/*
* Copyright (C) 2012, 2013
* Dale Weiler
*
* 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 "gmqcc.h"
/*
* A forward allcator for the corrector. This corrector requires a lot
* of allocations. This forward allocator combats all those allocations
* and speeds us up a little. It also saves us space in a way since each
* allocation isn't wasting a little header space for when NOTRACK isn't
* defined.
*/
#define CORRECT_POOLSIZE (128*1024*1024)
static unsigned char **correct_pool_data = NULL;
static unsigned char *correct_pool_this = NULL;
static size_t correct_pool_addr = 0;
static GMQCC_INLINE void correct_pool_new(void) {
correct_pool_addr = 0;
correct_pool_this = (unsigned char *)mem_a(CORRECT_POOLSIZE);
vec_push(correct_pool_data, correct_pool_this);
}
static GMQCC_INLINE void *correct_pool_alloc(size_t bytes) {
void *data;
if (correct_pool_addr + bytes >= CORRECT_POOLSIZE)
correct_pool_new();
data = correct_pool_this;
correct_pool_this += bytes;
correct_pool_addr += bytes;
return data;
}
static GMQCC_INLINE void correct_pool_delete(void) {
size_t i;
for (i = 0; i < vec_size(correct_pool_data); ++i)
mem_d(correct_pool_data[i]);
correct_pool_data = NULL;
correct_pool_this = NULL;
correct_pool_addr = 0;
}
static GMQCC_INLINE char *correct_outstr(const char *s) {
char *o = util_strdup(s);
correct_pool_delete();
return o;
}
correct_trie_t* correct_trie_new()
{
correct_trie_t *t = (correct_trie_t*)mem_a(sizeof(correct_trie_t));
t->value = NULL;
t->entries = NULL;
return t;
}
void correct_trie_del_sub(correct_trie_t *t)
{
size_t i;
for (i = 0; i < vec_size(t->entries); ++i)
correct_trie_del_sub(&t->entries[i]);
vec_free(t->entries);
}
void correct_trie_del(correct_trie_t *t)
{
size_t i;
for (i = 0; i < vec_size(t->entries); ++i)
correct_trie_del_sub(&t->entries[i]);
vec_free(t->entries);
mem_d(t);
}
void* correct_trie_get(const correct_trie_t *t, const char *key)
{
const unsigned char *data = (const unsigned char*)key;
while (*data) {
unsigned char ch = *data;
const size_t vs = vec_size(t->entries);
size_t i;
const correct_trie_t *entries = t->entries;
for (i = 0; i < vs; ++i) {
if (entries[i].ch == ch) {
t = &entries[i];
++data;
break;
}
}
if (i == vs)
return NULL;
}
return t->value;
}
void correct_trie_set(correct_trie_t *t, const char *key, void * const value)
{
const unsigned char *data = (const unsigned char*)key;
while (*data) {
unsigned char ch = *data;
correct_trie_t *entries = t->entries;
const size_t vs = vec_size(t->entries);
size_t i;
for (i = 0; i < vs; ++i) {
if (entries[i].ch == ch) {
t = &entries[i];
break;
}
}
if (i == vs) {
correct_trie_t *elem = (correct_trie_t*)vec_add(t->entries, 1);
elem->ch = ch;
elem->value = NULL;
elem->entries = NULL;
t = elem;
}
++data;
}
t->value = value;
}
/*
* This is a very clever method for correcting mistakes in QuakeC code
* most notably when invalid identifiers are used or inproper assignments;
* we can proprly lookup in multiple dictonaries (depening on the rules
* of what the task is trying to acomplish) to find the best possible
* match.
*
*
* A little about how it works, and probability theory:
*
* When given an identifier (which we will denote I), we're essentially
* just trying to choose the most likely correction for that identifier.
* (the actual "correction" can very well be the identifier itself).
* There is actually no way to know for sure that certian identifers
* such as "lates", need to be corrected to "late" or "latest" or any
* other permutations that look lexically the same. This is why we
* must advocate the usage of probabilities. This implies that we're
* trying to find the correction for C, out of all possible corrections
* that maximizes the probability of C for the original identifer I.
