mirror of
https://gitlab.futo.org/keyboard/latinime.git
synced 2024-09-28 14:54:30 +01:00
675 lines
32 KiB
C++
675 lines
32 KiB
C++
/*
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* Copyright (C) 2011 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef LATINIME_BINARY_FORMAT_H
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#define LATINIME_BINARY_FORMAT_H
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#include <cstdlib>
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#include <map>
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#include <stdint.h>
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#include "bloom_filter.h"
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#include "char_utils.h"
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namespace latinime {
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class BinaryFormat {
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public:
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// Mask and flags for children address type selection.
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static const int MASK_GROUP_ADDRESS_TYPE = 0xC0;
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// Flag for single/multiple char group
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static const int FLAG_HAS_MULTIPLE_CHARS = 0x20;
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// Flag for terminal groups
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static const int FLAG_IS_TERMINAL = 0x10;
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// Flag for shortcut targets presence
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static const int FLAG_HAS_SHORTCUT_TARGETS = 0x08;
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// Flag for bigram presence
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static const int FLAG_HAS_BIGRAMS = 0x04;
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// Flag for non-words (typically, shortcut only entries)
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static const int FLAG_IS_NOT_A_WORD = 0x02;
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// Flag for blacklist
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static const int FLAG_IS_BLACKLISTED = 0x01;
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// Attribute (bigram/shortcut) related flags:
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// Flag for presence of more attributes
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static const int FLAG_ATTRIBUTE_HAS_NEXT = 0x80;
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// Flag for sign of offset. If this flag is set, the offset value must be negated.
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static const int FLAG_ATTRIBUTE_OFFSET_NEGATIVE = 0x40;
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// Mask for attribute probability, stored on 4 bits inside the flags byte.
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static const int MASK_ATTRIBUTE_PROBABILITY = 0x0F;
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// The numeric value of the shortcut probability that means 'whitelist'.
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static const int WHITELIST_SHORTCUT_PROBABILITY = 15;
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// Mask and flags for attribute address type selection.
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static const int MASK_ATTRIBUTE_ADDRESS_TYPE = 0x30;
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static const int UNKNOWN_FORMAT = -1;
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static const int SHORTCUT_LIST_SIZE_SIZE = 2;
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static int detectFormat(const uint8_t *const dict);
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static int getHeaderSize(const uint8_t *const dict);
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static int getFlags(const uint8_t *const dict);
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static void readHeaderValue(const uint8_t *const dict, const char *const key, int *outValue,
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const int outValueSize);
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static int readHeaderValueInt(const uint8_t *const dict, const char *const key);
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static int getGroupCountAndForwardPointer(const uint8_t *const dict, int *pos);
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static uint8_t getFlagsAndForwardPointer(const uint8_t *const dict, int *pos);
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static int getCodePointAndForwardPointer(const uint8_t *const dict, int *pos);
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static int readProbabilityWithoutMovingPointer(const uint8_t *const dict, const int pos);
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static int skipOtherCharacters(const uint8_t *const dict, const int pos);
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static int skipChildrenPosition(const uint8_t flags, const int pos);
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static int skipProbability(const uint8_t flags, const int pos);
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static int skipShortcuts(const uint8_t *const dict, const uint8_t flags, const int pos);
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static int skipChildrenPosAndAttributes(const uint8_t *const dict, const uint8_t flags,
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const int pos);
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static int readChildrenPosition(const uint8_t *const dict, const uint8_t flags, const int pos);
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static bool hasChildrenInFlags(const uint8_t flags);
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static int getAttributeAddressAndForwardPointer(const uint8_t *const dict, const uint8_t flags,
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int *pos);
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static int getAttributeProbabilityFromFlags(const int flags);
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static int getTerminalPosition(const uint8_t *const root, const int *const inWord,
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const int length, const bool forceLowerCaseSearch);
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static int getWordAtAddress(const uint8_t *const root, const int address, const int maxDepth,
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int *outWord, int *outUnigramProbability);
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static int computeProbabilityForBigram(
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const int unigramProbability, const int bigramProbability);
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static int getProbability(const int position, const std::map<int, int> *bigramMap,
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const uint8_t *bigramFilter, const int unigramProbability);
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// Flags for special processing
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// Those *must* match the flags in makedict (BinaryDictInputOutput#*_PROCESSING_FLAG) or
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// something very bad (like, the apocalypse) will happen. Please update both at the same time.
