LatinIME/dictionary/src/dictionary.cpp
Amith Yamasani 1b62ff1a3d Increase target size of preferred letters while typing.
This increases the chance of hitting the correct letter when typing a word
that exists in the dictionary, rather than only correct it after the fact.
It is most effective after 2 or 3 letters of a word have been typed and gets
more accurate with more typed letters in the word.

If 2 adjacent letters have similar probabilities of occuring, then there is no
hit correction applied.
2010-02-08 15:22:37 -08:00

317 lines
9.5 KiB
C++

/*
**
** Copyright 2009, 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 <stdio.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#include <cutils/log.h>
#include <unicode/uchar.h>
//#define USE_ASSET_MANAGER
#ifdef USE_ASSET_MANAGER
#include <utils/AssetManager.h>
#include <utils/Asset.h>
#endif
#include "dictionary.h"
#include "basechars.h"
#define DEBUG_DICT 0
namespace latinime {
Dictionary::Dictionary(void *dict, int typedLetterMultiplier, int fullWordMultiplier)
{
mDict = (unsigned char*) dict;
mTypedLetterMultiplier = typedLetterMultiplier;
mFullWordMultiplier = fullWordMultiplier;
}
Dictionary::~Dictionary()
{
}
int Dictionary::getSuggestions(int *codes, int codesSize, unsigned short *outWords, int *frequencies,
int maxWordLength, int maxWords, int maxAlternatives, int skipPos,
int *nextLetters, int nextLettersSize)
{
int suggWords;
mFrequencies = frequencies;
mOutputChars = outWords;
mInputCodes = codes;
mInputLength = codesSize;
mMaxAlternatives = maxAlternatives;
mMaxWordLength = maxWordLength;
mMaxWords = maxWords;
mSkipPos = skipPos;
mMaxEditDistance = mInputLength < 5 ? 2 : mInputLength / 2;
mNextLettersFrequencies = nextLetters;
mNextLettersSize = nextLettersSize;
getWordsRec(0, 0, mInputLength * 3, false, 1, 0, 0);
// Get the word count
suggWords = 0;
while (suggWords < mMaxWords && mFrequencies[suggWords] > 0) suggWords++;
if (DEBUG_DICT) LOGI("Returning %d words", suggWords);
if (DEBUG_DICT) {
LOGI("Next letters: ");
for (int k = 0; k < nextLettersSize; k++) {
if (mNextLettersFrequencies[k] > 0) {
LOGI("%c = %d,", k, mNextLettersFrequencies[k]);
}
}
LOGI("\n");
}
return suggWords;
}
void
Dictionary::registerNextLetter(unsigned short c)
{
if (c < mNextLettersSize) {
mNextLettersFrequencies[c]++;
}
}
unsigned short
Dictionary::getChar(int *pos)
{
unsigned short ch = (unsigned short) (mDict[(*pos)++] & 0xFF);
// If the code is 255, then actual 16 bit code follows (in big endian)
if (ch == 0xFF) {
ch = ((mDict[*pos] & 0xFF) << 8) | (mDict[*pos + 1] & 0xFF);
(*pos) += 2;
}
return ch;
}
int
Dictionary::getAddress(int *pos)
{
int address = 0;
if ((mDict[*pos] & FLAG_ADDRESS_MASK) == 0) {
*pos += 1;
} else {
address += (mDict[*pos] & (ADDRESS_MASK >> 16)) << 16;
address += (mDict[*pos + 1] & 0xFF) << 8;
address += (mDict[*pos + 2] & 0xFF);
*pos += 3;
}
return address;
}
int
Dictionary::wideStrLen(unsigned short *str)
{
if (!str) return 0;
unsigned short *end = str;
while (*end)
end++;
return end - str;
}
bool
Dictionary::addWord(unsigned short *word, int length, int frequency)
{
word[length] = 0;
if (DEBUG_DICT) {
char s[length + 1];
for (int i = 0; i <= length; i++) s[i] = word[i];
LOGI("Found word = %s, freq = %d : \n", s, frequency);
}
// Find the right insertion point
int insertAt = 0;
while (insertAt < mMaxWords) {
if (frequency > mFrequencies[insertAt]
|| (mFrequencies[insertAt] == frequency
&& length < wideStrLen(mOutputChars + insertAt * mMaxWordLength))) {
break;
}
insertAt++;
}
if (insertAt < mMaxWords) {
memmove((char*) mFrequencies + (insertAt + 1) * sizeof(mFrequencies[0]),
(char*) mFrequencies + insertAt * sizeof(mFrequencies[0]),
(mMaxWords - insertAt - 1) * sizeof(mFrequencies[0]));
mFrequencies[insertAt] = frequency;
memmove((char*) mOutputChars + (insertAt + 1) * mMaxWordLength * sizeof(short),
