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 a value onto the stack */
void push_val(stackitem **stack_head, value *val)
{
  stackitem *new_item= malloc(sizeof(stackitem));
  new_item->item= val;
  val->refcount++;
  push(stack_head, new_item);
}

/* Push an integer onto the stack. */
int push_int(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_symbol= hash(env->symbols, in_string);
  new_value->content.ptr= *new_symbol;

  if(*new_symbol==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 symbol, determine if it's bound to a
   function value, and if it is, toss the symbol and execute the
   function. */
extern void eval(environment *env)
{
  funcp in_func;
  value* val;
  if(env->head==NULL) {
    printerr("Stack empty");
    return;
  }

  /* if it's a symbol */
  if(env->head->item->type==symb) {

    /* If it's not bound to anything */
    if (((symbol *)(env->head->item->content.ptr))->val == NULL) {
      printerr("Unbound variable");
      return;
    }
    
    /* If it contains a function */
    if (((symbol *)(env->head->item->content.ptr))->val->type == func) {
      in_func=
        (funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);
      toss(env);
      (*in_func)(env);          /* Run the function */
      return;
    } else {                    /* If it's not a function */
      val=((symbol *)(env->head->item->content.ptr))->val;
      toss(env);                /* toss the symbol */
      push_val(&(env->head), val); /* Return its bound value */
    }
  }

  /* If it's a lone function value, run it */
  if(env->head->item->type==func) {
    in_func= (funcp)(env->head->item->content.ptr);
    toss(env); 
    (*in_func)(env);
    return;
  }

}

/* 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_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;
      }

      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_int(&(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_int(&(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	masse	1.1	/* printf */
2			#include <stdio.h>
3			/* EXIT_SUCCESS */
4			#include <stdlib.h>
5			/* NULL */
6			#include <stddef.h>
7	teddy	1.3	/* dlopen, dlsym, dlerror */
8	masse	1.1	#include <dlfcn.h>
9	teddy	1.18	/* assert */
10			#include <assert.h>
11	masse	1.1
12			#define HASHTBLSIZE 65536
13
14	teddy	1.28	/* First, define some types. */
15
16			/* A value of some type */
17			typedef struct {
18	masse	1.16	enum {
19	teddy	1.28	integer,
20	teddy	1.18	string,
21			ref, /* Reference (to an element in the
22			hash table) */
23	masse	1.16	func, /* Function pointer */
24	teddy	1.28	symb,
25	masse	1.16	list
26	teddy	1.18	} type; /* Type of stack element */
27
28	masse	1.1	union {
29	teddy	1.28	void ptr; / Pointer to the content */
30	masse	1.16	int val; /* ...or an integer */
31			} content; /* Stores a pointer or an integer */
32	masse	1.1
33	teddy	1.28	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	masse	1.1	} stackitem;
55
56	teddy	1.28	/* 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	masse	1.1
67	teddy	1.28	/* Initialize a newly created environment */
68			void init_env(environment *env)
69	masse	1.1	{
70			long i;
71
72			for(i= 0; i<HASHTBLSIZE; i++)
73	teddy	1.28	env->symbols[i]= NULL;
74	masse	1.1	}
75
76	teddy	1.27	/* Returns a pointer to a pointer to an element in the hash table. */