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enum {
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REQUIRES_GERMAN_UMLAUT_PROCESSING = 0x1,
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REQUIRES_FRENCH_LIGATURES_PROCESSING = 0x4
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};
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private:
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DISALLOW_IMPLICIT_CONSTRUCTORS(BinaryFormat);
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static const int FLAG_GROUP_ADDRESS_TYPE_NOADDRESS = 0x00;
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static const int FLAG_GROUP_ADDRESS_TYPE_ONEBYTE = 0x40;
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static const int FLAG_GROUP_ADDRESS_TYPE_TWOBYTES = 0x80;
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static const int FLAG_GROUP_ADDRESS_TYPE_THREEBYTES = 0xC0;
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static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE = 0x10;
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static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES = 0x20;
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static const int FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES = 0x30;
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// Originally, format version 1 had a 16-bit magic number, then the version number `01'
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// then options that must be 0. Hence the first 32-bits of the format are always as follow
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// and it's okay to consider them a magic number as a whole.
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static const int FORMAT_VERSION_1_MAGIC_NUMBER = 0x78B10100;
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static const int FORMAT_VERSION_1_HEADER_SIZE = 5;
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// The versions of Latin IME that only handle format version 1 only test for the magic
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// number, so we had to change it so that version 2 files would be rejected by older
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// implementations. On this occasion, we made the magic number 32 bits long.
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static const int FORMAT_VERSION_2_MAGIC_NUMBER = -1681835266; // 0x9BC13AFE
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static const int CHARACTER_ARRAY_TERMINATOR_SIZE = 1;
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static const int MINIMAL_ONE_BYTE_CHARACTER_VALUE = 0x20;
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static const int CHARACTER_ARRAY_TERMINATOR = 0x1F;
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static const int MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE = 2;
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static const int NO_FLAGS = 0;
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static int skipAllAttributes(const uint8_t *const dict, const uint8_t flags, const int pos);
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static int skipBigrams(const uint8_t *const dict, const uint8_t flags, const int pos);
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};
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AK_FORCE_INLINE int BinaryFormat::detectFormat(const uint8_t *const dict) {
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// The magic number is stored big-endian.
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const int magicNumber = (dict[0] << 24) + (dict[1] << 16) + (dict[2] << 8) + dict[3];
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switch (magicNumber) {
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case FORMAT_VERSION_1_MAGIC_NUMBER:
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// Format 1 header is exactly 5 bytes long and looks like:
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// Magic number (2 bytes) 0x78 0xB1
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// Version number (1 byte) 0x01
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// Options (2 bytes) must be 0x00 0x00
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return 1;
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case FORMAT_VERSION_2_MAGIC_NUMBER:
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// Format 2 header is as follows:
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// Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE
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// Version number (2 bytes) 0x00 0x02
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// Options (2 bytes)
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// Header size (4 bytes) : integer, big endian
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return (dict[4] << 8) + dict[5];
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default:
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return UNKNOWN_FORMAT;
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}
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}
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inline int BinaryFormat::getFlags(const uint8_t *const dict) {
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switch (detectFormat(dict)) {
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case 1:
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return NO_FLAGS; // TODO: NO_FLAGS is unused anywhere else?
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default:
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return (dict[6] << 8) + dict[7];
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}
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}
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inline int BinaryFormat::getHeaderSize(const uint8_t *const dict) {
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switch (detectFormat(dict)) {
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case 1:
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return FORMAT_VERSION_1_HEADER_SIZE;
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case 2:
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// See the format of the header in the comment in detectFormat() above
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return (dict[8] << 24) + (dict[9] << 16) + (dict[10] << 8) + dict[11];
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default:
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return S_INT_MAX;
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}
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}
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inline void BinaryFormat::readHeaderValue(const uint8_t *const dict, const char *const key,
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int *outValue, const int outValueSize) {
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int outValueIndex = 0;
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// Only format 2 and above have header attributes as {key,value} string pairs. For prior
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// formats, we just return an empty string, as if the key wasn't found.
