cvs/stack/stack.c

/* printf */
#include <stdio.h>
/* EXIT_SUCCESS */
#include <stdlib.h>
/* NULL */
#include <stddef.h>
/* dlopen, dlsym, dlerror */
#include <dlfcn.h>

#define HASHTBLSIZE 65536

typedef struct stack_item
{
  enum {
    value,                      /* Integer */
    string, 
    ref,            /* Reference (to an element in the hash table) */ 
    func,                       /* Function pointer */
    symbol, 
    list
  } type;                       /* Tells what kind of stack element */
  
  union {
    void* ptr;                  /* Pointer to the content */
    int val;                    /* ...or an integer */
  } content;                    /* Stores a pointer or an integer */

  char* id;                     /* Symbol name */
  struct stack_item* next;      /* Next element */
} stackitem;


typedef stackitem* hashtbl[HASHTBLSIZE]; /* Hash table declaration */
typedef void (*funcp)(stackitem**); /* Function pointer declaration */


/* Initiates a newly created hash table. */
void init_hashtbl(hashtbl out_hash)
{
  long i;

  for(i= 0; i<HASHTBLSIZE; i++)
    out_hash[i]= NULL;
}

/* Returns a pointer to an element in the hash table. */
stackitem** hash(hashtbl in_hashtbl, const char* in_string)
{
  long i= 0;
  unsigned long out_hash= 0;
  char key= 0;
  stackitem** position;
  
  while(1){                     /* Hash in_string */
    key= in_string[i++];
    if(key=='\0')
      break;
    out_hash= out_hash*32+key;
  }

  out_hash= out_hash%HASHTBLSIZE;
  position= &(in_hashtbl[out_hash]);

  while(1){                     /* Return position if empty */
    if(*position==NULL)
      return position;
    
    if(strcmp(in_string, (*position)->id)==0) /* Return position if match */
      return position;

    position= &((*position)->next); /* Try next */
  }
}

/* Generic push function. */
int push(stackitem** stack_head, stackitem* in_item)
{
  in_item->next= *stack_head;
  *stack_head= in_item;
  return 1;
}

/* Push a value on the stack. */
int push_val(stackitem** stack_head, int in_val) 
{
  stackitem* new_item= malloc(sizeof(stackitem));
  new_item->content.val= in_val;
  new_item->type= value;

  push(stack_head, new_item);
  return 1;
}

/* Copy a string onto the stack. */
int push_cstring(stackitem** stack_head, const char* in_string)
{
  stackitem* new_item= malloc(sizeof(stackitem));
  new_item->content.ptr= malloc(strlen(in_string)+1);
  strcpy(new_item->content.ptr, in_string);
  new_item->type= string;

  push(stack_head, new_item);
  return 1;
}

/* Create a new hash entry. */
int mk_hashentry(hashtbl in_hashtbl, stackitem* in_item, const char* id)
{
  in_item->id= malloc(strlen(id)+1);

  strcpy(in_item->id, id);
  push(hash(in_hashtbl, id), in_item);

  return 1;
}

/* Define a function a new function in the hash table. */
void def_func(hashtbl in_hashtbl, funcp in_func, const char* id)
{
  stackitem* temp= malloc(sizeof(stackitem));

  temp->type= func;
  temp->content.ptr= in_func;

  mk_hashentry(in_hashtbl, temp, id);
}

/* Define a new symbol in the hash table. */
void def_sym(hashtbl in_hashtbl, const char* id)
{
  stackitem* temp= malloc(sizeof(stackitem));
  
  temp->type= symbol;
  mk_hashentry(in_hashtbl, temp, id);
}

/* Push a reference to an entry in the hash table onto the stack. */
int push_ref(stackitem** stack_head, hashtbl in_hash, const char* in_string)
{
  static void* handle= NULL;
  void* symbol;

  stackitem* new_item= malloc(sizeof(stackitem));
  new_item->content.ptr= *hash(in_hash, in_string);
  new_item->type= ref;

  if(new_item->content.ptr==NULL) { /* If hash entry empty */
    if(handle==NULL)            /* If no handle */
      handle= dlopen(NULL, RTLD_LAZY);    