77	teddy	1.28	symbol *hash(hashtbl in_hashtbl, const char in_string)
78	masse	1.1	{
79			long i= 0;
80			unsigned long out_hash= 0;
81	teddy	1.18	char key= '\0';
82	teddy	1.28	symbol **position;
83	masse	1.1
84	masse	1.16	while(1){ /* Hash in_string */
85	masse	1.1	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	masse	1.25	while(1){
95	teddy	1.18	if(position==NULL) / If empty */
96	masse	1.1	return position;
97
98	teddy	1.18	if(strcmp(in_string, (position)->id)==0) / If match */
99	masse	1.1	return position;
100
101	masse	1.16	position= &((position)->next); / Try next */
102	masse	1.1	}
103			}
104
105	masse	1.14	/* Generic push function. */
106	masse	1.1	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	teddy	1.29	/* Push a value onto the stack */
114			void push_val(stackitem *stack_head, value val)
115			{
116			stackitem *new_item= malloc(sizeof(stackitem));
117			new_item->item= val;
118			val->refcount++;
119			push(stack_head, new_item);
120			}
121
122	teddy	1.28	/* Push an integer onto the stack. */
123	teddy	1.29	int push_int(stackitem **stack_head, int in_val)
124	masse	1.1	{
125	teddy	1.28	value *new_value= malloc(sizeof(value));
126			stackitem *new_item= malloc(sizeof(stackitem));
127			new_item->item= new_value;
128
129			new_value->content.val= in_val;
130			new_value->type= integer;
131			new_value->refcount=1;
132	masse	1.1
133			push(stack_head, new_item);
134			return 1;
135			}
136
137	masse	1.14	/* Copy a string onto the stack. */
138	teddy	1.28	int push_cstring(stackitem *stack_head, const char in_string)
139	masse	1.1	{
140	teddy	1.28	value *new_value= malloc(sizeof(value));
141			stackitem *new_item= malloc(sizeof(stackitem));
142			new_item->item=new_value;
143
144			new_value->content.ptr= malloc(strlen(in_string)+1);
145			strcpy(new_value->content.ptr, in_string);
146			new_value->type= string;
147			new_value->refcount=1;
148	masse	1.1
149			push(stack_head, new_item);
150			return 1;
151			}
152
153	teddy	1.28	/* Push a symbol onto the stack. */
154			int push_sym(environment env, const char in_string)
155	masse	1.1	{
156	teddy	1.28	stackitem new_item; / The new stack item */
157			/* ...which will contain... */
158			value new_value; / A new symbol value */
159			/* ...which might point to... */
160	teddy	1.29	symbol *new_symbol; / (if needed) A new actual symbol */
161	teddy	1.28	/* ...which, if possible, will be bound to... */
162			value new_fvalue; / (if needed) A new function value */
163			/* ...which will point to... */
164			void funcptr; / A function pointer */
165
166			static void handle= NULL; / Dynamic linker handle */
167
168			/* Create a new stack item containing a new value */
169			new_item= malloc(sizeof(stackitem));
170			new_value= malloc(sizeof(value));
171			new_item->item=new_value;
172
173			/* The new value is a symbol */
174			new_value->type= symb;
175			new_value->refcount= 1;
176
177			/* Look up the symbol name in the hash table */
178	teddy	1.29	new_symbol= hash(env->symbols, in_string);
179			new_value->content.ptr= *new_symbol;
180	teddy	1.28
181	teddy	1.30	if(new_symbol==NULL) { / If symbol was undefined */
182	teddy	1.28
183			/* Create a new symbol */
184	teddy	1.30	(*new_symbol)= malloc(sizeof(symbol));
185	teddy	1.29	(new_symbol)->val= NULL; / undefined value */
186			(*new_symbol)->next= NULL;
187			(*new_symbol)->id= malloc(strlen(in_string)+1);
