X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/0bd984429304da7c1c5509103e3dc04149028a95..c6e0eaf00cd09a4e5237e70d8351049ec91d7653:/sym.c diff --git a/sym.c b/sym.c index fb3806b..a4445de 100644 --- a/sym.c +++ b/sym.c @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: sym.c,v 1.4 1999/05/06 19:51:35 mdw Exp $ + * $Id: sym.c,v 1.10 1999/12/10 23:42:04 mdw Exp $ * * Symbol table management * @@ -30,6 +30,25 @@ /*----- Revision history --------------------------------------------------* * * $Log: sym.c,v $ + * Revision 1.10 1999/12/10 23:42:04 mdw + * Change header file guard names. + * + * Revision 1.9 1999/10/22 22:36:37 mdw + * New test structure for symbol tables. + * + * Revision 1.8 1999/08/02 14:45:48 mdw + * Break low-level hashtable code out from sym. + * + * Revision 1.7 1999/06/01 09:49:08 mdw + * Allow things to be looked up by just their caller-supplied hashes. This + * actually needs to be thought through better. + * + * Revision 1.6 1999/05/26 21:08:31 mdw + * Rename symbols in line with newer conventions. + * + * Revision 1.5 1999/05/13 22:48:37 mdw + * Twiddle the extension threshold. Change `-ise' to `-ize' throughout. + * * Revision 1.4 1999/05/06 19:51:35 mdw * Reformatted the LGPL notice a little bit. * @@ -55,8 +74,10 @@ /* --- Local headers --- */ #include "alloc.h" +#include "bits.h" #include "crc32.h" #include "exc.h" +#include "hash.h" #include "sub.h" #include "sym.h" #include "track.h" @@ -69,7 +90,7 @@ * so that it can be used to mask of the bottom bits of a hash value. */ -#define SYM_INITSZ 255 /* Size of a new hash table */ +#define SYM_INITSZ 64 /* Size of a new hash table */ /* --- Maximum load factor --- * * @@ -78,43 +99,32 @@ * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is * added to the table and this relation is found to be false, the table is * doubled in size. - * - * The current function gives %$l = {3n \over 4}$%, which appears to be - * reasonable on the face of things. */ -#define SYM_LIMIT(n) (((n) * 3) >> 2) /* Load factor for growing table */ +#define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */ /*----- Main code ---------------------------------------------------------*/ -/* --- @sym_createTable@ --- * +/* --- @sym_create@ --- * * - * Arguments: @sym_table *t@ = symbol table to initialise + * Arguments: @sym_table *t@ = symbol table to initialize * * Returns: --- * - * Use: Initialises the given symbol table. Raises @EXC_NOMEM@ if + * Use: Initializes the given symbol table. Raises @EXC_NOMEM@ if * there isn't enough memory. */ -void sym_createTable(sym_table *t) +void sym_create(sym_table *t) { - size_t i; - TRACK_CTX("symbol table creation"); TRACK_PUSH; - - t->mask = SYM_INITSZ; - t->c = SYM_LIMIT(SYM_INITSZ); - t->a = xmalloc((t->mask + 1) * sizeof(sym_base *)); - - for (i = 0; i < SYM_INITSZ + 1; i++) - t->a[i] = 0; - + hash_create(&t->t, SYM_INITSZ); + t->load = SYM_LIMIT(SYM_INITSZ); TRACK_POP; } -/* --- @sym_destroyTable@ --- * +/* --- @sym_destroy@ --- * * * Arguments: @sym_table *t@ = pointer to symbol table in question * @@ -124,25 +134,24 @@ void sym_createTable(sym_table *t) * occupy. */ -void sym_destroyTable(sym_table *t) +void sym_destroy(sym_table *t) { - size_t i; - sym_base *p, *q; + sym_iter i; - TRACK_CTX("symbol table deletion"); + TRACK_CTX("symbol table destruction"); TRACK_PUSH; - for (i = 0; i <= t->mask; i++) { - p = t->a[i]; - while (p) { - q = p->next; - if (p->len > SYM_BUFSZ) - sub_free(p->name.p, p->len); - free(p); - p = q; - } + SYM_MKITER(&i, t); + for (;;) { + sym_base *p; + SYM_NEXT(&i, p); + if (!p) + break; + if (p->len > SYM_BUFSZ) + sub_free(p->name.p, p->len); + free(p); } - free(t->a); + hash_destroy(&t->t); TRACK_POP; } @@ -180,144 +189,91 @@ void sym_destroyTable(sym_table *t) void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f) { - unsigned long hash; /* Hash value for user's name */ - size_t len = l < 0 ? strlen(n) + 1 : l; /* Find length of user's name */ - sym_base *bin; /* Bin containing our item */ - sym_base *p, *q; /* Pointer wandering through list */ + uint32 hash; + size_t len = 0; + hash_base **bin, **p; + sym_base *q; /* --- Find the correct bin --- */ - CRC32(hash, 0, n, len); /* Find hash value for this name */ - bin = p = (sym_base *)(t->a + (hash & t->mask)); + len = l < 0 ? strlen(n) + 1 : l; + CRC32(hash, 0, n, len); + bin = HASH_BIN(&t->t, hash); /* --- Search the bin list --- */ - while (p->next) { - if (hash == p->next->hash && /* Check full hash values first */ - len == p->next->len && /* Then compare string lengths */ - !memcmp(n, SYM_NAME(p->next), len)) /* And finally compare names */ - { + for (p = bin; *p; p = &(*p)->next) { + q = (sym_base *)*p; + if (hash == q->b.hash && len == q->len && !memcmp(n, SYM_NAME(q), len)) { + /* --- Found a match --- * * * As a minor, and probably pointless, tweak, move the item to the * front of its bin list. */ - q = p->next; /* Find the actual symbol block */ - p->next = q->next; /* Extract block from bin list */ - q->next = bin->next; /* Set up symbol's next pointer */ - bin->next = q; /* And reinsert the block */ + (*p) = q->b.next; + q->b.next = *bin; + *bin = &q->b; /* --- Return the block --- */ - if (f) *f = 1; /* Didn't fail to find the item */ - return (q); /* And return the block */ + if (f) *f = 1; + return (q); } - - p = p->next; /* Move onto the next item */ } /* --- Couldn't find the item there --- */ - if (f) *f = 0; /* Failed to find the block */ - if (!sz) return (0); /* Return zero if not creating */ + if (f) *f = 0; + if (!sz) return (0); - /* --- Create a new symbol block and initialise it --- */ + /* --- Create a new symbol block and initialize it --- */ { TRACK_CTX("new symbol creation"); TRACK_PUSH; - p = xmalloc(sz); /* Create a new symbol block */ - p->next = bin->next; /* Set up the next pointer */ - p->hash = hash; /* Set up the hash value too */ - p->len = len; /* And set up the string length */ - if (len <= SYM_BUFSZ) - memcpy(p->name.b, n, len); /* And copy the string over */ - else { - TRY { - p->name.p = sub_alloc(len); /* Allocate a block for the name */ - memcpy(p->name.p, n, len); /* And copy the string over */ - } CATCH { - free(p); - TRACK_POP; - RETHROW; - } END_TRY; + q = xmalloc(sz); + q->b.next = *bin; + q->b.hash = hash; + q->len = len; + if (n) { + if (len <= SYM_BUFSZ) + memcpy(q->name.b, n, len); + else { + TRY { + q->name.p = sub_alloc(len); + memcpy(q->name.p, n, len); + } CATCH { + free(q); + TRACK_POP; + RETHROW; + } END_TRY; + } } TRACK_POP; } - bin->next = p; /* Put the pointer into the bin */ + *bin = &q->b; /* --- Consider growing the array --- */ - if (t->c) - t->c--; - if (!t->c) { - unsigned long m = t->mask + 1; /* Next set bit in has word */ - sym_base *p, *q, *r; /* More useful pointers */ - size_t i, lim; /* Loop counter and limit */ - - TRACK_CTX("symbol table extension"); - TRACK_PUSH; - - /* --- Update values in the anchor block --- */ - - TRY { - t->a = xrealloc(t->a, (t->mask + 1) * 2 * sizeof(sym_base *)); - } CATCH switch (exc_type) { - case EXC_NOMEM: - TRACK_POP; - return (bin->next); - default: - TRACK_POP; - RETHROW; - } END_TRY; - - t->c = SYM_LIMIT(t->mask + 1); /* Set load value */ - t->mask = (t->mask + 1) * 2 - 1; /* Set the new mask value */ - - /* --- Now wander through the table rehashing things --- * - * - * This loop is very careful to avoid problems with aliasing. The items - * are dealt