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if (2 <= detectFormat(dict)) {
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const int headerOptionsOffset = 4 /* magic number */
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+ 2 /* dictionary version */ + 2 /* flags */;
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const int headerSize =
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(dict[headerOptionsOffset] << 24) + (dict[headerOptionsOffset + 1] << 16)
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+ (dict[headerOptionsOffset + 2] << 8) + dict[headerOptionsOffset + 3];
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const int headerEnd = headerOptionsOffset + 4 + headerSize;
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int index = headerOptionsOffset + 4;
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while (index < headerEnd) {
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int keyIndex = 0;
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int codePoint = getCodePointAndForwardPointer(dict, &index);
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while (codePoint != NOT_A_CODE_POINT) {
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if (codePoint != key[keyIndex++]) {
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break;
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}
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codePoint = getCodePointAndForwardPointer(dict, &index);
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}
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if (codePoint == NOT_A_CODE_POINT && key[keyIndex] == 0) {
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// We found the key! Copy and return the value.
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codePoint = getCodePointAndForwardPointer(dict, &index);
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while (codePoint != NOT_A_CODE_POINT && outValueIndex < outValueSize) {
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outValue[outValueIndex++] = codePoint;
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codePoint = getCodePointAndForwardPointer(dict, &index);
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}
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// Finished copying. Break to go to the termination code.
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break;
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}
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// We didn't find the key, skip the remainder of it and its value
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while (codePoint != NOT_A_CODE_POINT) {
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codePoint = getCodePointAndForwardPointer(dict, &index);
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}
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codePoint = getCodePointAndForwardPointer(dict, &index);
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while (codePoint != NOT_A_CODE_POINT) {
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codePoint = getCodePointAndForwardPointer(dict, &index);
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}
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}
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// We couldn't find it - fall through and return an empty value.
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}
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// Put a terminator 0 if possible at all (always unless outValueSize is <= 0)
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if (outValueIndex >= outValueSize) outValueIndex = outValueSize - 1;
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if (outValueIndex >= 0) outValue[outValueIndex] = 0;
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}
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inline int BinaryFormat::readHeaderValueInt(const uint8_t *const dict, const char *const key) {
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const int bufferSize = LARGEST_INT_DIGIT_COUNT;
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int intBuffer[bufferSize];
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char charBuffer[bufferSize];
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BinaryFormat::readHeaderValue(dict, key, intBuffer, bufferSize);
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for (int i = 0; i < bufferSize; ++i) {
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charBuffer[i] = intBuffer[i];
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}
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// If not a number, return S_INT_MIN
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if (!isdigit(charBuffer[0])) return S_INT_MIN;
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return atoi(charBuffer);
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}
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AK_FORCE_INLINE int BinaryFormat::getGroupCountAndForwardPointer(const uint8_t *const dict,
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int *pos) {
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const int msb = dict[(*pos)++];
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if (msb < 0x80) return msb;
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return ((msb & 0x7F) << 8) | dict[(*pos)++];
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}
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inline uint8_t BinaryFormat::getFlagsAndForwardPointer(const uint8_t *const dict, int *pos) {
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return dict[(*pos)++];
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}
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AK_FORCE_INLINE int BinaryFormat::getCodePointAndForwardPointer(const uint8_t *const dict,
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int *pos) {
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const int origin = *pos;
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const int codePoint = dict[origin];
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if (codePoint < MINIMAL_ONE_BYTE_CHARACTER_VALUE) {
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if (codePoint == CHARACTER_ARRAY_TERMINATOR) {
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*pos = origin + 1;
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return NOT_A_CODE_POINT;
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} else {
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*pos = origin + 3;
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const int char_1 = codePoint << 16;
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const int char_2 = char_1 + (dict[origin + 1] << 8);
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return char_2 + dict[origin + 2];
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}
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} else {
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*pos = origin + 1;
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return codePoint;
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}
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}
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inline int BinaryFormat::readProbabilityWithoutMovingPointer(const uint8_t *const dict,
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const int pos) {
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return dict[pos];
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}
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AK_FORCE_INLINE int BinaryFormat::skipOtherCharacters(const uint8_t *const dict, const int pos) {
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int currentPos = pos;
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int character = dict[currentPos++];
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while (CHARACTER_ARRAY_TERMINATOR != character) {
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if (character < MINIMAL_ONE_BYTE_CHARACTER_VALUE) {
