/*
* 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"
/*
* 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(ht table, const char *word) {
return (size_t*)util_htget(table, word);
}
static int correct_update(ht *table, const char *word) {
size_t *data = correct_find(*table, word);
if (!data)
return 0;
(*data)++;
return 1;
}
/*
* _ 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_";
static char *correct_substr(const char *str, size_t off, size_t lim) {
char *nstr;
size_t slen = strlen(str);
/* lots of compares */
if ((lim > slen) || ((off + lim) > slen) || (slen < 1) || (!lim))
return NULL;
if (!(nstr = mem_a(lim + 1)))
return NULL;
strncpy(nstr, str+off, lim);
nstr[lim] = '\0';
return nstr;
}
static char *correct_concat(char *str1, char *str2) {
if (!str1) str1 = mem_a(1), *str1 = '\0';
if (!str2) str2 = mem_a(1), *str2 = '\0';
str1 = mem_r(str1, strlen(str1) + strlen(str2) + 1);
strcat(str1, str2);
return str1;
}
/*
* 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++) {
array[index + itr] = correct_concat (
correct_substr (ident, 0, itr),
correct_substr (ident, itr+1, len-(itr+1))
);
}
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++) {
array[index + itr] = correct_concat (
correct_concat (
correct_substr(ident, 0, itr),
correct_substr(ident, itr+1, 1)
),
correct_concat (
correct_substr(ident, itr, 1),
correct_substr(ident, itr+2, len-(itr+2))
)
);
}
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);
char cct[2] = { 0, 0 }; /* char code table, for concatenation */
for (itr = 0, ktr = 0; itr < len; itr++) {
for (jtr = 0; jtr < sizeof(correct_alpha); jtr++, ktr++) {
*cct = correct_alpha[jtr];
array[index + ktr] = correct_concat (
correct_concat (
correct_substr(ident, 0, itr),
(char *) &cct
),
correct_substr (
ident,
itr + 1,
len - (itr + 1)
)
);
}
}
return ktr;
}
static size_t correct_insertion(const char *ident, char **array, size_t index) {
size_t itr;
size_t jtr;
size_t ktr;
size_t len = strlen(ident);
char cct[2] = { 0, 0 }; /* char code table, for concatenation */
for (itr = 0, ktr = 0; itr <= len; itr++) {
for (jtr = 0; jtr < sizeof(correct_alpha); jtr++, ktr++) {
*cct = correct_alpha[jtr];
array[index + ktr] = correct_concat (
correct_concat (
correct_substr (ident, 0, itr),
(char *) &cct
),
correct_substr (
ident,
itr,
len - itr
)
);
}
}
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)) + (len + 1) * sizeof(correct_alpha);
}
static char **correct_edit(const char *ident) {
size_t next;
char **find = mem_a(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 char **correct_known(ht table, char **array, size_t rows, size_t *next) {
size_t itr;
size_t jtr;
size_t len;
size_t row;
char **res = NULL;
char **end;
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 = mem_r(res, sizeof(char*) * (len + 1));
res[len++] = end[jtr];
}
}
}
*next = len;
return res;
}
static char *correct_maximum(ht 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;
}
static void correct_cleanup(char **array, size_t rows) {
size_t itr;
for (itr = 0; itr < rows; itr++)
mem_d(array[itr]);
}
/*
* 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.
*/
void correct_add(ht 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);
util_htset(table, add, data);
}
}
char *correct_correct(ht table, const char *ident) {
char **e1;
char **e2;
char *e1ident;
char *e2ident;
char *found = util_strdup(ident);
size_t e1rows;
size_t e2rows;
/* needs to be allocated for free later */
if (correct_find(table, ident))
return found;
mem_d(found);
if ((e1rows = correct_size(ident))) {
e1 = correct_edit(ident);
if ((e1ident = correct_maximum(table, e1, e1rows))) {
found = util_strdup(e1ident);
correct_cleanup(e1, e1rows);
mem_d(e1);
return found;
}
}
e2 = correct_known(table, e1, e1rows, &e2rows);
if (e2rows && ((e2ident = correct_maximum(table, e2, e2rows))))
found = util_strdup(e2ident);
correct_cleanup(e1, e1rows);
correct_cleanup(e2, e2rows);
mem_d(e1);
mem_d(e2);
return found;
}
void correct_del(ht dictonary, size_t **data) {
size_t i;
for (i = 0; i < vec_size(data); i++)
mem_d(data[i]);
vec_free(data);
util_htdel(dictonary);
}
int main() {
opts.debug = true;
opts.memchk = true;
con_init();
ht t = util_htnew(1024);
size_t **d = NULL;
correct_add(t, &d, "hellobain");
correct_add(t, &d, "ellor");
correct_add(t, &d, "world");
printf("found identifiers: (2)\n");
printf(" 1: hello\n");
printf(" 2: world\n");
char *b = correct_correct(t, "rld");
char *a = correct_correct(t, "ello");
printf("%s, did you mean `%s` ?\n", "ello", a);
printf("%s, did you mean `%s` ?\n", "rld", b);
correct_del(t, d);
mem_d(b);
mem_d(a);
util_meminfo();
}