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Diffstat (limited to 'native/src/binary_format.h')
| -rw-r--r-- | native/src/binary_format.h | 481 |
1 files changed, 0 insertions, 481 deletions
diff --git a/native/src/binary_format.h b/native/src/binary_format.h deleted file mode 100644 index ab033ad90..000000000 --- a/native/src/binary_format.h +++ /dev/null @@ -1,481 +0,0 @@ -/* - * Copyright (C) 2011 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. - */ - -#ifndef LATINIME_BINARY_FORMAT_H -#define LATINIME_BINARY_FORMAT_H - -#include <limits> -#include "unigram_dictionary.h" - -namespace latinime { - -class BinaryFormat { - private: - const static int32_t MINIMAL_ONE_BYTE_CHARACTER_VALUE = 0x20; - const static int32_t CHARACTER_ARRAY_TERMINATOR = 0x1F; - const static int MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE = 2; - - public: - const static int UNKNOWN_FORMAT = -1; - // Originally, format version 1 had a 16-bit magic number, then the version number `01' - // then options that must be 0. Hence the first 32-bits of the format are always as follow - // and it's okay to consider them a magic number as a whole. - const static uint32_t FORMAT_VERSION_1_MAGIC_NUMBER = 0x78B10100; - const static unsigned int FORMAT_VERSION_1_HEADER_SIZE = 5; - // The versions of Latin IME that only handle format version 1 only test for the magic - // number, so we had to change it so that version 2 files would be rejected by older - // implementations. On this occasion, we made the magic number 32 bits long. - const static uint32_t FORMAT_VERSION_2_MAGIC_NUMBER = 0x9BC13AFE; - - static int detectFormat(const uint8_t* const dict); - static unsigned int getHeaderSize(const uint8_t* const dict); - static int getGroupCountAndForwardPointer(const uint8_t* const dict, int* pos); - static uint8_t getFlagsAndForwardPointer(const uint8_t* const dict, int* pos); - static int32_t getCharCodeAndForwardPointer(const uint8_t* const dict, int* pos); - static int readFrequencyWithoutMovingPointer(const uint8_t* const dict, const int pos); - static int skipOtherCharacters(const uint8_t* const dict, const int pos); - static int skipAttributes(const uint8_t* const dict, const int pos); - static int skipChildrenPosition(const uint8_t flags, const int pos); - static int skipFrequency(const uint8_t flags, const int pos); - static int skipAllAttributes(const uint8_t* const dict, const uint8_t flags, const int pos); - static int skipChildrenPosAndAttributes(const uint8_t* const dict, const uint8_t flags, - const int pos); - static int readChildrenPosition(const uint8_t* const dict, const uint8_t flags, const int pos); - static bool hasChildrenInFlags(const uint8_t flags); - static int getAttributeAddressAndForwardPointer(const uint8_t* const dict, const uint8_t flags, - int *pos); - static int getTerminalPosition(const uint8_t* const root, const uint16_t* const inWord, - const int length); - static int getWordAtAddress(const uint8_t* const root, const int address, const int maxDepth, - uint16_t* outWord); -}; - -inline int BinaryFormat::detectFormat(const uint8_t* const dict) { - // The magic number is stored big-endian. - const uint32_t magicNumber = (dict[0] << 24) + (dict[1] << 16) + (dict[2] << 8) + dict[3]; - switch (magicNumber) { - case FORMAT_VERSION_1_MAGIC_NUMBER: - // Format 1 header is exactly 5 bytes long and looks like: - // Magic number (2 bytes) 0x78 0xB1 - // Version number (1 byte) 0x01 - // Options (2 bytes) must be 0x00 0x00 - return 1; - case FORMAT_VERSION_2_MAGIC_NUMBER: - // Format 2 header is as follows: - // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE - // Version number (2 bytes) 0x00 0x02 - // Options (2 bytes) must be 0x00 0x00 - // Header size (4 bytes) : integer, big endian - return (dict[4] << 8) + dict[5]; - default: - return UNKNOWN_FORMAT; - } -} - -inline unsigned int BinaryFormat::getHeaderSize(const uint8_t* const dict) { - switch (detectFormat(dict)) { - case 1: - return FORMAT_VERSION_1_HEADER_SIZE; - case 2: - // See the format of the header in the comment in