cvs/stack/stack.c

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

#define HASHTBLSIZE 65536

/* First, define some types. */

/* A value of some type */
typedef struct {
  enum {
    integer,
    string,
    ref,                        /* Reference (to an element in the
                                   hash table) */
    func,                       /* Function pointer */
    symb, 
    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 */
} environment;

/* A type for pointers to external functions */
typedef void (*funcp)(environment *); /* funcp is a pointer to a void
                                         function (environment *) */

/* Initialize a newly created environment */
void init_env(environment *env)
{
  long i;

  for(i= 0; i<HASHTBLSIZE; i++)
    env->symbols[i]= NULL;
}

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

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

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

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

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

/* Push an integer onto the stack. */
int push_val(stackitem **stack_head, int in_val) 
{
  value *new_value= malloc(sizeof(value));
  stackitem *new_item= malloc(sizeof(stackitem));
  new_item->item= new_value;
  
  new_value->content.val= in_val;
  new_value->type= integer;
  new_value->refcount=1;

  push(stack_head, new_item);
  return 1;
}

/* Copy a string onto the stack. */
int push_cstring(stackitem **stack_head, const char *in_string)
{
  value *new_value= malloc(sizeof(value));
  stackitem *new_item= malloc(sizeof(stackitem));
  new_item->item=new_value;

  new_value->content.ptr= malloc(strlen(in_string)+1);
  strcpy(new_value->content.ptr, in_string);
  new_value->type= string;
  new_value->refcount=1;

  push(stack_head, new_item);
  return 1;
}

/* Push a symbol onto the stack. */
int push_sym(environment *env, const char *in_string)
{
  stackitem *new_item;          /* The new stack item */
  /* ...which will contain... */
  value *new_value;             /* A new symbol value */
  /* ...which might point to... */
  symbol *new_symbol;           /* (if needed) A new actual symbol */
  /* ...which, if possible, will be bound to... */
  value *new_fvalue;            /* (if needed) A new function value */
  /* ...which will point to... */
  void *funcptr;                /* A function pointer */

  static void *handle= NULL;    /* Dynamic linker handle */

  /* Create a new stack item containing a new value */
  new_item= malloc(sizeof(stackitem));
  new_value= malloc(sizeof(value));
  new_item->item=new_value;

  /* The new value is a symbol */
  new_value->type= symb;
  new_value->refcount= 1;

  /* Look up the symbol name in the hash table */
  new_value->content.ptr= *hash(env->symbols, in_string);

  if(new_value->content.ptr==NULL) { /* If symbol was undefined */

    /* Create a new symbol */
    new_symbol= malloc(sizeof(symbol));
    new_symbol->val= NULL;      /* undefined value */
    new_symbol->next= NULL;
    new_symbol->id= malloc(strlen(in_string)+1);
    strcpy(new_symbol->id, in_string);

    /* Intern the new symbol in the hash table */
    new_value->content.ptr= new_symbol;

    /* Try to load the symbol name as an external function, to see if
       we should bind the symbol to a new function pointer value */
    if(handle==NULL)            /* If no handle */
      handle= dlopen(NULL, RTLD_LAZY);

    funcptr= dlsym(handle, in_string); /* Get function pointer */
    if(dlerror()==NULL) {       /* If a function was found */
      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);
}

/* Throw away a value */
void free_val(value *val){
  stackitem *item, *temp;

  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;
    }
  }
}

/* Discard the top element of the stack. */
extern void toss(environment *env)
{
  stackitem *temp= env->head;

  if((env->head)==NULL) {
    printerr("Stack empty");
    return;
  }
  
  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 */
}

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

/* Prints the top element of the stack. */
void print_h(stackitem *stack_head)
{

  if(stack_head==NULL) {
    printerr("Stack empty");
    return;
  }

  switch(stack_head->item->type) {
  case integer:
    printf("%d", stack_head->item->content.val);
    break;
  case string:
    printf("\"%s\"", (char*)stack_head->item->content.ptr);
    break;
  case symb:
    printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
    break;
  default:
    printf("%p", (funcp)(stack_head->item->content.ptr));
    break;
  }
}

extern void print_(environment *env) {
  print_h(env->head);
}

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

/* Only to be called by function printstack. */
void print_st(stackitem *stack_head, long counter)
{ 
  if(stack_head->next != NULL)
    print_st(stack_head->next, counter+1);
  printf("%ld: ", counter);
  print_h(stack_head);
  nl();
}