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currentPos += MULTIPLE_BYTE_CHARACTER_ADDITIONAL_SIZE;
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}
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character = dict[currentPos++];
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}
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return currentPos;
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}
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static inline int attributeAddressSize(const uint8_t flags) {
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static const int ATTRIBUTE_ADDRESS_SHIFT = 4;
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return (flags & BinaryFormat::MASK_ATTRIBUTE_ADDRESS_TYPE) >> ATTRIBUTE_ADDRESS_SHIFT;
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/* Note: this is a value-dependant optimization of what may probably be
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more readably written this way:
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switch (flags * BinaryFormat::MASK_ATTRIBUTE_ADDRESS_TYPE) {
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE: return 1;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES: return 2;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTE: return 3;
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default: return 0;
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}
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*/
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}
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static AK_FORCE_INLINE int skipExistingBigrams(const uint8_t *const dict, const int pos) {
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int currentPos = pos;
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uint8_t flags = BinaryFormat::getFlagsAndForwardPointer(dict, ¤tPos);
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while (flags & BinaryFormat::FLAG_ATTRIBUTE_HAS_NEXT) {
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currentPos += attributeAddressSize(flags);
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flags = BinaryFormat::getFlagsAndForwardPointer(dict, ¤tPos);
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}
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currentPos += attributeAddressSize(flags);
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return currentPos;
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}
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static inline int childrenAddressSize(const uint8_t flags) {
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static const int CHILDREN_ADDRESS_SHIFT = 6;
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return (BinaryFormat::MASK_GROUP_ADDRESS_TYPE & flags) >> CHILDREN_ADDRESS_SHIFT;
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/* See the note in attributeAddressSize. The same applies here */
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}
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static AK_FORCE_INLINE int shortcutByteSize(const uint8_t *const dict, const int pos) {
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return (static_cast<int>(dict[pos] << 8)) + (dict[pos + 1]);
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}
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inline int BinaryFormat::skipChildrenPosition(const uint8_t flags, const int pos) {
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return pos + childrenAddressSize(flags);
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}
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inline int BinaryFormat::skipProbability(const uint8_t flags, const int pos) {
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return FLAG_IS_TERMINAL & flags ? pos + 1 : pos;
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}
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AK_FORCE_INLINE int BinaryFormat::skipShortcuts(const uint8_t *const dict, const uint8_t flags,
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const int pos) {
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if (FLAG_HAS_SHORTCUT_TARGETS & flags) {
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return pos + shortcutByteSize(dict, pos);
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} else {
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return pos;
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}
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}
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AK_FORCE_INLINE int BinaryFormat::skipBigrams(const uint8_t *const dict, const uint8_t flags,
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const int pos) {
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if (FLAG_HAS_BIGRAMS & flags) {
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return skipExistingBigrams(dict, pos);
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} else {
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return pos;
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}
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}
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AK_FORCE_INLINE int BinaryFormat::skipAllAttributes(const uint8_t *const dict, const uint8_t flags,
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const int pos) {
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// This function skips all attributes: shortcuts and bigrams.
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int newPos = pos;
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newPos = skipShortcuts(dict, flags, newPos);
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newPos = skipBigrams(dict, flags, newPos);
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return newPos;
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}
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AK_FORCE_INLINE int BinaryFormat::skipChildrenPosAndAttributes(const uint8_t *const dict,
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const uint8_t flags, const int pos) {
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int currentPos = pos;
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currentPos = skipChildrenPosition(flags, currentPos);
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currentPos = skipAllAttributes(dict, flags, currentPos);
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return currentPos;
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}
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AK_FORCE_INLINE int BinaryFormat::readChildrenPosition(const uint8_t *const dict,
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const uint8_t flags, const int pos) {
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int offset = 0;
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switch (MASK_GROUP_ADDRESS_TYPE & flags) {
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case FLAG_GROUP_ADDRESS_TYPE_ONEBYTE:
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offset = dict[pos];
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break;
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case FLAG_GROUP_ADDRESS_TYPE_TWOBYTES:
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offset = dict[pos] << 8;
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offset += dict[pos + 1];
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break;
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case FLAG_GROUP_ADDRESS_TYPE_THREEBYTES:
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offset = dict[pos] << 16;
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offset += dict[pos + 1] << 8;
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offset += dict[pos + 2];
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break;
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default:
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// If we come here, it means we asked for the children of a word with
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// no children.