(char*) mOutputChars + (insertAt ) * mMaxWordLength * sizeof(short),
(mMaxWords - insertAt - 1) * sizeof(short) * mMaxWordLength);
unsigned short *dest = mOutputChars + (insertAt ) * mMaxWordLength;
while (length--) {
*dest++ = *word++;
}
*dest = 0; // NULL terminate
if (DEBUG_DICT) LOGI("Added word at %d\n", insertAt);
return true;
}
return false;
}
unsigned short
Dictionary::toLowerCase(unsigned short c) {
if (c < sizeof(BASE_CHARS) / sizeof(BASE_CHARS[0])) {
c = BASE_CHARS[c];
}
if (c >='A' && c <= 'Z') {
c |= 32;
} else if (c > 127) {
c = u_tolower(c);
}
return c;
}
bool
Dictionary::sameAsTyped(unsigned short *word, int length)
{
if (length != mInputLength) {
return false;
}
int *inputCodes = mInputCodes;
while (length--) {
if ((unsigned int) *inputCodes != (unsigned int) *word) {
return false;
}
inputCodes += mMaxAlternatives;
word++;
}
return true;
}
static char QUOTE = '\'';
void
Dictionary::getWordsRec(int pos, int depth, int maxDepth, bool completion, int snr, int inputIndex,
int diffs)
{
// Optimization: Prune out words that are too long compared to how much was typed.
if (depth > maxDepth) {
return;
}
if (diffs > mMaxEditDistance) {
return;
}
int count = getCount(&pos);
int *currentChars = NULL;
if (mInputLength <= inputIndex) {
completion = true;
} else {
currentChars = mInputCodes + (inputIndex * mMaxAlternatives);
}
for (int i = 0; i < count; i++) {
unsigned short c = getChar(&pos);
unsigned short lowerC = toLowerCase(c);
bool terminal = getTerminal(&pos);
int childrenAddress = getAddress(&pos);
int freq = 1;
if (terminal) freq = getFreq(&pos);
// If we are only doing completions, no need to look at the typed characters.
if (completion) {
mWord[depth] = c;
if (terminal) {
addWord(mWord, depth + 1, freq * snr);
if (depth >= mInputLength && mSkipPos < 0) {
registerNextLetter(mWord[mInputLength]);
}
}
if (childrenAddress != 0) {
getWordsRec(childrenAddress, depth + 1, maxDepth,
completion, snr, inputIndex, diffs);
}
} else if (c == QUOTE && currentChars[0] != QUOTE || mSkipPos == depth) {
// Skip the ' or other letter and continue deeper
mWord[depth] = c;
if (childrenAddress != 0) {
getWordsRec(childrenAddress, depth + 1, maxDepth, false, snr, inputIndex, diffs);
}
} else {
int j = 0;
while (currentChars[j] > 0) {
if (currentChars[j] == lowerC || currentChars[j] == c) {
int addedWeight = j == 0 ? mTypedLetterMultiplier : 1;
mWord[depth] = c;
if (mInputLength == inputIndex + 1) {
if (terminal) {
if (//INCLUDE_TYPED_WORD_IF_VALID ||
!sameAsTyped(mWord, depth + 1)) {
int finalFreq = freq * snr * addedWeight;
if (mSkipPos < 0) finalFreq *= mFullWordMultiplier;
addWord(mWord, depth + 1, finalFreq);
}
}
if (childrenAddress != 0) {
getWordsRec(childrenAddress, depth + 1,
maxDepth, true, snr * addedWeight, inputIndex + 1,
diffs + (j > 0));
}
} else if (childrenAddress != 0) {
getWordsRec(childrenAddress, depth + 1, maxDepth,
false, snr * addedWeight, inputIndex + 1, diffs + (j > 0));
}
}
j++;
if (mSkipPos >= 0) break;
}
}
}
}
bool
Dictionary::isValidWord(unsigned short *word, int length)
{
return isValidWordRec(0, word, 0, length);
}
bool
Dictionary::isValidWordRec(int pos, unsigned short *word, int offset, int length) {
int count = getCount(&pos);
unsigned short currentChar = (unsigned short) word[offset];
for (int j = 0; j < count; j++) {
unsigned short c = getChar(&pos);
int terminal = getTerminal(&pos);
int childPos = getAddress(&pos);
if (c == currentChar) {
if (offset == length - 1) {
if (terminal) {
return true;
}
} else {
if (childPos != 0) {
if (isValidWordRec(childPos, word, offset + 1, length)) {
return true;
}
}
}
}
if (terminal) {
getFreq(&pos);
}
// There could be two instances of each alphabet - upper and lower case. So continue
// looking ...
}
return false;
}
} // namespace latinime