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 |
/* assert */ |
10 |
#include <assert.h> |
11 |
|
12 |
#define HASHTBLSIZE 65536 |
13 |
|
14 |
/* First, define some types. */ |
15 |
|
16 |
/* A value of some type */ |
17 |
typedef struct { |
18 |
enum { |
19 |
integer, |
20 |
string, |
21 |
func, /* Function pointer */ |
22 |
symb, |
23 |
list |
24 |
} type; /* Type of stack element */ |
25 |
|
26 |
union { |
27 |
void *ptr; /* Pointer to the content */ |
28 |
int val; /* ...or an integer */ |
29 |
} content; /* Stores a pointer or an integer */ |
30 |
|
31 |
int refcount; /* Reference counter */ |
32 |
|
33 |
} value; |
34 |
|
35 |
/* A symbol with a name and possible value */ |
36 |
/* (These do not need reference counters, they are kept unique by |
37 |
hashing.) */ |
38 |
typedef struct symbol_struct { |
39 |
char *id; /* Symbol name */ |
40 |
value *val; /* The value (if any) bound to it */ |
41 |
struct symbol_struct *next; /* In case of hashing conflicts, a */ |
42 |
} symbol; /* symbol is a kind of stack item. */ |
43 |
|
44 |
/* A type for a hash table for symbols */ |
45 |
typedef symbol *hashtbl[HASHTBLSIZE]; /* Hash table declaration */ |
46 |
|
47 |
/* An item (value) on a stack */ |
48 |
typedef struct stackitem_struct |
49 |
{ |
50 |
value *item; /* The value on the stack */ |
51 |
struct stackitem_struct *next; /* Next item */ |
52 |
} stackitem; |
53 |
|
54 |
/* An environment; gives access to the stack and a hash table of |
55 |
defined symbols */ |
56 |
typedef struct { |
57 |
stackitem *head; /* Head of the stack */ |
58 |
hashtbl symbols; /* Hash table of all variable bindings */ |
59 |
int err; /* Error flag */ |
60 |
} environment; |
61 |
|
62 |
/* A type for pointers to external functions */ |
63 |
typedef void (*funcp)(environment *); /* funcp is a pointer to a void |
64 |
function (environment *) */ |
65 |
|
66 |
/* Initialize a newly created environment */ |
67 |
void init_env(environment *env) |
68 |
{ |
69 |
long i; |
70 |
|
71 |
env->err=0; |
72 |
for(i= 0; i<HASHTBLSIZE; i++) |
73 |
env->symbols[i]= NULL; |
74 |
} |
75 |
|
76 |
/* Returns a pointer to a pointer to an element in the hash table. */ |
77 |
symbol **hash(hashtbl in_hashtbl, const char *in_string) |
78 |
{ |
79 |
long i= 0; |
80 |
unsigned long out_hash= 0; |
81 |
char key= '\0'; |
82 |
symbol **position; |
83 |
|
84 |
while(1){ /* Hash in_string */ |
85 |
key= in_string[i++]; |
86 |
if(key=='\0') |
87 |
break; |
88 |
out_hash= out_hash*32+key; |
89 |
} |
90 |
|
91 |
out_hash= out_hash%HASHTBLSIZE; |
92 |
position= &(in_hashtbl[out_hash]); |
93 |
|
94 |
while(1){ |
95 |
if(*position==NULL) /* If empty */ |
96 |
return position; |
97 |
|
98 |
if(strcmp(in_string, (*position)->id)==0) /* If match */ |
99 |
return position; |
100 |
|
101 |
position= &((*position)->next); /* Try next */ |
102 |
} |
103 |
} |
104 |
|
105 |
/* Generic push function. */ |
106 |
void push(stackitem** stack_head, stackitem* in_item) |
107 |
{ |
108 |
in_item->next= *stack_head; |
109 |
*stack_head= in_item; |
110 |
} |
111 |
|
112 |
/* Push a value onto the stack */ |
113 |
void push_val(stackitem **stack_head, value *val) |
114 |
{ |