*
* Bayes' Therom suggests something of the following:
* AC P(I|C) P(C) / P(I)
* Since P(I) is the same for every possibly I, we can ignore it giving
* AC P(I|C) P(C)
*
* This greatly helps visualize how the parts of the expression are performed
* there is essentially three, from right to left we perform the following:
*
* 1: P(C), the probability that a proposed correction C will stand on its
* own. This is called the language model.
*
* 2: P(I|C), the probability that I would be used, when the programmer
* really meant C. This is the error model.
*
* 3: AC, the control mechanisim, which implies the enumeration of all
* feasible values of C, and then determine the one that gives the
* greatest probability score. Selecting it as the "correction"
*
*
* The requirement for complex expression involving two models:
*
* In reality the requirement for a more complex expression involving
* two seperate models is considerably a waste. But one must recognize
* that P(C|I) is already conflating two factors. It's just much simpler
* to seperate the two models and deal with them explicitaly. To properly
* estimate P(C|I) you have to consider both the probability of C and
* probability of the transposition from C to I. It's simply much more
* cleaner, and direct to seperate the two factors.
*/
/* some hashtable management for dictonaries */
static size_t *correct_find(correct_trie_t *table, const char *word) {
return (size_t*)correct_trie_get(table, word);
}
static int correct_update(correct_trie_t* *table, const char *word) {
size_t *data = correct_find(*table, word);
if (!data)
return 0;
(*data)++;
return 1;
}
void correct_add(correct_trie_t* table, size_t ***size, const char *ident) {
size_t *data = NULL;
const char *add = ident;
if (!correct_update(&table, add)) {
data = (size_t*)mem_a(sizeof(size_t));
*data = 1;
vec_push((*size), data);
correct_trie_set(table, add, data);
}
}
void correct_del(correct_trie_t* dictonary, size_t **data) {
size_t i;
const size_t vs = vec_size(data);
for (i = 0; i < vs; i++)
mem_d(data[i]);
vec_free(data);
correct_trie_del(dictonary);
}
/*
* _ is valid in identifiers. I've yet to implement numerics however
* because they're only valid after the first character is of a _, or
* alpha character.
*/
static const char correct_alpha[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_";
/*
* correcting logic for the following forms of transformations:
* 1) deletion
* 2) transposition
* 3) alteration
* 4) insertion
*/
static size_t correct_deletion(const char *ident, char **array, size_t index) {
size_t itr;
size_t len = strlen(ident);
for (itr = 0; itr < len; itr++) {
char *a = (char*)correct_pool_alloc(len+1);
memcpy(a, ident, itr);
memcpy(a + itr, ident + itr + 1, len - itr);
array[index + itr] = a;
}
return itr;
}
static size_t correct_transposition(const char *ident, char **array, size_t index) {
size_t itr;
size_t len = strlen(ident);
for (itr = 0; itr < len - 1; itr++) {
char tmp;
char *a = (char*)correct_pool_alloc(len+1);
memcpy(a, ident, len+1);
tmp = a[itr];
a[itr ] = a[itr+1];
a[itr+1] = tmp;
array[index + itr] = a;
}
return itr;
}
static size_t correct_alteration(const char *ident, char **array, size_t index) {
size_t itr;
size_t jtr;
size_t ktr;
size_t len = strlen(ident);
for (itr = 0, ktr = 0; itr < len; itr++) {
for (jtr = 0; jtr < sizeof(correct_alpha)-1; jtr++, ktr++) {
char *a = (char*)correct_pool_alloc(len+1);
memcpy(a, ident, len+1);
a[itr] = correct_alpha[jtr];
array[index + ktr] = a;
}
}
return ktr;
}
