/[cvs]/stack/stack.c
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revision 1.14 by masse, Thu Jan 31 19:51:12 2002 UTC revision 1.31 by teddy, Tue Feb 5 22:25:04 2002 UTC
# Line 6  Line 6 
6  #include <stddef.h>  #include <stddef.h>
7  /* dlopen, dlsym, dlerror */  /* dlopen, dlsym, dlerror */
8  #include <dlfcn.h>  #include <dlfcn.h>
9    /* assert */
10    #include <assert.h>
11    
12  #define HASHTBLSIZE 65536  #define HASHTBLSIZE 65536
13    
14  typedef struct stack_item  /* First, define some types. */
 {  
   enum {value, string, ref, func, symbol, list} type;  
   union {  
     void* ptr;  
     int val;  
   } content;  
15    
16    char* id;  /* A value of some type */
17    struct stack_item* next;  typedef struct {
18  } stackitem;    enum {
19        integer,
20        string,
21        ref,                        /* Reference (to an element in the
22                                       hash table) */
23        func,                       /* Function pointer */
24        symb,
25        list
26      } type;                       /* Type of stack element */
27    
28      union {
29        void *ptr;                  /* Pointer to the content */
30        int val;                    /* ...or an integer */
31      } content;                    /* Stores a pointer or an integer */
32    
33      int refcount;                 /* Reference counter */
34    
35    } value;
36    
37    /* A symbol with a name and possible value */
38    /* (These do not need reference counters, they are kept unique by
39       hashing.) */
40    typedef struct symbol_struct {
41      char *id;                     /* Symbol name */
42      value *val;                   /* The value (if any) bound to it */
43      struct symbol_struct *next;   /* In case of hashing conflicts, a */
44    } symbol;                       /* symbol is a kind of stack item. */
45    
46    /* A type for a hash table for symbols */
47    typedef symbol *hashtbl[HASHTBLSIZE]; /* Hash table declaration */
48    
49  typedef stackitem* hashtbl[HASHTBLSIZE];  /* An item (value) on a stack */
50  typedef void (*funcp)(stackitem**);  typedef struct stackitem_struct
51    {
52      value *item;                  /* The value on the stack */
53      struct stackitem_struct *next; /* Next item */
54    } stackitem;
55    
56    /* An environment; gives access to the stack and a hash table of
57       defined symbols */
58    typedef struct {
59      stackitem *head;              /* Head of the stack */
60      hashtbl symbols;              /* Hash table of all variable bindings */
61    } environment;
62    
63    /* A type for pointers to external functions */
64    typedef void (*funcp)(environment *); /* funcp is a pointer to a void
65                                             function (environment *) */
66    
67  /* Initiates a newly created hash table. */  /* Initialize a newly created environment */
68  void init_hashtbl(hashtbl out_hash)  void init_env(environment *env)
69  {  {
70    long i;    long i;
71    
72    for(i= 0; i<HASHTBLSIZE; i++)    for(i= 0; i<HASHTBLSIZE; i++)
73      out_hash[i]= NULL;      env->symbols[i]= NULL;
74  }  }
75    
76  /* Returns a pointer to an element in the hash table. */  /* Returns a pointer to a pointer to an element in the hash table. */
77  stackitem** hash(hashtbl in_hashtbl, const char* in_string)  symbol **hash(hashtbl in_hashtbl, const char *in_string)
78  {  {
79    long i= 0;    long i= 0;
80    unsigned long out_hash= 0;    unsigned long out_hash= 0;
81    char key= 0;    char key= '\0';
82    stackitem** position;    symbol **position;
83        
84    while(1){    while(1){                     /* Hash in_string */
85      key= in_string[i++];      key= in_string[i++];
86      if(key=='\0')      if(key=='\0')
87        break;        break;
# Line 54  stackitem** hash(hashtbl in_hashtbl, con Line 92  stackitem** hash(hashtbl in_hashtbl, con
92    position= &(in_hashtbl[out_hash]);    position= &(in_hashtbl[out_hash]);
93    
94    while(1){    while(1){
95      if(*position==NULL)      if(*position==NULL)         /* If empty */
96        return position;        return position;
97            
98      if(strcmp(in_string, (*position)->id)==0)      if(strcmp(in_string, (*position)->id)==0) /* If match */
99        return position;        return position;
100    
101      position= &((*position)->next);      position= &((*position)->next); /* Try next */
102    }    }
103  }  }
104    
# Line 72  int push(stackitem** stack_head, stackit Line 110  int push(stackitem** stack_head, stackit
110    return 1;    return 1;
111  }  }
112    
113  /* Push a value on the stack. */  /* Push a value onto the stack */
114  int push_val(stackitem** stack_head, int in_val)  void push_val(stackitem **stack_head, value *val)
115  {  {
116    stackitem* new_item= malloc(sizeof(stackitem));    stackitem *new_item= malloc(sizeof(stackitem));
117    new_item->content.val= in_val;    new_item->item= val;
118    new_item->type= value;    val->refcount++;
   