115 |
stackitem *new_item= malloc(sizeof(stackitem)); |
116 |
new_item->item= val; |
117 |
val->refcount++; |
118 |
push(stack_head, new_item); |
119 |
} |
120 |
|
121 |
/* Push an integer onto the stack. */ |
122 |
void push_int(stackitem **stack_head, int in_val) |
123 |
{ |
124 |
value *new_value= malloc(sizeof(value)); |
125 |
stackitem *new_item= malloc(sizeof(stackitem)); |
126 |
new_item->item= new_value; |
127 |
|
128 |
new_value->content.val= in_val; |
129 |
new_value->type= integer; |
130 |
new_value->refcount=1; |
131 |
|
132 |
push(stack_head, new_item); |
133 |
} |
134 |
|
135 |
/* Copy a string onto the stack. */ |
136 |
void push_cstring(stackitem **stack_head, const char *in_string) |
137 |
{ |
138 |
value *new_value= malloc(sizeof(value)); |
139 |
stackitem *new_item= malloc(sizeof(stackitem)); |
140 |
new_item->item=new_value; |
141 |
|
142 |
new_value->content.ptr= malloc(strlen(in_string)+1); |
143 |
strcpy(new_value->content.ptr, in_string); |
144 |
new_value->type= string; |
145 |
new_value->refcount=1; |
146 |
|
147 |
push(stack_head, new_item); |
148 |
} |
149 |
|
150 |
/* Push a symbol onto the stack. */ |
151 |
void push_sym(environment *env, const char *in_string) |
152 |
{ |
153 |
stackitem *new_item; /* The new stack item */ |
154 |
/* ...which will contain... */ |
155 |
value *new_value; /* A new symbol value */ |
156 |
/* ...which might point to... */ |
157 |
symbol **new_symbol; /* (if needed) A new actual symbol */ |
158 |
/* ...which, if possible, will be bound to... */ |
159 |
value *new_fvalue; /* (if needed) A new function value */ |
160 |
/* ...which will point to... */ |
161 |
void *funcptr; /* A function pointer */ |
162 |
|
163 |
static void *handle= NULL; /* Dynamic linker handle */ |
164 |
|
165 |
/* Create a new stack item containing a new value */ |
166 |
new_item= malloc(sizeof(stackitem)); |
167 |
new_value= malloc(sizeof(value)); |
168 |
new_item->item=new_value; |
169 |
|
170 |
/* The new value is a symbol */ |
171 |
new_value->type= symb; |
172 |
new_value->refcount= 1; |
173 |
|
174 |
/* Look up the symbol name in the hash table */ |
175 |
new_symbol= hash(env->symbols, in_string); |
176 |
new_value->content.ptr= *new_symbol; |
177 |
|
178 |
if(*new_symbol==NULL) { /* If symbol was undefined */ |
179 |
|
180 |
/* Create a new symbol */ |
181 |
(*new_symbol)= malloc(sizeof(symbol)); |
182 |
(*new_symbol)->val= NULL; /* undefined value */ |
183 |
(*new_symbol)->next= NULL; |
184 |
(*new_symbol)->id= malloc(strlen(in_string)+1); |
185 |
strcpy((*new_symbol)->id, in_string); |
186 |
|
187 |
/* Intern the new symbol in the hash table */ |
188 |
new_value->content.ptr= *new_symbol; |
189 |
|
190 |
/* Try to load the symbol name as an external function, to see if |
191 |
we should bind the symbol to a new function pointer value */ |
192 |
if(handle==NULL) /* If no handle */ |
193 |
handle= dlopen(NULL, RTLD_LAZY); |
194 |
|
195 |
funcptr= dlsym(handle, in_string); /* Get function pointer */ |
196 |
if(dlerror()==NULL) { /* If a function was found */ |
197 |
new_fvalue= malloc(sizeof(value)); /* Create a new value */ |
198 |
new_fvalue->type=func; /* The new value is a function pointer */ |
