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 */
  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 *) */

/* 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;
}

/* Recall a value from a symbol, if bound */
extern void rcl(environment *env)
{
  value *val;

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

  if(env->head->item->type!=symb) {
    printerr("Not a symbol");
    return;
  }
  val=((symbol *)(env->head->item->content.ptr))->val;
  if(val == NULL){
    printerr("Unbound variable");
    return;
  }
  toss(env);            /* toss the symbol */
  push_val(&(env->head), val); /* Return its bound value */
}

/* 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);
}

/* List all defined words */
extern void words(environment *env)
{
  symbol *temp;
  int i;
  
  for(i= 0; i<HASHTBLSIZE; i++) {
    temp= env->symbols[i];
    while(temp!=NULL) {
      printf("%s\n", temp->id);
      temp= temp->next;
    }
  }
}

/* Forgets a symbol (remove it from the hash table) */
extern void forget(environment *env)
{
  char* sym_id;
  stackitem *stack_head= env->head;
  symbol **hash_entry, *temp;

  if(stack_head==NULL || stack_head->item->type!=symb) {
    printerr("Stack empty or not a symbol");
    return;
  }

  sym_id= ((symbol*)(stack_head->item->content.ptr))->id;
  toss(env);

  hash_entry= hash(env->symbols, sym_id);
  temp= *hash_entry;
  *hash_entry= (*hash_entry)->next;
  
  if(temp->val!=NULL) {
    free_val(temp->val);
  }
  free(temp->id);
  free(temp);
} 

