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revision 1.33 by teddy, Tue Feb 5 23:00:42 2002 UTC revision 1.130 by masse, Mon Aug 4 14:32:27 2003 UTC
# Line 1  Line 1 
1  /* printf */  /* -*- coding: utf-8; -*- */
2  #include <stdio.h>  /*
3  /* EXIT_SUCCESS */      stack - an interactive interpreter for a stack-based language
4  #include <stdlib.h>      Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn
5  /* NULL */  
6  #include <stddef.h>      This program is free software; you can redistribute it and/or modify
7  /* dlopen, dlsym, dlerror */      it under the terms of the GNU General Public License as published by
8  #include <dlfcn.h>      the Free Software Foundation; either version 2 of the License, or
9  /* assert */      (at your option) any later version.
10  #include <assert.h>  
11        This program is distributed in the hope that it will be useful,
12  #define HASHTBLSIZE 65536      but WITHOUT ANY WARRANTY; without even the implied warranty of
13        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  /* First, define some types. */      GNU General Public License for more details.
15    
16  /* A value of some type */      You should have received a copy of the GNU General Public License
17  typedef struct {      along with this program; if not, write to the Free Software
18    enum {      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19      integer,  
20      string,      Authors: Mats Alritzson <masse@fukt.bth.se>
21      ref,                        /* Reference (to an element in the               Teddy Hogeborn <teddy@fukt.bth.se>
22                                     hash table) */  */
23      func,                       /* Function pointer */  
24      symb,  #include "stack.h"
     list  
   } type;                       /* Type of stack element */  
   
   union {  
     void *ptr;                  /* Pointer to the content */  
     int val;                    /* ...or an integer */  
   } content;                    /* Stores a pointer or an integer */  
   
   int refcount;                 /* Reference counter */  
   
 } value;  
   
 /* A symbol with a name and possible value */  
 /* (These do not need reference counters, they are kept unique by  
    hashing.) */  
 typedef struct symbol_struct {  
   char *id;                     /* Symbol name */  
   value *val;                   /* The value (if any) bound to it */  
   struct symbol_struct *next;   /* In case of hashing conflicts, a */  
 } symbol;                       /* symbol is a kind of stack item. */  
   
 /* A type for a hash table for symbols */  
 typedef symbol *hashtbl[HASHTBLSIZE]; /* Hash table declaration */  
   
 /* An item (value) on a stack */  
 typedef struct stackitem_struct  
 {  
   value *item;                  /* The value on the stack */  
   struct stackitem_struct *next; /* Next item */  
 } stackitem;  
   
 /* An environment; gives access to the stack and a hash table of  
    defined symbols */  
 typedef struct {  
   stackitem *head;              /* Head of the stack */  
   hashtbl symbols;              /* Hash table of all variable bindings */  
   int err;                      /* Error flag */  
 } environment;  
   
