-/*
- * Copyright (C) 2012, 2013, 2014, 2015
- * Dale Weiler
- * Wolfgang Bumiller
- *
- * 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 <string.h>
-#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 means that instead of
- * just guessing, instead 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.
- *
- * Thankfully there exists some theroies for probalistic interpretations
- * of data. Since we're operating on two distictive intepretations, the
- * transposition from I to C. We need something that can express how much
- * degree of I should rationally change to become C. this is called the
- * Bayesian interpretation. You can read more about it from here:
- * http://www.celiagreen.com/charlesmccreery/statistics/bayestutorial.pdf
- * (which is probably the only good online documentation for bayes theroy
- * no lie. Everything else just sucks ..)
- *
- * Bayes' Thereom suggests something like the following:
- * AC P(I|C) P(C) / P(I)
- *
- * However since P(I) is the same for every possibility of I, we can
- * completley ignore it giving just:
- * 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, an enumerator if you will, one that
- * enumerates all feasible values of C, to determine the one that
- * gives the greatest probability score.
- *
- * 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.
- *
- * Research tells us that 80% to 95% of all spelling errors have an edit
- * distance no greater than one. Knowing this we can optimize for most
- * cases of mistakes without taking a performance hit. Which is what we
- * base longer edit distances off of. Opposed to the original method of
- * I had concieved of checking everything.
- *
- * A little information on additional algorithms used:
- *
- * Initially when I implemented this corrector, it was very slow.
- * Need I remind you this is essentially a brute force attack on strings,
- * and since every transformation requires dynamic memory allocations,
- * you can easily imagine where most of the runtime conflated. Yes
- * It went right to malloc. More than THREE MILLION malloc calls are
- * performed for an identifier about 16 bytes long. This was such a
- * shock to me. A forward allocator (or as some call it a bump-point
- * allocator, or just a memory pool) was implemented. To combat this.
- *
- * But of course even other factors were making it slow. Initially
- * this used a hashtable. And hashtables have a good constant lookup
- * time complexity. But the problem wasn't in the hashtable, it was
- * in the hashing (despite having one of the fastest hash functions
- * known). Remember those 3 million mallocs? Well for every malloc
- * there is also a hash. After 3 million hashes .. you start to get
- * very slow. To combat this I had suggested burst tries to Blub.
- * The next day he had implemented them. Sure enough this brought
- * down the runtime by a factor > 100%
- *
- * The trie initially was designed to work on all strings, but later it
- * became aparent that not only was this not a requirement. It was also
- * slowing down get/sets' for the trie. To fully understand, only
- * correct_alpha needs to be understood by the trie system, knowing this
- * We can combat the slowness using a very clever but evil optimization.
- * By Setting a fixed sized amount of branches for the trie using a
- * char-to-index map into the branches. We've complelty made the trie
- * accesses entierly constant in lookup time. No really, a lookup is
- * literally trie[str[0]] [str[1]] [2] .... .value.
- *
- *
- * Future Work (If we really need it)
- *
- * Currently we can only distinguish one source of error in the
- * language model we use. This could become an issue for identifiers
- * that have close colliding rates, e.g colate->coat yields collate.
- *
- * Currently the error model has been fairly trivial, the smaller the
- * edit distance the smaller the error. This usually causes some un-
- * expected problems. e.g reciet->recite yields recipt. For QuakeC
- * this could become a problem when lots of identifiers are involved.
- */
-
-
-#define CORRECT_POOL_SIZE (128*1024*1024)
-/*
- * 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.
- */
-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_POOL_SIZE);
-
- 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_POOL_SIZE)
- correct_pool_new();
-
- data = (void*)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_pool_claim(const char *data) {
- char *claim = util_strdup(data);
- return claim;
-}
-
-/*
- * _ 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[] = "abcdefghijklmnopqrstuvwxyz"
- "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
- "_"; /* TODO: Numbers ... */
-
-static const size_t correct_alpha_index[0x80] = {
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
- 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 52,
- 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
- 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0
-};
-
-/*
- * A fast space efficent trie for a dictionary of identifiers. This is
- * faster than a hashtable for one reason. A hashtable itself may have
- * fast constant lookup time, but the hash itself must be very fast. We
- * have one of the fastest hash functions for strings, but if you do a
- * lost of hashing (which we do, almost 3 million hashes per identifier)
- * a hashtable becomes slow.
