--- /dev/null
+/*
+ * 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 <stdio.h>
+ * #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 <stdio.h>
+#if __STDC__ == 1
+#include <string.h>
+#include <stdlib.h>
+#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 );
+}
projects / pccts / blobdiff