188			strcpy((*new_symbol)->id, in_string);
189	masse	1.1
190	teddy	1.28	/* Intern the new symbol in the hash table */
191	teddy	1.29	new_value->content.ptr= *new_symbol;
192	masse	1.1
193	teddy	1.28	/* Try to load the symbol name as an external function, to see if
194			we should bind the symbol to a new function pointer value */
195	masse	1.16	if(handle==NULL) /* If no handle */
196	teddy	1.28	handle= dlopen(NULL, RTLD_LAZY);
197	masse	1.6
198	teddy	1.28	funcptr= dlsym(handle, in_string); /* Get function pointer */
199			if(dlerror()==NULL) { /* If a function was found */
200			new_fvalue= malloc(sizeof(value)); /* Create a new value */
201			new_fvalue->type=func; /* The new value is a function pointer */
202			new_fvalue->content.ptr=funcptr; /* Store function pointer */
203	teddy	1.29	(new_symbol)->val= new_fvalue; / Bind the symbol to the new
204			function value */
205	teddy	1.28	new_fvalue->refcount= 1;
206			}
207	masse	1.1	}
208	teddy	1.28	push(&(env->head), new_item);
209	masse	1.1	return 1;
210			}
211
212	masse	1.17	void printerr(const char* in_string) {
213			fprintf(stderr, "Err: %s\n", in_string);
214			}
215
216	teddy	1.28	/* Throw away a value */
217			void free_val(value *val){
218			stackitem item, temp;
219
220			val->refcount--; /* Decrease the reference count */
221			if(val->refcount == 0){
222			switch (val->type){ /* and free the contents if necessary */
223			case string:
224			free(val->content.ptr);
225			case list: /* lists needs to be freed recursively */
226			item=val->content.ptr;
227			while(item != NULL) { /* for all stack items */
228			free_val(item->item); /* free the value */
229			temp=item->next; /* save next ptr */
230			free(item); /* free the stackitem */
231			item=temp; /* go to next stackitem */
232			}
233			free(val); /* Free the actual list value */
234			break;
235			default:
236			break;
237			}
238			}
239			}
240
241	masse	1.14	/* Discard the top element of the stack. */
242	teddy	1.28	extern void toss(environment *env)
243	masse	1.1	{
244	teddy	1.28	stackitem *temp= env->head;
245	masse	1.1
246	teddy	1.28	if((env->head)==NULL) {
247	masse	1.17	printerr("Stack empty");
248	masse	1.7	return;
249	masse	1.17	}
250	masse	1.7
251	teddy	1.28	free_val(env->head->item); /* Free the value */
252			env->head= env->head->next; /* Remove the top stack item */
253			free(temp); /* Free the old top stack item */
254	masse	1.1	}
255
256	masse	1.14	/* Print newline. */
257	masse	1.8	extern void nl()
258			{
259			printf("\n");
260			}
261	masse	1.1
262	masse	1.14	/* Prints the top element of the stack. */
263	teddy	1.28	void print_h(stackitem *stack_head)
264	masse	1.8	{
265	masse	1.23
266	teddy	1.28	if(stack_head==NULL) {
267	masse	1.17	printerr("Stack empty");
268	masse	1.8	return;
269	masse	1.17	}
270	masse	1.1
271	teddy	1.28	switch(stack_head->item->type) {
272			case integer:
273			printf("%d", stack_head->item->content.val);
274	teddy	1.2	break;
275			case string:
276	teddy	1.28	printf("\"%s\"", (char*)stack_head->item->content.ptr);
277	teddy	1.2	break;
278	teddy	1.28	case symb:
279			printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
280	masse	1.6	break;
281	masse	1.7	default:
282	teddy	1.28	printf("%p", (funcp)(stack_head->item->content.ptr));
283	teddy	1.2	break;
284			}
285	masse	1.1	}
286
287	teddy	1.28	extern void print_(environment *env) {
