4_DEV:
            return buffer->writeUintAndAdvancePosition(version /* data */,
                    HEADER_DICTIONARY_VERSION_SIZE, writingPos);
        default:
            return false;
    }
}

/* static */ bool HeaderReadWriteUtils::writeDictionaryFlags(
        BufferWithExtendableBuffer *const buffer, const DictionaryFlags flags,
        int *const writingPos) {
    return buffer->writeUintAndAdvancePosition(flags, HEADER_FLAG_SIZE, writingPos);
}

/* static */ bool HeaderReadWriteUtils::writeDictionaryHeaderSize(
        BufferWithExtendableBuffer *const buffer, const int size, int *const writingPos) {
    return buffer->writeUintAndAdvancePosition(size, HEADER_SIZE_FIELD_SIZE, writingPos);
}

/* static */ bool HeaderReadWriteUtils::writeHeaderAttributes(
        BufferWithExtendableBuffer *const buffer, const AttributeMap *const headerAttributes,
        int *const writingPos) {
    for (AttributeMap::const_iterator it = headerAttributes->begin();
            it != headerAttributes->end(); ++it) {
        if (it->first.empty() || it->second.empty()) {
            continue;
        }
        // Write a key.
        if (!buffer->writeCodePointsAndAdvancePosition(&(it->first.at(0)), it->first.size(),
                true /* writesTerminator */, writingPos)) {
            return false;
        }
        // Write a value.
        if (!buffer->writeCodePointsAndAdvancePosition(&(it->second.at(0)), it->second.size(),
                true /* writesTerminator */, writingPos)) {
            return false;
        }
    }
    return true;
}

/* static */ void HeaderReadWriteUtils::setCodePointVectorAttribute(
        AttributeMap *const headerAttributes, const char *const key, const std::vector<int> value) {
    AttributeMap::key_type keyVector;
    insertCharactersIntoVector(key, &keyVector);
    (*headerAttributes)[keyVector] = value;
}

/* static */ void HeaderReadWriteUtils::setBoolAttribute(AttributeMap *const headerAttributes,
        const char *const key, const bool value) {
    setIntAttribute(headerAttributes, key, value ? 1 : 0);
}

/* static */ void HeaderReadWriteUtils::setIntAttribute(AttributeMap *const headerAttributes,
        const char *const key, const int value) {
    AttributeMap::key_type keyVector;
    insertCharactersIntoVector(key, &keyVector);
    setIntAttributeInner(headerAttributes, &keyVector, value);
}

/* static */ void HeaderReadWriteUtils::setIntAttributeInner(AttributeMap *const headerAttributes,
        const AttributeMap::key_type *const key, const int value) {
    AttributeMap::mapped_type valueVector;
    char charBuf[LARGEST_INT_DIGIT_COUNT];
    snprintf(charBuf, sizeof(charBuf), "%d", value);
    insertCharactersIntoVector(charBuf, &valueVector);
    (*headerAttributes)[*key] = valueVector;
}

/* static */ const std::vector<int> HeaderReadWriteUtils::readCodePointVectorAttributeValue(
        const AttributeMap *const headerAttributes, const char *const key) {
    AttributeMap::key_type keyVector;
    insertCharactersIntoVector(key, &keyVector);
    AttributeMap::const_iterator it = headerAttributes->find(keyVector);
    if (it == headerAttributes->end()) {
        return std::vector<int>();
    } else {
        return it->second;
    }
}

/* static */ bool HeaderReadWriteUtils::readBoolAttributeValue(
        const AttributeMap *const headerAttributes, const char *const key,
        const bool defaultValue) {
    const int intDefaultValue = defaultValue ? 1 : 0;
    const int intValue = readIntAttributeValue(headerAttributes, key, intDefaultValue);
    return intValue != 0;
}

/* static */ int HeaderReadWriteUtils::readIntAttributeValue(
        const AttributeMap *const headerAttributes, const char *const key,
        const int defaultValue) {
    AttributeMap::key_type keyVector;
    insertCharactersIntoVector(key, &keyVector);
    return readIntAttributeValueInner(headerAttributes, &keyVector, defaultValue);
}

/* static */ int HeaderReadWriteUtils::readIntAttributeValueInner(
        const AttributeMap *const headerAttributes, const AttributeMap::key_type *const key,
        const int defaultValue) {
    AttributeMap::const_iterator it = headerAttributes->find(*key);
    if (it != headerAttributes->end()) {
        int value = 0;
        bool isNegative = false;
        for (size_t i = 0; i < it->second.size(); ++i) {
            if (i == 0 && it->second.at(i) == '-') {
                isNegative = true;
            } else {
                if (!isdigit(it->second.at(i))) {
                    // If not a number.
                    return defaultValue;
                }
                value *= 10;
                value += it->second.at(i) - '0';
            }
        }
        return isNegative ? -value : value;
    }
    return defaultValue;
}

/* static */ void HeaderReadWriteUtils::insertCharactersIntoVector(const char *const characters,
        std::vector<int> *const vector) {
    for (int i = 0; characters[i]; ++i) {
        vector->push_back(characters[i]);
    }
}

} // namespace latinime