text: /*
   * 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 defined(__STDC__) || defined(__USE_PROTOS)
  #include <string.h>
  #include <stdlib.h>
  #else
  #include <malloc.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;
  
  #ifdef __USE_PROTOS
  void zzs_init(int sz,int strs)
  #else
  void zzs_init(sz, strs)
  int sz, strs;
  #endif
  {
  	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;
  }
  
  #ifdef __USE_PROTOS
  void zzs_done(void)
  #else
  void zzs_done()
  #endif
  {
  	if ( table != NULL ) free( table );
  	if ( strings != NULL ) free( strings );
  }
  
  #ifdef __USE_PROTOS
  void zzs_add(char *key,Sym rec)
  #else
  void zzs_add(key, rec)
  char *key;
  register Sym *rec;
  #endif
  {
  	register unsigned int h=0;
  	register char *p=key;
  	
  	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]);
  }
  
  #ifdef __USE_PROTOS
  Sym * zzs_get(char *key)
  #else
  Sym * zzs_get(key)
  char *key;
  #endif
  {
  	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
   */
  #ifdef __USE_PROTOS
  void zzs_del(Sym *p)
  #else
  void zzs_del(p)
  register Sym *p;
  #endif
  {
  	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;
  }
  
  #ifdef __USE_PROTOS
  void zzs_keydel(char *key)
  #else
  void zzs_keydel(key)
  char *key;
  #endif
  {
  	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 */
  
  #ifdef __USE_PROTOS
  Sym ** zzs_scope(Sym **scope)
  #else
  Sym ** zzs_scope(scope)
  Sym **scope;
  #endif
  {
  	if ( scope == NULL ) return( CurScope );
  	CurScope = scope;
  	return( scope );
  }
  
  /* Remove a scope described by 'scope'.  Return pointer to 1st element in scope */
  
  #ifdef __USE_PROTOS
  Sym * zzs_rmscope(Sym **scope)
  #else
  Sym * zzs_rmscope(scope)
  register Sym **scope;
  #endif
  {
  	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 );
  }
  
  #ifdef __USE_PROTOS
  void zzs_stat(void)
  #else
  void zzs_stat()
  #endif
  {
  	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.
   */
  
  #ifdef __USE_PROTOS
  Sym * zzs_new(char *text)
  #else
  Sym * zzs_new(text)
  char *text;
  #endif
  {
  	Sym *p;
  	
  	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 */
  
  #ifdef __USE_PROTOS
  Sym * zzs_newadd(char *text)
  #else
  Sym * zzs_newadd(text)
  char *text;
  #endif
  {
  	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.
   */
  
  #ifdef __USE_PROTOS
  char * zzs_strdup(char *s)
  #else
  char * zzs_strdup(s)
  register char *s;
  #endif
  {
  	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 );
  }
  