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Implement an mmap-based LM parser.

This commit is contained in:
Lukhnos Liu 2012-09-10 22:55:40 -07:00
parent bf50e4fa7e
commit 67775e3ccf
2 changed files with 337 additions and 0 deletions
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257
Source/Engine/FastLM.cpp Normal file
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//
// FastLM.h: A fast unigram language model for Gramambular
//
// Copyright (c) 2012 Lukhnos Liu (http://lukhnos.org)
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
#include "FastLM.h"
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <fstream>
using namespace Formosa::Gramambular;
FastLM::FastLM()
: fd(-1)
, data(0)
, length(0)
{
}
FastLM::~FastLM()
{
if (data) {
close();
}
}
bool FastLM::open(const char *path)
{
if (data) {
return false;
}
fd = ::open(path, O_RDONLY);
if (fd == -1) {
return false;
}
struct stat sb;
if (fstat(fd, &sb) == -1) {
return false;
}
length = (size_t)sb.st_size;
data = mmap(NULL, length, PROT_WRITE, MAP_PRIVATE, fd, 0);
if (!data) {
::close(fd);
return false;
}
// we have 5 states
// 0
// end -> end
// lf -> forward, go to 0
// space -> error
// other -> record ptr, forward, goto 1
// 1
// end -> error
// lf -> error
// space -> zero out, check length, record ptr, go to 2
// other -> forward, go to 1
// 2
// lf -> error
// end -> error
// space -> zero out, check length, record ptr, go to 3
// other -> forward, go to 2
// 3
// end -> error
// lf -> save row, zero out, go to 0
// space -> error
// other -> forward, go to 3
char *head = (char *)data;
char *end = (char *)data + length;
char c;
Row row;
state0:
if (head == end) {
goto end;
}
c = *head;
if (c == '\n') {
head++;
goto state0;
}
else if (c == ' ') {
goto error;
}
row.value = head;
head++;
// fall through state 1
state1:
if (head == end) {
goto error;
}
c = *head;
if (c == '\n') {
goto error;
}
else if (c == ' ') {
if (row.value == head) {
goto error;
}
*head = 0;
head++;
row.key = head;
goto state2;
}
head++;
goto state1;
state2:
if (head == end) {
goto error;
}
c = *head;
if (c == '\n') {
goto error;
}
else if (c == ' ') {
if (row.key == head) {
goto error;
}
*head = 0;
head++;
row.logProbability = head;
goto state3;
}
head++;
goto state2;
state3:
if (head == end) {
goto error;
}
c = *head;
if (c == '\n') {
if (row.logProbability == head) {
goto error;
}
*head = 0;
head++;
keyRowMap[row.key].push_back(row);
goto state0;
}
if (c == ' ') {
goto error;
}
head++;
goto state3;
error:
close();
return false;
end:
static const char *space = " ";
static const char *zero = "0.0";
Row emptyRow;
emptyRow.key = space;
emptyRow.value = space;
emptyRow.logProbability = zero;
keyRowMap[space].push_back(emptyRow);
return true;
}
void FastLM::close()
{
if (data) {
munmap(data, length);
::close(fd);
data = 0;
}
keyRowMap.clear();
}
void FastLM::dump()
{
size_t rows = 0;
for (map<const char *, vector<Row> >::const_iterator i = keyRowMap.begin(), e = keyRowMap.end(); i != e; ++i) {
const vector<Row>& r = (*i).second;
for (vector<Row>::const_iterator ri = r.begin(), re = r.end(); ri != re; ++ri) {
const Row& row = *ri;
cerr << row.key << " " << row.value << " " << row.logProbability << "\n";
rows++;
}
}
}
const vector<Bigram> FastLM::bigramsForKeys(const string& preceedingKey, const string& key)
{
return vector<Bigram>();
}
const vector<Unigram> FastLM::unigramsForKeys(const string& key)
{
vector<Unigram> v;
map<const char *, vector<Row> >::const_iterator i = keyRowMap.find(key.c_str());
if (i != keyRowMap.end()) {
for (vector<Row>::const_iterator ri = (*i).second.begin(), re = (*i).second.end(); ri != re; ++ri) {
Unigram g;
const Row& r = *ri;
g.keyValue.key = r.key;
g.keyValue.value = r.value;
g.score = atof(r.logProbability);
v.push_back(g);
}
}
return v;
}
bool FastLM::hasUnigramsForKey(const string& key)
{
return keyRowMap.find(key.c_str()) != keyRowMap.end();
}

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Source/Engine/FastLM.h Normal file
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//
// FastLM.h: A fast unigram language model for Gramambular
//
// Copyright (c) 2012 Lukhnos Liu (http://lukhnos.org)
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
#ifndef FASTLM_H
#define FASTLM_H
#include <string>
#include <map>
#include <iostream>
#include "LanguageModel.h"
// this class relies on the fact that we have a space-separated data
// format, and we use mmap and zero-out the separators and line feeds
// to avoid creating new string objects; the parser is a simple DFA
namespace Formosa {
namespace Gramambular {
class FastLM : public LanguageModel
{
public:
FastLM();
~FastLM();
bool open(const char *path);
void close();
void dump();
virtual const vector<Bigram> bigramsForKeys(const string& preceedingKey, const string& key);
virtual const vector<Unigram> unigramsForKeys(const string& key);
virtual bool hasUnigramsForKey(const string& key);
protected:
struct CStringCmp
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};
struct Row {
const char *key;
const char *value;
const char *logProbability;
};
map<const char *, vector<Row>, CStringCmp> keyRowMap;
int fd;
void *data;
size_t length;
};
}
}
#endif