119    push(stack_head, new_item);    push(stack_head, new_item);
   return 1;  
120  }  }
121    
122  /* Copy a string onto the stack. */  /* Push an integer onto the stack. */
123  int push_cstring(stackitem** stack_head, const char* in_string)  int push_int(stackitem **stack_head, int in_val)
124  {  {
125    stackitem* new_item= malloc(sizeof(stackitem));    value *new_value= malloc(sizeof(value));
126    new_item->content.ptr= malloc(strlen(in_string)+1);    stackitem *new_item= malloc(sizeof(stackitem));
127    strcpy(new_item->content.ptr, in_string);    new_item->item= new_value;
128    new_item->type= string;    
129      new_value->content.val= in_val;
130      new_value->type= integer;
131      new_value->refcount=1;
132    
133    push(stack_head, new_item);    push(stack_head, new_item);
134    return 1;    return 1;
135  }  }
136    
137  /* Create a new hash entry. */  /* Copy a string onto the stack. */
138  int mk_hashentry(hashtbl in_hashtbl, stackitem* in_item, const char* id)  int push_cstring(stackitem **stack_head, const char *in_string)
139  {  {
140    in_item->id= malloc(strlen(id)+1);    value *new_value= malloc(sizeof(value));
141      stackitem *new_item= malloc(sizeof(stackitem));
142    strcpy(in_item->id, id);    new_item->item=new_value;
143    push(hash(in_hashtbl, id), in_item);  
144      new_value->content.ptr= malloc(strlen(in_string)+1);
145      strcpy(new_value->content.ptr, in_string);
146      new_value->type= string;
147      new_value->refcount=1;
148    
149      push(stack_head, new_item);
150    return 1;    return 1;
151  }  }
152    
153  /* Define a function a new function in the hash table. */  /* Push a symbol onto the stack. */
154  void def_func(hashtbl in_hashtbl, funcp in_func, const char* id)  int push_sym(environment *env, const char *in_string)
155  {  {
156    stackitem* temp= malloc(sizeof(stackitem));    stackitem *new_item;          /* The new stack item */
157      /* ...which will contain... */
158    temp->type= func;    value *new_value;             /* A new symbol value */
159    temp->content.ptr= in_func;    /* ...which might point to... */
160      symbol **new_symbol;          /* (if needed) A new actual symbol */
161    mk_hashentry(in_hashtbl, temp, id);    /* ...which, if possible, will be bound to... */
162      value *new_fvalue;            /* (if needed) A new function value */
163      /* ...which will point to... */
164      void *funcptr;                /* A function pointer */
165    
166      static void *handle= NULL;    /* Dynamic linker handle */
167    
168      /* Create a new stack item containing a new value */
169      new_item= malloc(sizeof(stackitem));
170      new_value= malloc(sizeof(value));
171      new_item->item=new_value;
172    
173      /* The new value is a symbol */
174      new_value->type= symb;
175      new_value->refcount= 1;
176    
177      /* Look up the symbol name in the hash table */
178      new_symbol= hash(env->symbols, in_string);
179      new_value->content.ptr= *new_symbol;
180    
181      if(*new_symbol==NULL) { /* If symbol was undefined */
182    
183        /* Create a new symbol */
184        (*new_symbol)= malloc(sizeof(symbol));
185        (*new_symbol)->val= NULL;   /* undefined value */
186        (*new_symbol)->next= NULL;
187        (*new_symbol)->id= malloc(strlen(in_string)+1);
188        strcpy((*new_symbol)->id, in_string);
189    
190        /* Intern the new symbol in the hash table */
191        new_value->content.ptr= *new_symbol;
192    
193        /* Try to load the symbol name as an external function, to see if
194           we should bind the symbol to a new function pointer value */
195        if(handle==NULL)            /* If no handle */
196          handle= dlopen(NULL, RTLD_LAZY);
197    
198        funcptr= dlsym(handle, in_string); /* Get function pointer */
199        if(dlerror()==NULL) {       /* If a function was found */
200          new_fvalue= malloc(sizeof(value)); /* Create a new value */
201          new_fvalue->type=func;    /* The new value is a function pointer */
202          new_fvalue->content.ptr=funcptr; /* Store function pointer */
203          (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
204                                             function value */
205          new_fvalue->refcount= 1;
206        }
207      }
208      push(&(env->head), new_item);
209      return 1;
210  }  }
211    
212  /* Define a new symbol in the hash table. */  void printerr(const char* in_string) {
213  void def_sym(hashtbl in_hashtbl, const char* id)    fprintf(stderr, "Err: %s\n", in_string);
 {  
   stackitem* temp= malloc(sizeof(stackitem));  
     