288			print_h(env->head);
289			}
290
291	masse	1.14	/* Prints the top element of the stack and then discards it. */
292	teddy	1.28	extern void print(environment *env)
293	masse	1.8	{
294	teddy	1.28	print_(env);
295			toss(env);
296	masse	1.8	}
297
298	masse	1.14	/* Only to be called by function printstack. */
299	teddy	1.28	void print_st(stackitem *stack_head, long counter)
300	masse	1.8	{
301			if(stack_head->next != NULL)
302			print_st(stack_head->next, counter+1);
303			printf("%ld: ", counter);
304	teddy	1.28	print_h(stack_head);
305	masse	1.8	nl();
306			}
307
308	teddy	1.28
309
310	masse	1.14	/* Prints the stack. */
311	teddy	1.28	extern void printstack(environment *env)
312	masse	1.1	{
313	teddy	1.28	if(env->head != NULL) {
314			print_st(env->head, 1);
315	masse	1.21	nl();
316	masse	1.17	} else {
317			printerr("Stack empty");
318	masse	1.1	}
319			}
320
321	masse	1.26	/* Swap the two top elements on the stack. */
322	teddy	1.28	extern void swap(environment *env)
323	masse	1.26	{
324	teddy	1.28	stackitem *temp= env->head;
325	masse	1.26
326	teddy	1.28	if((env->head)==NULL) {
327	masse	1.26	printerr("Stack empty");
328			return;
329			}
330
331	teddy	1.28	if(env->head->next==NULL) {
332			printerr("Not enough arguments");
333	masse	1.26	return;
334	teddy	1.28	}
335	masse	1.26
336	teddy	1.28	env->head= env->head->next;
337			temp->next= env->head->next;
338			env->head->next= temp;
339	masse	1.26	}
340
341			stackitem* copy(stackitem* in_item)
342			{
343	teddy	1.28	stackitem *out_item= malloc(sizeof(stackitem));
344	masse	1.26
345			memcpy(out_item, in_item, sizeof(stackitem));
346			out_item->next= NULL;
347
348			return out_item;
349			}
350
351
352	teddy	1.29	/* If the top element is a symbol, determine if it's bound to a
353			function value, and if it is, toss the symbol and execute the
354			function. */
355	teddy	1.28	extern void eval(environment *env)
356	masse	1.1	{
357			funcp in_func;
358	teddy	1.29	value* val;
359			if(env->head==NULL) {
360	masse	1.22	printerr("Stack empty");
361	masse	1.1	return;
362	masse	1.17	}
363	masse	1.1
364	teddy	1.29	/* if it's a symbol */
365			if(env->head->item->type==symb) {
366
367			/* If it's not bound to anything */
368			if (((symbol *)(env->head->item->content.ptr))->val == NULL) {
369			printerr("Unbound variable");
370			return;
371			}
372
373			/* If it contains a function */
374			if (((symbol *)(env->head->item->content.ptr))->val->type == func) {
375			in_func=
376			(funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);
377			toss(env);
378			(in_func)(env); / Run the function */
379			return;
380			} else { /* If it's not a function */
381			val=((symbol *)(env->head->item->content.ptr))->val;
382			toss(env); /* toss the symbol */
383			push_val(&(env->head), val); /* Return its bound value */
384			}
385	teddy	1.28	}
386	masse	1.22
387	teddy	1.29	/* If it's a lone function value, run it */
388			if(env->head->item->type==func) {
389			in_func= (funcp)(env->head->item->content.ptr);
390	teddy	1.28	toss(env);
391			(*in_func)(env);
392	masse	1.1	return;
393	masse	1.26	}
394
395	masse	1.1	}
396
397	masse	1.19	/* Make a list. */
398	teddy	1.28	extern void pack(environment *env)
399	masse	1.19	{
400			void* delimiter;
401	teddy	1.28	stackitem iterator, temp;
402			value *pack;
403	masse	1.19
404	teddy	1.28	delimiter= env->head->item->content.ptr; /* Get delimiter */