 /* A type for pointers to external functions */  
 typedef void (*funcp)(environment *); /* funcp is a pointer to a void  
                                          function (environment *) */  
25    
26  /* Initialize a newly created environment */  /* Initialize a newly created environment */
27  void init_env(environment *env)  void init_env(environment *env)
28  {  {
29    long i;    int i;
30    
31      env->gc_limit= 400000;
32      env->gc_count= 0;
33      env->gc_ref= NULL;
34    
35      env->head= new_val(env);
36    for(i= 0; i<HASHTBLSIZE; i++)    for(i= 0; i<HASHTBLSIZE; i++)
37      env->symbols[i]= NULL;      env->symbols[i]= NULL;
38      env->err= 0;
39      env->in_string= NULL;
40      env->free_string= NULL;
41      env->inputstream= stdin;
42      env->interactive= 1;
43    }
44    
45    void printerr(const char* in_string)
46    {
47      fprintf(stderr, "Err: %s\n", in_string);
48  }  }
49    
50  /* Returns a pointer to a pointer to an element in the hash table. */  /* Returns a pointer to a pointer to an element in the hash table. */
51  symbol **hash(hashtbl in_hashtbl, const char *in_string)  symbol **hash(hashtbl in_hashtbl, const char *in_string)
52  {  {
53    long i= 0;    int i= 0;
54    unsigned long out_hash= 0;    unsigned int out_hash= 0;
55    char key= '\0';    char key= '\0';
56    symbol **position;    symbol **position;
57        
# Line 103  symbol **hash(hashtbl in_hashtbl, const Line 76  symbol **hash(hashtbl in_hashtbl, const
76    }    }
77  }  }
78    
79  /* Generic push function. */  /* Create new value */
80  int push(stackitem** stack_head, stackitem* in_item)  value* new_val(environment *env)
81    {
82      value *nval= malloc(sizeof(value));
83      stackitem *nitem= malloc(sizeof(stackitem));
84    
85      assert(nval != NULL);
86      assert(nitem != NULL);
87    
88      nval->content.ptr= NULL;
89      nval->type= empty;
90    
91      nitem->item= nval;
92      nitem->next= env->gc_ref;
93    
94      env->gc_ref= nitem;
95    
96      env->gc_count += sizeof(value);
97      nval->gc.flag.mark= 0;
98      nval->gc.flag.protect= 0;
99    
100      return nval;
101    }
102    
103    
104    /* Mark values recursively.
105       Marked values are not collected by the GC. */
106    inline void gc_mark(value *val)
107    {
108      if(val==NULL || val->gc.flag.mark)
109        return;
110    
111      val->gc.flag.mark= 1;
112    
113      if(val->type==tcons) {
114        gc_mark(CAR(val));
115        gc_mark(CDR(val));
116      }
117    }
118    
119    
120    /* Start GC */
121    extern void gc_init(environment *env)
122    {
123      stackitem *new_head= NULL, *titem;
124      symbol *tsymb;
125      int i;
126    
127      if(env->interactive)
128        printf("Garbage collecting.");
129    
130      /* Mark values on stack */
131      gc_mark(env->head);
132    
133      if(env->interactive)
134        printf(".");
135    
136    
137      /* Mark values in hashtable */
138      for(i= 0; i<HASHTBLSIZE; i++)
139        for(tsymb= env->symbols[i]; tsymb!=NULL; tsymb= tsymb->next)
140          if (tsymb->val != NULL)
141            gc_mark(tsymb->val);
142    
143    
144      if(env->interactive)
145        printf(".");
146    
147      env->gc_count= 0;
148    
149      while(env->gc_ref!=NULL) {    /* Sweep unused values */
150    
151        if(!(env->gc_ref->item->gc.no_gc)){ /* neither mark nor protect */
152    
153          /* Remove content */
154          switch(env->gc_ref->item->type){
155          case string:
156            free(env->gc_ref->item->content.string);
157            break;
158          case tcons:
159            free(env->gc_ref->item->content.c);
160            break;
161          case port:
162          case empty:
163          case integer:
164          case tfloat:
165          case func:
166          case symb:
167            /* Symbol strings are freed when walking the hash table */
168            break;
169          }
170    
171          free(env->gc_ref->item);  /* Remove from gc_ref */
172          titem= env->gc_ref->next;
173          free(env->gc_ref);        /* Remove value */
174          env->gc_ref= titem;
175          continue;
176        }
177    #ifdef DEBUG
178        printf("Kept value (%p)", env->gc_ref->item);
179        if(env->gc_ref->item->gc.flag.mark)
180          printf(" (marked)");
181        if(env->gc_ref->item->gc.flag.protect)
182          printf(" (protected)");
183        switch(env->gc_ref->item->type){
184        case integer:
185          printf(" integer: %d", env->gc_ref->item->content.i);
186          break;
187        case func:
188          printf(" func: %p", env->gc_ref->item->content.func);
189          break;
190        case symb:
191          printf(" symb: %s", env->gc_ref->item->content.sym->id);
192          break;
193        case tcons:
194          printf(" tcons: %p\t%p", CAR(env->gc_ref->item),
195                 CDR(env->gc_ref->item));
196          break;
197        default:
198          printf(" <unknown %d>", (env->gc_ref->item->type));
199        }
200        printf("\n");
201    #endif /* DEBUG */
202    
203        /* Keep values */    
204        env->gc_count += sizeof(value);
205        if(env->gc_ref->item->type==string)
206          env->gc_count += strlen(env->gc_ref->item->content.string)+1;
207        
208        titem= env->gc_ref->next;
209        env->gc_ref->next= new_head;
210        new_head= env->gc_ref;
211        new_head->item->gc.flag.mark= 0;
212        env->gc_ref= titem;
213      }
214    
215      if (env->gc_limit < env->gc_count*2)
216        env->gc_limit= env->gc_count*2;
217    
218      env->gc_ref= new_head;
219    
220      if(env->interactive)
221        printf("done (%d bytes still allocated)\n", env->gc_count);
222    
223    }
224    
225    inline void gc_maybe(environment *env)
226    {
227      if(env->gc_count < env->gc_limit)
228        return;
229      else
230        return gc_init(env);
231    }
232    
233    /* Protect values from GC */
234    void protect(value *val)
235    {
236      if(val==NULL || val->gc.flag.protect)
237        return;
238    
239      val->gc.flag.protect= 1;
240    
241      if(val->type==tcons) {
242        protect(CAR(val));
243        protect(CDR(val));
244      }
245    }
246    
247    /* Unprotect values from GC */
248    void unprotect(value *val)
249  {  {
250    in_item->next= *stack_head;    if(val==NULL || !(val->gc.flag.protect))
251    *stack_head= in_item;      return;
252    return 1;  
253      val->gc.flag.protect= 0;
254    
255      if(val->type==tcons) {
256        unprotect(CAR(val));
257        unprotect(CDR(val));
258      }
259  }  }
260    
261  /* Push a value onto the stack */  /* Push a value onto the stack */
262  void push_val(stackitem **stack_head, value *val)  void push_val(environment *env, value *val)
263  {  {
264    stackitem *new_item= malloc(sizeof(stackitem));    value *new_value= new_val(env);
265    new_item->item= val;  
266    val->refcount++;    new_value->content.c= malloc(sizeof(pair));
267    push(stack_head, new_item);    assert(new_value->content.c!=NULL);
268      env->gc_count += sizeof(pair);
269      new_value->type= tcons;
270      CAR(new_value)= val;
271      CDR(new_value)= env->head;
272      env->head= new_value;
273  }  }
274    
275  /* Push an integer onto the stack. */  /* Push an integer onto the stack */
276  int push_int(stackitem **stack_head, int in_val)  void push_int(environment *env, int in_val)
277  {  {
278    value *new_value= malloc(sizeof(value));    value *new_value= new_val(env);
   stackitem *new_item= malloc(sizeof(stackitem));  
   new_item->item= new_value;  
279        
280    new_value->content.val= in_val;    new_value->content.i= in_val;
281    new_value->type= integer;    new_value->type= integer;
   new_value->refcount=1;  
282    
283    push(stack_head, new_item);    push_val(env, new_value);
284    return 1;  }
285    
286    /* Push a floating point number onto the stack */
287    void push_float(environment *env, float in_val)
288    {
289      value *new_value= new_val(env);
290    
291      new_value->content.f= in_val;
292      new_value->type= tfloat;
293    
294      push_val(env, new_value);
295  }  }
296    
297  /* Copy a string onto the stack. */  /* Copy a string onto the stack. */
298  int push_cstring(stackitem **stack_head, const char *in_string)  void push_cstring(environment *env, const char *in_string)
299  {  {
300    value *new_value= malloc(sizeof(value));    value *new_value= new_val(env);
301    stackitem *new_item= malloc(sizeof(stackitem));    int length= strlen(in_string)+1;
   new_item->item=new_value;  
302    
303    new_value->content.ptr= malloc(strlen(in_string)+1);    new_value->content.string= malloc(length);
304    strcpy(new_value->content.ptr, in_string);    assert(new_value != NULL);
305      env->gc_count += length;
306      strcpy(new_value->content.string, in_string);
307    new_value->type= string;    new_value->type= string;
   new_value->refcount=1;  
308    
309    push(stack_head, new_item);    push_val(env, new_value);
310    return 1;  }
311    
312    /* Mangle a symbol name to a valid C identifier name */
313    char *mangle_str(const char *old_string)
314    {
315      char validchars[]= "0123456789abcdef";
316      char *new_string, *current;
317    
318      new_string= malloc((strlen(old_string)*2)+4);
319      assert(new_string != NULL);
320      strcpy(new_string, "sx_");    /* Stack eXternal */
321      current= new_string+3;
322      while(old_string[0] != '\0'){
323        current[0]= validchars[(unsigned char)(old_string[0])/16];
324        current[1]= validchars[(unsigned char)(old_string[0])%16];
325        current+= 2;
326        old_string++;
327      }
328      current[0]= '\0';
329    
330      return new_string;            /* The caller must free() it */
331    }
332    
333    extern void mangle(environment *env)
334    {
335      char *new_string;
336    
337      if(env->head->type==empty) {
338        printerr("Too Few Arguments");
339        env->err= 1;
340        return;
341      }
342    
343      if(CAR(env->head)->type!=string) {
344        printerr("Bad Argument Type");
345        env->err= 2;
346        return;
347      }
348    
349      new_string= mangle_str(CAR(env->head)->content.string);
350    
351      toss(env);
352      if(env->err) return;
353    
354      push_cstring(env, new_string);
355  }  }
356    
357  /* Push a symbol onto the stack. */  /* Push a symbol onto the stack. */
358  int push_sym(environment *env, const char *in_string)  void push_sym(environment *env, const char *in_string)
359  {  {
   stackitem *new_item;          /* The new stack item */  
   /* ...which will contain... */  
360    value *new_value;             /* A new symbol value */    value *new_value;             /* A new symbol value */
361    /* ...which might point to... */    /* ...which might point to... */
362    symbol **new_symbol;          /* (if needed) A new actual symbol */    symbol **new_symbol;          /* (if needed) A new actual symbol */
# Line 165  int push_sym(environment *env, const cha Line 366  int push_sym(environment *env, const cha
366    void *funcptr;                /* A function pointer */    void *funcptr;                /* A function pointer */
367    
368    static void *handle= NULL;    /* Dynamic linker handle */    static void *handle= NULL;    /* Dynamic linker handle */
369      const char *dlerr;            /* Dynamic linker error */
370      char *mangled;                /* Mangled function name */
371    
372    /* Create a new stack item containing a new value */    new_value= new_val(env);
373    new_item= malloc(sizeof(stackitem));    protect(new_value);
374    new_value= malloc(sizeof(value));    new_fvalue= new_val(env);
375    new_item->item=new_value;    protect(new_fvalue);
376    
377    /* The new value is a symbol */    /* The new value is a symbol */
378    new_value->type= symb;    new_value->type= symb;
   new_value->refcount= 1;  
379    
380    /* Look up the symbol name in the hash table */    /* Look up the symbol name in the hash table */
381    new_symbol= hash(env->symbols, in_string);    new_symbol= hash(env->symbols, in_string);
382    new_value->content.ptr= *new_symbol;    new_value->content.sym= *new_symbol;
383    
384    if(*new_symbol==NULL) { /* If symbol was undefined */    if(*new_symbol==NULL) { /* If symbol was undefined */
385    
386      /* Create a new symbol */      /* Create a new symbol */
387      (*new_symbol)= malloc(sizeof(symbol));      (*new_symbol)= malloc(sizeof(symbol));
388        assert((*new_symbol) != NULL);
389      (*new_symbol)->val= NULL;   /* undefined value */      (*new_symbol)->val= NULL;   /* undefined value */
390      (*new_symbol)->next= NULL;      (*new_symbol)->next= NULL;
391      (*new_symbol)->id= malloc(strlen(in_string)+1);      (*new_symbol)->id= malloc(strlen(in_string)+1);
392        assert((*new_symbol)->id != NULL);
393      strcpy((*new_symbol)->id, in_string);      strcpy((*new_symbol)->id, in_string);
394    
395      /* Intern the new symbol in the hash table */      /* Intern the new symbol in the hash table */
396      new_value->content.ptr= *new_symbol;      new_value->content.sym= *new_symbol;
397    
398      /* Try to load the symbol name as an external function, to see if      /* Try to load the symbol name as an external function, to see if
399         we should bind the symbol to a new function pointer value */         we should bind the symbol to a new function pointer value */
400      if(handle==NULL)            /* If no handle */      if(handle==NULL)            /* If no handle */
401        handle= dlopen(NULL, RTLD_LAZY);        handle= dlopen(NULL, RTLD_LAZY);
402    
403      funcptr= dlsym(handle, in_string); /* Get function pointer */      mangled= mangle_str(in_string); /* mangle the name */
404      if(dlerror()==NULL) {       /* If a function was found */      funcptr= dlsym(handle, mangled); /* and try to find it */
       new_fvalue= malloc(sizeof(value)); /* Create a new value */  
       new_fvalue->type=func;    /* The new value is a function pointer */  
       new_fvalue->content.ptr=funcptr; /* Store function pointer */  
       (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new  
                                          function value */  
       new_fvalue->refcount= 1;  
     }  
   }  
   push(&(env->head), new_item);  
   return 1;  
 }  
   
