Move `DebugChar` into its own file

Change-Id: Ia40549e5d0b78ece8dd0722c3a5a032b9915f24b

1 files changed, 22 insertions, 0 deletions

diff --git a/src/libutil/escape-char.hh b/src/libutil/escape-char.hh
new file mode 100644
index 000000000..c7bae7ec0
--- /dev/null
+++ b/src/libutil/escape-char.hh
@@ -0,0 +1,22 @@
+#pragma once
+#include <ostream>
+
+namespace nix {
+
+/**
+ * A struct that prints a debug representation of a character, like `\x1f` for
+ * non-printable characters, or the character itself for other characters.
+ *
+ * Note that these are suitable for human readable output, but further care is
+ * necessary to include them in C++ strings to avoid running into adjacent
+ * hex-like characters. (`"puppy\x1bdoggy"` parses as `"puppy" "\x1bd" "oggy"`
+ * and errors because 0x1bd is too big for a `char`.)
+ */
+struct MaybeHexEscapedChar
+{
+    char c;
+};
+
+std::ostream & operator<<(std::ostream & s, MaybeHexEscapedChar c);
+
+} // namespace nix