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return -1;
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}
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return pos + offset;
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}
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inline bool BinaryFormat::hasChildrenInFlags(const uint8_t flags) {
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return (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS != (MASK_GROUP_ADDRESS_TYPE & flags));
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}
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AK_FORCE_INLINE int BinaryFormat::getAttributeAddressAndForwardPointer(const uint8_t *const dict,
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const uint8_t flags, int *pos) {
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int offset = 0;
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const int origin = *pos;
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switch (MASK_ATTRIBUTE_ADDRESS_TYPE & flags) {
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_ONEBYTE:
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offset = dict[origin];
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*pos = origin + 1;
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break;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_TWOBYTES:
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offset = dict[origin] << 8;
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offset += dict[origin + 1];
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*pos = origin + 2;
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break;
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case FLAG_ATTRIBUTE_ADDRESS_TYPE_THREEBYTES:
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offset = dict[origin] << 16;
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offset += dict[origin + 1] << 8;
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offset += dict[origin + 2];
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*pos = origin + 3;
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break;
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}
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if (FLAG_ATTRIBUTE_OFFSET_NEGATIVE & flags) {
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return origin - offset;
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} else {
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return origin + offset;
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}
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}
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inline int BinaryFormat::getAttributeProbabilityFromFlags(const int flags) {
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return flags & MASK_ATTRIBUTE_PROBABILITY;
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}
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// This function gets the byte position of the last chargroup of the exact matching word in the
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// dictionary. If no match is found, it returns NOT_VALID_WORD.
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AK_FORCE_INLINE int BinaryFormat::getTerminalPosition(const uint8_t *const root,
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const int *const inWord, const int length, const bool forceLowerCaseSearch) {
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int pos = 0;
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int wordPos = 0;
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while (true) {
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// If we already traversed the tree further than the word is long, there means
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// there was no match (or we would have found it).
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if (wordPos >= length) return NOT_VALID_WORD;
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int charGroupCount = BinaryFormat::getGroupCountAndForwardPointer(root, &pos);
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const int wChar = forceLowerCaseSearch ? toLowerCase(inWord[wordPos]) : inWord[wordPos];
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while (true) {
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// If there are no more character groups in this node, it means we could not
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// find a matching character for this depth, therefore there is no match.
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if (0 >= charGroupCount) return NOT_VALID_WORD;
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const int charGroupPos = pos;
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const uint8_t flags = BinaryFormat::getFlagsAndForwardPointer(root, &pos);
|
|
int character = BinaryFormat::getCodePointAndForwardPointer(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 (FLAG_HAS_MULTIPLE_CHARS & flags) {
|
|
character = BinaryFormat::getCodePointAndForwardPointer(root, &pos);
|
|
while (NOT_A_CODE_POINT != 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::getCodePointAndForwardPointer(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 (FLAG_IS_TERMINAL & flags) {
|
|
if (wordPos == length) {
|
|
return charGroupPos;
|
|
}
|
|
pos = BinaryFormat::skipProbability(FLAG_IS_TERMINAL, pos);
|
|
}
|
|
if (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS == (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 (FLAG_HAS_MULTIPLE_CHARS & flags) {
|
|
pos = BinaryFormat::skipOtherCharacters(root, pos);
|
|
}
|
|
pos = BinaryFormat::skipProbability(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.
|
|
* outUnigramProbability: a pointer to an int to write the probability into.
|
|
* Return value : the length of the word, of 0 if the word was not found.