199 |
new_fvalue->content.ptr=funcptr; /* Store function pointer */ |
200 |
(*new_symbol)->val= new_fvalue; /* Bind the symbol to the new |
201 |
function value */ |
202 |
new_fvalue->refcount= 1; |
203 |
} |
204 |
} |
205 |
push(&(env->head), new_item); |
206 |
} |
207 |
|
208 |
void printerr(const char* in_string) { |
209 |
fprintf(stderr, "Err: %s\n", in_string); |
210 |
} |
211 |
|
212 |
/* Throw away a value */ |
213 |
void free_val(value *val){ |
214 |
stackitem *item, *temp; |
215 |
|
216 |
val->refcount--; /* Decrease the reference count */ |
217 |
if(val->refcount == 0){ |
218 |
switch (val->type){ /* and free the contents if necessary */ |
219 |
case string: |
220 |
free(val->content.ptr); |
221 |
break; |
222 |
case list: /* lists needs to be freed recursively */ |
223 |
item=val->content.ptr; |
224 |
while(item != NULL) { /* for all stack items */ |
225 |
free_val(item->item); /* free the value */ |
226 |
temp=item->next; /* save next ptr */ |
227 |
free(item); /* free the stackitem */ |
228 |
item=temp; /* go to next stackitem */ |
229 |
} |
230 |
free(val); /* Free the actual list value */ |
231 |
break; |
232 |
default: |
233 |
break; |
234 |
} |
235 |
} |
236 |
} |
237 |
|
238 |
/* Discard the top element of the stack. */ |
239 |
extern void toss(environment *env) |
240 |
{ |
241 |
stackitem *temp= env->head; |
242 |
|
243 |
if((env->head)==NULL) { |
244 |
printerr("Too Few Arguments"); |
245 |
env->err=1; |
246 |
return; |
247 |
} |
248 |
|
249 |
free_val(env->head->item); /* Free the value */ |
250 |
env->head= env->head->next; /* Remove the top stack item */ |
251 |
free(temp); /* Free the old top stack item */ |
252 |
} |
253 |
|
254 |
/* Print newline. */ |
255 |
extern void nl() |
256 |
{ |
257 |
printf("\n"); |
258 |
} |
259 |
|
260 |
/* Gets the type of a value */ |
261 |
extern void type(environment *env){ |
262 |
int typenum; |
263 |
|
264 |
if((env->head)==NULL) { |
265 |
printerr("Too Few Arguments"); |
266 |
env->err=1; |
267 |
return; |
268 |
} |
269 |
typenum=env->head->item->type; |
270 |
toss(env); |
271 |
switch(typenum){ |
272 |
case integer: |
273 |
push_sym(env, "integer"); |
274 |
break; |
275 |
case string: |
276 |
push_sym(env, "string"); |
277 |
break; |
278 |
case symb: |
279 |
push_sym(env, "symbol"); |
280 |
break; |
281 |
case func: |
282 |
push_sym(env, "function"); |
283 |
break; |
284 |
case list: |
285 |
push_sym(env, "list"); |
286 |
break; |
287 |
default: |
288 |
push_sym(env, "unknown"); |
289 |
break; |
290 |
} |
291 |
} |
292 |
|
293 |
/* Prints the top element of the stack. */ |
294 |
void print_h(stackitem *stack_head) |
295 |
{ |
296 |
switch(stack_head->item->type) { |
297 |
case integer: |
298 |
printf("%d", stack_head->item->content.val); |
299 |
break; |
300 |
case string: |
301 |
printf("\"%s\"", (char*)stack_head->item->content.ptr); |
302 |
break; |
303 |
case symb: |
304 |
printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id); |
305 |
break; |
306 |
case func: |
307 |
printf("#<function %p>", (funcp)(stack_head->item->content.ptr)); |
308 |
break; |
309 |
case list: |
310 |
/* A list is just a stack, so make stack_head point to it */ |
