intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 19 insertions, 0 deletions

diff --git a/util/stream/labeled.h b/util/stream/labeled.h
new file mode 100644
index 00000000000..2cc539d241d
--- /dev/null
+++ b/util/stream/labeled.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <util/generic/va_args.h>
+
+/**
+ * Generates an output sequence for the provided expressions that is formatted
+ * as a labeled comma-separated list.
+ *
+ * Example usage:
+ * @code
+ * int a = 1, b = 2, c = 3;
+ * stream << LabeledOutput(a, b, c, a + b + c);
+ * // Outputs "a = 1, b = 2, c = 3, a + b + c = 6"
+ * @endcode
+ */
+#define LabeledOutput(...) "" Y_PASS_VA_ARGS(Y_MAP_ARGS_WITH_LAST(__LABELED_OUTPUT_NONLAST__, __LABELED_OUTPUT_IMPL__, __VA_ARGS__))
+
+#define __LABELED_OUTPUT_IMPL__(x) << #x " = " << (x)
+#define __LABELED_OUTPUT_NONLAST__(x) __LABELED_OUTPUT_IMPL__(x) << ", "