    symbol= dlsym(handle, in_string); /* Get function pointer */
    if(dlerror()==NULL)         /* If existing function pointer */
      def_func(in_hash, symbol, in_string); /* Store function pointer */
    else
      def_sym(in_hash, in_string); /* Make symbol */
      
    new_item->content.ptr= *hash(in_hash, in_string); /* XXX */
    new_item->type= ref;
  }

  push(stack_head, new_item);
  return 1;
}

/* Discard the top element of the stack. */
extern void toss(stackitem** stack_head)
{
  stackitem* temp= *stack_head;

  if((*stack_head)==NULL)
    return;
  
  if((*stack_head)->type==string)
    free((*stack_head)->content.ptr);

  *stack_head= (*stack_head)->next;
  free(temp);
}

/* Print newline. */
extern void nl()
{
  printf("\n");
}

/* Prints the top element of the stack. */
void print_(stackitem** stack_head)
{
  if((*stack_head)==NULL)
    return;

  switch((*stack_head)->type) {
  case value:
    printf("%d", (*stack_head)->content.val);
    break;
  case string:
    printf("%s", (char*)(*stack_head)->content.ptr);
    break;
  case ref:
    printf("%s", ((stackitem*)(*stack_head)->content.ptr)->id);
    break;
  case symbol:
  default:
    printf("%p", (*stack_head)->content.ptr);
    break;
  }
}

/* Prints the top element of the stack and then discards it. */
extern void print(stackitem** stack_head)
{
  print_(stack_head);
  toss(stack_head);
}

/* Only to be called by function printstack. */
void print_st(stackitem* stack_head, long counter)
{ 
  if(stack_head->next != NULL)
    print_st(stack_head->next, counter+1);

  printf("%ld: ", counter);
  print_(&stack_head);
  nl();
}

/* Prints the stack. */
extern void printstack(stackitem** stack_head)
{
  if(*stack_head != NULL) {
    print_st(*stack_head, 1);
    printf("\n");
  }
}

/* If the top element is a reference, determine if it's a reference to a
   function, and if it is, toss the reference and execute the function. */
extern void eval(stackitem** stack_head)
{
  funcp in_func;

  if((*stack_head)==NULL || (*stack_head)->type!=ref)
    return;

  if(((stackitem*)(*stack_head)->content.ptr)->type==func) {
    in_func= (funcp)((stackitem*)(*stack_head)->content.ptr)->content.ptr;
    toss(stack_head); 
    (*in_func)(stack_head);
    return;
  }
}

/* Parse input. */
int stack_read(stackitem** stack_head, hashtbl in_hash, char* in_line) 
{
  char *temp, *rest;
  int itemp;
  size_t inlength= strlen(in_line)+1;
  int convert= 0;

  temp= malloc(inlength);
  rest= malloc(inlength);

  do {
    /* If string */
    if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
      push_cstring(stack_head, temp);
      break;
    }
    /* If value */
    if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
      push_val(stack_head, itemp);
      break;
    }
    /* Escape ';' with '\' */
    if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
      temp[1]= '\0'; 
      push_ref(stack_head, in_hash, temp);
      break;
    } 
    /* If symbol */
    if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest))) {
        push_ref(stack_head, in_hash, temp);
        break;
    }
    /* If ';' */
    if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) && *temp==';') {
      eval(stack_head);         /* Evaluate top element */
      break;
    }
  } while(0);


  free(temp);

  if(convert<2) {
    free(rest);
    return 0;
  }
   
  stack_read(stack_head, in_hash, rest);
  
  free(rest);
  return 1;
}

/* Make a list. */
extern void pack(stackitem** stack_head)
{
  void* delimiter;
  stackitem *iterator, *temp, *pack;

  if((*stack_head)==NULL)       /* No delimiter */
    return;

  delimiter= (*stack_head)->content.ptr; /* Get delimiter */
  toss(stack_head);

  iterator= *stack_head;

  /* Search for first delimiter */
  while(iterator->next!=NULL && iterator->next->content.ptr!=delimiter)
    iterator= iterator->next;

