--- stack/stack.c	2002/02/14 19:20:28	1.81
+++ stack/stack.c	2002/02/15 18:27:18	1.87
@@ -1,4 +1,4 @@
-/* printf, sscanf, fgets, fprintf */
+/* printf, sscanf, fgets, fprintf, fopen, perror */
 #include <stdio.h>
 /* exit, EXIT_SUCCESS, malloc, free */
 #include <stdlib.h>
@@ -8,6 +8,12 @@
 #include <dlfcn.h>
 /* strcmp, strcpy, strlen, strcat, strdup */
 #include <string.h>
+/* getopt, STDIN_FILENO, STDOUT_FILENO */
+#include <unistd.h>
+/* EX_NOINPUT, EX_USAGE */
+#include <sysexits.h>
+/* mtrace, muntrace */
+#include <mcheck.h>
 
 #define HASHTBLSIZE 2048
 
@@ -28,7 +34,7 @@
     int val;			/* ...or an integer */
   } content;			/* Stores a pointer or an integer */
 
-  int refcount;			/* Reference counter */
+  int gc_garb;
 
 } value;
 
@@ -55,12 +61,17 @@
 /* An environment; gives access to the stack and a hash table of
    defined symbols */
 typedef struct {
+  stackitem *gc_ref;
+  int gc_limit, gc_count;
+
   stackitem *head;		/* Head of the stack */
   hashtbl symbols;		/* Hash table of all variable bindings */
   int err;			/* Error flag */
   char *in_string;		/* Input pending to be read */
   char *free_string;		/* Free this string when all input is
                                    read from in_string */
+  FILE *inputstream;		/* stdin or a file, most likely */
+  int interactive;		/* print prompts, stack, etc */
 } environment;
 
 /* A type for pointers to external functions */
@@ -72,46 +83,23 @@
 {
   int i;
 
-  env->in_string= NULL;
-  env->err= 0;
+  env->gc_limit= 20;
+  env->gc_count= 0;
+
+  env->head= NULL;
   for(i= 0; i<HASHTBLSIZE; i++)
     env->symbols[i]= NULL;
+  env->err= 0;
+  env->in_string= NULL;
+  env->free_string= NULL;
+  env->inputstream= stdin;
+  env->interactive= 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);
-      break;
-    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 */
-      }
-      break;
-    case integer:
-    case func:
-    case symb:
-      break;
-    }
-    if(val->id!=NULL)
-      free(val->id);
-    free(val);		/* Free the actual list value */
-  }
-}
-
 /* Discard the top element of the stack. */
 extern void toss(environment *env)
 {
@@ -123,7 +111,6 @@
     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 */
 }
@@ -157,12 +144,112 @@
   }
 }
 