- */
-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;
-}
-
-static GMQCC_INLINE void correct_trie_del_sub(correct_trie_t *t) {
- size_t i;
- if (!t->entries)
- return;
- for (i = 0; i < sizeof(correct_alpha)-1; ++i) {
- correct_trie_del_sub(&t->entries[i]);
- }
- mem_d(t->entries);
-}
-
-static GMQCC_INLINE void correct_trie_del(correct_trie_t *t) {
- size_t i;
- if (t->entries) {
- for (i = 0; i < sizeof(correct_alpha)-1; ++i)
- correct_trie_del_sub(&t->entries[i]);
- mem_d(t->entries);
- }
- mem_d(t);
-}
-
-static GMQCC_INLINE void* correct_trie_get(const correct_trie_t *t, const char *key) {
- const unsigned char *data = (const unsigned char*)key;
-
- while (*data) {
- if (!t->entries)
- return NULL;
- t = t->entries + correct_alpha_index[*data];
- ++data;
- }
- return t->value;
-}
-
-static GMQCC_INLINE void correct_trie_set(correct_trie_t *t, const char *key, void * const value) {
- const unsigned char *data = (const unsigned char*)key;
- while (*data) {
- if (!t->entries) {
- t->entries = (correct_trie_t*)mem_a(sizeof(correct_trie_t)*(sizeof(correct_alpha)-1));
- memset(t->entries, 0, sizeof(correct_trie_t)*(sizeof(correct_alpha)-1));
- }
- t = t->entries + correct_alpha_index[*data];
- ++data;
- }
- t->value = value;
-}
-
-
-/*
- * Implementation of the corrector algorithm commences. A very efficent
- * brute-force attack (thanks to tries and mempool :-)).
- */
-static GMQCC_INLINE size_t *correct_find(correct_trie_t *table, const char *word) {
- return (size_t*)correct_trie_get(table, word);
-}
-
-static GMQCC_INLINE bool correct_update(correct_trie_t* *table, const char *word) {
- size_t *data = correct_find(*table, word);
- if (!data)
- return false;
-
- (*data)++;
- return true;
-}
-
-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);
-}
-
-/*
- * correcting logic for the following forms of transformations:
- * 1) deletion
- * 2) transposition
- * 3) alteration
- * 4) insertion
- *
- * These functions could take an additional size_t **size paramater
- * and store back the results of their new length in an array that
- * is the same as **array for the memcmp in correct_exists. I'm just
- * not able to figure out how to do that just yet. As my brain is
- * not in the mood to figure out that logic. This is a reminder to
- * do it, or for someone else to :-) correct_edit however would also
- * need to take a size_t ** to carry it along (would all the argument
- * overhead be worth it?)
- */
-static GMQCC_INLINE size_t correct_deletion(const char *ident, char **array) {
- size_t itr = 0;
- const size_t len = strlen(ident);
-
- for (; itr < len; itr++) {
- char *a = (char*)correct_pool_alloc(len+1);
- memcpy(a, ident, itr);
- memcpy(a + itr, ident + itr + 1, len - itr);
- array[itr] = a;
- }
-
- return itr;
-}
-
-static GMQCC_INLINE size_t correct_transposition(const char *ident, char **array) {
- size_t itr = 0;
- const size_t len = strlen(ident);
-
- for (; 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[itr] = a;
- }
-
- return itr;
-}
-
-static GMQCC_INLINE size_t correct_alteration(const char *ident, char **array) {
- size_t itr = 0;
- size_t jtr = 0;
- size_t ktr = 0;
- const size_t len = strlen(ident);
-
- for (; 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[ktr] = a;
- }
- }
-
- return ktr;
-}
-
-static GMQCC_INLINE size_t correct_insertion(const char *ident, char **array) {
- size_t itr = 0;
- size_t jtr = 0;
- const size_t len = strlen(ident);
-
- for (; itr <= len; itr++) {
- for (jtr = 0; jtr < sizeof(correct_alpha)-1; jtr++) {
- 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[itr * (sizeof(correct_alpha)-1) + jtr] = a;
- }
- }
-
- return (len+1)*(sizeof(correct_alpha)-1);
-}
-
-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 GMQCC_INLINE char **correct_edit(const char *ident, size_t **lens) {
- size_t next;
- size_t size = correct_size(ident);
- char **find = (char**)correct_pool_alloc(size * sizeof(char*));
-
- if (!find || !(*lens = (size_t*)correct_pool_alloc(size * sizeof(size_t))))
- return NULL;
-
- next = correct_deletion (ident, find);
- next += correct_transposition(ident, find+next);
- next += correct_alteration (ident, find+next);
- /*****/ correct_insertion (ident, find+next);
-
- /* precompute lengths */
- for (next = 0; next < size; next++)
- (*lens)[next] = strlen(find[next]);
-
- return find;
-}
-
-static GMQCC_INLINE int correct_exist(char **array, register size_t *sizes, size_t rows, char *ident, register size_t len) {
- size_t itr;
- for (itr = 0; itr < rows; itr++) {
- /*
- * We can save tons of calls to memcmp if we simply ignore comparisions
- * that we know cannot contain the same length.