 void printerr(const char* in_string) {  
   fprintf(stderr, "Err: %s\n", in_string);  
 }  
405    
406  /* Throw away a value */      dlerr= dlerror();
407  void free_val(value *val){      if(dlerr != NULL) {         /* If no function was found */
408    stackitem *item, *temp;        funcptr= dlsym(handle, in_string); /* Get function pointer */
409          dlerr= dlerror();
   val->refcount--;              /* Decrease the reference count */  
   if(val->refcount == 0){  
     switch (val->type){         /* and free the contents if necessary */  
     case string:  
       free(val->content.ptr);  
     case list:                  /* lists needs to be freed recursively */  
       item=val->content.ptr;  
       while(item != NULL) {     /* for all stack items */  
         free_val(item->item);   /* free the value */  
         temp=item->next;        /* save next ptr */  
         free(item);             /* free the stackitem */  
         item=temp;              /* go to next stackitem */  
       }  
       free(val);                /* Free the actual list value */  
       break;  
     default:  
       break;  
410      }      }
   }  
 }  
411    
412  /* Discard the top element of the stack. */      if(dlerr==NULL) {           /* If a function was found */
413  extern void toss(environment *env)        new_fvalue->type= func;   /* The new value is a function pointer */
414  {        new_fvalue->content.func= funcptr; /* Store function pointer */
415    stackitem *temp= env->head;        (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
416                                             function value */
417        }
418    
419    if((env->head)==NULL) {      free(mangled);
     printerr("Stack empty");  
     return;  
420    }    }
     
   free_val(env->head->item);    /* Free the value */  
   env->head= env->head->next;   /* Remove the top stack item */  
   free(temp);                   /* Free the old top stack item */  
 }  
421    
422  /* Print newline. */    push_val(env, new_value);
423  extern void nl(environment *env)    unprotect(new_value); unprotect(new_fvalue);
 {  
   printf("\n");  
424  }  }
425    
426  /* Prints the top element of the stack. */  /* Print a value */
427  void print_h(stackitem *stack_head)  void print_val(environment *env, value *val, int noquote, stackitem *stack, FILE *stream)
428  {  {
429      stackitem *titem, *tstack;
430      int depth;
431    
432    if(stack_head==NULL) {    switch(val->type) {
433      printerr("Stack empty");    case empty:
434      return;      if(fprintf(stream, "[]") < 0){
435    }        perror("print_val");
436          env->err= 5;
437    switch(stack_head->item->type) {        return;
438        }
439        break;
440    case integer:    case integer:
441      printf("%d", stack_head->item->content.val);      if(fprintf(stream, "%d", val->content.i) < 0){
442          perror("print_val");
443          env->err= 5;
444          return;
445        }
446        break;
447      case tfloat:
448        if(fprintf(stream, "%f", val->content.f) < 0){
449          perror("print_val");
450          env->err= 5;
451          return;
452        }
453      break;      break;
454    case string:    case string:
455      printf("\"%s\"", (char*)stack_head->item->content.ptr);      if(noquote){
456          if(fprintf(stream, "%s", val->content.string) < 0){
457            perror("print_val");
458            env->err= 5;
459            return;
460          }
461        } else {                    /* quote */
462          if(fprintf(stream, "\"%s\"", val->content.string) < 0){
463            perror("print_val");
464            env->err= 5;
465            return;
466          }
467        }
468      break;      break;
469    case symb:    case symb:
470      printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);      if(fprintf(stream, "%s", val->content.sym->id) < 0){
471          perror("print_val");
472          env->err= 5;
473          return;
474        }
475      break;      break;
476    default:    case func:
477      printf("%p", (funcp)(stack_head->item->content.ptr));      if(fprintf(stream, "#<function %p>", val->content.func) < 0){
478          perror("print_val");
479          env->err= 5;
480          return;
481        }
482      break;      break;
483    }    case port:
484  }      if(fprintf(stream, "#<port %p>", val->content.p) < 0){
485          perror("print_val");
486  extern void print_(environment *env) {        env->err= 5;
487    print_h(env->head);        return;
488  }      }
489        break;
490  /* Prints the top element of the stack and then discards it. */    case tcons:
491  extern void print(environment *env)      if(fprintf(stream, "[ ") < 0){
492  {        perror("print_val");
493    print_(env);        env->err= 5;
494    toss(env);        return;
495  }      }
496        tstack= stack;
497  /* Only to be called by function printstack. */      do {
498  void print_st(stackitem *stack_head, long counter)        titem=malloc(sizeof(stackitem));
499  {        assert(titem != NULL);
500    if(stack_head->next != NULL)        titem->item=val;
501      print_st(stack_head->next, counter+1);        titem->next=tstack;
502    printf("%ld: ", counter);        tstack=titem;             /* Put it on the stack */
503    print_h(stack_head);        /* Search a stack of values being printed to see if we are already
504    nl();           printing this value */
505  }        titem=tstack;
506          depth=0;
507          while(titem != NULL && titem->item != CAR(val)){
508            titem=titem->next;
509            depth++;
510          }
511          if(titem != NULL){        /* If we found it on the stack, */
512            if(fprintf(stream, "#%d#", depth) < 0){ /* print a depth reference */
513              perror("print_val");
514              env->err= 5;
515              free(titem);
516              return;
517            }
518          } else {
519            print_val(env, CAR(val), noquote, tstack, stream);
520          }
521          val= CDR(val);
522          switch(val->type){
523          case empty:
524            break;
525          case tcons:
526            /* Search a stack of values being printed to see if we are already
527               printing this value */
528            titem=tstack;
529            depth=0;
530            while(titem != NULL && titem->item != val){
531              titem=titem->next;
532              depth++;
533            }
534            if(titem != NULL){      /* If we found it on the stack, */
535              if(fprintf(stream, " . #%d#", depth) < 0){ /* print a depth reference */
536                perror("print_val");
537                env->err= 5;
538                goto printval_end;
539              }
540            } else {
541              if(fprintf(stream, " ") < 0){
542                perror("print_val");
543                env->err= 5;
544                goto printval_end;
545              }
546            }
547            break;
548          default:
549            if(fprintf(stream, " . ") < 0){ /* Improper list */
550              perror("print_val");
551              env->err= 5;
552              goto printval_end;
553            }
554            print_val(env, val, noquote, tstack, stream);
555          }
556        } while(val->type == tcons && titem == NULL);
557    
558      printval_end:
559    
560        titem=tstack;
561        while(titem != stack){
562          tstack=titem->next;
563          free(titem);
564          titem=tstack;
565        }
566    
567  /* Prints the stack. */      if(! (env->err)){
568  extern void printstack(environment *env)        if(fprintf(stream, " ]") < 0){
569  {          perror("print_val");
570    if(env->head != NULL) {          env->err= 5;
571      print_st(env->head, 1);        }
572      nl();      }
573    } else {      break;
     printerr("Stack empty");  
574    }    }
575  }  }
576    
577  /* Swap the two top elements on the stack. */  /* Swap the two top elements on the stack. */
578  extern void swap(environment *env)  extern void swap(environment *env)
579  {  {
580    stackitem *temp= env->head;    value *temp= env->head;
581        
582    if((env->head)==NULL) {    if(env->head->type == empty || CDR(env->head)->type == empty) {
583      printerr("Stack empty");      printerr("Too Few Arguments");
584        env->err=1;
585      return;      return;
586    }    }
587    
588    if(env->head->next==NULL) {    env->head= CDR(env->head);
589      printerr("Not enough arguments");    CDR(temp)= CDR(env->head);
590      return;    CDR(env->head)= temp;
   }  
   
