src: implement debug output utilities

Implement utilities for easier debugging of Node.js core code,
inspired by the HTTP/2 debugging code. Debugging is, however,
implemented at runtime rather than at compile time, controlled
through a new `NODE_DEBUG_NATIVE=categories` environment variable.

The runtime overhead in the debugging-disabled case amounts to
1 well-cachable one-byte read per debug call.

PR-URL: https://github.com/nodejs/node/pull/20987
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/util-inl.h b/src/util-inl.h
index ff0d47c078..90c7447f7e 100644
--- a/src/util-inl.h
+++ b/src/util-inl.h
@@ -293,6 +293,13 @@ char ToLower(char c) {
   return c >= 'A' && c <= 'Z' ? c + ('a' - 'A') : c;
 }
 
+std::string ToLower(const std::string& in) {
+  std::string out(in.size(), 0);
+  for (size_t i = 0; i < in.size(); ++i)
+    out[i] = ToLower(in[i]);
+  return out;
+}
+
 bool StringEqualNoCase(const char* a, const char* b) {
   do {
     if (*a == '\0')