   temp->type= symbol;  
   
   mk_hashentry(in_hashtbl, temp, id);  
214  }  }
215    
216  /* Push a reference to an entry in the hash table onto the stack. */  /* Throw away a value */
217  int push_ref(stackitem** stack_head, hashtbl in_hash, const char* in_string)  void free_val(value *val){
218  {    stackitem *item, *temp;
219    static void* handle= NULL;  
220    void* symbol;    val->refcount--;              /* Decrease the reference count */
221      if(val->refcount == 0){
222    stackitem* new_item= malloc(sizeof(stackitem));      switch (val->type){         /* and free the contents if necessary */
223    new_item->content.ptr= *hash(in_hash, in_string);      case string:
224    new_item->type= ref;        free(val->content.ptr);
225        case list:                  /* lists needs to be freed recursively */
226    if(new_item->content.ptr==NULL) {        item=val->content.ptr;
227      if(handle==NULL)        while(item != NULL) {     /* for all stack items */
228        handle= dlopen(NULL, RTLD_LAZY);              free_val(item->item);   /* free the value */
229            temp=item->next;        /* save next ptr */
230      symbol= dlsym(handle, in_string);          free(item);             /* free the stackitem */
231      if(dlerror()==NULL)          item=temp;              /* go to next stackitem */
232        def_func(in_hash, symbol, in_string);        }
233      else        free(val);                /* Free the actual list value */
234        def_sym(in_hash, in_string);        break;
235              default:
236      new_item->content.ptr= *hash(in_hash, in_string);        break;
237      new_item->type= ref;      }
238    }    }
   