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	teddy	1.33	int err; /* Error flag */
62	teddy	1.28	} environment;
63
64			/* A type for pointers to external functions */
65			typedef void (funcp)(environment ); /* funcp is a pointer to a void
66			function (environment ) /
67	masse	1.1
68	teddy	1.28	/* Initialize a newly created environment */
69			void init_env(environment *env)
70	masse	1.1	{
71			long i;
72
73			for(i= 0; i<HASHTBLSIZE; i++)
74	teddy	1.28	env->symbols[i]= NULL;
75	masse	1.1	}
76
77	teddy	1.27	/* Returns a pointer to a pointer to an element in the hash table. */
78	teddy	1.28	symbol *hash(hashtbl in_hashtbl, const char in_string)
79	masse	1.1	{
80			long i= 0;
81			unsigned long out_hash= 0;
82	teddy	1.18	char key= '\0';
83	teddy	1.28	symbol **position;
84	masse	1.1
85	masse	1.16	while(1){ /* Hash in_string */
86	masse	1.1	key= in_string[i++];
87			if(key=='\0')
88			break;
89			out_hash= out_hash*32+key;
90			}
91
92			out_hash= out_hash%HASHTBLSIZE;
93			position= &(in_hashtbl[out_hash]);
94
95	masse	1.25	while(1){
96	teddy	1.18	if(position==NULL) / If empty */
97	masse	1.1	return position;
98
99	teddy	1.18	if(strcmp(in_string, (position)->id)==0) / If match */
100	masse	1.1	return position;
101
102	masse	1.16	position= &((position)->next); / Try next */
103	masse	1.1	}
104			}
105
106	masse	1.14	/* Generic push function. */
107	masse	1.1	int push(stackitem** stack_head, stackitem* in_item)
108			{
109			in_item->next= *stack_head;
110			*stack_head= in_item;
111			return 1;
112			}
113
114	teddy	1.29	/* Push a value onto the stack */
115			void push_val(stackitem *stack_head, value val)
116			{
117			stackitem *new_item= malloc(sizeof(stackitem));
118			new_item->item= val;
119			val->refcount++;
120			push(stack_head, new_item);
121			}
122
123	teddy	1.28	/* Push an integer onto the stack. */
124	teddy	1.29	int push_int(stackitem **stack_head, int in_val)
125	masse	1.1	{
126	teddy	1.28	value *new_value= malloc(sizeof(value));
127			stackitem *new_item= malloc(sizeof(stackitem));
128			new_item->item= new_value;
129
130			new_value->content.val= in_val;
131			new_value->type= integer;
132			new_value->refcount=1;
133	masse	1.1
134			push(stack_head, new_item);
135			return 1;
136			}
137
138	masse	1.14	/* Copy a string onto the stack. */
139	teddy	1.28	int push_cstring(stackitem *stack_head, const char in_string)
140	masse	1.1	{
141	teddy	1.28	value *new_value= malloc(sizeof(value));
142			stackitem *new_item= malloc(sizeof(stackitem));
143			new_item->item=new_value;
144
145			new_value->content.ptr= malloc(strlen(in_string)+1);
146			strcpy(new_value->content.ptr, in_string);
147			new_value->type= string;
148			new_value->refcount=1;
149	masse	1.1
150			push(stack_head, new_item);
151			return 1;
152			}
153
154	teddy	1.28	/* Push a symbol onto the stack. */
155			int push_sym(environment env, const char in_string)
156	masse	1.1	{
157	teddy	1.28	stackitem new_item; / The new stack item */
158			/* ...which will contain... */
159			value new_value; / A new symbol value */
160			/* ...which might point to... */
161	teddy	1.29	symbol *new_symbol; / (if needed) A new actual symbol */
162	teddy	1.28	/* ...which, if possible, will be bound to... */
163			value new_fvalue; / (if needed) A new function value */
164			/* ...which will point to... */
165			void funcptr; / A function pointer */
166
167			static void handle= NULL; / Dynamic linker handle */
168
169			/* Create a new stack item containing a new value */
170			new_item= malloc(sizeof(stackitem));
171			new_value= malloc(sizeof(value));
172			new_item->item=new_value;
173
174			/* The new value is a symbol */
175			new_value->type= symb;
176			new_value->refcount= 1;
177
178			/* Look up the symbol name in the hash table */
179	teddy	1.29	new_symbol= hash(env->symbols, in_string);
180			new_value->content.ptr= *new_symbol;