+extern void gc_init(environment*);
+
+value* new_val(environment *env) {
+  value *nval= malloc(sizeof(value));
+  stackitem *nitem= malloc(sizeof(stackitem));
+
+  if(env->gc_count >= env->gc_limit)
+    gc_init(env);
+
+  nval->content.ptr= NULL;
+
+  nitem->item= nval;
+  nitem->next= env->gc_ref;
+  env->gc_ref= nitem;
+
+  env->gc_count++;
+
+  return nval;
+}
+
+void gc_mark(value *val) {
+  stackitem *iterator;
+
+  if(val==NULL || val->gc_garb==0)
+    return;
+
+  val->gc_garb= 0;
+
+  if(val->type==list) {
+    iterator= val->content.ptr;
+
+    while(iterator!=NULL) {
+      gc_mark(iterator->item);
+      iterator= iterator->next;
+    }
+  }
+}
+
+extern void gc_init(environment *env) {
+  stackitem *new_head= NULL, *titem, *iterator= env->gc_ref;
+  symbol *tsymb;
+  int i;
+
+  while(iterator!=NULL) {
+    iterator->item->gc_garb= 1;
+    iterator= iterator->next;
+  }
+
+  /* Mark */
+  iterator= env->head;
+  while(iterator!=NULL) {
+    gc_mark(iterator->item);
+    iterator= iterator->next;
+  }
+
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    tsymb= env->symbols[i];
+    while(tsymb!=NULL) {
+      gc_mark(tsymb->val);
+      tsymb= tsymb->next;
+    }
+  }
+
+  env->gc_count= 0;
+
+  /* Sweep */
+  while(env->gc_ref!=NULL) {
+    if(env->gc_ref->item->gc_garb) {
+      switch(env->gc_ref->item->type) {
+      case string:
+	free(env->gc_ref->item->content.ptr);
+	break;
+      case integer:
+	break;
+      case list:
+	while(env->gc_ref->item->content.ptr!=NULL) {
+	  titem= env->gc_ref->item->content.ptr;
+	  env->gc_ref->item->content.ptr= titem->next;
+	  free(titem);
+	}
+	break;
+      default:
+	break;
+      }
+      free(env->gc_ref->item);
+      titem= env->gc_ref->next;
+      free(env->gc_ref);
+      env->gc_ref= titem;
+    } else {
+      titem= env->gc_ref->next;
+      env->gc_ref->next= new_head;
+      new_head= env->gc_ref;
+      env->gc_ref= titem;
+      env->gc_count++;
+    }
+  }
+
+  env->gc_limit= env->gc_count+20;
+  env->gc_ref= new_head;
+}
+
 /* Push a value onto the stack */
 void push_val(environment *env, value *val)
 {
   stackitem *new_item= malloc(sizeof(stackitem));
   new_item->item= val;
-  val->refcount++;
   new_item->next= env->head;
   env->head= new_item;
 }
@@ -170,12 +257,10 @@
 /* Push an integer onto the stack. */
 void push_int(environment *env, int in_val) 
 {
-  value *new_value= malloc(sizeof(value));
+  value *new_value= new_val(env);
   
   new_value->content.val= in_val;
   new_value->type= integer;
-  new_value->refcount= 1;
-  new_value->id= NULL;
 
   push_val(env, new_value);
 }
@@ -183,13 +268,11 @@
 /* Copy a string onto the stack. */
 void push_cstring(environment *env, const char *in_string)
 {
-  value *new_value= malloc(sizeof(value));
+  value *new_value= new_val(env);
 
   new_value->content.ptr= malloc(strlen(in_string)+1);
   strcpy(new_value->content.ptr, in_string);
   new_value->type= string;
-  new_value->refcount= 1;
-  new_value->id= NULL;
 
   push_val(env, new_value);
 }
@@ -252,11 +335,10 @@
   const char *dlerr;		/* Dynamic linker error */
   char *mangled;		/* Mangled function name */
 
-  new_value= malloc(sizeof(value));
+  new_value= new_val(env);
 
   /* 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);
@@ -279,21 +361,20 @@
     if(handle==NULL)		/* If no handle */
       handle= dlopen(NULL, RTLD_LAZY);
 
-    funcptr= dlsym(handle, in_string); /* Get function pointer */
+    mangled=mangle_str(in_string); /* mangle the name */
+    funcptr= dlsym(handle, mangled); /* and try to find it */
+    free(mangled);
     dlerr=dlerror();
     if(dlerr != NULL) {		/* If no function was found */
-      mangled=mangle_str(in_string);
-      funcptr= dlsym(handle, mangled); /* try mangling it */
-      free(mangled);
+      funcptr= dlsym(handle, in_string); /* Get function pointer */
       dlerr=dlerror();
     }
     if(dlerr==NULL) {		/* If a function was found */
-      new_fvalue= malloc(sizeof(value)); /* Create a new value */
+      new_fvalue= new_val(env); /* 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_val(env, new_value);
@@ -521,7 +602,6 @@
     /* If it's a list */
   case list:
     temp_val= env->head->item;
-    env->head->item->refcount++;
     toss(env);
     if(env->err) return;
     iterator= (stackitem*)temp_val->content.ptr;
@@ -532,7 +612,6 @@
 	toss(env);
 	if(env->err) return;
 	if(iterator->next == NULL){
-	  free_val(temp_val);
 	  goto eval_start;
 	}
 	eval(env);
@@ -540,7 +619,6 @@
       }
       iterator= iterator->next;
     }
-    free_val(temp_val);
     return;
 
   default:
@@ -605,10 +683,9 @@
   }
 
   /* Push list */
-  pack= malloc(sizeof(value));
+  pack= new_val(env);
   pack->type= list;
   pack->content.ptr= temp;
-  pack->refcount= 1;
 