   push(stack_head, new_item);  
   return 1;  
239  }  }
240    
241  /* Discard the top element of the stack. */  /* Discard the top element of the stack. */
242  extern void toss(stackitem** stack_head)  extern void toss(environment *env)
243  {  {
244    stackitem* temp= *stack_head;    stackitem *temp= env->head;
245    
246    if((*stack_head)==NULL)    if((env->head)==NULL) {
247        printerr("Stack empty");
248      return;      return;
249      }
250        
251    if((*stack_head)->type==string)    free_val(env->head->item);    /* Free the value */
252      free((*stack_head)->content.ptr);    env->head= env->head->next;   /* Remove the top stack item */
253      free(temp);                   /* Free the old top stack item */
   *stack_head= (*stack_head)->next;  
   free(temp);  
254  }  }
255    
256  /* Print newline. */  /* Print newline. */
# Line 177  extern void nl() Line 260  extern void nl()
260  }  }
261    
262  /* Prints the top element of the stack. */  /* Prints the top element of the stack. */
263  void print_(stackitem** stack_head)  void print_h(stackitem *stack_head)
264  {  {
265    if((*stack_head)==NULL)  
266      if(stack_head==NULL) {
267        printerr("Stack empty");
268      return;      return;
269      }
270    
271    switch((*stack_head)->type) {    switch(stack_head->item->type) {
272    case value:    case integer:
273      printf("%d", (*stack_head)->content.val);      printf("%d", stack_head->item->content.val);
274      break;      break;
275    case string:    case string:
276      printf("%s", (char*)(*stack_head)->content.ptr);      printf("\"%s\"", (char*)stack_head->item->content.ptr);
277      break;      break;
278    case ref:    case symb:
279      printf("%s", ((stackitem*)(*stack_head)->content.ptr)->id);      printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
280      break;      break;
   case symbol:  
281    default:    default:
282      printf("%p", (*stack_head)->content.ptr);      printf("%p", (funcp)(stack_head->item->content.ptr));
283      break;      break;
284    }    }
285  }  }
286    
287    extern void print_(environment *env) {
288      print_h(env->head);
289    }
290    
291  /* Prints the top element of the stack and then discards it. */  /* Prints the top element of the stack and then discards it. */
292  extern void print(stackitem** stack_head)  extern void print(environment *env)
293  {  {
294    print_(stack_head);    print_(env);
295    toss(stack_head);    toss(env);
296  }  }
297    
298  /* Only to be called by function printstack. */  /* Only to be called by function printstack. */
299  void print_st(stackitem* stack_head, long counter)  void print_st(stackitem *stack_head, long counter)
300  {  {
301    if(stack_head->next != NULL)    if(stack_head->next != NULL)
302      print_st(stack_head->next, counter+1);      print_st(stack_head->next, counter+1);
   