181	teddy	1.28
182	teddy	1.30	if(new_symbol==NULL) { / If symbol was undefined */
183	teddy	1.28
184			/* Create a new symbol */
185	teddy	1.30	(*new_symbol)= malloc(sizeof(symbol));
186	teddy	1.29	(new_symbol)->val= NULL; / undefined value */
187			(*new_symbol)->next= NULL;
188			(*new_symbol)->id= malloc(strlen(in_string)+1);
189			strcpy((*new_symbol)->id, in_string);
190	masse	1.1
191	teddy	1.28	/* Intern the new symbol in the hash table */
192	teddy	1.29	new_value->content.ptr= *new_symbol;
193	masse	1.1
194	teddy	1.28	/* Try to load the symbol name as an external function, to see if
195			we should bind the symbol to a new function pointer value */
196	masse	1.16	if(handle==NULL) /* If no handle */
197	teddy	1.28	handle= dlopen(NULL, RTLD_LAZY);
198	masse	1.6
199	teddy	1.28	funcptr= dlsym(handle, in_string); /* Get function pointer */
200			if(dlerror()==NULL) { /* If a function was found */
201			new_fvalue= malloc(sizeof(value)); /* Create a new value */
202			new_fvalue->type=func; /* The new value is a function pointer */
203			new_fvalue->content.ptr=funcptr; /* Store function pointer */
204	teddy	1.29	(new_symbol)->val= new_fvalue; / Bind the symbol to the new
205			function value */
206	teddy	1.28	new_fvalue->refcount= 1;
207			}
208	masse	1.1	}
209	teddy	1.28	push(&(env->head), new_item);
210	masse	1.1	return 1;
211			}
212
213	masse	1.17	void printerr(const char* in_string) {
214			fprintf(stderr, "Err: %s\n", in_string);
215			}
216
217	teddy	1.28	/* Throw away a value */
218			void free_val(value *val){
219			stackitem item, temp;
220
221			val->refcount--; /* Decrease the reference count */
222			if(val->refcount == 0){
223			switch (val->type){ /* and free the contents if necessary */
224			case string:
225			free(val->content.ptr);
226			case list: /* lists needs to be freed recursively */
227			item=val->content.ptr;
228			while(item != NULL) { /* for all stack items */
229			free_val(item->item); /* free the value */
230			temp=item->next; /* save next ptr */
231			free(item); /* free the stackitem */
232			item=temp; /* go to next stackitem */
233			}
234			free(val); /* Free the actual list value */
235			break;
236			default:
237			break;
238			}
239			}
240			}
241
242	masse	1.14	/* Discard the top element of the stack. */
243	teddy	1.28	extern void toss(environment *env)
244	masse	1.1	{
245	teddy	1.28	stackitem *temp= env->head;
246	masse	1.1
247	teddy	1.28	if((env->head)==NULL) {
248	masse	1.17	printerr("Stack empty");
249	masse	1.7	return;
250	masse	1.17	}
251	masse	1.7
252	teddy	1.28	free_val(env->head->item); /* Free the value */
253			env->head= env->head->next; /* Remove the top stack item */
254			free(temp); /* Free the old top stack item */
255	masse	1.1	}
256
257	masse	1.14	/* Print newline. */
258	masse	1.34	extern void nl()
259	masse	1.8	{
260			printf("\n");
261			}
262	masse	1.1
263	masse	1.14	/* Prints the top element of the stack. */
264	teddy	1.28	void print_h(stackitem *stack_head)
265	masse	1.8	{
266	masse	1.23
267	teddy	1.28	if(stack_head==NULL) {
268	masse	1.17	printerr("Stack empty");
269	masse	1.8	return;
270	masse	1.17	}
271	masse	1.1
272	teddy	1.28	switch(stack_head->item->type) {
273			case integer:
274			printf("%d", stack_head->item->content.val);
275	teddy	1.2	break;
276			case string:
277	teddy	1.28	printf("\"%s\"", (char*)stack_head->item->content.ptr);
278	teddy	1.2	break;
279	teddy	1.28	case symb:
280			printf("'%s'", ((symbol *)(stack_head->item->content.ptr))->id);
281	masse	1.6	break;
282	masse	1.7	default:
283	teddy	1.28	printf("%p", (funcp)(stack_head->item->content.ptr));
284	teddy	1.2	break;
285			}
286	masse	1.1	}
287
288	teddy	1.28	extern void print_(environment *env) {
289			print_h(env->head);
290			}
291
292	masse	1.14	/* Prints the top element of the stack and then discards it. */
293	teddy	1.28	extern void print(environment *env)