   env->head= env->head->next;  
   temp->next= env->head->next;  
   env->head->next= temp;  
591  }  }
592    
 stackitem* copy(stackitem* in_item)  
 {  
   stackitem *out_item= malloc(sizeof(stackitem));  
   
   memcpy(out_item, in_item, sizeof(stackitem));  
   out_item->next= NULL;  
   
   return out_item;  
 }  
   
593  /* Recall a value from a symbol, if bound */  /* Recall a value from a symbol, if bound */
594  extern void rcl(environment *env)  extern void rcl(environment *env)
595  {  {
596    value *val;    value *val;
597    
598    if(env->head == NULL) {    if(env->head->type==empty) {
599      printerr("Stack empty");      printerr("Too Few Arguments");
600        env->err= 1;
601      return;      return;
602    }    }
603    
604    if(env->head->item->type!=symb) {    if(CAR(env->head)->type!=symb) {
605      printerr("Not a symbol");      printerr("Bad Argument Type");
606        env->err= 2;
607      return;      return;
608    }    }
609    val=((symbol *)(env->head->item->content.ptr))->val;  
610      val= CAR(env->head)->content.sym->val;
611    if(val == NULL){    if(val == NULL){
612      printerr("Unbound variable");      printerr("Unbound Variable");
613        env->err= 3;
614      return;      return;
615    }    }
616    toss(env);            /* toss the symbol */    push_val(env, val);           /* Return the symbol's bound value */
617    push_val(&(env->head), val); /* Return its bound value */    swap(env);
618      if(env->err) return;
619      toss(env);                    /* toss the symbol */
620      if(env->err) return;
621  }  }
622    
623    
624  /* 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
625     function value, and if it is, toss the symbol and execute the     function value, and if it is, toss the symbol and execute the
626     function. */     function. */
627  extern void eval(environment *env)  extern void eval(environment *env)
628  {  {
629    funcp in_func;    funcp in_func;
630    value* val;    value* temp_val;
631    if(env->head==NULL) {    value* iterator;
632      printerr("Stack empty");  
633     eval_start:
634    
635      gc_maybe(env);
636    
637      if(env->head->type==empty) {
638        printerr("Too Few Arguments");
639        env->err= 1;
640      return;      return;
641    }    }
642    
643    /* if it's a symbol */    switch(CAR(env->head)->type) {
644    if(env->head->item->type==symb) {      /* if it's a symbol */
645      case symb:
646      /* If it's not bound to anything */      rcl(env);                   /* get its contents */
647      if (((symbol *)(env->head->item->content.ptr))->val == NULL) {      if(env->err) return;
648        printerr("Unbound variable");      if(CAR(env->head)->type!=symb){ /* don't recurse symbols */
649        return;        goto eval_start;
650      }      }
651        return;
652    
653        /* If it's a lone function value, run it */
654      case func:
655        in_func= CAR(env->head)->content.func;
656        toss(env);
657        if(env->err) return;
658        return in_func(env);
659    
660        /* If it's a list */
661      case tcons:
662        temp_val= CAR(env->head);
663        protect(temp_val);
664    
665        toss(env); if(env->err) return;
666        iterator= temp_val;
667            
668      /* If it contains a function */      while(iterator->type != empty) {
669      if (((symbol *)(env->head->item->content.ptr))->val->type == func) {        push_val(env, CAR(iterator));
670        in_func=        
671          (funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);        if(CAR(env->head)->type==symb
672        toss(env);           && CAR(env->head)->content.sym->id[0]==';') {
673        (*in_func)(env);          /* Run the function */          toss(env);
674        return;          if(env->err) return;
675      } else {                    /* If it's not a function */          
676        val=((symbol *)(env->head->item->content.ptr))->val;          if(CDR(iterator)->type == empty){
677        toss(env);                /* toss the symbol */            goto eval_start;
678        push_val(&(env->head), val); /* Return its bound value */          }
679            eval(env);
680            if(env->err) return;
681          }
682          if (CDR(iterator)->type == empty || CDR(iterator)->type == tcons)
683            iterator= CDR(iterator);
684          else {
685            printerr("Bad Argument Type"); /* Improper list */
686            env->err= 2;
687            return;
688          }
689      }      }
690    }      unprotect(temp_val);
691        return;
692    
693    /* If it's a lone function value, run it */    case empty:
   if(env->head->item->type==func) {  
     in_func= (funcp)(env->head->item->content.ptr);  
694      toss(env);      toss(env);
695      (*in_func)(env);    case integer:
696      case tfloat:
697      case string:
698      case port:
699      return;      return;
700    }    }
   