/* Prints the stack. */
extern void printstack(environment *env)
{
  if(env->head != NULL) {
    print_st(env->head, 1);
    nl();
  } else {
    printerr("Stack empty");
  }
}

/* Swap the two top elements on the stack. */
extern void swap(environment *env)
{
  stackitem *temp= env->head;
  
  if((env->head)==NULL) {
    printerr("Stack empty");
    return;
  }

  if(env->head->next==NULL) {
    printerr("Not enough arguments");
    return;
  }

  env->head= env->head->next;
  temp->next= env->head->next;
  env->head->next= temp;
} 

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;
}


/* If the top element is a reference, determine if it's a reference to a
   function, and if it is, toss the reference and execute the function. */
extern void eval(environment *env)
{
  funcp in_func;
  stackitem* temp= env->head;

  if(temp==NULL) {
    printerr("Stack empty");
    return;
  }

  if(temp->item->type==symb
     && ((symbol *)(temp->item->content.ptr))->val != NULL
     && ((symbol *)(temp->item->content.ptr))->val->type == func) {
    in_func= (funcp)(((symbol *)(temp->item->content.ptr))->val->content.ptr);
    toss(env);
    (*in_func)(env);
    return;
  }
    

  if(temp->item->type==func) {
    in_func= (funcp)(temp->item->content.ptr);
    toss(env); 
    (*in_func)(env);
    return;
  }

  push(&(env->head), copy(temp));
  swap(env);
  toss(env);
}

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

  delimiter= env->head->item->content.ptr; /* Get delimiter */
  toss(env);

  iterator= env->head;

  if(iterator==NULL || iterator->item->content.ptr==delimiter) {
    temp= NULL;
    toss(env);
  } else {
    /* Search for first delimiter */
    while(iterator->next!=NULL
          && iterator->next->item->content.ptr!=delimiter)
      iterator= iterator->next;
    
    /* Extract list */
    temp= env->head;
    env->head= iterator->next;
    iterator->next= NULL;
    
    if(env->head!=NULL)
      toss(env);
  }

  /* Push list */
  pack= malloc(sizeof(value));
  pack->type= list;
  pack->content.ptr= temp;
  pack->refcount= 1;

  temp= malloc(sizeof(stackitem));
  temp->item= pack;

  push(&(env->head), temp);
}

/* Parse input. */
int stack_read(environment *env, char *in_line) 
{
  char *temp, *rest;
  int itemp;
  size_t inlength= strlen(in_line)+1;
  int convert= 0;
  static int non_eval_flag= 0;

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

  do {
    /* If string */
    if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
      push_cstring(&(env->head), temp);
      break;
    }
    /* If integer */
    if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
      push_val(&(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;
      }

      if(*temp==']') {
        push_sym(env, "[");
        pack(env);
        if(non_eval_flag!=0)
          non_eval_flag--;
        break;
      }

      if(*temp=='[') {
        push_sym(env, "[");
        non_eval_flag++;
        break;
      }
    }
  } while(0);


  free(temp);

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

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

  /* Is top element a list? */
  if(env->head==NULL || env->head->item->type!=list) {
    printerr("Stack empty or not a list");
    return;
  }

  /* The first list element is the new stack head */
  new_head= temp= env->head->item->content.ptr;

  env->head->item->refcount++;
  toss(env);

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

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

}

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

  if((env->head)==NULL || env->head->next==NULL) {
    printerr("Not enough elements to compare");
    return;
  }

  left= env->head->item->content.ptr;
  swap(env);
  right= env->head->item->content.ptr;
  result= (left==right);
  
  toss(env); toss(env);
  push_val(&(env->head), result);
}

/* Negates the top element on the stack. */
extern void not(environment *env)
{
  int val;

  if((env->head)==NULL || env->head->item->type!=integer) {
    printerr("Stack empty or element is not a integer");
    return;
  }

  val= env->head->item->content.val;
  toss(env);
  push_val(&(env->head), !val);
}