294	masse	1.8	{
295	teddy	1.28	print_(env);
296			toss(env);
297	masse	1.8	}
298
299	masse	1.14	/* Only to be called by function printstack. */
300	teddy	1.28	void print_st(stackitem *stack_head, long counter)
301	masse	1.8	{
302			if(stack_head->next != NULL)
303			print_st(stack_head->next, counter+1);
304			printf("%ld: ", counter);
305	teddy	1.28	print_h(stack_head);
306	masse	1.8	nl();
307			}
308
309	teddy	1.28
310
311	masse	1.14	/* Prints the stack. */
312	teddy	1.28	extern void printstack(environment *env)
313	masse	1.1	{
314	teddy	1.28	if(env->head != NULL) {
315			print_st(env->head, 1);
316	masse	1.21	nl();
317	masse	1.17	} else {
318			printerr("Stack empty");
319	masse	1.1	}
320			}
321
322	masse	1.26	/* Swap the two top elements on the stack. */
323	teddy	1.28	extern void swap(environment *env)
324	masse	1.26	{
325	teddy	1.28	stackitem *temp= env->head;
326	masse	1.26
327	teddy	1.28	if((env->head)==NULL) {
328	masse	1.26	printerr("Stack empty");
329			return;
330			}
331
332	teddy	1.28	if(env->head->next==NULL) {
333			printerr("Not enough arguments");
334	masse	1.26	return;
335	teddy	1.28	}
336	masse	1.26
337	teddy	1.28	env->head= env->head->next;
338			temp->next= env->head->next;
339			env->head->next= temp;
340	masse	1.26	}
341
342			stackitem* copy(stackitem* in_item)
343			{
344	teddy	1.28	stackitem *out_item= malloc(sizeof(stackitem));
345	masse	1.26
346			memcpy(out_item, in_item, sizeof(stackitem));
347			out_item->next= NULL;
348
349			return out_item;
350			}
351
352	teddy	1.33	/* Recall a value from a symbol, if bound */
353	teddy	1.31	extern void rcl(environment *env)
354			{
355			value *val;
356
357			if(env->head == NULL) {
358			printerr("Stack empty");
359			return;
360			}
361
362			if(env->head->item->type!=symb) {
363			printerr("Not a symbol");
364			return;
365			}
366			val=((symbol *)(env->head->item->content.ptr))->val;
367	teddy	1.33	if(val == NULL){
368			printerr("Unbound variable");
369			return;
370			}
371	teddy	1.31	toss(env); /* toss the symbol */
372			push_val(&(env->head), val); /* Return its bound value */
373			}
374	masse	1.26
375	teddy	1.29	/* If the top element is a symbol, determine if it's bound to a
376			function value, and if it is, toss the symbol and execute the
377			function. */
378	teddy	1.28	extern void eval(environment *env)
379	masse	1.1	{
380			funcp in_func;
381	teddy	1.29	value* val;
382			if(env->head==NULL) {
383	masse	1.22	printerr("Stack empty");
384	masse	1.1	return;
385	masse	1.17	}
386	masse	1.1
387	teddy	1.29	/* if it's a symbol */
388			if(env->head->item->type==symb) {
389
390			/* If it's not bound to anything */
391			if (((symbol *)(env->head->item->content.ptr))->val == NULL) {
392			printerr("Unbound variable");
393			return;
394			}
395
396			/* If it contains a function */
397			if (((symbol *)(env->head->item->content.ptr))->val->type == func) {
398			in_func=
399			(funcp)(((symbol *)(env->head->item->content.ptr))->val->content.ptr);
400			toss(env);
401			(in_func)(env); / Run the function */
402			return;
403			} else { /* If it's not a function */
404			val=((symbol *)(env->head->item->content.ptr))->val;
405			toss(env); /* toss the symbol */
406			push_val(&(env->head), val); /* Return its bound value */
407			}
408	teddy	1.28	}
409	masse	1.22
410	teddy	1.29	/* If it's a lone function value, run it */
411			if(env->head->item->type==func) {
412			in_func= (funcp)(env->head->item->content.ptr);
413	teddy	1.28	toss(env);
414			(*in_func)(env);
415	masse	1.1	return;
416	masse	1.26	}
417
418	masse	1.1	}
419
420	masse	1.19	/* Make a list. */
421	teddy	1.28	extern void pack(environment *env)
422	masse	1.19	{
423			void* delimiter;
424	teddy	1.28	stackitem iterator, temp;
425			value *pack;
426	masse	1.19
427	teddy	1.28	delimiter= env->head->item->content.ptr; /* Get delimiter */