701  }  }
702    
703  /* Make a list. */  /* List all defined words */
704  extern void pack(environment *env)  extern void words(environment *env)
705  {  {
706    void* delimiter;    symbol *temp;
707    stackitem *iterator, *temp;    int i;
708    value *pack;    
709      for(i= 0; i<HASHTBLSIZE; i++) {
710    delimiter= env->head->item->content.ptr; /* Get delimiter */      temp= env->symbols[i];
711    toss(env);      while(temp!=NULL) {
712    #ifdef DEBUG
713          if (temp->val != NULL && temp->val->gc.flag.protect)
714            printf("(protected) ");
715    #endif /* DEBUG */
716          printf("%s ", temp->id);
717          temp= temp->next;
718        }
719      }
720    }
721    
722    iterator= env->head;  /* Quit stack. */
723    extern void quit(environment *env)
724    {
725      int i;
726    
727    if(iterator==NULL || iterator->item->content.ptr==delimiter) {    while(env->head->type != empty)
     temp= NULL;  
728      toss(env);      toss(env);
729    } else {  
730      /* Search for first delimiter */    if (env->err) return;
731      while(iterator->next!=NULL    for(i= 0; i<HASHTBLSIZE; i++) {
732            && iterator->next->item->content.ptr!=delimiter)      while(env->symbols[i]!= NULL) {
733        iterator= iterator->next;        forget_sym(&(env->symbols[i]));
734            }
735      /* Extract list */      env->symbols[i]= NULL;
     temp= env->head;  
     env->head= iterator->next;  
     iterator->next= NULL;  
       
     if(env->head!=NULL)  
       toss(env);  
736    }    }
737    
738    /* Push list */    env->gc_limit= 0;
739    pack= malloc(sizeof(value));    gc_maybe(env);
740    pack->type= list;  
741    pack->content.ptr= temp;    words(env);
   pack->refcount= 1;  
742    
743    temp= malloc(sizeof(stackitem));    if(env->free_string!=NULL)
744    temp->item= pack;      free(env->free_string);
745      
746    #ifdef __linux__
747      muntrace();
748    #endif
749    
750    push(&(env->head), temp);    exit(EXIT_SUCCESS);
751  }  }
752    
753  /* Parse input. */  /* Internal forget function */
754  int stack_read(environment *env, char *in_line)  void forget_sym(symbol **hash_entry)
755  {  {
756    char *temp, *rest;    symbol *temp;
   int itemp;  
   size_t inlength= strlen(in_line)+1;  
   int convert= 0;  
   static int non_eval_flag= 0;  
757    
758    temp= malloc(inlength);    temp= *hash_entry;
759    rest= malloc(inlength);    *hash_entry= (*hash_entry)->next;
760      
761      free(temp->id);
762      free(temp);
763    }
764    
765    do {  /* Only to be called by itself function printstack. */
766      /* If string */  void print_st(environment *env, value *stack_head, long counter)
767      if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {  {
768        push_cstring(&(env->head), temp);    if(CDR(stack_head)->type != empty)
769        break;      print_st(env, CDR(stack_head), counter+1);
770      }    printf("%ld: ", counter);
771      /* If integer */    print_val(env, CAR(stack_head), 0, NULL, stdout);
772      if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {    printf("\n");
773        push_int(&(env->head), itemp);  }
       break;  
     }  
     /* Escape ';' with '\' */  
     if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {  
       temp[1]= '\0';  
       push_sym(env, temp);  
       break;  
     }  
     /* If symbol */  
     if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {  
         push_sym(env, temp);  
         break;  
     }  
     /* If single char */  
     if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {  
       if(*temp==';') {  
         if(!non_eval_flag) {  
           eval(env);            /* Evaluate top element */  
           break;  
         }  
           
         push_sym(env, ";");  
         break;  
       }  
774    
775        if(*temp==']') {  /* Prints the stack. */
776          push_sym(env, "[");  extern void printstack(environment *env)
777          pack(env);  {
778          if(non_eval_flag!=0)    if(env->head->type == empty) {
779            non_eval_flag--;      printf("Stack Empty\n");
780          break;      return;
781        }    }
782    
783      print_st(env, env->head, 1);
784    }
785    
786        if(*temp=='[') {  int main(int argc, char **argv)
787          push_sym(env, "[");  {
788          non_eval_flag++;    environment myenv;
789    
790      int c;                        /* getopt option character */
791    
792    #ifdef __linux__
793      mtrace();
794    #endif
795    
796      init_env(&myenv);
797    
798      myenv.interactive = isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
799    
800      while ((c = getopt (argc, argv, "i")) != -1)
801        switch (c)
802          {
803          case 'i':
804            myenv.interactive = 1;
805          break;          break;
806          case '?':
807            fprintf (stderr,
808                     "Unknown option character '\\x%x'.\n",
809                     optopt);
810            return EX_USAGE;
811          default:
812            abort ();
813        }        }
814      
815      if (optind < argc) {
816        myenv.interactive = 0;
817        myenv.inputstream= fopen(argv[optind], "r");
818        if(myenv.inputstream== NULL) {
819          perror(argv[0]);
820          exit (EX_NOINPUT);
821      }      }
822    } while(0);    }
   
823    
824    free(temp);    if(myenv.interactive) {
825        printf("Stack version $Revision$\n\
826    Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn\n\
827    Stack comes with ABSOLUTELY NO WARRANTY; for details type 'warranty;'.\n\
828    This is free software, and you are welcome to redistribute it\n\
829    under certain conditions; type 'copying;' for details.\n");
830      }
831    
832    if(convert<2) {    while(1) {
833      free(rest);      if(myenv.in_string==NULL) {
834      return 0;        if (myenv.interactive) {
835            if(myenv.err) {
836              printf("(error %d)\n", myenv.err);
837              myenv.err= 0;
838            }
839            printf("\n");
840            printstack(&myenv);
841            printf("> ");
842          }
843          myenv.err=0;
844        }
845        readstream(&myenv, myenv.inputstream);
846        if (myenv.err) {            /* EOF or other error */
847          myenv.err=0;
848          quit(&myenv);
849        } else if(myenv.head->type!=empty
850                  && CAR(myenv.head)->type==symb
851                  && CAR(myenv.head)->content.sym->id[0] == ';') {
852          toss(&myenv); if(myenv.err) continue;
853          eval(&myenv);
854        } else {
855          gc_maybe(&myenv);
856        }
857    }    }
858        quit(&myenv);
859    stack_read(env, rest);    return EXIT_FAILURE;
     
   free(rest);  
   return 1;  
860  }  }
861    
862  /* Relocate elements of the list on the stack. */  /* Return copy of a value */
863  extern void expand(environment *env)  value *copy_val(environment *env, value *old_value)
864  {  {
865    stackitem *temp, *new_head;    value *new_value;
866    
867    /* Is top element a list? */    if(old_value==NULL)
868    if(env->head==NULL || env->head->item->type!=list) {      return NULL;
     printerr("Stack empty or not a list");  
     return;  
   }  
869    
870    /* The first list element is the new stack head */    new_value= new_val(env);
871    new_head= temp= env->head->item->content.ptr;    new_value->type= old_value->type;
872    
873    env->head->item->refcount++;    switch(old_value->type){
874    toss(env);    case tfloat:
875      case integer:
876      case func:
877      case symb:
878      case empty:
879      case port:
880        new_value->content= old_value->content;
881        break;
882      case string:
883        new_value->content.string= strdup(old_value->content.string);
884        break;
885      case tcons:
886    
887    /* Find the end of the list */      new_value->content.c= malloc(sizeof(pair));
888    while(temp->next!=NULL)      assert(new_value->content.c!=NULL);
889      temp= temp->next;      env->gc_count += sizeof(pair);
890    
891    /* Connect the tail of the list with the old stack head */      CAR(new_value)= copy_val(env, CAR(old_value)); /* recurse */
892    temp->next= env->head;      CDR(new_value)= copy_val(env, CDR(old_value)); /* recurse */
893    env->head= new_head;          /* ...and voila! */      break;
894      }
895    
896      return new_value;
897  }  }
898    
899  /* Compares two elements by reference. */  /* read a line from a stream; used by readline */
900  extern void eq(environment *env)  void readlinestream(environment *env, FILE *stream)
901  {  {
902    void *left, *right;    char in_string[101];
   int result;  
903    
904    if((env->head)==NULL || env->head->next==NULL) {    if(fgets(in_string, 100, stream)==NULL) {
905      printerr("Not enough elements to compare");      push_cstring(env, "");
906      return;      if (! feof(stream)){
907          perror("readline");
908          env->err= 5;
909        }
910      } else {
911        push_cstring(env, in_string);
912    }    }
   