  /* Extract list */
  temp= *stack_head;
  *stack_head= iterator->next;
  iterator->next= NULL;
  
  if(*stack_head!=NULL && (*stack_head)->content.ptr==delimiter)
    toss(stack_head);

  /* Push list */
  pack= malloc(sizeof(stackitem));
  pack->type= list;
  pack->content.ptr= temp;

  push(stack_head, pack);
}

/* Relocate elements of the list on the stack. */
extern void expand(stackitem** stack_head)
{
  stackitem *temp, *new_head;

  /* Is top element a list? */
  if((*stack_head)==NULL || (*stack_head)->type!=list)
    return;

  /* The first list element is the new stack head */
  new_head= temp= (*stack_head)->content.ptr;
  toss(stack_head);

  /* Search the end of the list */
  while(temp->next!=NULL)
    temp= temp->next;

  /* Connect the the tail of the list with the old stack head */
  temp->next= *stack_head;
  *stack_head= new_head;        /* ...and voila! */
}

/* Swap the two top elements on the stack. */
extern void swap(stackitem** stack_head)
{
  stackitem* temp= (*stack_head);
  
  if((*stack_head)==NULL || (*stack_head)->next==NULL)
    return;

  *stack_head= (*stack_head)->next;
  temp->next= (*stack_head)->next;
  (*stack_head)->next= temp;
} 

/* Compares two elements by reference. */
extern void eq(stackitem** stack_head)
{
  void *left, *right;
  int result;

  if((*stack_head)==NULL || (*stack_head)->next==NULL)
    return;

  left= (*stack_head)->content.ptr;
  swap(stack_head);
  right= (*stack_head)->content.ptr;
  result= (left==right);
  
  toss(stack_head); toss(stack_head);
  push_val(stack_head, (left==right));
}

/* Negates the top element on the stack. */
extern void not(stackitem** stack_head)
{
  int value;

  if((*stack_head)==NULL || (*stack_head)->type!=value)
    return;

  value= (*stack_head)->content.val;
  toss(stack_head);
  push_val(stack_head, !value);
}

/* Compares the two top elements on the stack and return 0 if they're the
   same. */
extern void neq(stackitem** stack_head)
{
  eq(stack_head);
  not(stack_head);
}

/* Give a symbol some content. */
extern void def(stackitem** stack_head)
{
  stackitem *temp, *value;

  if(*stack_head==NULL || (*stack_head)->next==NULL 
     || (*stack_head)->type!=ref)
    return;

  temp= (*stack_head)->content.ptr;
  value= (*stack_head)->next;
  temp->content= value->content;
  value->content.ptr=NULL;
  temp->type= value->type;

  toss(stack_head); toss(stack_head);
} 

/* Quit stack. */
extern void quit()
{
  exit(EXIT_SUCCESS);
}

int main()
{
  stackitem* s= NULL;
  hashtbl myhash;
  char in_string[100];

  init_hashtbl(myhash);

  printf("okidok\n ");

  while(fgets(in_string, 100, stdin) != NULL) {
    stack_read(&s, myhash, in_string);
    printf("okidok\n ");
  }