311 |
stack_head=(stackitem *)(stack_head->item->content.ptr); |
312 |
printf("[ "); |
313 |
while(stack_head != NULL) { |
314 |
print_h(stack_head); |
315 |
printf(" "); |
316 |
stack_head=stack_head->next; |
317 |
} |
318 |
printf("]"); |
319 |
break; |
320 |
default: |
321 |
printf("#<unknown %p>", (stack_head->item->content.ptr)); |
322 |
break; |
323 |
} |
324 |
} |
325 |
|
326 |
extern void print_(environment *env) { |
327 |
if(env->head==NULL) { |
328 |
printerr("Too Few Arguments"); |
329 |
env->err=1; |
330 |
return; |
331 |
} |
332 |
print_h(env->head); |
333 |
} |
334 |
|
335 |
/* Prints the top element of the stack and then discards it. */ |
336 |
extern void print(environment *env) |
337 |
{ |
338 |
print_(env); |
339 |
if(env->err) return; |
340 |
toss(env); |
341 |
} |
342 |
|
343 |
/* Only to be called by function printstack. */ |
344 |
void print_st(stackitem *stack_head, long counter) |
345 |
{ |
346 |
if(stack_head->next != NULL) |
347 |
print_st(stack_head->next, counter+1); |
348 |
printf("%ld: ", counter); |
349 |
print_h(stack_head); |
350 |
nl(); |
351 |
} |
352 |
|
353 |
|
354 |
|
355 |
/* Prints the stack. */ |
356 |
extern void printstack(environment *env) |
357 |
{ |
358 |
if(env->head == NULL) { |
359 |
return; |
360 |
} |
361 |
print_st(env->head, 1); |
362 |
nl(); |
363 |
} |
364 |
|
365 |
/* Swap the two top elements on the stack. */ |
366 |
extern void swap(environment *env) |
367 |
{ |
368 |
stackitem *temp= env->head; |
369 |
|
370 |
if((env->head)==NULL) { |
371 |
printerr("Too Few Arguments"); |
372 |
env->err=1; |
373 |
return; |
374 |
} |
375 |
|
376 |
if(env->head->next==NULL) { |
377 |
printerr("Too Few Arguments"); |
378 |
env->err=1; |
379 |
return; |
380 |
} |
381 |
|
382 |
env->head= env->head->next; |
383 |
temp->next= env->head->next; |
384 |
env->head->next= temp; |
385 |
} |
386 |
|
387 |
stackitem* copy(stackitem* in_item) |
388 |
{ |
389 |
stackitem *out_item= malloc(sizeof(stackitem)); |
390 |
|
391 |
memcpy(out_item, in_item, sizeof(stackitem)); |
392 |
out_item->next= NULL; |
393 |
|
394 |
return out_item; |
395 |
} |
396 |
|
397 |
/* Recall a value from a symbol, if bound */ |
398 |
extern void rcl(environment *env) |
399 |
{ |
400 |
value *val; |
401 |
|
402 |
if(env->head == NULL) { |
403 |
printerr("Too Few Arguments"); |
404 |
env->err=1; |
405 |
return; |
406 |
} |
407 |
|
408 |
if(env->head->item->type!=symb) { |
409 |
printerr("Bad Argument Type"); |
410 |
env->err=2; |
411 |
return; |
412 |
} |
413 |
|
414 |
val=((symbol *)(env->head->item->content.ptr))->val; |
415 |
if(val == NULL){ |
416 |
printerr("Unbound Variable"); |
417 |
env->err=3; |
418 |
return; |
419 |
} |
420 |
toss(env); /* toss the symbol */ |
421 |
if(env->err) return; |
422 |
push_val(&(env->head), val); /* Return its bound value */ |
423 |
} |
424 |
|
425 |
/* If the top element is a symbol, determine if it's bound to a |
426 |
function value, and if it is, toss the symbol and execute the |
427 |
function. */ |
428 |
extern void eval(environment *env) |
429 |
{ |
430 |
funcp in_func; |
431 |
if(env->head==NULL) { |
432 |
printerr("Too Few Arguments"); |
433 |