   left= env->head->item->content.ptr;  
   swap(env);  
   right= env->head->item->content.ptr;  
   result= (left==right);  
     
   toss(env); toss(env);  
   push_int(&(env->head), result);  
913  }  }
914    
915  /* Negates the top element on the stack. */  /* Reverse (flip) a list */
916  extern void not(environment *env)  extern void rev(environment *env)
917  {  {
918    int val;    value *old_head, *new_head, *item;
919    
920    if((env->head)==NULL || env->head->item->type!=integer) {    if(env->head->type==empty) {
921      printerr("Stack empty or element is not a integer");      printerr("Too Few Arguments");
922        env->err= 1;
923      return;      return;
924    }    }
925    
926    val= env->head->item->content.val;    if(CAR(env->head)->type==empty)
927    toss(env);      return;                     /* Don't reverse an empty list */
   push_int(&(env->head), !val);  
 }  
928    
929  /* Compares the two top elements on the stack and return 0 if they're the    if(CAR(env->head)->type!=tcons) {
930     same. */      printerr("Bad Argument Type");
931  extern void neq(environment *env)      env->err= 2;
932  {      return;
933    eq(env);    }
934    not(env);  
935      old_head= CAR(env->head);
936      new_head= new_val(env);
937      while(old_head->type != empty) {
938        item= old_head;
939        old_head= CDR(old_head);
940        CDR(item)= new_head;
941        new_head= item;
942      }
943      CAR(env->head)= new_head;
944  }  }
945    
946  /* Give a symbol some content. */  /* Make a list. */
947  extern void def(environment *env)  extern void pack(environment *env)
948  {  {
949    symbol *sym;    value *iterator, *temp, *ending;
950    
951    /* Needs two values on the stack, the top one must be a symbol */    ending=new_val(env);
   if(env->head==NULL || env->head->next==NULL  
      || env->head->item->type!=symb) {  
     printerr("Define what?");  
     return;  
   }  
   
   /* long names are a pain */  
   sym=env->head->item->content.ptr;  
952    
953    /* if the symbol was bound to something else, throw it away */    iterator= env->head;
954    if(sym->val != NULL)    if(iterator->type == empty
955      free_val(sym->val);       || (CAR(iterator)->type==symb
956         && CAR(iterator)->content.sym->id[0]=='[')) {
957        temp= ending;
958        toss(env);
959      } else {
960        /* Search for first delimiter */
961        while(CDR(iterator)->type != empty
962              && (CAR(CDR(iterator))->type!=symb
963               || CAR(CDR(iterator))->content.sym->id[0]!='['))
964          iterator= CDR(iterator);
965        
966        /* Extract list */
967        temp= env->head;
968        env->head= CDR(iterator);
969        CDR(iterator)= ending;
970    
971    /* Bind the symbol to the value */      if(env->head->type != empty)
972    sym->val= env->head->next->item;        toss(env);
973    sym->val->refcount++;         /* Increase the reference counter */    }
974    
975    toss(env); toss(env);    /* Push list */
 }  
976    
977  /* Quit stack. */    push_val(env, temp);
978  extern void quit(environment *env)    rev(env);
 {  
   exit(EXIT_SUCCESS);  
979  }  }
980    
981  /* Clear stack */  /* read from a stream; used by "read" and "readport" */
982  extern void clear(environment *env)  void readstream(environment *env, FILE *stream)
983  {  {
984    while(env->head!=NULL)    const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
985      toss(env);    const char strform[]= "\"%[^\"]\"%n";
986  }    const char intform[]= "%i%n";
987      const char fltform[]= "%f%n";
988      const char blankform[]= "%*[ \t]%n";
989      const char ebrackform[]= "]%n";
990      const char semicform[]= ";%n";
991      const char bbrackform[]= "[%n";
992    
993      int itemp, readlength= -1;
994      int count= -1;
995      float ftemp;
996      static int depth= 0;
997      char *match;
998      size_t inlength;
999    
1000      if(env->in_string==NULL) {
1001        if(depth > 0 && env->interactive) {
1002          printf("]> ");
1003        }
1004        readlinestream(env, env->inputstream);
1005        if(env->err) return;
1006    
1007  /* List all defined words */      if((CAR(env->head)->content.string)[0]=='\0'){
1008  extern void words(environment *env)        env->err= 4;              /* "" means EOF */
1009  {        return;
1010    symbol *temp;      }
1011    int i;      
1012        env->in_string= malloc(strlen(CAR(env->head)->content.string)+1);
1013        assert(env->in_string != NULL);
1014        env->free_string= env->in_string; /* Save the original pointer */
1015        strcpy(env->in_string, CAR(env->head)->content.string);
1016        toss(env); if(env->err) return;
1017      }
1018        
1019    for(i= 0; i<HASHTBLSIZE; i++) {    inlength= strlen(env->in_string)+1;
1020      temp= env->symbols[i];    match= malloc(inlength);
1021      while(temp!=NULL) {    assert(match != NULL);
1022        printf("%s\n", temp->id);  
1023        temp= temp->next;    if(sscanf(env->in_string, blankform, &readlength) != EOF
1024         && readlength != -1) {
1025        ;
1026      } else if(sscanf(env->in_string, fltform, &ftemp, &readlength) != EOF
1027                && readlength != -1) {
1028        if(sscanf(env->in_string, intform, &itemp, &count) != EOF
1029           && count==readlength) {
1030          push_int(env, itemp);
1031        } else {
1032          push_float(env, ftemp);
1033      }      }
1034      } else if(sscanf(env->in_string, "\"\"%n", &readlength) != EOF
1035                && readlength != -1) {
1036        push_cstring(env, "");
1037      } else if(sscanf(env->in_string, strform, match, &readlength) != EOF
1038                && readlength != -1) {
1039        push_cstring(env, match);
1040      } else if(sscanf(env->in_string, symbform, match, &readlength) != EOF
1041                && readlength != -1) {
1042        push_sym(env, match);
1043      } else if(sscanf(env->in_string, ebrackform, &readlength) != EOF
1044                && readlength != -1) {
1045        pack(env); if(env->err) return;
1046        if(depth != 0) depth--;
1047      } else if(sscanf(env->in_string, semicform, &readlength) != EOF
1048                && readlength != -1) {
1049        push_sym(env, ";");
1050      } else if(sscanf(env->in_string, bbrackform, &readlength) != EOF
1051                && readlength != -1) {
1052        push_sym(env, "[");
1053        depth++;
1054      } else {
1055        free(env->free_string);
1056        env->in_string = env->free_string = NULL;
1057      }
1058      if (env->in_string != NULL) {
1059        env->in_string += readlength;
1060    }    }
 }  
   