405			toss(env);
406	masse	1.19
407	teddy	1.28	iterator= env->head;
408	masse	1.19
409	teddy	1.28	if(iterator==NULL \|\| iterator->item->content.ptr==delimiter) {
410	masse	1.24	temp= NULL;
411	teddy	1.28	toss(env);
412	masse	1.24	} else {
413			/* Search for first delimiter */
414	teddy	1.28	while(iterator->next!=NULL
415			&& iterator->next->item->content.ptr!=delimiter)
416	masse	1.24	iterator= iterator->next;
417
418			/* Extract list */
419	teddy	1.28	temp= env->head;
420			env->head= iterator->next;
421	masse	1.24	iterator->next= NULL;
422
423	teddy	1.28	if(env->head!=NULL)
424			toss(env);
425	masse	1.24	}
426	masse	1.19
427			/* Push list */
428	teddy	1.28	pack= malloc(sizeof(value));
429	masse	1.19	pack->type= list;
430			pack->content.ptr= temp;
431	teddy	1.28	pack->refcount= 1;
432
433			temp= malloc(sizeof(stackitem));
434			temp->item= pack;
435	masse	1.19
436	teddy	1.28	push(&(env->head), temp);
437	masse	1.19	}
438
439	masse	1.14	/* Parse input. */
440	teddy	1.28	int stack_read(environment env, char in_line)
441	masse	1.1	{
442			char temp, rest;
443			int itemp;
444			size_t inlength= strlen(in_line)+1;
445			int convert= 0;
446	masse	1.20	static int non_eval_flag= 0;
447	masse	1.1
448			temp= malloc(inlength);
449			rest= malloc(inlength);
450
451	masse	1.15	do {
452	masse	1.16	/* If string */
453	masse	1.15	if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
454	teddy	1.28	push_cstring(&(env->head), temp);
455	masse	1.15	break;
456			}
457	teddy	1.28	/* If integer */
458	masse	1.15	if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
459	teddy	1.29	push_int(&(env->head), itemp);
460	masse	1.15	break;
461			}
462	masse	1.16	/* Escape ';' with '\' */
463	masse	1.15	if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
464	teddy	1.28	temp[1]= '\0';
465			push_sym(env, temp);
466	masse	1.15	break;
467			}
468	masse	1.16	/* If symbol */
469	teddy	1.28	if((convert= sscanf(in_line, "%[^][ ;\n\r_]%[^\n\r]", temp, rest))) {
470			push_sym(env, temp);
471	masse	1.15	break;
472			}
473	masse	1.19	/* If single char */
474			if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {
475			if(*temp==';') {
476	masse	1.21	if(!non_eval_flag) {
477	teddy	1.28	eval(env); /* Evaluate top element */
478	masse	1.20	break;
479			}
480
481	teddy	1.28	push_sym(env, ";");
482	masse	1.19	break;
483			}
484
485			if(*temp==']') {
486	teddy	1.28	push_sym(env, "[");
487			pack(env);
488	masse	1.21	if(non_eval_flag!=0)
489			non_eval_flag--;
490	masse	1.20	break;
491			}
492
493			if(*temp=='[') {
494	teddy	1.28	push_sym(env, "[");
495	masse	1.20	non_eval_flag++;
496	masse	1.19	break;
497			}
498	masse	1.15	}
499			} while(0);
500
501	masse	1.1
502			free(temp);
503
504			if(convert<2) {
505			free(rest);
506			return 0;
507			}
508
509	teddy	1.28	stack_read(env, rest);
510	masse	1.1
511			free(rest);
512			return 1;
513	masse	1.7	}
514	masse	1.1
515	masse	1.16	/* Relocate elements of the list on the stack. */
516	teddy	1.28	extern void expand(environment *env)
517	masse	1.1	{
518	masse	1.8	stackitem temp, new_head;
519
520	masse	1.16	/* Is top element a list? */
521	teddy	1.28	if(env->head==NULL \|\| env->head->item->type!=list) {
522	masse	1.17	printerr("Stack empty or not a list");
523	masse	1.8	return;
524	masse	1.17	}
525	masse	1.8
526	masse	1.16	/* The first list element is the new stack head */
