X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FPreprocessor.h;h=c753585424657cccd69cb0dd33f5f9cf2f2c023f;hb=a0359850fd45080ff0862ca0a11884efb424d7d2;hp=20fafabf9000369753312a6853fac00a5eb32da9;hpb=5c77fedbef46995a71ffa268c9fcaf49efddd01b;p=folly.git

diff --git a/folly/Preprocessor.h b/folly/Preprocessor.h
index 20fafabf..c7535854 100644
--- a/folly/Preprocessor.h
+++ b/folly/Preprocessor.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,8 +28,24 @@
  * FB_ONE_OR_NONE(hello) expands to nothing. This macro is used to
  * insert or eliminate text based on the presence of another argument.
  */
+#ifdef _MSC_VER
+
+#define VA_NARGS_IMPL(_1, _2, _3, _4, _5, N, ...) N
+#define VA_NARGS(...) VA_NARGS_IMPL(X,##__VA_ARGS__, 4, 3, 2, 1, 0)
+#define VARARG_IMPL2(base, count, ...) base##count(__VA_ARGS__)
+#define VARARG_IMPL(base, count, ...) VARARG_IMPL2(base, count, __VA_ARGS__)
+#define VARARG(base, ...) VARARG_IMPL(base, VA_NARGS(__VA_ARGS__), __VA_ARGS__)
+
+#define FB_ONE_OR_NONE0() /* */
+#define FB_ONE_OR_NONE1(x) /* */
+#define FB_ONE_OR_NONE2(x, y) x
+#define FB_ONE_OR_NONE3(x, y, z) x
+#define FB_ONE_OR_NONE(...) VARARG(FB_ONE_OR_NONE, __VA_ARGS__)
+
+#else
 #define FB_ONE_OR_NONE(a, ...) FB_THIRD(a, ## __VA_ARGS__, a)
 #define FB_THIRD(a, b, ...) __VA_ARGS__
+#endif
 
 /**
  * Helper macro that extracts the first argument out of a list of any
@@ -46,6 +62,17 @@
 // Support macro for the above
 #define FB_ARG_2_OR_1_IMPL(a, b, ...) b
 
+/**
+ * Helper macro that provides a way to pass argument with commas in it to
+ * some other macro whose syntax doesn't allow using extra parentheses.
+ * Example:
+ *
+ *   #define MACRO(type, name) type name
+ *   MACRO(FB_SINGLE_ARG(std::pair<size_t, size_t>), x);
+ *
+ */
+#define FB_SINGLE_ARG(...) __VA_ARGS__
+
 /**
  * FB_ANONYMOUS_VARIABLE(str) introduces an identifier starting with
  * str and ending with a number that varies with the line.
@@ -61,10 +88,9 @@
 #endif
 
 /**
- * Use FB_STRINGIZE(name) when you'd want to do what #name does inside
+ * Use FB_STRINGIZE(x) when you'd want to do what #x does inside
  * another macro expansion.
  */
-#define FB_STRINGIZE(name) #name
-
+#define FB_STRINGIZE(x) #x
 
 #endif // FOLLY_PREPROCESSOR_