cppmagic: Logical operations

[ccan] / ccan / cppmagic / cppmagic.h

diff --git a/ccan/cppmagic/cppmagic.h b/ccan/cppmagic/cppmagic.h
index f29e0ec6cee39b39114f3849dadce50d00a2f6e3..c4454e776392f4edff78ff8289d432ce4e09ddf4 100644 (file)
--- a/ccan/cppmagic/cppmagic.h
+++ b/ccan/cppmagic/cppmagic.h
@@ -39,4 +39,49 @@
  */
 #define CPPMAGIC_2ND(a_, b_, ...)      b_
 
+/**
+ * CPPMAGIC_ISZERO - is argument '0'
+ *
+ * CPPMAGIC_ISZERO(@a)
+ *     expands to '1' if @a is '0', otherwise expands to '0'.
+ */
+#define _CPPMAGIC_ISPROBE(...)         CPPMAGIC_2ND(__VA_ARGS__, 0)
+#define _CPPMAGIC_PROBE()              $, 1
+#define _CPPMAGIC_ISZERO_0             _CPPMAGIC_PROBE()
+#define CPPMAGIC_ISZERO(a_)            \
+       _CPPMAGIC_ISPROBE(CPPMAGIC_GLUE2(_CPPMAGIC_ISZERO_, a_))
+
+/**
+ * CPPMAGIC_NONZERO - is argument not '0'
+ *
+ * CPPMAGIC_NONZERO(@a)
+ *     expands to '0' if @a is '0', otherwise expands to '1'.
+ */
+#define CPPMAGIC_NONZERO(a_)           CPPMAGIC_ISZERO(CPPMAGIC_ISZERO(a_))
+
+/**
+ * CPPMAGIC_NONEMPTY - does the macro have any arguments?
+ *
+ * CPPMAGIC_NONEMPTY()
+ *     expands to '0'
+ * CPPMAGIC_NONEMPTY(@a)
+ * CPPMAGIC_NONEMPTY(@a, ...)
+ *     expand to '1'
+ */
+#define _CPPMAGIC_EOA()                        0
+#define CPPMAGIC_NONEMPTY(...)         \
+       CPPMAGIC_NONZERO(CPPMAGIC_1ST(_CPPMAGIC_EOA __VA_ARGS__)())
+
+/**
+ * CPPMAGIC_ISEMPTY - does the macro have no arguments?
+ *
+ * CPPMAGIC_ISEMPTY()
+ *     expands to '1'
+ * CPPMAGIC_ISEMPTY(@a)
+ * CPPMAGIC_ISEMPTY(@a, ...)
+ *     expand to '0'
+ */
+#define CPPMAGIC_ISEMPTY(...)          \
+       CPPMAGIC_ISZERO(CPPMAGIC_NONEMPTY(__VA_ARGS__))
+
 #endif /* CCAN_CPPMAGIC_H */