detectFormat() above - return (dict[8] << 24) + (dict[9] << 16) + (dict[10] << 8) + dict[11]; - default: - return std::numeric_limits<unsigned int>::max(); - } -} - -inline int BinaryFormat::getGroupCountAndForwardPointer(const uint8_t* const dict, int* pos) { - const int msb = dict[(*pos)++]; - if (msb < 0x80) return msb; - return ((msb & 0x7F) << 8) | dict[(*pos)++]; -} - -inline uint8_t BinaryFormat::getFlagsAndForwardPointer(const uint8_t* const dict, int* pos) { - return dict[(*pos)++]; -} - -inline int32_t BinaryFormat::getCharCodeAndForwardPointer(const uint8_t* const dict, int* pos) { - const int origin = *pos; - const int32_t character = dict[origin]; - if (character < MINIMAL_ONE_BYTE_CHARACTER_VALUE) { - if (character == CHARACTER_ARRAY_TERMINATOR) { - *pos = origin + 1; - return NOT_A_CHARACTER; - } else { - *pos = origin + 3; - const int32_t char_1 = character << 16; - const int32_t char_2 = char_1 + (dict[origin + 1] << 8); - return char_2 + dict[origin + 2]; - } - } else { - *pos = origin + 1; - return character; - } -} - -inline int BinaryFormat::readFrequencyWithoutMovingPointer(const uint8_t* const dict, - const int pos) { - return dict[pos]; -} - -inline int BinaryFormat::skipOtherCharacters(const uint8_t* const dict, const int pos) { - int currentPos = pos; - int32_t character = dict[currentPos++]; - while (CHARACTER_ARRAY_TERMINATOR != character) { - if (character < MINIMAL_ONE_BYTE_CHARACTER_VALUE) { - currentPos += MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE; - } - character = dict[currentPos++]; - } - return currentPos; -} - -static inline int attributeAddressSize(const uint8_t flags) { - static const int ATTRIBUTE_ADDRESS_SHIFT = 4; - return (flags & UnigramDictionary::MASK_ATTRIBUTE_ADDRESS_TYPE) >> ATTRIBUTE_ADDRESS_SHIFT; - /* Note: this is a value-dependant optimization of what may probably be - more readably written this way: - switch (flags * UnigramDictionary::MASK_ATTRIBUTE_ADDRESS_TYPE) { - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE: return 1; - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES: return 2; - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTE: return 3; - default: return 0; - } - */ -} - -inline int BinaryFormat::skipAttributes(const uint8_t* const dict, const int pos) { - int currentPos = pos; - uint8_t flags = getFlagsAndForwardPointer(dict, ¤tPos); - while (flags & UnigramDictionary::FLAG_ATTRIBUTE_HAS_NEXT) { - currentPos += attributeAddressSize(flags); - flags = getFlagsAndForwardPointer(dict, ¤tPos); - } - currentPos += attributeAddressSize(flags); - return currentPos; -} - -static inline int childrenAddressSize(const uint8_t flags) { - static const int CHILDREN_ADDRESS_SHIFT = 6; - return (UnigramDictionary::MASK_GROUP_ADDRESS_TYPE & flags) >> CHILDREN_ADDRESS_SHIFT; - /* See the note in attributeAddressSize. The same applies here */ -} - -inline int BinaryFormat::skipChildrenPosition(const uint8_t flags, const int pos) { - return pos + childrenAddressSize(flags); -} - -inline int BinaryFormat::skipFrequency(const uint8_t flags, const int pos) { - return UnigramDictionary::FLAG_IS_TERMINAL & flags ? pos + 1 : pos; -} - -inline int BinaryFormat::skipAllAttributes(const uint8_t* const dict, const uint8_t flags, - const int pos) { - // This function skips all attributes: shortcuts and bigrams. - int newPos = pos; - if (UnigramDictionary::FLAG_HAS_SHORTCUT_TARGETS & flags) { - newPos = skipAttributes(dict, newPos); - } - if (UnigramDictionary::FLAG_HAS_BIGRAMS & flags) { - newPos = skipAttributes(dict, newPos); - } - return newPos; -} - -inline int BinaryFormat::skipChildrenPosAndAttributes(const uint8_t* const dict, - const uint8_t flags, const int pos) { - int currentPos = pos; - currentPos = skipChildrenPosition(flags, currentPos); - currentPos = skipAllAttributes(dict, flags, currentPos); - return currentPos; -} - -inline int BinaryFormat::readChildrenPosition(const uint8_t* const dict, const uint8_t flags, - const int pos) { - int offset = 0; - switch (UnigramDictionary::MASK_GROUP_ADDRESS_TYPE & flags) { - case UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_ONEBYTE: - offset = dict[pos]; - break; - case UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_TWOBYTES: - offset = dict[pos] << 8; - offset += dict[pos + 1]; - break; - case UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_THREEBYTES: - offset = dict[pos] << 16; - offset += dict[pos + 1] << 8; - offset += dict[pos + 2]; - break; - default: - // If we come here, it means we asked for the children of a word with - // no children. - return -1; - } - return pos + offset; -} - -inline bool BinaryFormat::hasChildrenInFlags(const uint8_t flags) { - return (UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_NOADDRESS - != (UnigramDictionary::MASK_GROUP_ADDRESS_TYPE & flags)); -} - -inline int BinaryFormat::getAttributeAddressAndForwardPointer(const uint8_t* const dict, - const uint8_t flags, int *pos) { - int offset = 0; - const int origin = *pos; - switch (UnigramDictionary::MASK_ATTRIBUTE_ADDRESS_TYPE & flags) { - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE: - offset = dict[origin]; - *pos = origin + 1; - break; - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES: - offset = dict[origin] << 8; - offset += dict[origin + 1]; - *pos = origin + 2; - break; - case UnigramDictionary::FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES: - offset = dict[origin] << 16; - offset += dict[origin + 1] << 8; - offset += dict[origin + 2]; - *pos = origin + 3; - break; - } - if (UnigramDictionary::FLAG_ATTRIBUTE_OFFSET_NEGATIVE & flags) { - return origin - offset; - } else { - return origin + offset; - } -} - -// This function gets the byte position of the last chargroup of the exact matching word in the -// dictionary. If no match is found, it returns NOT_VALID_WORD. -inline int BinaryFormat::getTerminalPosition(const uint8_t* const root, - const uint16_t* const inWord, const int length) { - int pos = 0; - int wordPos = 0; - - while (true) { - // If we already traversed the tree further than the word is long, there means - // there was no match (or we would have found it). - if (wordPos > length) return NOT_VALID_WORD; - int charGroupCount = BinaryFormat::getGroupCountAndForwardPointer(root, &pos); - const uint16_t wChar = inWord[wordPos]; - while (true) { - // If there are no more character groups in this node, it means we could not - // find a matching character for this depth, therefore there is no match. - if (0 >= charGroupCount) return NOT_VALID_WORD; - const int charGroupPos = pos; - const uint8_t flags = BinaryFormat::getFlagsAndForwardPointer(root, &pos); - int32_t character = BinaryFormat::getCharCodeAndForwardPointer(root, &pos); - if (character == wChar) { - // This is the correct node. Only one character group may start with the same - // char within a node, so either we found our match in this node, or there is - // no match and we can return NOT_VALID_WORD. So we will check all the characters - // in this character group indeed does match. - if (UnigramDictionary::FLAG_HAS_MULTIPLE_CHARS & flags) { - character = BinaryFormat::getCharCodeAndForwardPointer(root, &pos); - while (NOT_A_CHARACTER != character) { - ++wordPos; - // If we shoot the length of the word we search for, or if we find a single - // character that does not match, as explained above, it means the word is - // not in the dictionary (by virtue of this chargroup being the only one to - // match the word on the first character, but not matching the whole word). - if (wordPos > length) return NOT_VALID_WORD; - if (inWord[wordPos] != character) return NOT_VALID_WORD; - character = BinaryFormat::getCharCodeAndForwardPointer(root, &pos); - } - } - // If we come here we know that so far, we do match. Either we are on a terminal - // and we match the length, in which case we found it, or we traverse children. - // If we don't match the length AND don't have children, then a word in the - // dictionary fully matches a prefix of the searched word but not the full word. - ++wordPos; - if (UnigramDictionary::FLAG_IS_TERMINAL & flags) { - if (wordPos == length) { - return