X-Git-Url: https://pd.if.org/git/?p=pccts;a=blobdiff_plain;f=support%2Fsym%2Fsym.c;fp=support%2Fsym%2Fsym.c;h=29340d811530ac84f13071a03b7e3d0b7f1e9084;hp=0000000000000000000000000000000000000000;hb=cb15b978c765a661bf3154d865fa3e2401d649f5;hpb=c4e55222e892b8762e11f2425a64611e898ef20e diff --git a/support/sym/sym.c b/support/sym/sym.c new file mode 100755 index 0000000..29340d8 --- /dev/null +++ b/support/sym/sym.c @@ -0,0 +1,366 @@ +/* + * Simple symbol table manager using coalesced chaining to resolve collisions + * + * Doubly-linked lists are used for fast removal of entries. + * + * 'sym.h' must have a definition for typedef "Sym". Sym must include at + * minimum the following fields: + * + * ... + * char *symbol; + * struct ... *next, *prev, **head, *scope; + * unsigned int hash; + * ... + * + * 'template.h' can be used as a template to create a 'sym.h'. + * + * 'head' is &(table[hash(itself)]). + * The hash table is not resizable at run-time. + * The scope field is used to link all symbols of a current scope together. + * Scope() sets the current scope (linked list) to add symbols to. + * Any number of scopes can be handled. The user passes the address of + * a pointer to a symbol table + * entry (INITIALIZED TO NULL first time). + * + * Available Functions: + * + * zzs_init(s1,s2) -- Create hash table with size s1, string table size s2. + * zzs_done() -- Free hash and string table created with zzs_init(). + * zzs_add(key,rec)-- Add 'rec' with key 'key' to the symbol table. + * zzs_newadd(key) -- create entry; add using 'key' to the symbol table. + * zzs_get(key) -- Return pointer to last record entered under 'key' + * Else return NULL + * zzs_del(p) -- Unlink the entry associated with p. This does + * NOT free 'p' and DOES NOT remove it from a scope + * list. If it was a part of your intermediate code + * tree or another structure. It will still be there. + * It is only removed from further consideration + * by the symbol table. + * zzs_keydel(s) -- Unlink the entry associated with key s. + * Calls zzs_del(p) to unlink. + * zzs_scope(sc) -- Specifies that everything added to the symbol + * table with zzs_add() is added to the list (scope) + * 'sc'. 'sc' is of 'Sym **sc' type and must be + * initialized to NULL before trying to add anything + * to it (passing it to zzs_scope()). Scopes can be + * switched at any time and merely links a set of + * symbol table entries. If a NULL pointer is + * passed, the current scope is returned. + * zzs_rmscope(sc) -- Remove (zzs_del()) all elements of scope 'sc' + * from the symbol table. The entries are NOT + * free()'d. A pointer to the first + * element in the "scope" is returned. The user + * can then manipulate the list as he/she chooses + * (such as freeing them all). NOTE that this + * function sets your scope pointer to NULL, + * but returns a pointer to the list for you to use. + * zzs_stat() -- Print out the symbol table and some relevant stats. + * zzs_new(key) -- Create a new record with calloc() of type Sym. + * Add 'key' to the string table and make the new + * records 'symbol' pointer point to it. + * zzs_strdup(s) -- Add s to the string table and return a pointer + * to it. Very fast allocation routine + * and does not require strlen() nor calloc(). + * + * Example: + * + * #include + * #include "sym.h" + * + * main() + * { + * Sym *scope1=NULL, *scope2=NULL, *a, *p; + * + * zzs_init(101, 100); + * + * a = zzs_new("Apple"); zzs_add(a->symbol, a); -- No scope + * zzs_scope( &scope1 ); -- enter scope 1 + * a = zzs_new("Plum"); zzs_add(a->symbol, a); + * zzs_scope( &scope2 ); -- enter scope 2 + * a = zzs_new("Truck"); zzs_add(a->symbol, a); + * + * p = zzs_get("Plum"); + * if ( p == NULL ) fprintf(stderr, "Hmmm...Can't find 'Plum'\n"); + * + * p = zzs_rmscope(&scope1) + * for (; p!=NULL; p=p->scope) {printf("Scope1: %s\n", p->symbol);} + * p = zzs_rmscope(&scope2) + * for (; p!=NULL; p=p->scope) {printf("Scope2: %s\n", p->symbol);} + * } + * + * Terence Parr + * Purdue University + * February 1990 + * + * CHANGES + * + * Terence Parr + * May 1991 + * Renamed functions to be consistent with ANTLR + * Made HASH macro + * Added zzs_keydel() + * Added zzs_newadd() + * Fixed up zzs_stat() + * + * July 1991 + * Made symbol table entry save its hash code for fast comparison + * during searching etc... + */ + +#include +#if __STDC__ == 1 +#include +#include +#else +#include "malloc.h" +#endif +#ifdef MEMCHK +#include "trax.h" +#endif +#include "sym.h" + +#define StrSame 0 + +static Sym **CurScope = NULL; +static unsigned size = 0; +static Sym **table=NULL; +static char *strings; +static char *strp; +static int strsize = 0; + +void +zzs_init(sz, strs) +int sz, strs; +{ + if ( sz <= 0 || strs <= 0 ) return; + table = (Sym **) calloc(sz, sizeof(Sym *)); + if ( table == NULL ) + { + fprintf(stderr, "Cannot allocate table of size %d\n", sz); + exit(1); + } + strings = (char *) calloc(strs, sizeof(char)); + if ( strings == NULL ) + { + fprintf(stderr, "Cannot allocate string table of size %d\n", strs); + exit(1); + } + size = sz; + strsize = strs; + strp = strings; +} + +void +zzs_done() +{ + if ( table != NULL ) free( table ); + if ( strings != NULL ) free( strings ); +} + +void +zzs_add(key, rec) +char *key; +register Sym *rec; +{ + register unsigned int h=0; + register char *p=key; + extern Sym *Globals; + + HASH(p, h); + rec->hash = h; /* save hash code for fast comp later */ + h %= size; + + if ( CurScope != NULL ) {rec->scope = *CurScope; *CurScope = rec;} + rec->next = table[h]; /* Add to doubly-linked list */ + rec->prev = NULL; + if ( rec->next != NULL ) (rec->next)->prev = rec; + table[h] = rec; + rec->head = &(table[h]); +} + +Sym * +zzs_get(key) +char *key; +{ + register unsigned int h=0; + register char *p=key; + register Sym *q; + + HASH(p, h); + + for (q = table[h%size]; q != NULL; q = q->next) + { + if ( q->hash == h ) /* do we even have a chance of matching? */ + if ( strcmp(key, q->symbol) == StrSame ) return( q ); + } + return( NULL ); +} + +/* + * Unlink p from the symbol table. Hopefully, it's actually in the + * symbol table. + * + * If p is not part of a bucket chain of the symbol table, bad things + * will happen. + * + * Will do nothing if all list pointers are NULL + */ +void +zzs_del(p) +register Sym *p; +{ + if ( p == NULL ) {fprintf(stderr, "zzs_del(NULL)\n"); exit(1);} + if ( p->prev == NULL ) /* Head of list */ + { + register Sym **t = p->head; + + if ( t == NULL ) return; /* not part of symbol table */ + (*t) = p->next; + if ( (*t) != NULL ) (*t)->prev = NULL; + } + else + { + (p->prev)->next = p->next; + if ( p->next != NULL ) (p->next)->prev = p->prev; + } + p->next = p->prev = NULL; /* not part of symbol table anymore */ + p->head = NULL; +} + +void +zzs_keydel(key) +char *key; +{ + Sym *p = zzs_get(key); + + if ( p != NULL ) zzs_del( p ); +} + +/* S c o p e S t u f f */ + +/* Set current scope to 'scope'; return current scope if 'scope' == NULL */ +Sym ** +zzs_scope(scope) +Sym **scope; +{ + if ( scope == NULL ) return( CurScope ); + CurScope = scope; + return( scope ); +} + +/* Remove a scope described by 'scope'. Return pointer to 1st element in scope */ +Sym * +zzs_rmscope(scope) +register Sym **scope; +{ + register Sym *p; + Sym *start; + + if ( scope == NULL ) return(NULL); + start = p = *scope; + for (; p != NULL; p=p->scope) { zzs_del( p ); } + *scope = NULL; + return( start ); +} + +void +zzs_stat() +{ + static unsigned short count[20]; + unsigned int i,n=0,low=0, hi=0; + register Sym **p; + float avg=0.0; + + for (i=0; i<20; i++) count[i] = 0; + for (p=table; p<&(table[size]); p++) + { + register Sym *q = *p; + unsigned int len; + + if ( q != NULL && low==0 ) low = p-table; + len = 0; + if ( q != NULL ) printf("[%d]", p-table); + while ( q != NULL ) + { + len++; + n++; + printf(" %s", q->symbol); + q = q->next; + if ( q == NULL ) printf("\n"); + } + if ( len>=20 ) printf("zzs_stat: count table too small\n"); + else count[len]++; + if ( *p != NULL ) hi = p-table; + } + + printf("Storing %d recs used %d hash positions out of %d\n", + n, size-count[0], size); + printf("%f %% utilization\n", + ((float)(size-count[0]))/((float)size)); + for (i=0; i<20; i++) + { + if ( count[i] != 0 ) + { + avg += (((float)(i*count[i]))/((float)n)) * i; + printf("Buckets of len %d == %d (%f %% of recs)\n", + i, count[i], 100.0*((float)(i*count[i]))/((float)n)); + } + } + printf("Avg bucket length %f\n", avg); + printf("Range of hash function: %d..%d\n", low, hi); +} + +/* + * Given a string, this function allocates and returns a pointer to a + * symbol table record whose "symbol" pointer is reset to a position + * in the string table. + */ +Sym * +zzs_new(text) +char *text; +{ + Sym *p; + char *zzs_strdup(); + + if ( (p = (Sym *) calloc(1,sizeof(Sym))) == 0 ) + { + fprintf(stderr,"Out of memory\n"); + exit(1); + } + p->symbol = zzs_strdup(text); + + return p; +} + +/* create a new symbol table entry and add it to the symbol table */ +Sym * +zzs_newadd(text) +char *text; +{ + Sym *p = zzs_new(text); + if ( p != NULL ) zzs_add(text, p); + return p; +} + +/* Add a string to the string table and return a pointer to it. + * Bump the pointer into the string table to next avail position. + */ +char * +zzs_strdup(s) +register char *s; +{ + register char *start=strp; + + while ( *s != '\0' ) + { + if ( strp >= &(strings[strsize-2]) ) + { + fprintf(stderr, "sym: string table overflow (%d chars)\n", strsize); + exit(-1); + } + *strp++ = *s++; + } + *strp++ = '\0'; + + return( start ); +}