   push_val(env, pack);
   rev(env);
@@ -639,7 +716,6 @@
   /* 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 */
@@ -725,12 +801,9 @@
   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);
 } 
@@ -744,6 +817,7 @@
   long i;
 
   clear(env);
+
   if (env->err) return;
   for(i= 0; i<HASHTBLSIZE; i++) {
     while(env->symbols[i]!= NULL) {
@@ -751,6 +825,14 @@
     }
     env->symbols[i]= NULL;
   }
+
+  gc_init(env);
+
+  if(env->free_string!=NULL)
+    free(env->free_string);
+  
+  muntrace();
+
   exit(EXIT_SUCCESS);
 }
 
@@ -783,9 +865,6 @@
   temp= *hash_entry;
   *hash_entry= (*hash_entry)->next;
   
-  if(temp->val!=NULL) {
-    free_val(temp->val);
-  }
   free(temp->id);
   free(temp);
 }
@@ -819,24 +898,59 @@
   push_int(env, env->err);
 }
 
-extern void read(environment*);
+extern void sx_72656164(environment*);
 
-int main()
+int main(int argc, char **argv)
 {
   environment myenv;
 
+  int c;			/* getopt option character */
+
+  mtrace();
+
   init_env(&myenv);
 
+  myenv.interactive = isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
+
+  while ((c = getopt (argc, argv, "i")) != -1)
+    switch (c)
+      {
+      case 'i':
+	myenv.interactive = 1;
+	break;
+      case '?':
+	fprintf (stderr,
+		 "Unknown option character `\\x%x'.\n",
+		 optopt);
+	return EX_USAGE;
+      default:
+	abort ();
+      }
+  
+  if (optind < argc) {
+    myenv.interactive = 0;
+    myenv.inputstream= fopen(argv[optind], "r");
+    if(myenv.inputstream== NULL) {
+      perror(argv[0]);
+      exit (EX_NOINPUT);
+    }
+  }
+
   while(1) {
     if(myenv.in_string==NULL) {
-      nl();
-      printstack(&myenv);
-      printf("> ");
-    }
-    read(&myenv);
-    if(myenv.err) {
-      printf("(error %d) ", myenv.err);
+      if (myenv.interactive) {
+	if(myenv.err) {
+	  printf("(error %d)\n", myenv.err);
+	}
+	nl();
+	printstack(&myenv);
+	printf("> ");
+      }
       myenv.err=0;
+    }
+    sx_72656164(&myenv);
+    if (myenv.err==4) {
+      return EX_NOINPUT;
     } else if(myenv.head!=NULL
 	      && myenv.head->item->type==symb
 	      && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {
@@ -848,7 +962,7 @@
   return EXIT_FAILURE;
 }
 
-/* + */
+/* "+" */
 extern void sx_2b(environment *env) {
   int a, b;
   size_t len;
@@ -865,15 +979,12 @@
      && env->head->next->item->type==string) {
     a_val= env->head->item;
     b_val= env->head->next->item;
-    a_val->refcount++;
-    b_val->refcount++;
     toss(env); if(env->err) return;
     toss(env); if(env->err) return;
     len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
     new_string= malloc(len);
     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, new_string);
     free(new_string);
     return;
@@ -886,19 +997,14 @@
     return;
   }
   a=env->head->item->content.val;
-  toss(env);
-  if(env->err) return;
-  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);
-  }
+  toss(env); if(env->err) return;
+  
+  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;
 
@@ -915,19 +1021,13 @@
     return;
   }
   a=env->head->item->content.val;
-  toss(env);
-  if(env->err) return;
-  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);
-  }
+  toss(env); if(env->err) return;
+  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;
 
@@ -944,28 +1044,20 @@
     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);
-  }
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b>a);
 }
 
 /* Return copy of a value */
-value *copy_val(value *old_value){
+value *copy_val(environment *env, value *old_value){
   stackitem *old_item, *new_item, *prev_item;
 