 int main()  
 {  
   environment myenv;  
   char in_string[100];  
1061    
1062    init_env(&myenv);    free(match);
1063    
1064    printf("okidok\n ");    if(depth)
1065        return readstream(env, env->inputstream);
1066    }
1067    
1068    extern void copying(environment *env)
1069    {
1070      printf("                  GNU GENERAL PUBLIC LICENSE\n\
1071                           Version 2, June 1991\n\
1072    \n\
1073     Copyright (C) 1989, 1991 Free Software Foundation, Inc.\n\
1074         59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\n\
1075     Everyone is permitted to copy and distribute verbatim copies\n\
1076     of this license document, but changing it is not allowed.\n\
1077    \n\
1078                                Preamble\n\
1079    \n\
1080      The licenses for most software are designed to take away your\n\
1081    freedom to share and change it.  By contrast, the GNU General Public\n\
1082    License is intended to guarantee your freedom to share and change free\n\
1083    software--to make sure the software is free for all its users.  This\n\
1084    General Public License applies to most of the Free Software\n\
1085    Foundation's software and to any other program whose authors commit to\n\
1086    using it.  (Some other Free Software Foundation software is covered by\n\
1087    the GNU Library General Public License instead.)  You can apply it to\n\
1088    your programs, too.\n\
1089    \n\
1090      When we speak of free software, we are referring to freedom, not\n\
1091    price.  Our General Public Licenses are designed to make sure that you\n\
1092    have the freedom to distribute copies of free software (and charge for\n\
1093    this service if you wish), that you receive source code or can get it\n\
1094    if you want it, that you can change the software or use pieces of it\n\
1095    in new free programs; and that you know you can do these things.\n\
1096    \n\
1097      To protect your rights, we need to make restrictions that forbid\n\
1098    anyone to deny you these rights or to ask you to surrender the rights.\n\
1099    These restrictions translate to certain responsibilities for you if you\n\
1100    distribute copies of the software, or if you modify it.\n\
1101    \n\
1102      For example, if you distribute copies of such a program, whether\n\
1103    gratis or for a fee, you must give the recipients all the rights that\n\
1104    you have.  You must make sure that they, too, receive or can get the\n\
1105    source code.  And you must show them these terms so they know their\n\
1106    rights.\n\
1107    \n\
1108      We protect your rights with two steps: (1) copyright the software, and\n\
1109    (2) offer you this license which gives you legal permission to copy,\n\
1110    distribute and/or modify the software.\n\
1111    \n\
1112      Also, for each author's protection and ours, we want to make certain\n\
1113    that everyone understands that there is no warranty for this free\n\
1114    software.  If the software is modified by someone else and passed on, we\n\
1115    want its recipients to know that what they have is not the original, so\n\
1116    that any problems introduced by others will not reflect on the original\n\
1117    authors' reputations.\n\
1118    \n\
1119      Finally, any free program is threatened constantly by software\n\
1120    patents.  We wish to avoid the danger that redistributors of a free\n\
1121    program will individually obtain patent licenses, in effect making the\n\
1122    program proprietary.  To prevent this, we have made it clear that any\n\
1123    patent must be licensed for everyone's free use or not licensed at all.\n\
1124    \n\
1125      The precise terms and conditions for copying, distribution and\n\
1126    modification follow.\n\
1127    \n\
1128                        GNU GENERAL PUBLIC LICENSE\n\
1129       TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION\n\
1130    \n\
1131      0. This License applies to any program or other work which contains\n\
1132    a notice placed by the copyright holder saying it may be distributed\n\
1133    under the terms of this General Public License.  The \"Program\", below,\n\
1134    refers to any such program or work, and a \"work based on the Program\"\n\
1135    means either the Program or any derivative work under copyright law:\n\
1136    that is to say, a work containing the Program or a portion of it,\n\
1137    either verbatim or with modifications and/or translated into another\n\
1138    language.  (Hereinafter, translation is included without limitation in\n\
1139    the term \"modification\".)  Each licensee is addressed as \"you\".\n\
1140    \n\
1141    Activities other than copying, distribution and modification are not\n\
1142    covered by this License; they are outside its scope.  The act of\n\
1143    running the Program is not restricted, and the output from the Program\n\
1144    is covered only if its contents constitute a work based on the\n\
1145    Program (independent of having been made by running the Program).\n\
1146    Whether that is true depends on what the Program does.\n\
1147    \n\
1148      1. You may copy and distribute verbatim copies of the Program's\n\
1149    source code as you receive it, in any medium, provided that you\n\
1150    conspicuously and appropriately publish on each copy an appropriate\n\
1151    copyright notice and disclaimer of warranty; keep intact all the\n\
1152    notices that refer to this License and to the absence of any warranty;\n\
1153    and give any other recipients of the Program a copy of this License\n\
1154    along with the Program.\n\
1155    \n\
1156    You may charge a fee for the physical act of transferring a copy, and\n\
1157    you may at your option offer warranty protection in exchange for a fee.\n\
1158    \n\
1159      2. You may modify your copy or copies of the Program or any portion\n\
1160    of it, thus forming a work based on the Program, and copy and\n\
1161    distribute such modifications or work under the terms of Section 1\n\
1162    above, provided that you also meet all of these conditions:\n\
1163    \n\
1164        a) You must cause the modified files to carry prominent notices\n\
1165        stating that you changed the files and the date of any change.\n\
1166    \n\
1167        b) You must cause any work that you distribute or publish, that in\n\
1168        whole or in part contains or is derived from the Program or any\n\
1169        part thereof, to be licensed as a whole at no charge to all third\n\
1170        parties under the terms of this License.\n\
1171    \n\
1172        c) If the modified program normally reads commands interactively\n\
1173        when run, you must cause it, when started running for such\n\
1174        interactive use in the most ordinary way, to print or display an\n\
1175        announcement including an appropriate copyright notice and a\n\
1176        notice that there is no warranty (or else, saying that you provide\n\
1177        a warranty) and that users may redistribute the program under\n\
1178        these conditions, and telling the user how to view a copy of this\n\
1179        License.  (Exception: if the Program itself is interactive but\n\
1180        does not normally print such an announcement, your work based on\n\
1181        the Program is not required to print an announcement.)\n\
1182    \n\
1183    These requirements apply to the modified work as a whole.  If\n\
1184    identifiable sections of that work are not derived from the Program,\n\
1185    and can be reasonably considered independent and separate works in\n\
1186    themselves, then this License, and its terms, do not apply to those\n\
1187    sections when you distribute them as separate works.  But when you\n\
1188    distribute the same sections as part of a whole which is a work based\n\
1189    on the Program, the distribution of the whole must be on the terms of\n\
1190    this License, whose permissions for other licensees extend to the\n\
1191    entire whole, and thus to each and every part regardless of who wrote it.\n\
1192    \n\
1193    Thus, it is not the intent of this section to claim rights or contest\n\
1194    your rights to work written entirely by you; rather, the intent is to\n\
1195    exercise the right to control the distribution of derivative or\n\
1196    collective works based on the Program.\n\
1197    \n\
1198    In addition, mere aggregation of another work not based on the Program\n\
1199    with the Program (or with a work based on the Program) on a volume of\n\
1200    a storage or distribution medium does not bring the other work under\n\
1201    the scope of this License.\n\
1202    \n\
1203      3. You may copy and distribute the Program (or a work based on it,\n\
1204    under Section 2) in object code or executable form under the terms of\n\
1205    Sections 1 and 2 above provided that you also do one of the following:\n\
1206    \n\
1207        a) Accompany it with the complete corresponding machine-readable\n\
1208        source code, which must be distributed under the terms of Sections\n\
1209        1 and 2 above on a medium customarily used for software interchange; or,\n\
1210    \n\
1211        b) Accompany it with a written offer, valid for at least three\n\
1212        years, to give any third party, for a charge no more than your\n\
