X-Git-Url: http://de.git.xonotic.org/?p=voretournament%2Fvoretournament.git;a=blobdiff_plain;f=misc%2Fsource%2Fgmqcc-src%2Fcorrect.c;fp=misc%2Fsource%2Fgmqcc-src%2Fcorrect.c;h=f501817acc86582223c524df96a202a614a08bc8;hp=0000000000000000000000000000000000000000;hb=f345f0f6d2962633e2e3a560b044ab1b91a8f937;hpb=b2df32d96df3e954d54f6e4b9bbb6c98d77ef507;ds=sidebyside diff --git a/misc/source/gmqcc-src/correct.c b/misc/source/gmqcc-src/correct.c new file mode 100644 index 00000000..f501817a --- /dev/null +++ b/misc/source/gmqcc-src/correct.c @@ -0,0 +1,548 @@ +/* + * Copyright (C) 2012, 2013 + * 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 +#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); +}