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

/* Give a symbol some content. */
extern void def(environment *env)
{
  symbol *sym;

  /* Needs two values on the stack, the top one must be a symbol */
  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;

  /* if the symbol was bound to something else, throw it away */
  if(sym->val != NULL)
    free_val(sym->val);

  /* Bind the symbol to the value */
  sym->val= env->head->next->item;
  sym->val->refcount++;         /* Increase the reference counter */

  toss(env); toss(env);
} 

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

/* Clear stack */
extern void clear(environment *env)
{
  while(env->head!=NULL)
    toss(env);
}

int main()
{
  environment myenv;
  char in_string[100];

  init_env(&myenv);

  printf("okidok\n ");

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

  exit(EXIT_SUCCESS);
}
1	/* printf */
2	#include <stdio.h>
3	/* EXIT_SUCCESS */
4	#include <stdlib.h>
5	/* NULL */
6	#include <stddef.h>
7	/* dlopen, dlsym, dlerror */
8	#include <dlfcn.h>
9	/* assert */
10	#include <assert.h>
11
12	#define HASHTBLSIZE 65536
13
14	/* First, define some types. */
15
16	/* A value of some type */
17	typedef struct {
18	enum {
19	integer,
20	string,
21	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	/* An item (value) on a stack */
50	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	/* Initialize a newly created environment */
68	void init_env(environment *env)
69	{
70	long i;
71
72	for(i= 0; i<HASHTBLSIZE; i++)
73	env->symbols[i]= NULL;
74	}
75
76	/* Returns a pointer to a pointer to an element in the hash table. */
77	symbol *hash(hashtbl in_hashtbl, const char in_string)
78	{
79	long i= 0;
80	unsigned long out_hash= 0;
81	char key= '\0';
82	symbol **position;
83
84	while(1){ /* Hash in_string */
85	key= in_string[i++];
86	if(key=='\0')
87	break;
88	out_hash= out_hash*32+key;
89	}
90
91	out_hash= out_hash%HASHTBLSIZE;
92	position= &(in_hashtbl[out_hash]);
93
94	while(1){
95	if(position==NULL) / If empty */
96	return position;
97
98	if(strcmp(in_string, (position)->id)==0) / If match */
99	return position;
100
101	position= &((position)->next); / Try next */
102	}
103	}
104
105	/* Generic push function. */
106	int push(stackitem** stack_head, stackitem* in_item)
107	{
108	in_item->next= *stack_head;
109	*stack_head= in_item;
110	return 1;
111	}
112
113	/* Push an integer onto the stack. */
114	int push_val(stackitem **stack_head, int in_val)
115	{
116	value *new_value= malloc(sizeof(value));
117	stackitem *new_item= malloc(sizeof(stackitem));
118	new_item->item= new_value;
119
120	new_value->content.val= in_val;
121	new_value->type= integer;
122	new_value->refcount=1;
123
124	push(stack_head, new_item);
125	return 1;
126	}
127
128	/* Copy a string onto the stack. */
129	int push_cstring(stackitem *stack_head, const char in_string)
130	{
131	value *new_value= malloc(sizeof(value));
132	stackitem *new_item= malloc(sizeof(stackitem));
133	new_item->item=new_value;
134
135	new_value->content.ptr= malloc(strlen(in_string)+1);
136	strcpy(new_value->content.ptr, in_string);
137	new_value->type= string;
138	new_value->refcount=1;
139
140	push(stack_head, new_item);
141	return 1;
142	}
143
144	/* Push a symbol onto the stack. */
145	int push_sym(environment env, const char in_string)
146	{
147	stackitem new_item; / The new stack item */
148	/* ...which will contain... */
149	value new_value; / A new symbol value */
150	/* ...which might point to... */
151	symbol new_symbol; / (if needed) A new actual symbol */
152	/* ...which, if possible, will be bound to... */