static size_t correct_insertion(const char *ident, char **array, size_t index) {
size_t itr;
size_t jtr;
size_t ktr;
const size_t len = strlen(ident);
for (itr = 0, ktr = 0; itr <= len; itr++) {
for (jtr = 0; jtr < sizeof(correct_alpha)-1; jtr++, ktr++) {
char *a = (char*)correct_pool_alloc(len+2);
memcpy(a, ident, itr);
memcpy(a + itr + 1, ident + itr, len - itr + 1);
a[itr] = correct_alpha[jtr];
array[index + ktr] = a;
}
}
return ktr;
}
static GMQCC_INLINE size_t correct_size(const char *ident) {
/*
* deletion = len
* transposition = len - 1
* alteration = len * sizeof(correct_alpha)
* insertion = (len + 1) * sizeof(correct_alpha)
*/
register size_t len = strlen(ident);
return (len) + (len - 1) + (len * (sizeof(correct_alpha)-1)) + ((len + 1) * (sizeof(correct_alpha)-1));
}
static char **correct_edit(const char *ident) {
size_t next;
char **find = (char**)correct_pool_alloc(correct_size(ident) * sizeof(char*));
if (!find)
return NULL;
next = correct_deletion (ident, find, 0);
next += correct_transposition(ident, find, next);
next += correct_alteration (ident, find, next);
/*****/ correct_insertion (ident, find, next);
return find;
}
/*
* We could use a hashtable but the space complexity isn't worth it
* since we're only going to determine the "did you mean?" identifier
* on error.
*/
static int correct_exist(char **array, size_t rows, char *ident) {
size_t itr;
for (itr = 0; itr < rows; itr++)
if (!strcmp(array[itr], ident))
return 1;
return 0;
}
static GMQCC_INLINE char **correct_known_resize(char **res, size_t *allocated, size_t size) {
size_t oldallocated = *allocated;
char **out;
if (size+1 < *allocated)
return res;
*allocated += 32;
out = correct_pool_alloc(sizeof(*res) * *allocated);
memcpy(out, res, sizeof(*res) * oldallocated);
return out;
}
static char **correct_known(correct_trie_t* table, char **array, size_t rows, size_t *next) {
size_t itr;
size_t jtr;
size_t len;
size_t row;
size_t nxt = 8;
char **res = correct_pool_alloc(sizeof(char *) * nxt);
char **end = NULL;
for (itr = 0, len = 0; itr < rows; itr++) {
end = correct_edit(array[itr]);
row = correct_size(array[itr]);
for (jtr = 0; jtr < row; jtr++) {
if (correct_find(table, end[jtr]) && !correct_exist(res, len, end[jtr])) {
res = correct_known_resize(res, &nxt, len+1);
res[len++] = end[jtr];
}
}
}
*next = len;
return res;
}
static char *correct_maximum(correct_trie_t* table, char **array, size_t rows) {
char *str = NULL;
size_t *itm = NULL;
size_t itr;
size_t top;
for (itr = 0, top = 0; itr < rows; itr++) {
if ((itm = correct_find(table, array[itr])) && (*itm > top)) {
top = *itm;
str = array[itr];
}
}
return str;
}
/*
* This is the exposed interface:
* takes a table for the dictonary a vector of sizes (used for internal
* probability calculation, and an identifier to "correct"
*
* the add function works the same. Except the identifier is used to
* add to the dictonary.
*/
char *correct_str(correct_trie_t* table, const char *ident) {
char **e1;
char **e2;
char *e1ident;
char *e2ident;
char *found = util_strdup(ident);
size_t e1rows = 0;
size_t e2rows = 0;
correct_pool_new();
/* needs to be allocated for free later */
if (correct_find(table, ident))
return correct_outstr(found);
if ((e1rows = correct_size(ident))) {
e1 = correct_edit(ident);
if ((e1ident = correct_maximum(table, e1, e1rows))) {
found = util_strdup(e1ident);
return correct_outstr(found);
}
}
e2 = correct_known(table, e1, e1rows, &e2rows);
if (e2rows && ((e2ident = correct_maximum(table, e2, e2rows)))) {
found = util_strdup(e2ident);
}
return correct_outstr(found);
}