303    printf("%ld: ", counter);    printf("%ld: ", counter);
304    print_(&stack_head);    print_h(stack_head);
305    nl();    nl();
306  }  }
307    
308    
309    
310  /* Prints the stack. */  /* Prints the stack. */
311  extern void printstack(stackitem** stack_head)  extern void printstack(environment *env)
312    {
313      if(env->head != NULL) {
314        print_st(env->head, 1);
315        nl();
316      } else {
317        printerr("Stack empty");
318      }
319    }
320    
321    /* Swap the two top elements on the stack. */
322    extern void swap(environment *env)
323  {  {
324    if(*stack_head != NULL) {    stackitem *temp= env->head;
325      print_st(*stack_head, 1);    
326      printf("\n");    if((env->head)==NULL) {
327        printerr("Stack empty");
328        return;
329    }    }
330    
331      if(env->head->next==NULL) {
332        printerr("Not enough arguments");
333        return;
334      }
335    
336      env->head= env->head->next;
337      temp->next= env->head->next;
338      env->head->next= temp;
339    }
340    
341    stackitem* copy(stackitem* in_item)
342    {
343      stackitem *out_item= malloc(sizeof(stackitem));
344    
345      memcpy(out_item, in_item, sizeof(stackitem));
346      out_item->next= NULL;
347    
348      return out_item;
349  }  }
350    
351  /* If the top element is a reference, determine if it's a reference to a  extern void rcl(environment *env)
352     function, and if it is execute and pop the reference and execute the  {
353      value *val;
354    
355      if(env->head == NULL) {
356        printerr("Stack empty");
357        return;
358      }
359    
360      if(env->head->item->type!=symb) {
361        printerr("Not a symbol");
362        return;
363      }
364      val=((symbol *)(env->head->item->content.ptr))->val;
365      toss(env);            /* toss the symbol */
366      push_val(&(env->head), val); /* Return its bound value */
367    }
368    
369    /* If the top element is a symbol, determine if it's bound to a
370       function value, and if it is, toss the symbol and execute the
371     function. */     function. */
372  extern void eval(stackitem** stack_head)  extern void eval(environment *env)
373  {  {
374    funcp in_func;    funcp in_func;
375      value* val;
376    if((*stack_head)==NULL || (*stack_head)->type!=ref)    if(env->head==NULL) {
377        printerr("Stack empty");
378      return;      return;
379      }
380    
381      /* if it's a symbol */
382      if(env->head->item->type==symb) {
383    
384        /* If it's not bound to anything */
385        if (((symbol *)(env->head->item->content.ptr))->val == NULL) {
386          printerr("Unbound variable");
387          return;
388        }
389        
390        /* If it contains a function */
391        if (((symbol *)(env->head->item->content.ptr))->val->type == func) {
392          in_func=
393            (funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);
394          toss(env);
395          (*in_func)(env);          /* Run the function */
396          return;
397        } else {                    /* If it's not a function */
398          val=((symbol *)(env->head->item->content.ptr))->val;
399          toss(env);                /* toss the symbol */
400          push_val(&(env->head), val); /* Return its bound value */
401        }
402      }
403    
404    if(((stackitem*)(*stack_head)->content.ptr)->type==func) {    /* If it's a lone function value, run it */
405      in_func= (funcp)((stackitem*)(*stack_head)->content.ptr)->content.ptr;    if(env->head->item->type==func) {
406      toss(stack_head);      in_func= (funcp)(env->head->item->content.ptr);
407      (*in_func)(stack_head);      toss(env);
408        (*in_func)(env);
409      return;      return;
410    }    }
411    
412    }
413    
414    /* Make a list. */
415    extern void pack(environment *env)
416    {
417      void* delimiter;
418      stackitem *iterator, *temp;
419      value *pack;
420    
421      delimiter= env->head->item->content.ptr; /* Get delimiter */
422      toss(env);