153	value new_fvalue; / (if needed) A new function value */
154	/* ...which will point to... */
155	void funcptr; / A function pointer */
156
157	static void handle= NULL; / Dynamic linker handle */
158
159	/* Create a new stack item containing a new value */
160	new_item= malloc(sizeof(stackitem));
161	new_value= malloc(sizeof(value));
162	new_item->item=new_value;
163
164	/* The new value is a symbol */
165	new_value->type= symb;
166	new_value->refcount= 1;
167
168	/* Look up the symbol name in the hash table */
169	new_value->content.ptr= *hash(env->symbols, in_string);
170
171	if(new_value->content.ptr==NULL) { /* If symbol was undefined */
172
173	/* Create a new symbol */
174	new_symbol= malloc(sizeof(symbol));
175	new_symbol->val= NULL; /* undefined value */
176	new_symbol->next= NULL;
177	new_symbol->id= malloc(strlen(in_string)+1);
178	strcpy(new_symbol->id, in_string);
179
180	/* Intern the new symbol in the hash table */
181	new_value->content.ptr= new_symbol;
182
183	/* Try to load the symbol name as an external function, to see if
184	we should bind the symbol to a new function pointer value */
185	if(handle==NULL) /* If no handle */
186	handle= dlopen(NULL, RTLD_LAZY);
187
188	funcptr= dlsym(handle, in_string); /* Get function pointer */
189	if(dlerror()==NULL) { /* If a function was found */
190	new_fvalue= malloc(sizeof(value)); /* Create a new value */
191	new_fvalue->type=func; /* The new value is a function pointer */
192	new_fvalue->content.ptr=funcptr; /* Store function pointer */
193	new_symbol->val= new_fvalue; /* Bind the symbol to the new
194	function value */
195	new_fvalue->refcount= 1;
196	}
197	}
198	push(&(env->head), new_item);
199	return 1;
200	}
201
202	void printerr(const char* in_string) {
203	fprintf(stderr, "Err: %s\n", in_string);
204	}
205
206	/* Throw away a value */
207	void free_val(value *val){
208	stackitem item, temp;
209
210	val->refcount--; /* Decrease the reference count */
211	if(val->refcount == 0){
212	switch (val->type){ /* and free the contents if necessary */
213	case string:
214	free(val->content.ptr);
215	case list: /* lists needs to be freed recursively */
216	item=val->content.ptr;
217	while(item != NULL) { /* for all stack items */
218	free_val(item->item); /* free the value */
219	temp=item->next; /* save next ptr */
220	free(item); /* free the stackitem */
221	item=temp; /* go to next stackitem */
222	}
223	free(val); /* Free the actual list value */
224	break;
225	default:
226	break;
227	}
228	}
229	}
230
231	/* Discard the top element of the stack. */
232	extern void toss(environment *env)
233	{
234	stackitem *temp= env->head;
235
236	if((env->head)==NULL) {
237	printerr("Stack empty");
238	return;
239	}
240
241	free_val(env->head->item); /* Free the value */
242	env->head= env->head->next; /* Remove the top stack item */
243	free(temp); /* Free the old top stack item */
244	}
245
246	/* Print newline. */
247	extern void nl()
248	{
249	printf("\n");
250	}
251
252	/* Prints the top element of the stack. */
253	void print_h(stackitem *stack_head)
254	{
255
256	if(stack_head==NULL) {
257	printerr("Stack empty");
258	return;
259	}
260
261	switch(stack_head->item->type) {
262	case integer:
263	printf("%d", stack_head->item->content.val);
264	break;
265	case string:
266	printf("\"%s\"", (char*)stack_head->item->content.ptr);
267	break;
268	case symb:
269	printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
270	break;
271	default:
272	printf("%p", (funcp)(stack_head->item->content.ptr));
273	break;
274	}
275	}
276
277	extern void print_(environment *env) {
278	print_h(env->head);
279	}
280
281	/* Prints the top element of the stack and then discards it. */
