1 files changed, 40 insertions, 0 deletions
diff --git a/third_party/rust/bytes/src/debug.rs b/third_party/rust/bytes/src/debug.rs
new file mode 100644
index 0000000000..b1a3cc8189
--- /dev/null
+++ b/third_party/rust/bytes/src/debug.rs
@@ -0,0 +1,40 @@
+use core::fmt;
+
+/// Alternative implementation of `fmt::Debug` for byte slice.
+///
+/// Standard `Debug` implementation for `[u8]` is comma separated
+/// list of numbers. Since large amount of byte strings are in fact
+/// ASCII strings or contain a lot of ASCII strings (e. g. HTTP),
+/// it is convenient to print strings as ASCII when possible.
+///
+/// This struct wraps `&[u8]` just to override `fmt::Debug`.
+///
+/// `BsDebug` is not a part of public API of bytes crate.
+pub struct BsDebug<'a>(pub &'a [u8]);
+
+impl fmt::Debug for BsDebug<'_> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
+        write!(fmt, "b\"")?;
+        for &c in self.0 {
+            // https://doc.rust-lang.org/reference.html#byte-escapes
+            if c == b'\n' {
+                write!(fmt, "\\n")?;
+            } else if c == b'\r' {
+                write!(fmt, "\\r")?;
+            } else if c == b'\t' {
+                write!(fmt, "\\t")?;
+            } else if c == b'\\' || c == b'"' {
+                write!(fmt, "\\{}", c as char)?;
+            } else if c == b'\0' {
+                write!(fmt, "\\0")?;
+            // ASCII printable
+            } else if c >= 0x20 && c < 0x7f {
+                write!(fmt, "{}", c as char)?;
+            } else {
+                write!(fmt, "\\x{:02x}", c)?;
+            }
+        }
+        write!(fmt, "\"")?;
+        Ok(())
+    }
+}