--- stack/stack.c	2002/02/08 00:59:34	1.55
+++ stack/stack.c	2002/02/13 19:53:55	1.77
@@ -9,7 +9,7 @@
 /* strcmp, strcpy, strlen, strcat, strdup */
 #include <string.h>
 
-#define HASHTBLSIZE 65536
+#define HASHTBLSIZE 2048
 
 /* First, define some types. */
 
@@ -48,6 +48,7 @@
 typedef struct stackitem_struct
 {
   value *item;			/* The value on the stack */
+				/* (This is never NULL) */
   struct stackitem_struct *next; /* Next item */
 } stackitem;
 
@@ -58,6 +59,7 @@
   hashtbl symbols;		/* Hash table of all variable bindings */
   int err;			/* Error flag */
   int non_eval_flag;
+  char *in_string;		/* Input pending to be read */
 } environment;
 
 /* A type for pointers to external functions */
@@ -69,6 +71,7 @@
 {
   int i;
 
+  env->in_string= NULL;
   env->err= 0;
   env->non_eval_flag= 0;
   for(i= 0; i<HASHTBLSIZE; i++)
@@ -152,49 +155,39 @@
   }
 }
 
-/* Generic push function. */
-void push(stackitem** stack_head, stackitem* in_item)
-{
-  in_item->next= *stack_head;
-  *stack_head= in_item;
-}
-
 /* Push a value onto the stack */
-void push_val(stackitem **stack_head, value *val)
+void push_val(environment *env, value *val)
 {
   stackitem *new_item= malloc(sizeof(stackitem));
   new_item->item= val;
   val->refcount++;
-  push(stack_head, new_item);
+  new_item->next= env->head;
+  env->head= new_item;
 }
 
 /* Push an integer onto the stack. */
-void push_int(stackitem **stack_head, int in_val) 
+void push_int(environment *env, 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);
+  push_val(env, new_value);
 }
 
 /* Copy a string onto the stack. */
-void push_cstring(stackitem **stack_head, const char *in_string)
+void push_cstring(environment *env, 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);
+  push_val(env, new_value);
 }
 
 /* Mangle a symbol name to a valid C identifier name */
@@ -243,14 +236,12 @@
   new_value->type= string;
   new_value->refcount=1;
 
-  push_val(&(env->head), new_value);
+  push_val(env, new_value);
 }
 
 /* Push a symbol onto the stack. */
 void 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 */
@@ -263,10 +254,7 @@
   const char *dlerr;		/* Dynamic linker error */
   char *mangled;		/* Mangled function name */
 
-  /* 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;
@@ -310,7 +298,7 @@
       new_fvalue->refcount= 1;
     }
   }
-  push(&(env->head), new_item);
+  push_val(env, new_value);
 }
 
 /* Print newline. */
@@ -346,9 +334,6 @@
   case list:
     push_sym(env, "list");
     break;
-  default:
-    push_sym(env, "unknown");
-    break;
   }
 }    
 
@@ -360,7 +345,7 @@
     printf("%d", stack_head->item->content.val);
     break;
   case string:
-    printf("\"%s\"", (char*)stack_head->item->content.ptr);
+    printf("%s", (char*)stack_head->item->content.ptr);
     break;
   case symb:
     printf("%s", ((symbol *)(stack_head->item->content.ptr))->id);
@@ -379,9 +364,6 @@
     }
     printf("]");
     break;
-  default:
-    printf("#<unknown %p>", (stack_head->item->content.ptr));
-    break;
   }
 }
 
@@ -438,6 +420,23 @@
   env->head->next= temp;
 } 
 
+/* Rotate the first three elements on the stack. */
+extern void rot(environment *env)
+{
+  stackitem *temp= env->head;
+  
+  if(env->head==NULL || env->head->next==NULL
+      || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  env->head= env->head->next->next;
+  temp->next->next= env->head->next;
+  env->head->next= temp;
+}
+
 /* Recall a value from a symbol, if bound */
 extern void rcl(environment *env)
 {
@@ -463,11 +462,9 @@
   }
   toss(env);		/* toss the symbol */
   if(env->err) return;
-  push_val(&(env->head), val); /* Return its bound value */
+  push_val(env, val); /* Return its bound value */
 }
 
-void stack_read(environment*, char*);
-
 /* 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. */
@@ -476,7 +473,6 @@
   funcp in_func;
   value* temp_val;
   stackitem* iterator;
-  char* temp_string;
 
   if(env->head==NULL) {
     printerr("Too Few Arguments");
@@ -484,24 +480,24 @@
     return;
   }
 
