/[cvs]/stack/stack.c
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revision 1.29 by teddy, Tue Feb 5 12:14:42 2002 UTC revision 1.34 by masse, Tue Feb 5 23:26:46 2002 UTC
# Line 58  typedef struct stackitem_struct Line 58  typedef struct stackitem_struct
58  typedef struct {  typedef struct {
59    stackitem *head;              /* Head of the stack */    stackitem *head;              /* Head of the stack */
60    hashtbl symbols;              /* Hash table of all variable bindings */    hashtbl symbols;              /* Hash table of all variable bindings */
61      int err;                      /* Error flag */
62  } environment;  } environment;
63    
64  /* A type for pointers to external functions */  /* A type for pointers to external functions */
# Line 178  int push_sym(environment *env, const cha Line 179  int push_sym(environment *env, const cha
179    new_symbol= hash(env->symbols, in_string);    new_symbol= hash(env->symbols, in_string);
180    new_value->content.ptr= *new_symbol;    new_value->content.ptr= *new_symbol;
181    
182    if(new_value->content.ptr==NULL) { /* If symbol was undefined */    if(*new_symbol==NULL) { /* If symbol was undefined */
183    
184      /* Create a new symbol */      /* Create a new symbol */
185      *new_symbol= malloc(sizeof(symbol));      (*new_symbol)= malloc(sizeof(symbol));
186      (*new_symbol)->val= NULL;   /* undefined value */      (*new_symbol)->val= NULL;   /* undefined value */
187      (*new_symbol)->next= NULL;      (*new_symbol)->next= NULL;
188      (*new_symbol)->id= malloc(strlen(in_string)+1);      (*new_symbol)->id= malloc(strlen(in_string)+1);
# Line 348  stackitem* copy(stackitem* in_item) Line 349  stackitem* copy(stackitem* in_item)
349    return out_item;    return out_item;
350  }  }
351    
352    /* Recall a value from a symbol, if bound */
353    extern void rcl(environment *env)
354    {
355      value *val;
356    
357      if(env->head == NULL) {
358        printerr("Stack empty");
359        return;
360      }
361    
362      if(env->head->item->type!=symb) {
363        printerr("Not a symbol");
364        return;
365      }
366      val=((symbol *)(env->head->item->content.ptr))->val;
367      if(val == NULL){
368        printerr("Unbound variable");
369        return;
370      }
371      toss(env);            /* toss the symbol */
372      push_val(&(env->head), val); /* Return its bound value */
373    }
374    
375  /* If the top element is a symbol, determine if it's bound to a  /* If the top element is a symbol, determine if it's bound to a
376     function value, and if it is, toss the symbol and execute the     function value, and if it is, toss the symbol and execute the
# Line 392  extern void eval(environment *env) Line 415  extern void eval(environment *env)
415      return;      return;
416    }    }
417    
 /*    push(&(env->head), copy(env->head)); */  
 /*    swap(env); */  
 /*    toss(env); */  
418  }  }
419    
420  /* Make a list. */  /* Make a list. */
# Line 469  int stack_read(environment *env, char *i Line 489  int stack_read(environment *env, char *i
489        break;        break;
490      }      }
491      /* If symbol */      /* If symbol */
492      if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {      if((convert= sscanf(in_line, "%[^][ ;\n\r]%[^\n\r]", temp, rest))) {
493          push_sym(env, temp);          push_sym(env, temp);
494          break;          break;
495      }      }
# Line 624  extern void clear(environment *env) Line 644  extern void clear(environment *env)
644      toss(env);      toss(env);
645  }  }
646    
647    /* List all defined words */
648    extern void words(environment *env)
649    {
650      symbol *temp;
651      int i;
652      
653      for(i= 0; i<HASHTBLSIZE; i++) {
654        temp= env->symbols[i];
655        while(temp!=NULL) {
656          printf("%s\n", temp->id);
657          temp= temp->next;
658        }
659      }
660    }
661    
662    /* Forgets a symbol (remove it from the hash table) */
663    extern void forget(environment *env)
664    {
665      char* sym_id;
666      stackitem *stack_head= env->head;
667      symbol **hash_entry, *temp;
668    
669      if(stack_head==NULL || stack_head->item->type!=symb) {
670        printerr("Stack empty or not a symbol");
671        return;
672      }
673    
674      sym_id= ((symbol*)(stack_head->item->content.ptr))->id;
675      toss(env);
676    
677      hash_entry= hash(env->symbols, sym_id);
678      temp= *hash_entry;
679      *hash_entry= (*hash_entry)->next;
680      
681      if(temp->val!=NULL) {
682        free_val(temp->val);
683      }
684      free(temp->id);
685      free(temp);
686    }
687    
688  int main()  int main()
689  {  {
690    environment myenv;    environment myenv;
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