env->err=1; |
434 |
return; |
435 |
} |
436 |
|
437 |
/* if it's a symbol */ |
438 |
if(env->head->item->type==symb) { |
439 |
|
440 |
rcl(env); /* get its contents */ |
441 |
if(env->err) return; |
442 |
if(env->head->item->type!=symb){ /* don't recurse symbols */ |
443 |
eval(env); /* evaluate the value */ |
444 |
return; |
445 |
} |
446 |
} |
447 |
|
448 |
/* If it's a lone function value, run it */ |
449 |
if(env->head->item->type==func) { |
450 |
in_func= (funcp)(env->head->item->content.ptr); |
451 |
toss(env); |
452 |
if(env->err) return; |
453 |
(*in_func)(env); |
454 |
} |
455 |
} |
456 |
|
457 |
/* Reverse a list */ |
458 |
extern void rev(environment *env){ |
459 |
stackitem *old_head, *new_head, *item; |
460 |
|
461 |
if((env->head)==NULL) { |
462 |
printerr("Too Few Arguments"); |
463 |
env->err=1; |
464 |
return; |
465 |
} |
466 |
|
467 |
if(env->head->item->type!=list) { |
468 |
printerr("Bad Argument Type"); |
469 |
env->err=2; |
470 |
return; |
471 |
} |
472 |
|
473 |
old_head=(stackitem *)(env->head->item->content.ptr); |
474 |
new_head=NULL; |
475 |
while(old_head != NULL){ |
476 |
item=old_head; |
477 |
old_head=old_head->next; |
478 |
item->next=new_head; |
479 |
new_head=item; |
480 |
} |
481 |
env->head->item->content.ptr=new_head; |
482 |
} |
483 |
|
484 |
/* Make a list. */ |
485 |
extern void pack(environment *env) |
486 |
{ |
487 |
void* delimiter; |
488 |
stackitem *iterator, *temp; |
489 |
value *pack; |
490 |
|
491 |
delimiter= env->head->item->content.ptr; /* Get delimiter */ |
492 |
toss(env); |
493 |
|
494 |
iterator= env->head; |
495 |
|
496 |
if(iterator==NULL || iterator->item->content.ptr==delimiter) { |
497 |
temp= NULL; |
498 |
toss(env); |
499 |
} else { |
500 |
/* Search for first delimiter */ |
501 |
while(iterator->next!=NULL |
502 |
&& iterator->next->item->content.ptr!=delimiter) |
503 |
iterator= iterator->next; |
504 |
|
505 |
/* Extract list */ |
506 |
temp= env->head; |
507 |
env->head= iterator->next; |
508 |
iterator->next= NULL; |
509 |
|
510 |
if(env->head!=NULL) |
511 |
toss(env); |
512 |
} |
513 |
|
514 |
/* Push list */ |
515 |
pack= malloc(sizeof(value)); |
516 |
pack->type= list; |
517 |
pack->content.ptr= temp; |
518 |
pack->refcount= 1; |
519 |
|
520 |
temp= malloc(sizeof(stackitem)); |
521 |
temp->item= pack; |
522 |
|
523 |
push(&(env->head), temp); |
524 |
rev(env); |
525 |
} |
526 |
|
527 |
/* Parse input. */ |
528 |
void stack_read(environment *env, char *in_line) |
529 |
{ |
530 |
char *temp, *rest; |
531 |
int itemp; |
532 |
size_t inlength= strlen(in_line)+1; |
533 |
int convert= 0; |
534 |
static int non_eval_flag= 0; |
535 |
|
536 |
temp= malloc(inlength); |
537 |
rest= malloc(inlength); |
538 |
|
539 |
do { |
540 |
/* If comment */ |
541 |
if((convert= sscanf(in_line, "#%[^\n\r]", rest))) { |
542 |
free(temp); free(rest); |
543 |
return; |
544 |
} |
545 |
|
546 |
/* If string */ |
547 |
if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) { |
548 |
push_cstring(&(env->head), temp); |
549 |
break; |
550 |
} |
551 |
/* If integer */ |
552 |
if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) { |
553 |
push_int(&(env->head), itemp); |
