cppmagic: Conditionals

[ccan] / ccan / cppmagic / cppmagic.h

diff --git a/ccan/cppmagic/cppmagic.h b/ccan/cppmagic/cppmagic.h
index c4454e776392f4edff78ff8289d432ce4e09ddf4..b5c35782f78ca5e58ab16fa45bddb0649c87333c 100644 (file)
--- a/ccan/cppmagic/cppmagic.h
+++ b/ccan/cppmagic/cppmagic.h
@@ -84,4 +84,18 @@
 #define CPPMAGIC_ISEMPTY(...)          \
        CPPMAGIC_ISZERO(CPPMAGIC_NONEMPTY(__VA_ARGS__))
 
+/*
+ * CPPMAGIC_IFELSE - preprocessor conditional
+ *
+ * CPPMAGIC_IFELSE(@cond)(@if)(@else)
+ *     expands to @else if @cond is '0', otherwise expands to @if
+ */
+#define _CPPMAGIC_IF_0(...)            _CPPMAGIC_IF_0_ELSE
+#define _CPPMAGIC_IF_1(...)            __VA_ARGS__ _CPPMAGIC_IF_1_ELSE
+#define _CPPMAGIC_IF_0_ELSE(...)       __VA_ARGS__
+#define _CPPMAGIC_IF_1_ELSE(...)
+#define _CPPMAGIC_IFELSE(cond_)                CPPMAGIC_GLUE2(_CPPMAGIC_IF_, cond_)
+#define CPPMAGIC_IFELSE(cond_)         \
+       _CPPMAGIC_IFELSE(CPPMAGIC_NONZERO(cond_))
+
 #endif /* CCAN_CPPMAGIC_H */