+ eval_start:
+
   switch(env->head->item->type) {
     /* if it's a symbol */
   case symb:
     rcl(env);			/* get its contents */
     if(env->err) return;
     if(env->head->item->type!=symb){ /* don't recurse symbols */
-      eval(env);			/* evaluate the value */
-      return;
+      goto eval_start;
     }
-    break;
+    return;
 
     /* If it's a lone function value, run it */
   case func:
     in_func= (funcp)(env->head->item->content.ptr);
     toss(env); 
     if(env->err) return;
-    (*in_func)(env);
-    break;
+    return (*in_func)(env);
 
     /* If it's a list */
   case list:
@@ -510,45 +506,32 @@
     toss(env);
     if(env->err) return;
     iterator= (stackitem*)temp_val->content.ptr;
-    while(iterator!=NULL && iterator->item!=NULL) {
-      push_val(&(env->head), iterator->item);
+    while(iterator!=NULL) {
+      push_val(env, iterator->item);
       if(env->head->item->type==symb
 	&& strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
 	toss(env);
 	if(env->err) return;
+	if(iterator->next == NULL){
+	  free_val(temp_val);
+	  goto eval_start;
+	}
 	eval(env);
 	if(env->err) return;
       }
       iterator= iterator->next;
     }
     free_val(temp_val);
-    break;
-
-    /* If it's a string */
-  case string:
-    temp_val= env->head->item;
-    env->head->item->refcount++;
-    toss(env);
-    if(env->err) return;
-    temp_string= malloc(strlen((char*)temp_val->content.ptr)+5);
-    strcpy(temp_string, "[ ");
-    strcat(temp_string, (char*)temp_val->content.ptr);
-    strcat(temp_string, " ]");
-    stack_read(env, temp_string);
-    eval(env);
-    if(env->err) return;
-    free_val(temp_val);
-    free(temp_string);
-    break;
+    return;
 
-  case integer:
-    break;
+  default:
+    return;
   }
 }
 
 /* Reverse (flip) a list */
 extern void rev(environment *env){
-  stackitem *old_head, *new_head, *item;
+  stackitem *item, *temp, *prev= NULL;
 
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
@@ -562,36 +545,36 @@
     return;
   }
 
-  old_head=(stackitem *)(env->head->item->content.ptr);
-  new_head=NULL;
-  while(old_head != NULL){
-    item=old_head;
-    old_head=old_head->next;
-    item->next=new_head;
-    new_head=item;
+  item= (stackitem *)(env->head->item->content.ptr);
+  while(item->next!=NULL){
+    temp= item->next;
+    item->next= prev;
+    prev= item;
+    item= temp;
   }
-  env->head->item->content.ptr=new_head;
+  item->next= prev;
+
+  env->head->item->content.ptr=item;
 }
 
 /* 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) {
+  if(iterator==NULL
+     || (iterator->item->type==symb
+     && ((symbol*)(iterator->item->content.ptr))->id[0]=='[')) {
     temp= NULL;
     toss(env);
   } else {
     /* Search for first delimiter */
     while(iterator->next!=NULL
-	  && iterator->next->item->content.ptr!=delimiter)
+	  && (iterator->next->item->type!=symb
+	  || ((symbol*)(iterator->next->item->content.ptr))->id[0]!='['))
       iterator= iterator->next;
     
     /* Extract list */
@@ -609,92 +592,10 @@
   pack->content.ptr= temp;
   pack->refcount= 1;
 
-  temp= malloc(sizeof(stackitem));
-  temp->item= pack;
-
-  push(&(env->head), temp);
+  push_val(env, pack);
   rev(env);
 }
 
-/* Parse input. */
-void stack_read(environment *env, char *in_line) 
-{
-  char *temp, *rest;
-  int itemp;
-  size_t inlength= strlen(in_line)+1;
-  int convert= 0;
-
-  temp= malloc(inlength);
-  rest= malloc(inlength);
-
-  do {
-    /* If comment */
-    if((convert= sscanf(in_line, "#%[^\n\r]", rest))) {
-      free(temp); free(rest);
-      return;
-    }
-
-    /* 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(!env->non_eval_flag) {
-	  eval(env);		/* Evaluate top element */
-	  break;
-	}
-	
-	push_sym(env, ";");
-	break;
-      }
-
-      if(*temp==']') {
-	push_sym(env, "[");
-	pack(env);
-	if(env->non_eval_flag)
-	  env->non_eval_flag--;
-	break;
-      }
-
-      if(*temp=='[') {
-	push_sym(env, "[");
-	env->non_eval_flag++;
-	break;
-      }
-    }
-  } while(0);
-
-  free(temp);
-
-  if(convert<2) {
-    free(rest);
-    return;
-  }
-   
-  stack_read(env, rest);
-  
-  free(rest);
-}
-
 /* Relocate elements of the list on the stack. */
 extern void expand(environment *env)
 {
@@ -751,7 +652,7 @@
   result= (left==right);
   
   toss(env); toss(env);
-  push_int(&(env->head), result);
+  push_int(env, result);
 }
 