554 |
break; |
555 |
} |
556 |
/* Escape ';' with '\' */ |
557 |
if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) { |
558 |
temp[1]= '\0'; |
559 |
push_sym(env, temp); |
560 |
break; |
561 |
} |
562 |
/* If symbol */ |
563 |
if((convert= sscanf(in_line, "%[^][ ;\n\r]%[^\n\r]", temp, rest))) { |
564 |
push_sym(env, temp); |
565 |
break; |
566 |
} |
567 |
/* If single char */ |
568 |
if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) { |
569 |
if(*temp==';') { |
570 |
if(!non_eval_flag) { |
571 |
eval(env); /* Evaluate top element */ |
572 |
break; |
573 |
} |
574 |
|
575 |
push_sym(env, ";"); |
576 |
break; |
577 |
} |
578 |
|
579 |
if(*temp==']') { |
580 |
push_sym(env, "["); |
581 |
pack(env); |
582 |
if(non_eval_flag!=0) |
583 |
non_eval_flag--; |
584 |
break; |
585 |
} |
586 |
|
587 |
if(*temp=='[') { |
588 |
push_sym(env, "["); |
589 |
non_eval_flag++; |
590 |
break; |
591 |
} |
592 |
} |
593 |
} while(0); |
594 |
|
595 |
free(temp); |
596 |
|
597 |
if(convert<2) { |
598 |
free(rest); |
599 |
return; |
600 |
} |
601 |
|
602 |
stack_read(env, rest); |
603 |
|
604 |
free(rest); |
605 |
} |
606 |
|
607 |
/* Relocate elements of the list on the stack. */ |
608 |
extern void expand(environment *env) |
609 |
{ |
610 |
stackitem *temp, *new_head; |
611 |
|
612 |
/* Is top element a list? */ |
613 |
if(env->head==NULL) { |
614 |
printerr("Too Few Arguments"); |
615 |
env->err=1; |
616 |
return; |
617 |
} |
618 |
if(env->head->item->type!=list) { |
619 |
printerr("Bad Argument Type"); |
620 |
env->err=2; |
621 |
return; |
622 |
} |
623 |
|
624 |
rev(env); |
625 |
|
626 |
if(env->err) |
627 |
return; |
628 |
|
629 |
/* The first list element is the new stack head */ |
630 |
new_head= temp= env->head->item->content.ptr; |
631 |
|
632 |
env->head->item->refcount++; |
633 |
toss(env); |
634 |
|
635 |
/* Find the end of the list */ |
636 |
while(temp->next!=NULL) |
637 |
temp= temp->next; |
638 |
|
639 |
/* Connect the tail of the list with the old stack head */ |
640 |
temp->next= env->head; |
641 |
env->head= new_head; /* ...and voila! */ |
642 |
|
643 |
} |
644 |
|
645 |
/* Compares two elements by reference. */ |
646 |
extern void eq(environment *env) |
647 |
{ |
648 |
void *left, *right; |
649 |
int result; |
650 |
|
651 |
if((env->head)==NULL || env->head->next==NULL) { |
652 |
printerr("Too Few Arguments"); |
653 |
env->err=1; |
654 |
return; |
655 |
} |
656 |
|
657 |
left= env->head->item->content.ptr; |
658 |
swap(env); |
659 |
right= env->head->item->content.ptr; |
660 |
result= (left==right); |
661 |
|
662 |
toss(env); toss(env); |
663 |
push_int(&(env->head), result); |
664 |
} |
665 |
|
666 |
/* Negates the top element on the stack. */ |
667 |
extern void not(environment *env) |
668 |
{ |
669 |
int val; |
670 |
|
671 |
if((env->head)==NULL) { |
672 |
printerr("Too Few Arguments"); |
673 |
env->err=1; |
674 |
return; |
675 |
} |
676 |
|
677 |
if(env->head->item->type!=integer) { |
678 |
printerr("Bad Argument Type"); |
679 |
env->err=2; |
680 |
return; |
681 |
} |
682 |
|
683 |
val= env->head->item->content.val; |
684 |
toss(env); |
685 |
push_int(&(env->head), !val); |
686 |
} |
687 |
|