- */
- if (sizes[itr] == len && !memcmp(array[itr], ident, len))
- 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 < oldallocated)
- return res;
-
- out = (char**)correct_pool_alloc(sizeof(*res) * oldallocated + 32);
- memcpy(out, res, sizeof(*res) * oldallocated);
-
- *allocated += 32;
- return out;
-}
-
-static char **correct_known(correction_t *corr, correct_trie_t* table, char **array, size_t rows, size_t *next) {
- size_t itr = 0;
- size_t jtr = 0;
- size_t len = 0;
- size_t row = 0;
- size_t nxt = 8;
- char **res = (char**)correct_pool_alloc(sizeof(char *) * nxt);
- char **end = NULL;
- size_t *bit = NULL;
-
- for (; itr < rows; itr++) {
- if (!array[itr][0])
- continue;
- if (vec_size(corr->edits) > itr+1) {
- end = corr->edits[itr+1];
- bit = corr->lens [itr+1];
- } else {
- end = correct_edit(array[itr], &bit);
- vec_push(corr->edits, end);
- vec_push(corr->lens, bit);
- }
- row = correct_size(array[itr]);
-
- for (jtr = 0; jtr < row; jtr++) {
- if (correct_find(table, end[jtr]) && !correct_exist(res, bit, len, end[jtr], bit[jtr])) {
- res = correct_known_resize(res, &nxt, len+1);
- res[len++] = end[jtr];
- }
- }
- }
-
- *next = len;
- return res;
-}
-
-static GMQCC_INLINE char *correct_maximum(correct_trie_t* table, char **array, size_t rows) {
- char *str = NULL;
- size_t *itm = NULL;
- size_t itr = 0;
- size_t top = 0;
-
- for (; 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".
- */
-void correct_init(correction_t *c)
-{
- correct_pool_new();
- c->edits = NULL;
- c->lens = NULL;
-}
-
-void correct_free(correction_t *c)
-{
- vec_free(c->edits);
- vec_free(c->lens);
- correct_pool_delete();
-}
-
-char *correct_str(correction_t *corr, correct_trie_t* table, const char *ident) {
- char **e1 = NULL;
- char **e2 = NULL;
- char *e1ident = NULL;
- char *e2ident = NULL;
- size_t e1rows = 0;
- size_t e2rows = 0;
- size_t *bits = NULL;
-
- /* needs to be allocated for free later */
- if (correct_find(table, ident))
- return correct_pool_claim(ident);
-
- if ((e1rows = correct_size(ident))) {
- if (vec_size(corr->edits) > 0)
- e1 = corr->edits[0];
- else {
- e1 = correct_edit(ident, &bits);
- vec_push(corr->edits, e1);
- vec_push(corr->lens, bits);
- }
-
- if ((e1ident = correct_maximum(table, e1, e1rows)))
- return correct_pool_claim(e1ident);
- }
-
- e2 = correct_known(corr, table, e1, e1rows, &e2rows);
- if (e2rows && ((e2ident = correct_maximum(table, e2, e2rows))))
- return correct_pool_claim(e2ident);
-
-
- return util_strdup(ident);
-}
projects / xonotic / gmqcc.git / commitdiff