X-Git-Url: https://de.git.xonotic.org/?p=xonotic%2Fgmqcc.git;a=blobdiff_plain;f=correct.c;h=5be4f3528d405f112b7e8b0a31c71e0c9629bd76;hp=e32678e754e3770ebb5d142d06a9fc7c0a283ec4;hb=3fa771f51d920b9816894fc0453dc2492a9dbf0b;hpb=2d96b2a3ecb3610493c261c297da8a0ed429cd15 diff --git a/correct.c b/correct.c index e32678e..5be4f35 100644 --- a/correct.c +++ b/correct.c @@ -1,7 +1,8 @@ /* * 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 @@ -38,13 +39,25 @@ * 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. + * 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. * - * Bayes' Therom suggests something of the following: + * 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) - * Since P(I) is the same for every possibly I, we can ignore it giving + * + * 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 @@ -56,12 +69,9 @@ * 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: + * 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 @@ -70,130 +80,287 @@ * 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 factory > 100% + * + * Future Work (If we really need it) + * + * Currently we can only distinguishes 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. + * + * Our control mechanisim could use a limit, i.e limit the number of + * sets of edits for distance X. This would also increase execution + * speed considerably. + */ + + +#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; -/* some hashtable management for dictonaries */ -static size_t *correct_find(ht table, const char *word) { - return (size_t*)util_htget(table, word); +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 int correct_update(ht *table, const char *word) { - size_t *data = correct_find(*table, word); - if (!data) - return 0; +static GMQCC_INLINE void *correct_pool_alloc(size_t bytes) { + void *data; + if (correct_pool_addr + bytes>= CORRECT_POOL_SIZE) + correct_pool_new(); - (*data)++; - return 1; + 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); + correct_pool_delete(); + 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. + * 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. */ -static const char correct_alpha[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_"; +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 char *correct_strndup(const char *src, size_t n) { - char *ret; - size_t len = strlen(src); +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); +} - if (n < len) - len = n; +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); +} - if (!(ret = (char*)mem_a(len + 1))) - return NULL; +void* correct_trie_get(const correct_trie_t *t, const char *key) { + const unsigned char *data = (const unsigned char*)key; - ret[len] = '\0'; - return (char*)memcpy(ret, src, len); + while (*data) { + const correct_trie_t *entries = t->entries; + unsigned char ch = *data; + const size_t vs = vec_size(entries); + size_t i; + + for (i = 0; i < vs; ++i) { + if (entries[i].ch == ch) { + t = &entries[i]; + ++data; + break; + } + } + if (i == vs) + return NULL; + } + return t->value; } -static char *correct_concat(char *str1, char *str2, bool next) { - char *ret = NULL; +void correct_trie_set(correct_trie_t *t, const char *key, void * const value) { + const unsigned char *data = (const unsigned char*)key; + while (*data) { + correct_trie_t *entries = t->entries; + const size_t vs = vec_size(entries); + unsigned char ch = *data; + 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); -#if 0 - if (!str1) { - str1 = mem_a(1); - *str1 = '\0'; + elem->ch = ch; + elem->value = NULL; + elem->entries = NULL; + t = elem; + } + ++data; } -#endif + t->value = value; +} - str1 = mem_r (str1, strlen(str1) + strlen(str2) + 1); - ret = strcat(str1, str2); - if (str2 && next) - mem_d(str2); +/* + * 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; - return ret; + (*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); } +/* + * _ 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 ... */ + /* * 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 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_strndup (ident, itr), - correct_strndup (ident+itr+1, len-(itr+1)), - true - ); + 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[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++) { - array[index + itr] = correct_concat ( - correct_concat ( - correct_strndup(ident, itr), - correct_strndup(ident+itr+1, 1), - true - ), - correct_concat ( - correct_strndup(ident+itr, 1), - correct_strndup(ident+itr+2, len-(itr+2)), - true - ), - true - ); + 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[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); - 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_strndup(ident, itr), - (char *) &cct, - false - ), - correct_strndup ( - ident + (itr+1), - len - (itr+1) - ), - true - ); + 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[index + ktr] = a; } } @@ -201,27 +368,18 @@ static size_t correct_alteration(const char *ident, char **array, size_t index) } 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_strndup (ident, itr), - (char *) &cct, - false - ), - correct_strndup ( - ident+itr, - len - itr - ), - true - ); + 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+2); + memcpy(a, ident, itr); + memcpy(a + itr + 1, ident + itr, len - itr + 1); + a[itr] = correct_alpha[jtr]; + array[index + ktr] = a; } } @@ -234,15 +392,15 @@ static GMQCC_INLINE size_t correct_size(const char *ident) { * 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)); + 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**)mem_a(correct_size(ident) * sizeof(char*)); + char **find = (char**)correct_pool_alloc(correct_size(ident) * sizeof(char*)); if (!find) return NULL; @@ -259,51 +417,89 @@ static char **correct_edit(const char *ident) { * 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)) + /* + * As an experiment I tried the following assembly for memcmp here: + * + * correct_cmp_loop: + * incl %eax ; eax = LHS + * incl %edx ; edx = LRS + * cmpl %eax, %ebx ; ebx = &LHS[END_POS] + * + * jbe correct_cmp_eq + * movb (%edx), %cl ; micro-optimized even on atoms :-) + * cmpb %cl, (%eax) ; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + * jg correct_cmp_gt + * jge correct_cmp_loop + * ... + * + * Despite how much optimization went in to this, the speed was the + * being conflicted by the strlen(ident) used for &LHS[END_POS] + * If we could eliminate the strlen with what I suggested on line + * 311 ... we can accelerate this whole damn thing quite a bit. + * + * However there is still something we can do here that does give + * us a little more speed. Although one more branch, we know for + * sure there is at least one byte to compare, if that one byte + * simply isn't the same we can skip the full check. Which means + * we skip a whole strlen call. + */ + for (itr = 0; itr < rows; itr++) { + if (!memcmp(array[itr], ident, strlen(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; +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; - for (itr = 0, len = 0; itr < rows; itr++) { + out = correct_pool_alloc(sizeof(*res) * oldallocated + 32); + memcpy(out, res, sizeof(*res) * oldallocated); + + *allocated += 32; + return out; +} + +static char **correct_known(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 = correct_pool_alloc(sizeof(char *) * nxt); + char **end = NULL; + + for (; itr < rows; itr++) { end = correct_edit(array[itr]); row = correct_size(array[itr]); + /* removing jtr=0 here speeds it up by 100ms O_o */ 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 = correct_known_resize(res, &nxt, len+1); res[len++] = end[jtr]; - } else { - mem_d(end[jtr]); } } - - mem_d(end); } *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; +static 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 = 0, top = 0; itr < rows; itr++) { + for (; itr < rows; itr++) { if ((itm = correct_find(table, array[itr])) && (*itm > top)) { top = *itm; str = array[itr]; @@ -313,77 +509,37 @@ static char *correct_maximum(ht table, char **array, size_t rows) { return str; } -static void correct_cleanup(char **array, size_t rows) { - size_t itr; - for (itr = 0; itr < rows; itr++) - mem_d(array[itr]); - - mem_d(array); -} - /* * 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_str(ht table, const char *ident) { - char **e1; - char **e2; - char *e1ident; - char *e2ident; - char *found = util_strdup(ident); + * probability calculation), and an identifier to "correct". + */ +char *correct_str(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 e1rows = 0; - size_t e2rows = 0; + correct_pool_new(); /* needs to be allocated for free later */ if (correct_find(table, ident)) - return found; + return correct_pool_claim(ident); if ((e1rows = correct_size(ident))) { e1 = correct_edit(ident); - if ((e1ident = correct_maximum(table, e1, e1rows))) { - mem_d(found); - found = util_strdup(e1ident); - correct_cleanup(e1, e1rows); - return found; - } + if ((e1ident = correct_maximum(table, e1, e1rows))) + return correct_pool_claim(e1ident); } e2 = correct_known(table, e1, e1rows, &e2rows); - if (e2rows && ((e2ident = correct_maximum(table, e2, e2rows)))) { - mem_d(found); - found = util_strdup(e2ident); - } - - correct_cleanup(e1, e1rows); - correct_cleanup(e2, e2rows); - - return found; -} + if (e2rows && ((e2ident = correct_maximum(table, e2, e2rows)))) + return correct_pool_claim(e2ident); -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); + correct_pool_delete(); + return util_strdup(ident); }