688 |
/* Compares the two top elements on the stack and return 0 if they're the |
689 |
same. */ |
690 |
extern void neq(environment *env) |
691 |
{ |
692 |
eq(env); |
693 |
not(env); |
694 |
} |
695 |
|
696 |
/* Give a symbol some content. */ |
697 |
extern void def(environment *env) |
698 |
{ |
699 |
symbol *sym; |
700 |
|
701 |
/* Needs two values on the stack, the top one must be a symbol */ |
702 |
if(env->head==NULL || env->head->next==NULL) { |
703 |
printerr("Too Few Arguments"); |
704 |
env->err=1; |
705 |
return; |
706 |
} |
707 |
|
708 |
if(env->head->item->type!=symb) { |
709 |
printerr("Bad Argument Type"); |
710 |
env->err=2; |
711 |
return; |
712 |
} |
713 |
|
714 |
/* long names are a pain */ |
715 |
sym=env->head->item->content.ptr; |
716 |
|
717 |
/* if the symbol was bound to something else, throw it away */ |
718 |
if(sym->val != NULL) |
719 |
free_val(sym->val); |
720 |
|
721 |
/* Bind the symbol to the value */ |
722 |
sym->val= env->head->next->item; |
723 |
sym->val->refcount++; /* Increase the reference counter */ |
724 |
|
725 |
toss(env); toss(env); |
726 |
} |
727 |
|
728 |
/* Quit stack. */ |
729 |
extern void quit(environment *env) |
730 |
{ |
731 |
exit(EXIT_SUCCESS); |
732 |
} |
733 |
|
734 |
/* Clear stack */ |
735 |
extern void clear(environment *env) |
736 |
{ |
737 |
while(env->head!=NULL) |
738 |
toss(env); |
739 |
} |
740 |
|
741 |
/* List all defined words */ |
742 |
extern void words(environment *env) |
743 |
{ |
744 |
symbol *temp; |
745 |
int i; |
746 |
|
747 |
for(i= 0; i<HASHTBLSIZE; i++) { |
748 |
temp= env->symbols[i]; |
749 |
while(temp!=NULL) { |
750 |
printf("%s\n", temp->id); |
751 |
temp= temp->next; |
752 |
} |
753 |
} |
754 |
} |
755 |
|
756 |
/* Forgets a symbol (remove it from the hash table) */ |
757 |
extern void forget(environment *env) |
758 |
{ |
759 |
char* sym_id; |
760 |
stackitem *stack_head= env->head; |
761 |
symbol **hash_entry, *temp; |
762 |
|
763 |
if(stack_head==NULL) { |
764 |
printerr("Too Few Arguments"); |
765 |
env->err=1; |
766 |
return; |
767 |
} |
768 |
|
769 |
if(stack_head->item->type!=symb) { |
770 |
printerr("Bad Argument Type"); |
771 |
env->err=2; |
772 |
return; |
773 |
} |
774 |
|
775 |
sym_id= ((symbol*)(stack_head->item->content.ptr))->id; |
776 |
toss(env); |
777 |
|
778 |
hash_entry= hash(env->symbols, sym_id); |
779 |
temp= *hash_entry; |
780 |
*hash_entry= (*hash_entry)->next; |
781 |
|
782 |
if(temp->val!=NULL) { |
783 |
free_val(temp->val); |
784 |
} |
785 |
free(temp->id); |
786 |
free(temp); |
787 |
} |
788 |
|
789 |
/* Returns the current error number to the stack */ |
790 |
extern void errn(environment *env){ |
791 |
push_int(&(env->head), env->err); |
792 |
} |
793 |
|
794 |
int main() |
795 |
{ |
796 |
environment myenv; |
797 |
char in_string[100]; |
798 |
|
799 |
init_env(&myenv); |
800 |
|
801 |
printf("okidok\n "); |
802 |
|
803 |
while(fgets(in_string, 100, stdin) != NULL) { |
804 |
stack_read(&myenv, in_string); |
805 |
if(myenv.err) { |
806 |
printf("(error %d) ", myenv.err); |
807 |
myenv.err=0; |
808 |
} |
809 |
printf("okidok\n "); |
810 |
} |
811 |
quit(&myenv); |
812 |
return EXIT_FAILURE; |
813 |
} |