charGroupPos; - } - pos = BinaryFormat::skipFrequency(UnigramDictionary::FLAG_IS_TERMINAL, pos); - } - if (UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_NOADDRESS - == (UnigramDictionary::MASK_GROUP_ADDRESS_TYPE & flags)) { - return NOT_VALID_WORD; - } - // We have children and we are still shorter than the word we are searching for, so - // we need to traverse children. Put the pointer on the children position, and - // break - pos = BinaryFormat::readChildrenPosition(root, flags, pos); - break; - } else { - // This chargroup does not match, so skip the remaining part and go to the next. - if (UnigramDictionary::FLAG_HAS_MULTIPLE_CHARS & flags) { - pos = BinaryFormat::skipOtherCharacters(root, pos); - } - pos = BinaryFormat::skipFrequency(flags, pos); - pos = BinaryFormat::skipChildrenPosAndAttributes(root, flags, pos); - } - --charGroupCount; - } - } -} - -// This function searches for a terminal in the dictionary by its address. -// Due to the fact that words are ordered in the dictionary in a strict breadth-first order, -// it is possible to check for this with advantageous complexity. For each node, we search -// for groups with children and compare the children address with the address we look for. -// When we shoot the address we look for, it means the word we look for is in the children -// of the previous group. The only tricky part is the fact that if we arrive at the end of a -// node with the last group's children address still less than what we are searching for, we -// must descend the last group's children (for example, if the word we are searching for starts -// with a z, it's the last group of the root node, so all children addresses will be smaller -// than the address we look for, and we have to descend the z node). -/* Parameters : - * root: the dictionary buffer - * address: the byte position of the last chargroup of the word we are searching for (this is - * what is stored as the "bigram address" in each bigram) - * outword: an array to write the found word, with MAX_WORD_LENGTH size. - * Return value : the length of the word, of 0 if the word was not found. - */ -inline int BinaryFormat::getWordAtAddress(const uint8_t* const root, const int address, - const int maxDepth, uint16_t* outWord) { - int pos = 0; - int wordPos = 0; - - // One iteration of the outer loop iterates through nodes. As stated above, we will only - // traverse nodes that are actually a part of the terminal we are searching, so each time - // we enter this loop we are one depth level further than last time. - // The only reason we count nodes is because we want to reduce the probability of infinite - // looping in case there is a bug. Since we know there is an upper bound to the depth we are - // supposed to traverse, it does not hurt to count iterations. - for (int loopCount = maxDepth; loopCount > 0; --loopCount) { - int lastCandidateGroupPos = 0; - // Let's loop through char groups in this node searching for either the terminal - // or one of its ascendants. - for (int charGroupCount = getGroupCountAndForwardPointer(root, &pos); charGroupCount > 0; - --charGroupCount) { - const int startPos = pos; - const uint8_t flags = getFlagsAndForwardPointer(root, &pos); - const int32_t character = getCharCodeAndForwardPointer(root, &pos); - if (address == startPos) { - // We found the address. Copy the rest of the word in the buffer and return - // the length. - outWord[wordPos] = character; - if (UnigramDictionary::FLAG_HAS_MULTIPLE_CHARS & flags) { - int32_t nextChar = getCharCodeAndForwardPointer(root, &pos); - // We count chars in order to avoid infinite loops if the file is broken or - // if there is some other bug - int charCount = maxDepth; - while (-1 != nextChar && --charCount > 0) { - outWord[++wordPos] = nextChar; - nextChar = getCharCodeAndForwardPointer(root, &pos); - } - } - return ++wordPos; - } - // We need to skip past this char group, so skip any remaining chars after the - // first and possibly the frequency. - if (UnigramDictionary::FLAG_HAS_MULTIPLE_CHARS & flags) { - pos = skipOtherCharacters(root, pos); - } - pos = skipFrequency(flags, pos); - - // The fact that this group has children is very important. Since we already know - // that this group does not match, if it has no children we know it is irrelevant - // to what we are searching for. - const bool hasChildren = (UnigramDictionary::FLAG_GROUP_ADDRESS_TYPE_NOADDRESS != - (UnigramDictionary::MASK_GROUP_ADDRESS_TYPE & flags)); - // We will write in `found' whether we have passed the children address we are - // searching for. For example if we search for "beer", the children of b are less - // than the address we are searching for and the children of c are greater. When we - // come here for c, we realize this is too big, and that we should descend b. - bool found; - if (hasChildren) { - // Here comes the tricky part. First, read the children position. - const int childrenPos = readChildrenPosition(root, flags, pos); - if (childrenPos > address) { - // If the children pos is greater than address, it means the previous chargroup, - // which address is stored in lastCandidateGroupPos, was the right one. - found = true; - } else if (1 >= charGroupCount) { - // However if we are on the LAST group of this node, and we have NOT shot the - // address we should descend THIS node. So we trick the lastCandidateGroupPos - // so that we will descend this node, not the previous one. - lastCandidateGroupPos = startPos; - found = true; - } else { - // Else, we should continue looking. - found = false; - } - } else { - // Even if we don't have children here, we could still be on the last group of this - // node. If this is the case, we should descend the last group that had children, - // and their address is already in lastCandidateGroup. - found = (1 >= charGroupCount); - } - - if (found) { - // Okay, we found the group we should descend. Its address is in - // the lastCandidateGroupPos variable, so we just re-read it. - if (0 != lastCandidateGroupPos) { - const uint8_t lastFlags = - getFlagsAndForwardPointer(root, &lastCandidateGroupPos); - const int32_t lastChar = - getCharCodeAndForwardPointer(root, &lastCandidateGroupPos); - // We copy all the characters in this group to the buffer - outWord[wordPos] = lastChar; - if (UnigramDictionary::FLAG_HAS_MULTIPLE_CHARS & lastFlags) { - int32_t nextChar = - getCharCodeAndForwardPointer(root, &lastCandidateGroupPos); - int charCount = maxDepth; - while (-1 != nextChar && --charCount > 0) { - outWord[++wordPos] = nextChar; - nextChar = getCharCodeAndForwardPointer(root, &lastCandidateGroupPos); - } - } - ++wordPos; - // Now we only need to branch to the children address. Skip the frequency if - // it's there, read pos, and break to resume the search at pos. - lastCandidateGroupPos = skipFrequency(lastFlags, lastCandidateGroupPos); - pos = readChildrenPosition(root, lastFlags, lastCandidateGroupPos); - break; - } else { - // Here is a little tricky part: we come here if we found out that all children - // addresses in this group are bigger than the address we are searching for. - // Should we conclude the word is not in the dictionary? No! It could still be - // one of the remaining chargroups in this node, so we have to keep looking in - // this node until we find it (or we realize it's not there either, in which - // case it's actually not in the dictionary). Pass the end of this group, ready - // to start the next one. - pos = skipChildrenPosAndAttributes(root, flags, pos); - } - } else { - // If we did not find it, we should record the last children address for the next - // iteration. - if (hasChildren) lastCandidateGroupPos = startPos; - // Now skip the end of this group (children pos and the attributes if any) so that - // our pos is after the end of this char group, at the start of the next one. - pos = skipChildrenPosAndAttributes(root, flags, pos); - } - - } - } - // If we have looked through all the chargroups and found no match, the address is - // not the address of a terminal in this dictionary. - return 0; -} - -} // namespace latinime - -#endif // LATINIME_BINARY_FORMAT_H |