1213        cost of physically performing source distribution, a complete\n\
1214        machine-readable copy of the corresponding source code, to be\n\
1215        distributed under the terms of Sections 1 and 2 above on a medium\n\
1216        customarily used for software interchange; or,\n\
1217    \n\
1218        c) Accompany it with the information you received as to the offer\n\
1219        to distribute corresponding source code.  (This alternative is\n\
1220        allowed only for noncommercial distribution and only if you\n\
1221        received the program in object code or executable form with such\n\
1222        an offer, in accord with Subsection b above.)\n\
1223    \n\
1224    The source code for a work means the preferred form of the work for\n\
1225    making modifications to it.  For an executable work, complete source\n\
1226    code means all the source code for all modules it contains, plus any\n\
1227    associated interface definition files, plus the scripts used to\n\
1228    control compilation and installation of the executable.  However, as a\n\
1229    special exception, the source code distributed need not include\n\
1230    anything that is normally distributed (in either source or binary\n\
1231    form) with the major components (compiler, kernel, and so on) of the\n\
1232    operating system on which the executable runs, unless that component\n\
1233    itself accompanies the executable.\n\
1234    \n\
1235    If distribution of executable or object code is made by offering\n\
1236    access to copy from a designated place, then offering equivalent\n\
1237    access to copy the source code from the same place counts as\n\
1238    distribution of the source code, even though third parties are not\n\
1239    compelled to copy the source along with the object code.\n\
1240    \n\
1241      4. You may not copy, modify, sublicense, or distribute the Program\n\
1242    except as expressly provided under this License.  Any attempt\n\
1243    otherwise to copy, modify, sublicense or distribute the Program is\n\
1244    void, and will automatically terminate your rights under this License.\n\
1245    However, parties who have received copies, or rights, from you under\n\
1246    this License will not have their licenses terminated so long as such\n\
1247    parties remain in full compliance.\n\
1248    \n\
1249      5. You are not required to accept this License, since you have not\n\
1250    signed it.  However, nothing else grants you permission to modify or\n\
1251    distribute the Program or its derivative works.  These actions are\n\
1252    prohibited by law if you do not accept this License.  Therefore, by\n\
1253    modifying or distributing the Program (or any work based on the\n\
1254    Program), you indicate your acceptance of this License to do so, and\n\
1255    all its terms and conditions for copying, distributing or modifying\n\
1256    the Program or works based on it.\n\
1257    \n\
1258      6. Each time you redistribute the Program (or any work based on the\n\
1259    Program), the recipient automatically receives a license from the\n\
1260    original licensor to copy, distribute or modify the Program subject to\n\
1261    these terms and conditions.  You may not impose any further\n\
1262    restrictions on the recipients' exercise of the rights granted herein.\n\
1263    You are not responsible for enforcing compliance by third parties to\n\
1264    this License.\n\
1265    \n\
1266      7. If, as a consequence of a court judgment or allegation of patent\n\
1267    infringement or for any other reason (not limited to patent issues),\n\
1268    conditions are imposed on you (whether by court order, agreement or\n\
1269    otherwise) that contradict the conditions of this License, they do not\n\
1270    excuse you from the conditions of this License.  If you cannot\n\
1271    distribute so as to satisfy simultaneously your obligations under this\n\
1272    License and any other pertinent obligations, then as a consequence you\n\
1273    may not distribute the Program at all.  For example, if a patent\n\
1274    license would not permit royalty-free redistribution of the Program by\n\
1275    all those who receive copies directly or indirectly through you, then\n\
1276    the only way you could satisfy both it and this License would be to\n\
1277    refrain entirely from distribution of the Program.\n\
1278    \n\
1279    If any portion of this section is held invalid or unenforceable under\n\
1280    any particular circumstance, the balance of the section is intended to\n\
1281    apply and the section as a whole is intended to apply in other\n\
1282    circumstances.\n\
1283    \n\
1284    It is not the purpose of this section to induce you to infringe any\n\
1285    patents or other property right claims or to contest validity of any\n\
1286    such claims; this section has the sole purpose of protecting the\n\
1287    integrity of the free software distribution system, which is\n\
1288    implemented by public license practices.  Many people have made\n\
1289    generous contributions to the wide range of software distributed\n\
1290    through that system in reliance on consistent application of that\n\
1291    system; it is up to the author/donor to decide if he or she is willing\n\
1292    to distribute software through any other system and a licensee cannot\n\
1293    impose that choice.\n\
1294    \n\
1295    This section is intended to make thoroughly clear what is believed to\n\
1296    be a consequence of the rest of this License.\n\
1297    \n\
1298      8. If the distribution and/or use of the Program is restricted in\n\
1299    certain countries either by patents or by copyrighted interfaces, the\n\
1300    original copyright holder who places the Program under this License\n\
1301    may add an explicit geographical distribution limitation excluding\n\
1302    those countries, so that distribution is permitted only in or among\n\
1303    countries not thus excluded.  In such case, this License incorporates\n\
1304    the limitation as if written in the body of this License.\n\
1305    \n\
1306      9. The Free Software Foundation may publish revised and/or new versions\n\
1307    of the General Public License from time to time.  Such new versions will\n\
1308    be similar in spirit to the present version, but may differ in detail to\n\
1309    address new problems or concerns.\n\
1310    \n\
1311    Each version is given a distinguishing version number.  If the Program\n\
1312    specifies a version number of this License which applies to it and \"any\n\
1313    later version\", you have the option of following the terms and conditions\n\
1314    either of that version or of any later version published by the Free\n\
1315    Software Foundation.  If the Program does not specify a version number of\n\
1316    this License, you may choose any version ever published by the Free Software\n\
1317    Foundation.\n\
1318    \n\
1319      10. If you wish to incorporate parts of the Program into other free\n\
1320    programs whose distribution conditions are different, write to the author\n\
1321    to ask for permission.  For software which is copyrighted by the Free\n\
1322    Software Foundation, write to the Free Software Foundation; we sometimes\n\
1323    make exceptions for this.  Our decision will be guided by the two goals\n\
1324    of preserving the free status of all derivatives of our free software and\n\
1325    of promoting the sharing and reuse of software generally.\n");
1326    }
1327    
1328    extern void warranty(environment *env)
1329    {
1330      printf("                          NO WARRANTY\n\
1331    \n\
1332      11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\n\
1333    FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN\n\
1334    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\n\
1335    PROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\n\
1336    OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF\n\
1337    MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS\n\
1338    TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE\n\
1339    PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,\n\
1340    REPAIR OR CORRECTION.\n\
1341    \n\
1342      12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING\n\
1343    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR\n\
1344    REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,\n\
1345    INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING\n\
1346    OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED\n\
1347    TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY\n\
1348    YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\n\
1349    PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\n\
1350    POSSIBILITY OF SUCH DAMAGES.\n");
1351    }
1352    
1353    while(fgets(in_string, 100, stdin) != NULL) {  /* Discard the top element of the stack. */
1354      stack_read(&myenv, in_string);  extern void toss(environment *env)
1355      printf("okidok\n ");  {
1356      if(env->head->type==empty) {
1357        printerr("Too Few Arguments");
1358        env->err= 1;
1359        return;
1360    }    }
1361      
1362    exit(EXIT_SUCCESS);    env->head= CDR(env->head); /* Remove the top stack item */
1363  }  }
1364    
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