 /* Negates the top element on the stack. */
@@ -773,7 +674,7 @@
 
   val= env->head->item->content.val;
   toss(env);
-  push_int(&(env->head), !val);
+  push_int(env, !val);
 }
 
 /* Compares the two top elements on the stack and return 0 if they're the
@@ -816,9 +717,22 @@
   toss(env); toss(env);
 } 
 
+extern void clear(environment *);
+void forget_sym(symbol **);
+
 /* Quit stack. */
 extern void quit(environment *env)
 {
+  long i;
+
+  clear(env);
+  if (env->err) return;
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    if (env->symbols[i]!= NULL) {
+      forget_sym(&(env->symbols[i]));
+      env->symbols[i]= NULL;
+    }
+  }
   exit(EXIT_SUCCESS);
 }
 
@@ -844,12 +758,25 @@
   }
 }
 
+/* Internal forget function */
+void forget_sym(symbol **hash_entry) {
+  symbol *temp;
+
+  temp= *hash_entry;
+  *hash_entry= (*hash_entry)->next;
+  
+  if(temp->val!=NULL) {
+    free_val(temp->val);
+  }
+  free(temp->id);
+  free(temp);
+}
+
 /* 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) {
     printerr("Too Few Arguments");
@@ -866,38 +793,35 @@
   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);
+  return forget_sym(hash(env->symbols, sym_id));
 }
 
 /* Returns the current error number to the stack */
 extern void errn(environment *env){
-  push_int(&(env->head), env->err);
+  push_int(env, env->err);
 }
 
+extern void read(environment*);
+
 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);
+  while(1) {
+    if(myenv.in_string==NULL)
+      printstack(&myenv);
+    read(&myenv);
     if(myenv.err) {
       printf("(error %d) ", myenv.err);
       myenv.err=0;
+    } else if(myenv.head!=NULL
+	      && myenv.head->item->type==symb
+	      && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {
+      toss(&myenv); 		/* No error check in main */
+      eval(&myenv);
     }
-    printf("okidok\n ");
   }
   quit(&myenv);
   return EXIT_FAILURE;
@@ -929,7 +853,7 @@
     strcpy(new_string, b_val->content.ptr);
     strcat(new_string, a_val->content.ptr);
     free_val(a_val); free_val(b_val);
-    push_cstring(&(env->head), new_string);
+    push_cstring(env, new_string);
     free(new_string);
     return;
   }
@@ -943,10 +867,72 @@
   a=env->head->item->content.val;
   toss(env);
   if(env->err) return;
-  b=env->head->item->content.val;
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val += a;
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, a+b);
+  }
+}
+
+/* - */
+extern void sx_2d(environment *env) {
+  int a, b;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a=env->head->item->content.val;
   toss(env);
   if(env->err) return;
-  push_int(&(env->head), a+b);
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val -= a;
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, b-a);
+  }
+}
+
+/* > */
+extern void sx_3e(environment *env) {
+  int a, b;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a=env->head->item->content.val;
+  toss(env);
+  if(env->err) return;
+  if(env->head->item->refcount == 1)
+    env->head->item->content.val = (env->head->item->content.val > a);
+  else {
+    b=env->head->item->content.val;
+    toss(env);
+    if(env->err) return;
+    push_int(env, b>a);
+  }
 }
 
