True and False values.

diff --git a/implementations/C/joy.c b/implementations/C/joy.c
index 206d7e9..a15e576 100644 (file)
--- a/implementations/C/joy.c
+++ b/implementations/C/joy.c
@@ -62,6 +62,8 @@ Ulam Spiral).
 
 
 const char *BLANKS = " \t";
+const char *FALSE = "false";
+const char *TRUE = "true";
 
 
 enum JoyTypeType {
@@ -85,7 +87,7 @@ struct JoyType {
 
 
 struct list_node {
-       struct JoyType head;
+       struct JoyType head;  /* Should this be a pointer? */
        struct list_node* tail;
 } JoyList;
 
@@ -182,11 +184,24 @@ struct list_node*
 make_symbol_node(char *text, size_t size)
 {
        struct list_node *node;
+       char * sym;
+
+       sym = GC_malloc(size + 1);  /* one more for the zero, right? */
+       strncat(sym, text, size);
+
        node = GC_malloc(sizeof(struct list_node));
-       node->head.kind = joySymbol;
-       node->head.value.symbol = (char *)GC_malloc(size + 1);
-       strncat(node->head.value.symbol, text, size);
-       /*printf("%s\n", node->head.value.symbol);*/
+       if (!strncmp(sym, FALSE, 6)) {  /* I know it's wrong to hardcode the length here.  Sorry. */
+               /* If head was a pointer we could reuse Boolean singletons... */
+               node->head.kind = joyFalse;
+               node->head.value.boolean = 0;
+       } else if (!strncmp(sym, TRUE, 5)) {  /* I know it's wrong to hardcode the length here.  Sorry. */
+               node->head.kind = joyTrue;
+               node->head.value.boolean = 1;
+       } else {
+               node->head.kind = joySymbol;
+               node->head.value.symbol = sym;
+       }
+
        return node;
 }
 
@@ -327,7 +342,6 @@ text_to_expression(char *text)
        return result;
 }
 
-
 int
 main(void)
 {
@@ -345,6 +359,20 @@ main(void)
        while (1) {
                status = gets_s(line, 1025);
                if (NULL == status) {
+                       /*
+                       From the man page:
+
+                       > Upon successful completion, fgets(), gets_s(), and gets() return a
+                       pointer to the string.  If end-of-file occurs before any characters are
+                       read, they return NULL and the buffer contents remain unchanged.  If an
+                       error occurs, they return NULL and the buffer contents are indeterminate.
+                       The fgets(), gets_s(), and gets() functions do not distinguish between
+                       end-of-file and error, and callers must use feof(3) and ferror(3) to
+                       determine which occurred.
+
+                       TODO: "use feof(3) and ferror(3)"...
+
+                       */
                        printf("bye\n");
                        break;
                }