iris

commit a253fe487b61b0f734d8e4d38fcbbcbe2afd7f76
parent a29d9e01a68ebf4bfa8dd66452358cb3610ee46d
Author: sin <sin@2f30.org>
Date:   Fri, 16 May 2014 11:46:41 +0100

Add null predicate

Diffstat:
M
parser.c
 | 
22
++++++++++++++++++++++

1 file changed, 22 insertions(+), 0 deletions(-)
diff --git a/parser.c b/parser.c
@@ -75,6 +75,7 @@ static struct object *evalset(struct object *);
 /* primitive procedures */
 static struct object *evalboolean(struct object *);
 static struct object *evaldiff(struct object *);
+static struct object *evalnull(struct object *);
 static struct object *evalplus(struct object *);
 
 struct {
@@ -96,6 +97,7 @@ struct {
 } procs[] = {
 	{ .name = "boolean", .fn = evalboolean },
 	{ .name = "diff",    .fn = evaldiff },
+	{ .name = "null",    .fn = evalnull },
 	{ .name = "plus",    .fn = evalplus },
 };
 
@@ -465,6 +467,26 @@ evaldiff(struct object *o)
 }
 
 static struct object *
+evalnull(struct object *o)
+{
+	struct object *arg;
+
+	if (o->type != OPair)
+		return NULL;
+	if (car(o)->type != OIdentifier ||
+	    strcmp(car(o)->d.i.s, "null") != 0)
+		return NULL;
+	arg = eval(cadr(o));
+	if (arg->type == OError)
+		return arg;
+	if (caddr(o))
+		return error("multiple arguments");
+	if (arg->type == OEmptylist)
+		return boolean(true);
+	return boolean(false);
+}
+
+static struct object *
 doplus(struct object *o, struct object *n)
 {
 	struct object *otmp;