423    
424      iterator= env->head;
425    
426      if(iterator==NULL || iterator->item->content.ptr==delimiter) {
427        temp= NULL;
428        toss(env);
429      } else {
430        /* Search for first delimiter */
431        while(iterator->next!=NULL
432              && iterator->next->item->content.ptr!=delimiter)
433          iterator= iterator->next;
434        
435        /* Extract list */
436        temp= env->head;
437        env->head= iterator->next;
438        iterator->next= NULL;
439        
440        if(env->head!=NULL)
441          toss(env);
442      }
443    
444      /* Push list */
445      pack= malloc(sizeof(value));
446      pack->type= list;
447      pack->content.ptr= temp;
448      pack->refcount= 1;
449    
450      temp= malloc(sizeof(stackitem));
451      temp->item= pack;
452    
453      push(&(env->head), temp);
454  }  }
455    
456  /* Parse input. */  /* Parse input. */
457  int stack_read(stackitem** stack_head, hashtbl in_hash, char* in_line)  int stack_read(environment *env, char *in_line)
458  {  {
459    char *temp, *rest;    char *temp, *rest;
460    int itemp;    int itemp;
461    size_t inlength= strlen(in_line)+1;    size_t inlength= strlen(in_line)+1;
462    int convert= 0;    int convert= 0;
463      static int non_eval_flag= 0;
464    
465    temp= malloc(inlength);    temp= malloc(inlength);
466    rest= malloc(inlength);    rest= malloc(inlength);
467    
468    if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest)) >= 1)    do {
469      push_cstring(stack_head, temp);      /* If string */
470    else if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest)) >= 1)      if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
471      push_val(stack_head, itemp);        push_cstring(&(env->head), temp);
472    else if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest)) >= 1) {        break;
473      temp[1]= '\0'; push_ref(stack_head, in_hash, temp);      }
474    } else if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest)) >= 1)      /* If integer */
475      push_ref(stack_head, in_hash, temp);      if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
476    else if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) >= 1)        push_int(&(env->head), itemp);
477      if(*temp==';')        break;
478        eval(stack_head);      }
479        /* Escape ';' with '\' */
480        if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
481          temp[1]= '\0';
482          push_sym(env, temp);
483          break;
484        }
485        /* If symbol */
486        if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {
487            push_sym(env, temp);
488            break;
489        }
490        /* If single char */
491        if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {
492          if(*temp==';') {
493            if(!non_eval_flag) {
494              eval(env);            /* Evaluate top element */
495              break;
496            }
497            
498            push_sym(env, ";");
499            break;
500          }
501    
502          if(*temp==']') {
503            push_sym(env, "[");
504            pack(env);
505            if(non_eval_flag!=0)
506              non_eval_flag--;
507            break;
508          }
509    
510          if(*temp=='[') {
511            push_sym(env, "[");
512            non_eval_flag++;
513            break;
514          }
515        }
516      } while(0);
517    
518    
519    free(temp);    free(temp);
520    
# Line 274  int stack_read(stackitem** stack_head, h Line 523  int stack_read(stackitem** stack_head, h
523      return 0;      return 0;
524    }    }
525        
526    stack_read(stack_head, in_hash, rest);    stack_read(env, rest);
527        
528    free(rest);    free(rest);
529    return 1;    return 1;
530  }  }
531    
532  /* Make a list. */  /* Relocate elements of the list on the stack. */
533  extern void pack(stackitem** stack_head)  extern void expand(environment *env)
 {  
   void* delimiter;  
   stackitem *iterator, *temp, *pack;  
   