-  value *new_value=malloc(sizeof(value));
+  value *new_value=new_val(env);
 
   new_value->type=old_value->type;
-  new_value->refcount=0;	/* This is increased if/when this
-				   value is referenced somewhere, like
-				   in a stack item or a variable */
+
   switch(old_value->type){
   case integer:
     new_value->content.val=old_value->content.val;
@@ -986,7 +1078,7 @@
 
     while(old_item != NULL) {	/* While list is not empty */
       new_item= malloc(sizeof(stackitem));
-      new_item->item=copy_val(old_item->item); /* recurse */
+      new_item->item=copy_val(env, old_item->item); /* recurse */
       new_item->next=NULL;
       if(prev_item != NULL)	/* If this wasn't the first item */
 	prev_item->next=new_item; /* point the previous item to the
@@ -1001,14 +1093,14 @@
   return new_value;
 }
 
-/* duplicates an item on the stack */
-extern void dup(environment *env) {
+/* "dup"; duplicates an item on the stack */
+extern void sx_647570(environment *env) {
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
     return;
   }
-  push_val(env, copy_val(env->head->item));
+  push_val(env, copy_val(env, env->head->item));
 }
 
 /* "if", If-Then */
@@ -1078,7 +1170,7 @@
   eval(env);
 }
 
-/* while */
+/* "while" */
 extern void sx_7768696c65(environment *env) {
 
   int truth;
@@ -1091,11 +1183,9 @@
   }
 
   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 {
@@ -1119,12 +1209,9 @@
     }
   
   } while(truth);
-
-  free_val(test);
-  free_val(loop);
 }
 
-/* For-loop */
+/* "for"; For-loop */
 extern void sx_666f72(environment *env) {
   
   value *loop, *foo;
@@ -1143,11 +1230,9 @@
   }
 
   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;
@@ -1158,12 +1243,9 @@
     eval(env); if(env->err) return;
     iterator= iterator->next;
   }
-
-  free_val(loop);
-  free_val(foo);
 }
 
-/* 'to' */
+/* "to" */
 extern void to(environment *env) {
   int i, start, ending;
   stackitem *temp_head;
@@ -1198,9 +1280,8 @@
       push_int(env, i);
   }
 
-  temp_val= malloc(sizeof(value));
+  temp_val= new_val(env);
   temp_val->content.ptr= env->head;
-  temp_val->refcount= 1;
   temp_val->type= list;
   env->head= temp_head;
   push_val(env, temp_val);
@@ -1210,12 +1291,14 @@
 extern void readline(environment *env) {
   char in_string[101];
 
-  fgets(in_string, 100, stdin);
-  push_cstring(env, in_string);
+  if(fgets(in_string, 100, env->inputstream)==NULL)
+    push_cstring(env, "");
+  else
+    push_cstring(env, in_string);
 }
 
-/* Read a value and place on stack */
-extern void read(environment *env) {
+/* "read"; Read a value and place on stack */
+extern void sx_72656164(environment *env) {
   const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
   const char strform[]= "\"%[^\"]\"%n";
   const char intform[]= "%i%n";
@@ -1226,14 +1309,19 @@
 
   int itemp, readlength= -1;
   static int depth= 0;
-  char *rest, *match;
+  char *match;
   size_t inlength;
 
   if(env->in_string==NULL) {
-    if(depth > 0) {
+    if(depth > 0 && env->interactive) {
       printf("]> ");
     }
     readline(env); if(env->err) return;
+
+    if(((char *)(env->head->item->content.ptr))[0]=='\0'){
+      env->err= 4;		/* "" means EOF */
+      return;
+    }
     
     env->in_string= malloc(strlen(env->head->item->content.ptr)+1);
     env->free_string= env->in_string; /* Save the original pointer */
@@ -1243,7 +1331,6 @@
   
   inlength= strlen(env->in_string)+1;
   match= malloc(inlength);
-  rest= malloc(inlength);
 
   if(sscanf(env->in_string, blankform, &readlength)!=EOF
      && readlength != -1) {
@@ -1271,12 +1358,13 @@
   } else {
     free(env->free_string);
     env->in_string = env->free_string = NULL;
-    free(match);
   }
   if ( env->in_string != NULL) {
     env->in_string += readlength;
   }
 
+  free(match);
+
   if(depth)
-    return read(env);
+    return sx_72656164(env);
 }