  exit(EXIT_SUCCESS);
}

/* Local Variables: */
/* compile-command:"make CFLAGS=\"-Wall -g -rdynamic -ldl\" stack" */
/* End: */
1	/* printf */
2	#include <stdio.h>
3	/* EXIT_SUCCESS */
4	#include <stdlib.h>
5	/* NULL */
6	#include <stddef.h>
7	/* dlopen, dlsym, dlerror */
8	#include <dlfcn.h>
9
10	#define HASHTBLSIZE 65536
11
12	typedef struct stack_item
13	{
14	enum {
15	value, /* Integer */
16	string,
17	ref, /* Reference (to an element in the hash table) */
18	func, /* Function pointer */
19	symbol,
20	list
21	} type; /* Tells what kind of stack element */
22
23	union {
24	void* ptr; /* Pointer to the content */
25	int val; /* ...or an integer */
26	} content; /* Stores a pointer or an integer */
27
28	char* id; /* Symbol name */
29	struct stack_item* next; /* Next element */
30	} stackitem;
31
32
33	typedef stackitem* hashtbl[HASHTBLSIZE]; /* Hash table declaration */
34	typedef void (funcp)(stackitem); / Function pointer declaration */
35
36
37	/* Initiates a newly created hash table. */
38	void init_hashtbl(hashtbl out_hash)
39	{
40	long i;
41
42	for(i= 0; i<HASHTBLSIZE; i++)
43	out_hash[i]= NULL;
44	}
45
46	/* Returns a pointer to an element in the hash table. */
47	stackitem** hash(hashtbl in_hashtbl, const char* in_string)
48	{
49	long i= 0;
50	unsigned long out_hash= 0;
51	char key= 0;
52	stackitem** position;
53
54	while(1){ /* Hash in_string */
55	key= in_string[i++];
56	if(key=='\0')
57	break;
58	out_hash= out_hash*32+key;
59	}
60
61	out_hash= out_hash%HASHTBLSIZE;
62	position= &(in_hashtbl[out_hash]);
63
64	while(1){ /* Return position if empty */
65	if(*position==NULL)
66	return position;
67
68	if(strcmp(in_string, (position)->id)==0) / Return position if match */
69	return position;
70
71	position= &((position)->next); / Try next */
72	}
73	}
74
75	/* Generic push function. */
76	int push(stackitem** stack_head, stackitem* in_item)
77	{
78	in_item->next= *stack_head;
79	*stack_head= in_item;
80	return 1;
81	}
82
83	/* Push a value on the stack. */
84	int push_val(stackitem** stack_head, int in_val)
85	{
86	stackitem* new_item= malloc(sizeof(stackitem));
87	new_item->content.val= in_val;
88	new_item->type= value;
89
90	push(stack_head, new_item);
91	return 1;
92	}
93
94	/* Copy a string onto the stack. */
95	int push_cstring(stackitem** stack_head, const char* in_string)
96	{
97	stackitem* new_item= malloc(sizeof(stackitem));
98	new_item->content.ptr= malloc(strlen(in_string)+1);
99	strcpy(new_item->content.ptr, in_string);
100	new_item->type= string;
101
102	push(stack_head, new_item);
103	return 1;
104	}
105
106	/* Create a new hash entry. */
107	int mk_hashentry(hashtbl in_hashtbl, stackitem* in_item, const char* id)
108	{
109	in_item->id= malloc(strlen(id)+1);
110
111	strcpy(in_item->id, id);
112	push(hash(in_hashtbl, id), in_item);
113
114	return 1;
115	}
116
117	/* Define a function a new function in the hash table. */
118	void def_func(hashtbl in_hashtbl, funcp in_func, const char* id)
119	{
120	stackitem* temp= malloc(sizeof(stackitem));
121
122	temp->type= func;
123	temp->content.ptr= in_func;
124
125	mk_hashentry(in_hashtbl, temp, id);
126	}
127
128	/* Define a new symbol in the hash table. */
129	void def_sym(hashtbl in_hashtbl, const char* id)
130	{
131	stackitem* temp= malloc(sizeof(stackitem));
132
133	temp->type= symbol;
134	mk_hashentry(in_hashtbl, temp, id);
135	}
136
137	/* Push a reference to an entry in the hash table onto the stack. */
138	int push_ref(stackitem** stack_head, hashtbl in_hash, const char* in_string)
139	{
140	static void* handle= NULL;
141	void* symbol;
142
143	stackitem* new_item= malloc(sizeof(stackitem));
144	new_item->content.ptr= *hash(in_hash, in_string);
145	new_item->type= ref;
146