   if((*stack_head)==NULL)  
     return;  
   
   delimiter= (*stack_head)->content.ptr;  
   toss(stack_head);  
   
   iterator= *stack_head;  
   
   while(iterator->next!=NULL && iterator->next->content.ptr!=delimiter)  
     iterator= iterator->next;  
   
   temp= *stack_head;  
   *stack_head= iterator->next;  
   iterator->next= NULL;  
     
   if(*stack_head!=NULL && (*stack_head)->content.ptr==delimiter)  
     toss(stack_head);  
   
   pack= malloc(sizeof(stackitem));  
   pack->type= list;  
   pack->content.ptr= temp;  
   
   push(stack_head, pack);  
 }  
   
 /* Push elements of the list on the stack. */  
 extern void expand(stackitem** stack_head)  
534  {  {
535    stackitem *temp, *new_head;    stackitem *temp, *new_head;
536    
537    if((*stack_head)==NULL || (*stack_head)->type!=list)    /* Is top element a list? */
538      if(env->head==NULL || env->head->item->type!=list) {
539        printerr("Stack empty or not a list");
540      return;      return;
541      }
542    
543    new_head= temp= (*stack_head)->content.ptr;    /* The first list element is the new stack head */
544    toss(stack_head);    new_head= temp= env->head->item->content.ptr;
545    
546      env->head->item->refcount++;
547      toss(env);
548    
549      /* Find the end of the list */
550    while(temp->next!=NULL)    while(temp->next!=NULL)
551      temp= temp->next;      temp= temp->next;
552    
553    temp->next= *stack_head;    /* Connect the tail of the list with the old stack head */
554    *stack_head= new_head;    temp->next= env->head;
555  }    env->head= new_head;          /* ...and voila! */
556    
557  /* 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;  
 }  
558    
559  /* Compares two elements by reference. */  /* Compares two elements by reference. */
560  extern void eq(stackitem** stack_head)  extern void eq(environment *env)
561  {  {
562    void *left, *right;    void *left, *right;
563    int result;    int result;
564    
565    if((*stack_head)==NULL || (*stack_head)->next==NULL)    if((env->head)==NULL || env->head->next==NULL) {
566        printerr("Not enough elements to compare");
567      return;      return;
568      }
569    
570    left= (*stack_head)->content.ptr;    left= env->head->item->content.ptr;
571    swap(stack_head);    swap(env);
572    right= (*stack_head)->content.ptr;    right= env->head->item->content.ptr;
573    result= (left==right);    result= (left==right);
574        
575    toss(stack_head); toss(stack_head);    toss(env); toss(env);
576    push_val(stack_head, (left==right));    push_int(&(env->head), result);
577  }  }
578    
579  /* Negates the top element on the stack. */  /* Negates the top element on the stack. */
580  extern void not(stackitem** stack_head)  extern void not(environment *env)
581  {  {
582    int value;    int val;
583    
584    if((*stack_head)==NULL)    if((env->head)==NULL || env->head->item->type!=integer) {
585        printerr("Stack empty or element is not a integer");
586      return;      return;
587      }
588    
589    value= (*stack_head)->content.val;    val= env->head->item->content.val;
590    toss(stack_head);    toss(env);
591    push_val(stack_head, !value);    push_int(&(env->head), !val);
592  }  }
593    
594  /* Compares the two top elements on the stack and return 0 if they're the  /* Compares the two top elements on the stack and return 0 if they're the
595     same. */     same. */
596  extern void neq(stackitem** stack_head)  extern void neq(environment *env)
597  {  {
598    eq(stack_head);    eq(env);
599    not(stack_head);    not(env);
600  }  }
601    
602  /* Give a symbol some content. */  /* Give a symbol some content. */
603  extern void def(stackitem** stack_head)  extern void def(environment *env)
604  {  {
605    stackitem *temp, *value;    symbol *sym;
606    
607    if(*stack_head==NULL || (*stack_head)->next==NULL    /* Needs two values on the stack, the top one must be a symbol */
608       || (*stack_head)->type!=ref)    if(env->head==NULL || env->head->next==NULL
609         || env->head->item->type!=symb) {
610        printerr("Define what?");
611      return;      return;
612      }
613    
614    temp= (*stack_head)->content.ptr;    /* long names are a pain */
615    value= (*stack_head)->next;    sym=env->head->item->content.ptr;
   temp->content= value->content;  
   value->content.ptr=NULL;  
   temp->type= value->type;  
616    
617    toss(stack_head); toss(stack_head);    /* if the symbol was bound to something else, throw it away */
618      if(sym->val != NULL)
619        free_val(sym->val);
620    
621      /* Bind the symbol to the value */
622      sym->val= env->head->next->item;
623      sym->val->refcount++;         /* Increase the reference counter */
624    
625      toss(env); toss(env);
626  }  }
627    
628  /* Quit stack. */  /* Quit stack. */
629  extern void quit()  extern void quit(environment *env)
630  {  {
631    exit(EXIT_SUCCESS);    exit(EXIT_SUCCESS);
632  }  }
633    
634    /* Clear stack */
635    extern void clear(environment *env)
636    {
637      while(env->head!=NULL)
638        toss(env);
639    }
640    
641  int main()  int main()
642  {  {
643    stackitem* s= NULL;    environment myenv;
   hashtbl myhash;  
644    char in_string[100];    char in_string[100];
645    
646    init_hashtbl(myhash);    init_env(&myenv);
647    
648    printf("okidok\n ");    printf("okidok\n ");
649    
650    while(fgets(in_string, 100, stdin) != NULL) {    while(fgets(in_string, 100, stdin) != NULL) {
651      stack_read(&s, myhash, in_string);      stack_read(&myenv, in_string);
652      printf("okidok\n ");      printf("okidok\n ");
653    }    }
654    
655    exit(EXIT_SUCCESS);    exit(EXIT_SUCCESS);
656  }  }
   
 /* Local Variables: */  
 /* compile-command:"make CFLAGS=\"-Wall -g -rdynamic -ldl\" stack" */  
 /* End: */  
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