with from the end backwards to avoid overwriting bins before - * they've been processed. - */ - - lim = (t->mask + 1) >> 1; - for (i = 0; i < lim; i++) { - - /* --- Some initialisation --- */ - - r = t->a[i]; /* Find the list we're dissecting */ - p = (sym_base *)(t->a + i); /* Find bit-clear list */ - q = (sym_base *)(t->a + i + lim); /* And the bit-set lsit */ - - /* --- Now go through the @r@ list --- */ - - while (r) { - if (r->hash & m) /* Is the next bit set? */ - q = q->next = r; /* Yes, so fit up previous link */ - else - p = p->next = r; /* No, so fit up previous link */ - r = r->next; /* Move onto the next item */ - } - p->next = q->next = 0; /* Null terminate the new lists */ - } - - TRACK_POP; - } + if (t->load) + t->load--; + if (!t->load && hash_extend(&t->t)) + t->load = SYM_LIMIT(t->t.mask / 2 + 1); /* --- Finished that, so return the new symbol block --- */ - return (p); + return (q); } /* --- @sym_remove@ --- * * - * Arguments: @sym_table *i@ = pointer to a symbol table object - * @void *b@ = pointer to symbol table entry + * Arguments: @sym_table *t@ = pointer to a symbol table object + * @void *p@ = pointer to symbol table entry * * Returns: --- * @@ -326,41 +282,17 @@ void *sym_find(sym_table *t, const char *n, long l, size_t sz, unsigned *f) * to the entry should already be gone by this point. */ -void sym_remove(sym_table *t, void *b) +void sym_remove(sym_table *t, void *p) { - /* --- A quick comment --- * - * - * Since the @sym_base@ block contains the hash, finding the element in the - * bin list is really quick -- it's not worth bothering with things like - * doubly linked lists. - */ - - sym_base *p = b; - sym_base *bin = (sym_base *)(t->a + (p->hash & t->mask)); - - /* --- Find the item in the bin list --- */ - - while (bin->next) { - if (bin->next == p) - break; - bin = bin->next; - } - if (!bin->next) - return; - - /* --- Now just remove the item from the list and free it --- * - * - * Oh, and bump the load counter. - */ - - bin->next = p->next; - if (p->len > SYM_BUFSZ) - sub_free(p->name.p, p->len); - free(p); - t->c++; + sym_base *q = p; + hash_remove(&t->t, &q->b); + if (q->len > SYM_BUFSZ) + sub_free(q->name.p, q->len); + free(q); + t->load++; } -/* --- @sym_createIter@ --- * +/* --- @sym_mkiter@ --- * * * Arguments: @sym_iter *i@ = pointer to an iterator object * @sym_table *t@ = pointer to a symbol table object @@ -371,12 +303,7 @@ void sym_remove(sym_table *t, void *b) * iterate through a symbol table. */ -void sym_createIter(sym_iter *i, sym_table *t) -{ - i->t = t; - i->i = 0; - i->n = 0; -} +void sym_mkiter(sym_iter *i, sym_table *t) { SYM_MKITER(i, t); } /* --- @sym_next@ --- * * @@ -390,242 +317,9 @@ void sym_createIter(sym_iter *i, sym_table *t) void *sym_next(sym_iter *i) { - sym_base *p; - - /* --- Find the next item --- */ - - while (!i->n) { - if (i->i > i->t->mask) - return (0); - i->n = i->t->a[i->i++]; - } - - /* --- Update the iterator block --- */ - - p = i->n; - i->n = p->next; - - /* --- Done --- */ - + void *p; + SYM_NEXT(i, p); return (p); } -/*----- Symbol table test code --------------------------------------------*/ - -#ifdef TEST_RIG - -#include -#include - -typedef struct sym_word { - sym_base base; - size_t i; -} sym_word; - - -/* --- What it does --- * - * - * Reads the file /usr/dict/words (change to some other file full of - * interesting and appropriate bits of text to taste) into a big buffer and - * picks apart into lines. Then picks lines at random and enters them into - * the symbol table. - */ - -int main(void) -{ - char *buff, *p, *lim; - size_t sz, done; - FILE *fp; - int i; - char **line; - sym_word **flag; - sym_table tbl; - int entries; - - /* --- Initialise