147	if(new_item->content.ptr==NULL) { /* If hash entry empty */
148	if(handle==NULL) /* If no handle */
149	handle= dlopen(NULL, RTLD_LAZY);
150
151	symbol= dlsym(handle, in_string); /* Get function pointer */
152	if(dlerror()==NULL) /* If existing function pointer */
153	def_func(in_hash, symbol, in_string); /* Store function pointer */
154	else
155	def_sym(in_hash, in_string); /* Make symbol */
156
157	new_item->content.ptr= hash(in_hash, in_string); / XXX */
158	new_item->type= ref;
159	}
160
161	push(stack_head, new_item);
162	return 1;
163	}
164
165	/* Discard the top element of the stack. */
166	extern void toss(stackitem** stack_head)
167	{
168	stackitem* temp= *stack_head;
169
170	if((*stack_head)==NULL)
171	return;
172
173	if((*stack_head)->type==string)
174	free((*stack_head)->content.ptr);
175
176	stack_head= (stack_head)->next;
177	free(temp);
178	}
179
180	/* Print newline. */
181	extern void nl()
182	{
183	printf("\n");
184	}
185
186	/* Prints the top element of the stack. */
187	void print_(stackitem** stack_head)
188	{
189	if((*stack_head)==NULL)
190	return;
191
192	switch((*stack_head)->type) {
193	case value:
194	printf("%d", (*stack_head)->content.val);
195	break;
196	case string:
197	printf("%s", (char)(stack_head)->content.ptr);
198	break;
199	case ref:
200	printf("%s", ((stackitem)(stack_head)->content.ptr)->id);
201	break;
202	case symbol:
203	default:
204	printf("%p", (*stack_head)->content.ptr);
205	break;
206	}
207	}
208
209	/* Prints the top element of the stack and then discards it. */
210	extern void print(stackitem** stack_head)
211	{
212	print_(stack_head);
213	toss(stack_head);
214	}
215
216	/* Only to be called by function printstack. */
217	void print_st(stackitem* stack_head, long counter)
218	{
219	if(stack_head->next != NULL)
220	print_st(stack_head->next, counter+1);
221
222	printf("%ld: ", counter);
223	print_(&stack_head);
224	nl();
225	}
226
227	/* Prints the stack. */
228	extern void printstack(stackitem** stack_head)
229	{
230	if(*stack_head != NULL) {
231	print_st(*stack_head, 1);
232	printf("\n");
233	}
234	}
235
236	/* If the top element is a reference, determine if it's a reference to a
237	function, and if it is, toss the reference and execute the function. */
238	extern void eval(stackitem** stack_head)
239	{
240	funcp in_func;
241
242	if((stack_head)==NULL \|\| (stack_head)->type!=ref)
243	return;
244
245	if(((stackitem)(stack_head)->content.ptr)->type==func) {
246	in_func= (funcp)((stackitem)(stack_head)->content.ptr)->content.ptr;
247	toss(stack_head);
248	(*in_func)(stack_head);
249	return;
250	}
251	}
252
253	/* Parse input. */
254	int stack_read(stackitem** stack_head, hashtbl in_hash, char* in_line)
255	{
256	char temp, rest;
257	int itemp;
258	size_t inlength= strlen(in_line)+1;
259	int convert= 0;
260
261	temp= malloc(inlength);
262	rest= malloc(inlength);
263
264	do {
265	/* If string */
266	if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
267	push_cstring(stack_head, temp);
268	break;
269	}
270	/* If value */
271	if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
272	push_val(stack_head, itemp);
273	break;
274	}
275	/* Escape ';' with '\' */
276	if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
277	temp[1]= '\0';
278	push_ref(stack_head, in_hash, temp);
279	break;
280	}
281	/* If symbol */
282	if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest))) {
283	push_ref(stack_head, in_hash, temp);
284	break;
285	}
286	/* If ';' */
287	if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) && *temp==';') {
288	eval(stack_head); /* Evaluate top element */
289	break;
290	}
291	} while(0);
292
293
294	free(temp);
295
296	if(convert<2) {
297	free(rest);
298	return 0;
299	}
300