282	extern void print(environment *env)
283	{
284	print_(env);
285	toss(env);
286	}
287
288	/* Only to be called by function printstack. */
289	void print_st(stackitem *stack_head, long counter)
290	{
291	if(stack_head->next != NULL)
292	print_st(stack_head->next, counter+1);
293	printf("%ld: ", counter);
294	print_h(stack_head);
295	nl();
296	}
297
298
299
300	/* Prints the stack. */
301	extern void printstack(environment *env)
302	{
303	if(env->head != NULL) {
304	print_st(env->head, 1);
305	nl();
306	} else {
307	printerr("Stack empty");
308	}
309	}
310
311	/* Swap the two top elements on the stack. */
312	extern void swap(environment *env)
313	{
314	stackitem *temp= env->head;
315
316	if((env->head)==NULL) {
317	printerr("Stack empty");
318	return;
319	}
320
321	if(env->head->next==NULL) {
322	printerr("Not enough arguments");
323	return;
324	}
325
326	env->head= env->head->next;
327	temp->next= env->head->next;
328	env->head->next= temp;
329	}
330
331	stackitem* copy(stackitem* in_item)
332	{
333	stackitem *out_item= malloc(sizeof(stackitem));
334
335	memcpy(out_item, in_item, sizeof(stackitem));
336	out_item->next= NULL;
337
338	return out_item;
339	}
340
341
342	/* If the top element is a reference, determine if it's a reference to a
343	function, and if it is, toss the reference and execute the function. */
344	extern void eval(environment *env)
345	{
346	funcp in_func;
347	stackitem* temp= env->head;
348
349	if(temp==NULL) {
350	printerr("Stack empty");
351	return;
352	}
353
354	if(temp->item->type==symb
355	&& ((symbol *)(temp->item->content.ptr))->val != NULL
356	&& ((symbol *)(temp->item->content.ptr))->val->type == func) {
357	in_func= (funcp)(((symbol *)(temp->item->content.ptr))->val->content.ptr);
358	toss(env);
359	(*in_func)(env);
360	return;
361	}
362
363
364	if(temp->item->type==func) {
365	in_func= (funcp)(temp->item->content.ptr);
366	toss(env);
367	(*in_func)(env);
368	return;
369	}
370
371	push(&(env->head), copy(temp));
372	swap(env);
373	toss(env);
374	}
375
376	/* Make a list. */
377	extern void pack(environment *env)
378	{
379	void* delimiter;
380	stackitem iterator, temp;
381	value *pack;
382
383	delimiter= env->head->item->content.ptr; /* Get delimiter */
384	toss(env);
385
386	iterator= env->head;
387
388	if(iterator==NULL \|\| iterator->item->content.ptr==delimiter) {
389	temp= NULL;
390	toss(env);
391	} else {
392	/* Search for first delimiter */
393	while(iterator->next!=NULL
394	&& iterator->next->item->content.ptr!=delimiter)
395	iterator= iterator->next;
396
397	/* Extract list */
398	temp= env->head;
399	env->head= iterator->next;
400	iterator->next= NULL;
401
402	if(env->head!=NULL)
403	toss(env);
404	}
405
406	/* Push list */
407	pack= malloc(sizeof(value));
408	pack->type= list;
409	pack->content.ptr= temp;
410	pack->refcount= 1;
411
412	temp= malloc(sizeof(stackitem));
413	temp->item= pack;
414
415	push(&(env->head), temp);
416	}
417
418	/* Parse input. */
419	int stack_read(environment env, char in_line)
420	{
421	char temp, rest;
422	int itemp;
423	size_t inlength= strlen(in_line)+1;
424	int convert= 0;
425	static int non_eval_flag= 0;
426
427	temp= malloc(inlength);
428	rest= malloc(inlength);
429
430	do {
431	/* If string */
432	if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
433	push_cstring(&(env->head), temp);
434	break;
435	}
436	/* If integer */
437	if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
438	push_val(&(env->head), itemp);
439	break;
440	}
441	/* Escape ';' with '\' */
442	if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
443	temp[1]= '\0';
444	push_sym(env, temp);