527	teddy	1.28	new_head= temp= env->head->item->content.ptr;
528	masse	1.8
529	teddy	1.28	env->head->item->refcount++;
530			toss(env);
531	masse	1.24
532	teddy	1.28	/* Find the end of the list */
533	masse	1.8	while(temp->next!=NULL)
534			temp= temp->next;
535
536	teddy	1.28	/* Connect the tail of the list with the old stack head */
537			temp->next= env->head;
538			env->head= new_head; /* ...and voila! */
539
540	teddy	1.5	}
541	masse	1.11
542	masse	1.14	/* Compares two elements by reference. */
543	teddy	1.28	extern void eq(environment *env)
544	masse	1.11	{
545			void left, right;
546			int result;
547
548	teddy	1.28	if((env->head)==NULL \|\| env->head->next==NULL) {
549	masse	1.17	printerr("Not enough elements to compare");
550	masse	1.11	return;
551	masse	1.17	}
552	masse	1.11
553	teddy	1.28	left= env->head->item->content.ptr;
554			swap(env);
555			right= env->head->item->content.ptr;
556	masse	1.11	result= (left==right);
557
558	teddy	1.28	toss(env); toss(env);
559	teddy	1.29	push_int(&(env->head), result);
560	masse	1.11	}
561
562	masse	1.14	/* Negates the top element on the stack. */
563	teddy	1.28	extern void not(environment *env)
564	masse	1.11	{
565	teddy	1.28	int val;
566	masse	1.11
567	teddy	1.28	if((env->head)==NULL \|\| env->head->item->type!=integer) {
568			printerr("Stack empty or element is not a integer");
569	masse	1.11	return;
570	masse	1.17	}
571	masse	1.11
572	teddy	1.28	val= env->head->item->content.val;
573			toss(env);
574	teddy	1.29	push_int(&(env->head), !val);
575	masse	1.11	}
576
577	masse	1.14	/* Compares the two top elements on the stack and return 0 if they're the
578			same. */
579	teddy	1.28	extern void neq(environment *env)
580	masse	1.11	{
581	teddy	1.28	eq(env);
582			not(env);
583	masse	1.11	}
584	masse	1.12
585	masse	1.14	/* Give a symbol some content. */
586	teddy	1.28	extern void def(environment *env)
587	masse	1.12	{
588	teddy	1.28	symbol *sym;
589	masse	1.12
590	teddy	1.28	/* Needs two values on the stack, the top one must be a symbol */
591			if(env->head==NULL \|\| env->head->next==NULL
592			\|\| env->head->item->type!=symb) {
593	masse	1.17	printerr("Define what?");
594	masse	1.12	return;
595	masse	1.17	}
596	masse	1.12
597	teddy	1.28	/* long names are a pain */
598			sym=env->head->item->content.ptr;
599
600			/* if the symbol was bound to something else, throw it away */
601			if(sym->val != NULL)
602			free_val(sym->val);
603
604			/* Bind the symbol to the value */
605			sym->val= env->head->next->item;
606			sym->val->refcount++; /* Increase the reference counter */
607	masse	1.12
608	teddy	1.28	toss(env); toss(env);
609	masse	1.12	}
610	masse	1.10
611	masse	1.14	/* Quit stack. */
612	teddy	1.28	extern void quit(environment *env)
613	teddy	1.5	{
614			exit(EXIT_SUCCESS);
615	masse	1.24	}
616
617			/* Clear stack */
618	teddy	1.28	extern void clear(environment *env)
619	masse	1.24	{
620	teddy	1.28	while(env->head!=NULL)
621			toss(env);
622	masse	1.1	}
623
624			int main()
625			{
626	teddy	1.28	environment myenv;
627	masse	1.1	char in_string[100];
628
629	teddy	1.28	init_env(&myenv);
630	masse	1.1
631			printf("okidok\n ");
632
633			while(fgets(in_string, 100, stdin) != NULL) {
634	teddy	1.28	stack_read(&myenv, in_string);
635	masse	1.1	printf("okidok\n ");
636			}
637
638	masse	1.10	exit(EXIT_SUCCESS);
639	masse	1.1	}