|
|
*/
|
|
AK_FORCE_INLINE int BinaryFormat::getWordAtAddress(const uint8_t *const root, const int address,
|
|
const int maxDepth, int *outWord, int *outUnigramProbability) {
|
|
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 int character = getCodePointAndForwardPointer(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 (FLAG_HAS_MULTIPLE_CHARS & flags) {
|
|
int nextChar = getCodePointAndForwardPointer(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 (NOT_A_CODE_POINT != nextChar && --charCount > 0) {
|
|
outWord[++wordPos] = nextChar;
|
|
nextChar = getCodePointAndForwardPointer(root, &pos);
|
|
}
|
|
}
|
|
*outUnigramProbability = readProbabilityWithoutMovingPointer(root, pos);
|
|
return ++wordPos;
|
|
}
|
|
// We need to skip past this char group, so skip any remaining chars after the
|
|
// first and possibly the probability.
|
|
if (FLAG_HAS_MULTIPLE_CHARS & flags) {
|
|
pos = skipOtherCharacters(root, pos);
|
|
}
|
|
pos = skipProbability(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 = (FLAG_GROUP_ADDRESS_TYPE_NOADDRESS !=
|
|
(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 int lastChar =
|
|
getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
|
|
// We copy all the characters in this group to the buffer
|
|
outWord[wordPos] = lastChar;
|
|
if (FLAG_HAS_MULTIPLE_CHARS & lastFlags) {
|
|
int nextChar = getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
|
|
int charCount = maxDepth;
|
|
while (-1 != nextChar && --charCount > 0) {
|
|
outWord[++wordPos] = nextChar;
|
|
nextChar = getCodePointAndForwardPointer(root, &lastCandidateGroupPos);
|
|
}
|
|
}
|
|
++wordPos;
|
|
// Now we only need to branch to the children address. Skip the probability if
|
|
// it's there, read pos, and break to resume the search at pos.
|
|
lastCandidateGroupPos = skipProbability(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;
|
|
}
|
|
|
|
static inline int backoff(const int unigramProbability) {
|
|
return unigramProbability;
|
|
// For some reason, applying the backoff weight gives bad results in tests. To apply the
|
|
// backoff weight, we divide the probability by 2, which in our storing format means
|
|
// decreasing the score by 8.
|
|
// TODO: figure out what's wrong with this.
|
|
// return unigramProbability > 8 ? unigramProbability - 8 : (0 == unigramProbability ? 0 : 8);
|
|
}
|
|
|
|
inline int BinaryFormat::computeProbabilityForBigram(
|
|
const int unigramProbability, const int bigramProbability) {
|
|
// We divide the range [unigramProbability..255] in 16.5 steps - in other words, we want the
|
|
// unigram probability to be the median value of the 17th step from the top. A value of
|
|
// 0 for the bigram probability represents the middle of the 16th step from the top,
|
|
// while a value of 15 represents the middle of the top step.
|
|
// See makedict.BinaryDictInputOutput for details.
|
|
const float stepSize = static_cast<float>(MAX_PROBABILITY - unigramProbability)
|
|
/ (1.5f + MAX_BIGRAM_ENCODED_PROBABILITY);
|
|
return unigramProbability
|
|
+ static_cast<int>(static_cast<float>(bigramProbability + 1) * stepSize);
|
|
}
|
|
|
|
// This returns a probability in log space.
|
|
inline int BinaryFormat::getProbability(const int position, const std::map<int, int> *bigramMap,
|
|
const uint8_t *bigramFilter, const int unigramProbability) {
|
|
if (!bigramMap || !bigramFilter) return backoff(unigramProbability);
|
|
if (!isInFilter(bigramFilter, position)) return backoff(unigramProbability);
|
|
const std::map<int, int>::const_iterator bigramProbabilityIt = bigramMap->find(position);
|
|
if (bigramProbabilityIt != bigramMap->end()) {
|
|
const int bigramProbability = bigramProbabilityIt->second;
|
|
return computeProbabilityForBigram(unigramProbability, bigramProbability);
|
|
}
|
|
return backoff(unigramProbability);
|
|
}
|
|
} // namespace latinime
|
|
#endif // LATINIME_BINARY_FORMAT_H
|