428			toss(env);
429	masse	1.19
430	teddy	1.28	iterator= env->head;
431	masse	1.19
432	teddy	1.28	if(iterator==NULL \|\| iterator->item->content.ptr==delimiter) {
433	masse	1.24	temp= NULL;
434	teddy	1.28	toss(env);
435	masse	1.24	} else {
436			/* Search for first delimiter */
437	teddy	1.28	while(iterator->next!=NULL
438			&& iterator->next->item->content.ptr!=delimiter)
439	masse	1.24	iterator= iterator->next;
440
441			/* Extract list */
442	teddy	1.28	temp= env->head;
443			env->head= iterator->next;
444	masse	1.24	iterator->next= NULL;
445
446	teddy	1.28	if(env->head!=NULL)
447			toss(env);
448	masse	1.24	}
449	masse	1.19
450			/* Push list */
451	teddy	1.28	pack= malloc(sizeof(value));
452	masse	1.19	pack->type= list;
453			pack->content.ptr= temp;
454	teddy	1.28	pack->refcount= 1;
455
456			temp= malloc(sizeof(stackitem));
457			temp->item= pack;
458	masse	1.19
459	teddy	1.28	push(&(env->head), temp);
460	masse	1.19	}
461
462	masse	1.14	/* Parse input. */
463	teddy	1.28	int stack_read(environment env, char in_line)
464	masse	1.1	{
465			char temp, rest;
466			int itemp;
467			size_t inlength= strlen(in_line)+1;
468			int convert= 0;
469	masse	1.20	static int non_eval_flag= 0;
470	masse	1.1
471			temp= malloc(inlength);
472			rest= malloc(inlength);
473
474	masse	1.15	do {
475	masse	1.16	/* If string */
476	masse	1.15	if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest))) {
477	teddy	1.28	push_cstring(&(env->head), temp);
478	masse	1.15	break;
479			}
480	teddy	1.28	/* If integer */
481	masse	1.15	if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest))) {
482	teddy	1.29	push_int(&(env->head), itemp);
483	masse	1.15	break;
484			}
485	masse	1.16	/* Escape ';' with '\' */
486	masse	1.15	if((convert= sscanf(in_line, "\\%c%[^\n\r]", temp, rest))) {
487	teddy	1.28	temp[1]= '\0';
488			push_sym(env, temp);
489	masse	1.15	break;
490			}
491	masse	1.16	/* If symbol */
492	masse	1.34	if((convert= sscanf(in_line, "%[^][ ;\n\r]%[^\n\r]", temp, rest))) {
493	teddy	1.28	push_sym(env, temp);
494	masse	1.15	break;
495			}
496	masse	1.19	/* If single char */
497			if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest))) {
498			if(*temp==';') {
499	masse	1.21	if(!non_eval_flag) {
500	teddy	1.28	eval(env); /* Evaluate top element */
501	masse	1.20	break;
502			}
503
504	teddy	1.28	push_sym(env, ";");
505	masse	1.19	break;
506			}
507
508			if(*temp==']') {
509	teddy	1.28	push_sym(env, "[");
510			pack(env);
511	masse	1.21	if(non_eval_flag!=0)
512			non_eval_flag--;
513	masse	1.20	break;
514			}
515
516			if(*temp=='[') {
517	teddy	1.28	push_sym(env, "[");
518	masse	1.20	non_eval_flag++;
519	masse	1.19	break;
520			}
521	masse	1.15	}
522			} while(0);
523
524	masse	1.1
525			free(temp);
526
527			if(convert<2) {
528			free(rest);
529			return 0;
530			}
531
532	teddy	1.28	stack_read(env, rest);
533	masse	1.1
534			free(rest);
535			return 1;
536	masse	1.7	}
537	masse	1.1
538	masse	1.16	/* Relocate elements of the list on the stack. */
539	teddy	1.28	extern void expand(environment *env)
540	masse	1.1	{
541	masse	1.8	stackitem temp, new_head;
542
543	masse	1.16	/* Is top element a list? */
544	teddy	1.28	if(env->head==NULL \|\| env->head->item->type!=list) {
545	masse	1.17	printerr("Stack empty or not a list");
546	masse	1.8	return;
547	masse	1.17	}
548	masse	1.8
549	masse	1.16	/* The first list element is the new stack head */
550	teddy	1.28	new_head= temp= env->head->item->content.ptr;
551	masse	1.8
552	teddy	1.28	env->head->item->refcount++;
553			toss(env);
554	masse	1.24
555	teddy	1.28	/* Find the end of the list */
556	masse	1.8	while(temp->next!=NULL)
557			temp= temp->next;
558
559	teddy	1.28	/* Connect the tail of the list with the old stack head */
560			temp->next= env->head;
561			env->head= new_head; /* ...and voila! */
562
563	teddy	1.5	}
564	masse	1.11