445	break;
446	}
447	/* If symbol */
448	if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {
449	push_sym(env, temp);
450	break;
451	}
452	/* If single char */
453	if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {
454	if(*temp==';') {
455	if(!non_eval_flag) {
456	eval(env); /* Evaluate top element */
457	break;
458	}
459
460	push_sym(env, ";");
461	break;
462	}
463
464	if(*temp==']') {
465	push_sym(env, "[");
466	pack(env);
467	if(non_eval_flag!=0)
468	non_eval_flag--;
469	break;
470	}
471
472	if(*temp=='[') {
473	push_sym(env, "[");
474	non_eval_flag++;
475	break;
476	}
477	}
478	} while(0);
479
480
481	free(temp);
482
483	if(convert<2) {
484	free(rest);
485	return 0;
486	}
487
488	stack_read(env, rest);
489
490	free(rest);
491	return 1;
492	}
493
494	/* Relocate elements of the list on the stack. */
495	extern void expand(environment *env)
496	{
497	stackitem temp, new_head;
498
499	/* Is top element a list? */
500	if(env->head==NULL \|\| env->head->item->type!=list) {
501	printerr("Stack empty or not a list");
502	return;
503	}
504
505	/* The first list element is the new stack head */
506	new_head= temp= env->head->item->content.ptr;
507
508	env->head->item->refcount++;
509	toss(env);
510
511	/* Find the end of the list */
512	while(temp->next!=NULL)
513	temp= temp->next;
514
515	/* Connect the tail of the list with the old stack head */
516	temp->next= env->head;
517	env->head= new_head; /* ...and voila! */
518
519	}
520
521	/* Compares two elements by reference. */
522	extern void eq(environment *env)
523	{
524	void left, right;
525	int result;
526
527	if((env->head)==NULL \|\| env->head->next==NULL) {
528	printerr("Not enough elements to compare");
529	return;
530	}
531
532	left= env->head->item->content.ptr;
533	swap(env);
534	right= env->head->item->content.ptr;
535	result= (left==right);
536
537	toss(env); toss(env);
538	push_val(&(env->head), result);
539	}
540
541	/* Negates the top element on the stack. */
542	extern void not(environment *env)
543	{
544	int val;
545
546	if((env->head)==NULL \|\| env->head->item->type!=integer) {
547	printerr("Stack empty or element is not a integer");
548	return;
549	}
550
551	val= env->head->item->content.val;
552	toss(env);
553	push_val(&(env->head), !val);
554	}
555
556	/* Compares the two top elements on the stack and return 0 if they're the
557	same. */
558	extern void neq(environment *env)
559	{
560	eq(env);
561	not(env);
562	}
563
564	/* Give a symbol some content. */
565	extern void def(environment *env)
566	{
567	symbol *sym;
568
569	/* Needs two values on the stack, the top one must be a symbol */
570	if(env->head==NULL \|\| env->head->next==NULL
571	\|\| env->head->item->type!=symb) {
572	printerr("Define what?");
573	return;
574	}
575
576	/* long names are a pain */
577	sym=env->head->item->content.ptr;
578
579	/* if the symbol was bound to something else, throw it away */
580	if(sym->val != NULL)
581	free_val(sym->val);
582
583	/* Bind the symbol to the value */
584	sym->val= env->head->next->item;
585	sym->val->refcount++; /* Increase the reference counter */
586
587	toss(env); toss(env);
588	}
589
590	/* Quit stack. */
591	extern void quit(environment *env)
592	{
593	exit(EXIT_SUCCESS);
594	}
595
596	/* Clear stack */
597	extern void clear(environment *env)
598	{
599	while(env->head!=NULL)
600	toss(env);
601	}
602
603	int main()
604	{
605	environment myenv;
606	char in_string[100];
607
608	init_env(&myenv);
609
610	printf("okidok\n ");
611
612	while(fgets(in_string, 100, stdin) != NULL) {
613	stack_read(&myenv, in_string);
614	printf("okidok\n ");
615	}
616
617	exit(EXIT_SUCCESS);
618	}