 /* Return copy of a value */
@@ -1001,5 +987,265 @@
     env->err=1;
     return;
   }
-  push_val(&(env->head), copy_val(env->head->item));
+  push_val(env, copy_val(env->head->item));
+}
+
+/* "if", If-Then */
+extern void sx_6966(environment *env) {
+
+  int truth;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  
+  swap(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  toss(env);
+  if(env->err) return;
+
+  if(truth)
+    eval(env);
+  else
+    toss(env);
+}
+
+/* If-Then-Else */
+extern void ifelse(environment *env) {
+
+  int truth;
+
+  if((env->head)==NULL || env->head->next==NULL
+     || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  
+  rot(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  toss(env);
+  if(env->err) return;
+
+  if(!truth)
+    swap(env);
+  if(env->err) return;
+
+  toss(env);
+  if(env->err) return;
+
+  eval(env);
+}
+
+/* while */
+extern void sx_7768696c65(environment *env) {
+
+  int truth;
+  value *loop, *test;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  loop= env->head->item;
+  loop->refcount++;
+  toss(env); if(env->err) return;
+
+  test= env->head->item;
+  test->refcount++;
+  toss(env); if(env->err) return;
+
+  do {
+    push_val(env, test);
+    eval(env);
+    
+    if(env->head->item->type != integer) {
+      printerr("Bad Argument Type");
+      env->err=2;
+      return;
+    }
+    
+    truth= env->head->item->content.val;
+    toss(env); if(env->err) return;
+    
+    if(truth) {
+      push_val(env, loop);
+      eval(env);
+    } else {
+      toss(env);
+    }
+  
+  } while(truth);
+
+  free_val(test);
+  free_val(loop);
+}
+
+/* For-loop */
+extern void sx_666f72(environment *env) {
+  
+  value *loop, *foo;
+  stackitem *iterator;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->next->item->type != list) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  loop= env->head->item;
+  loop->refcount++;
+  toss(env); if(env->err) return;
+
+  foo= env->head->item;
+  foo->refcount++;
+  toss(env); if(env->err) return;
+
+  iterator= foo->content.ptr;
+
+  while(iterator!=NULL) {
+    push_val(env, iterator->item);
+    push_val(env, loop);
+    eval(env); if(env->err) return;
+    iterator= iterator->next;
+  }
+
+  free_val(loop);
+  free_val(foo);
+}
+
+/* 'to' */
+extern void to(environment *env) {
+  int i, start, ending;
+  stackitem *temp_head;
+  value *temp_val;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=integer 
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  ending= env->head->item->content.val;
+  toss(env); if(env->err) return;
+  start= env->head->item->content.val;
+  toss(env); if(env->err) return;
+
+  temp_head= env->head;
+  env->head= NULL;
+
+  if(ending>=start) {
+    for(i= ending; i>=start; i--)
+      push_int(env, i);
+  } else {
+    for(i= ending; i<=start; i++)
+      push_int(env, i);
+  }
+
+  temp_val= malloc(sizeof(value));
+  temp_val->content.ptr= env->head;
+  temp_val->refcount= 1;
+  temp_val->type= list;
+  env->head= temp_head;
+  push_val(env, temp_val);
+}
+
+/* Read a string */
+extern void readline(environment *env) {
+  char in_string[101];
+
+  fgets(in_string, 100, stdin);
+  push_cstring(env, in_string);
+}
+
+/* Read a value and place on stack */
+extern void read(environment *env) {
+  const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%[\001-\377]";
+  const char strform[]= "\"%[^\"]\"%[\001-\377]";
+  const char intform[]= "%i%[\001-\377]";
+  const char blankform[]= "%*[ \t]%[\001-\377]";
+  const char ebrackform[]= "%*1[]]%[\001-\377]";
+  const char semicform[]= "%*1[;]%[\001-\377]";
+  const char bbrackform[]= "%*1[[]%[\001-\377]";
+
+  int itemp;
+  static int depth= 0;
+  char *rest, *match;
+  size_t inlength;
+
+  if(env->in_string==NULL) {
+    readline(env); if(env->err) return;
+    
+    env->in_string= malloc(strlen(env->head->item->content.ptr)+1);
+    strcpy(env->in_string, env->head->item->content.ptr);
+    toss(env); if(env->err) return;
+  }
+  
+  inlength= strlen(env->in_string)+1;
+  match= malloc(inlength);
+  rest= malloc(inlength);
+
+  if(sscanf(env->in_string, blankform, rest)) {
+    ; 
+  } else if(sscanf(env->in_string, intform, &itemp, rest) > 0) {
+    push_int(env, itemp);
+  } else if(sscanf(env->in_string, strform, match, rest) > 0) {
+    push_cstring(env, match);
+  } else if(sscanf(env->in_string, symbform, match, rest) > 0) {
+    push_sym(env, match);
+  } else if(sscanf(env->in_string, ebrackform, rest) > 0) {
+    pack(env); if(env->err) return;
+    if(depth!=0) depth--;
+  } else if(sscanf(env->in_string, semicform, rest) > 0) {
+    push_sym(env, ";");
+  } else if(sscanf(env->in_string, bbrackform, rest) > 0) {
+    push_sym(env, "[");
+    depth++;
+  } else {
+    free(rest);
+    rest= NULL;
+  }
+      
+  free(env->in_string);
+  free(match);
+
+  env->in_string= rest;
+
+  if(depth)
+    return read(env);
 }