565	masse	1.14	/* Compares two elements by reference. */
566	teddy	1.28	extern void eq(environment *env)
567	masse	1.11	{
568			void left, right;
569			int result;
570
571	teddy	1.28	if((env->head)==NULL \|\| env->head->next==NULL) {
572	masse	1.17	printerr("Not enough elements to compare");
573	masse	1.11	return;
574	masse	1.17	}
575	masse	1.11
576	teddy	1.28	left= env->head->item->content.ptr;
577			swap(env);
578			right= env->head->item->content.ptr;
579	masse	1.11	result= (left==right);
580
581	teddy	1.28	toss(env); toss(env);
582	teddy	1.29	push_int(&(env->head), result);
583	masse	1.11	}
584
585	masse	1.14	/* Negates the top element on the stack. */
586	teddy	1.28	extern void not(environment *env)
587	masse	1.11	{
588	teddy	1.28	int val;
589	masse	1.11
590	teddy	1.28	if((env->head)==NULL \|\| env->head->item->type!=integer) {
591			printerr("Stack empty or element is not a integer");
592	masse	1.11	return;
593	masse	1.17	}
594	masse	1.11
595	teddy	1.28	val= env->head->item->content.val;
596			toss(env);
597	teddy	1.29	push_int(&(env->head), !val);
598	masse	1.11	}
599
600	masse	1.14	/* Compares the two top elements on the stack and return 0 if they're the
601			same. */
602	teddy	1.28	extern void neq(environment *env)
603	masse	1.11	{
604	teddy	1.28	eq(env);
605			not(env);
606	masse	1.11	}
607	masse	1.12
608	masse	1.14	/* Give a symbol some content. */
609	teddy	1.28	extern void def(environment *env)
610	masse	1.12	{
611	teddy	1.28	symbol *sym;
612	masse	1.12
613	teddy	1.28	/* Needs two values on the stack, the top one must be a symbol */
614			if(env->head==NULL \|\| env->head->next==NULL
615			\|\| env->head->item->type!=symb) {
616	masse	1.17	printerr("Define what?");
617	masse	1.12	return;
618	masse	1.17	}
619	masse	1.12
620	teddy	1.28	/* long names are a pain */
621			sym=env->head->item->content.ptr;
622
623			/* if the symbol was bound to something else, throw it away */
624			if(sym->val != NULL)
625			free_val(sym->val);
626
627			/* Bind the symbol to the value */
628			sym->val= env->head->next->item;
629			sym->val->refcount++; /* Increase the reference counter */
630	masse	1.12
631	teddy	1.28	toss(env); toss(env);
632	masse	1.12	}
633	masse	1.10
634	masse	1.14	/* Quit stack. */
635	teddy	1.28	extern void quit(environment *env)
636	teddy	1.5	{
637			exit(EXIT_SUCCESS);
638	masse	1.24	}
639
640			/* Clear stack */
641	teddy	1.28	extern void clear(environment *env)
642	masse	1.24	{
643	teddy	1.28	while(env->head!=NULL)
644			toss(env);
645	masse	1.1	}
646
647	teddy	1.33	/* List all defined words */
648	masse	1.32	extern void words(environment *env)
649			{
650			symbol *temp;
651			int i;
652
653			for(i= 0; i<HASHTBLSIZE; i++) {
654			temp= env->symbols[i];
655			while(temp!=NULL) {
656			printf("%s\n", temp->id);
657			temp= temp->next;
658			}
659			}
660			}
661	masse	1.34
662			/* Forgets a symbol (remove it from the hash table) */
663			extern void forget(environment *env)
664			{
665			char* sym_id;
666			stackitem *stack_head= env->head;
667			symbol *hash_entry, temp;
668
669			if(stack_head==NULL \|\| stack_head->item->type!=symb) {
670			printerr("Stack empty or not a symbol");
671			return;
672			}
673
674			sym_id= ((symbol*)(stack_head->item->content.ptr))->id;
675			toss(env);
676
677			hash_entry= hash(env->symbols, sym_id);
678			temp= *hash_entry;
679			hash_entry= (hash_entry)->next;
680
681			if(temp->val!=NULL) {
682			free_val(temp->val);
683			}
684			free(temp->id);
685			free(temp);
686			}
687	masse	1.32
688	masse	1.1	int main()
689			{
690	teddy	1.28	environment myenv;
691	masse	1.1	char in_string[100];
692
693	teddy	1.28	init_env(&myenv);
694	masse	1.1
695			printf("okidok\n ");
696
697			while(fgets(in_string, 100, stdin) != NULL) {
698	teddy	1.28	stack_read(&myenv, in_string);
699	masse	1.1	printf("okidok\n ");
700			}
701
702	masse	1.10	exit(EXIT_SUCCESS);
703	masse	1.1	}