for reading the file --- */ - - sz = BUFSIZ; - buff = xmalloc(sz + 1); - done = 0; - sub_init(); - - if ((fp = fopen("/usr/dict/words", "r")) == 0) - fprintf(stderr, "buggered ;-( (%s)\n", strerror(errno)); - - /* --- Read buffers of text --- * - * - * Read a buffer. If more to come, double the buffer size and try again. - * This is the method I recommended to comp.lang.c, so I may as well try - * it. - */ - - for (;;) { - i = fread(buff + done, 1, sz - done, fp); - done += i; - if (done != sz) - break; - sz <<= 1; - buff = xrealloc(buff, sz + 1); - } - - /* --- Count the lines --- */ - - lim = buff + done; - - sz = 1; - for (p = buff; p < lim; p++) - if (*p == '\n') sz++; - - /* --- Build a table of line starts --- */ - - line = xmalloc(sz * sizeof(char *)); - i = 0; - line[i++] = buff; - for (p = buff; p < lim; p++) - if (*p == '\n') *p = 0, line[i++] = p + 1; - *lim = 0; - - /* --- Build a table of lines --- * - * - * This reverses the mapping which the symbol table performs, so that its - * accuracy can be tested. - */ - - flag = xmalloc(sz * sizeof(sym_word *)); - for (i = 0; i < sz; i++) - flag[i] = 0; - entries = 0; - - sym_createTable(&tbl); - - for (;;) { - i = (unsigned)rand() % sz; - - switch (rand() % 5) - { - case 0: { - sym_word *w; - - printf("find `%s'\n", line[i]); - if ((rand() & 1023) == 0) { - putchar('.'); fflush(stdout); - } - - w = sym_find(&tbl, line[i], -1, 0, 0); - if (w != flag[i]) - printf("*** error: find `%s' gave %p not %p\n", - line[i], (void *)w, (void *)flag[i]); - else if (w && w->i != i) - printf("*** error: find sym for `%s' gives index %i not %i\n", - line[i], w->i, i); - } break; - - case 1: { - unsigned f; - sym_word *w; - - printf("create `%s'\n", line[i]); - if ((rand() & 1023) == 0) { - putchar('+'); fflush(stdout); - } - - w = sym_find(&tbl, line[i], -1, sizeof(sym_word), &f); - if (f) - { - if (w != flag[i]) - printf("*** error: create `%s' gave %p not %p\n", - line[i], (void *)w, (void *)flag[i]); - else if (w && w->i != i) - printf("*** error: create sym for `%s' gives index %i not %i\n", - line[i], w->i, i); - } - else - { - if (flag[i]) - printf("*** error: create `%s' gave new block, should be %p\n", - line[i], (void *)flag[i]); - else { - flag[i] = w; - w->i = i; - entries++; - } - } - } break; - - case 2: { - sym_iter it; - sym_word *w, **ntbl; - int v; - - if (!entries) - break; - v = (rand() % entries) == 0; - if (!v) - break; - printf("\niterated %i entries\n", entries); - break; - - printf("iterate\n"); - - ntbl = xmalloc(sz * sizeof(sym_word *)); - memcpy(ntbl, flag, sz * sizeof(sym_word *)); - sym_createIter(&it, &tbl); - - while ((w = sym_next(&it)) != 0) { - if (ntbl[w->i] == 0) - printf("*** error: iterate returned duff item %i\n", w->i); - else - ntbl[w->i] = 0; - } - - for (i = 0; i < sz; i++) - if (ntbl[i]) printf("*** error: iterate didn't return item %i\n", - i); - free(ntbl); - } break; - - case 3: { - sym_base *b; - int v = rand() & 255 ? 0 : 1; - break; - - printf("dump\n"); - - for (i = 0; i <= tbl.mask; i++) { - if (!tbl.a[i]) continue; - if (v) printf(" %i: ", i); - b = tbl.a[i]; - while (b) { - if ((b->hash & tbl.mask) != i) - printf("*** error: bad hash value found"); - if (v) printf("`%s'(%08lx:%lu) ", - line[((sym_word *)b)->i], - b->hash, - b->hash & tbl.mask); - b = b->next; - } - if (v) putchar('\n'); - } - } break; - - case 4: { - if (flag[i]) { - printf("remove `%s'\n", SYM_NAME(&flag[i]->base)); - if ((rand() & 1023) == 0) { - putchar('-'); fflush(stdout); - } - sym_remove(&tbl, flag[i]); - flag[i] = 0; - entries--; - } - } break; - } - - } - - return (0); -} - -#endif - /*----- That's all, folks -------------------------------------------------*/