altos/lisp: Add scheme-style bools (#t and #f)

Cond and while compare against #f, just like scheme says to.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/src/lisp/ao_lisp_bool.c b/src/lisp/ao_lisp_bool.c
new file mode 100644
index 00000000..ad25afba
--- /dev/null
+++ b/src/lisp/ao_lisp_bool.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright © 2017 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+static void bool_mark(void *addr)
+{
+	(void) addr;
+}
+
+static int bool_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_bool);
+}
+
+static void bool_move(void *addr)
+{
+	(void) addr;
+}
+
+const struct ao_lisp_type ao_lisp_bool_type = {
+	.mark = bool_mark,
+	.size = bool_size,
+	.move = bool_move,
+	.name = "bool"
+};
+
+void
+ao_lisp_bool_print(ao_poly v)
+{
+	struct ao_lisp_bool	*b = ao_lisp_poly_bool(v);
+
+	if (b->value)
+		printf("#t");
+	else
+		printf("#f");
+}
+
+#ifdef AO_LISP_MAKE_CONST
+
+struct ao_lisp_bool	*ao_lisp_true, *ao_lisp_false;
+
+struct ao_lisp_bool *
+ao_lisp_bool_get(uint8_t value)
+{
+	struct ao_lisp_bool	**b;
+
+	if (value)
+		b = &ao_lisp_true;
+	else
+		b = &ao_lisp_false;
+
+	if (!*b) {
+		*b = ao_lisp_alloc(sizeof (struct ao_lisp_bool));
+		(*b)->type = AO_LISP_BOOL;
+		(*b)->value = value;
+	}
+	return *b;
+}
+
+#endif