301	stack_read(stack_head, in_hash, rest);
302
303	free(rest);
304	return 1;
305	}
306
307	/* Make a list. */
308	extern void pack(stackitem** stack_head)
309	{
310	void* delimiter;
311	stackitem iterator, temp, *pack;
312
313	if((stack_head)==NULL) / No delimiter */
314	return;
315
316	delimiter= (stack_head)->content.ptr; / Get delimiter */
317	toss(stack_head);
318
319	iterator= *stack_head;
320
321	/* Search for first delimiter */
322	while(iterator->next!=NULL && iterator->next->content.ptr!=delimiter)
323	iterator= iterator->next;
324
325	/* Extract list */
326	temp= *stack_head;
327	*stack_head= iterator->next;
328	iterator->next= NULL;
329
330	if(stack_head!=NULL && (stack_head)->content.ptr==delimiter)
331	toss(stack_head);
332
333	/* Push list */
334	pack= malloc(sizeof(stackitem));
335	pack->type= list;
336	pack->content.ptr= temp;
337
338	push(stack_head, pack);
339	}
340
341	/* Relocate elements of the list on the stack. */
342	extern void expand(stackitem** stack_head)
343	{
344	stackitem temp, new_head;
345
346	/* Is top element a list? */
347	if((stack_head)==NULL \|\| (stack_head)->type!=list)
348	return;
349
350	/* The first list element is the new stack head */
351	new_head= temp= (*stack_head)->content.ptr;
352	toss(stack_head);
353
354	/* Search the end of the list */
355	while(temp->next!=NULL)
356	temp= temp->next;
357
358	/* Connect the the tail of the list with the old stack head */
359	temp->next= *stack_head;
360	stack_head= new_head; / ...and voila! */
361	}
362
363	/* Swap the two top elements on the stack. */
364	extern void swap(stackitem** stack_head)
365	{
366	stackitem* temp= (*stack_head);
367
368	if((stack_head)==NULL \|\| (stack_head)->next==NULL)
369	return;
370
371	stack_head= (stack_head)->next;
372	temp->next= (*stack_head)->next;
373	(*stack_head)->next= temp;
374	}
375
376	/* Compares two elements by reference. */
377	extern void eq(stackitem** stack_head)
378	{
379	void left, right;
380	int result;
381
382	if((stack_head)==NULL \|\| (stack_head)->next==NULL)
383	return;
384
385	left= (*stack_head)->content.ptr;
386	swap(stack_head);
387	right= (*stack_head)->content.ptr;
388	result= (left==right);
389
390	toss(stack_head); toss(stack_head);
391	push_val(stack_head, (left==right));
392	}
393
394	/* Negates the top element on the stack. */
395	extern void not(stackitem** stack_head)
396	{
397	int value;
398
399	if((stack_head)==NULL \|\| (stack_head)->type!=value)
400	return;
401
402	value= (*stack_head)->content.val;
403	toss(stack_head);
404	push_val(stack_head, !value);
405	}
406
407	/* Compares the two top elements on the stack and return 0 if they're the
408	same. */
409	extern void neq(stackitem** stack_head)
410	{
411	eq(stack_head);
412	not(stack_head);
413	}
414
415	/* Give a symbol some content. */
416	extern void def(stackitem** stack_head)
417	{
418	stackitem temp, value;
419
420	if(stack_head==NULL \|\| (stack_head)->next==NULL
421	\|\| (*stack_head)->type!=ref)
422	return;
423
424	temp= (*stack_head)->content.ptr;
425	value= (*stack_head)->next;
426	temp->content= value->content;
427	value->content.ptr=NULL;
428	temp->type= value->type;
429
430	toss(stack_head); toss(stack_head);
431	}
432
433	/* Quit stack. */
434	extern void quit()
435	{
436	exit(EXIT_SUCCESS);
437	}
438
439	int main()
440	{
441	stackitem* s= NULL;
442	hashtbl myhash;
443	char in_string[100];
444
445	init_hashtbl(myhash);
446
447	printf("okidok\n ");
448
449	while(fgets(in_string, 100, stdin) != NULL) {
450	stack_read(&s, myhash, in_string);
451	printf("okidok\n ");
452	}
453
454	exit(EXIT_SUCCESS);
455	}
456
457	/* Local Variables: */
458	/* compile-command:"make CFLAGS=\"-Wall -g -rdynamic -ldl\" stack" */
459	/* End: */