From cd1db3bdc42dc40178950d64c84501ff19a59dad Mon Sep 17 00:00:00 2001
From: Paul Colomiets <paul@colomiets.name>
Date: Thu, 11 Jun 2020 16:33:05 +0300
Subject: [PATCH] Better (shorter, clearer) debug implementation

Fixes #56
---
 src/impls.rs | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/src/impls.rs b/src/impls.rs
index 375e5be..a60e1ea 100644
--- a/src/impls.rs
+++ b/src/impls.rs
@@ -329,13 +329,22 @@ mod bstr {
         fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
             write!(f, "\"")?;
             for (s, e, ch) in self.char_indices() {
-                if ch == '\u{FFFD}' {
-                    for &b in self[s..e].as_bytes() {
-                        write!(f, r"\x{:X}", b)?;
+                match ch {
+                    '\0' => write!(f, "\\0")?,
+                    '\u{FFFD}' => {
+                        for &b in self[s..e].as_bytes() {
+                            write!(f, r"\x{:02X}", b)?;
+                        }
                     }
-                } else {
-                    write!(f, "{}", ch.escape_debug())?;
-                }
+                    // ASCII control characters except \0 \n, \r, \t
+                    '\x01'..='\x08' | '\x0b' | '\x0c' | '\x0e'..='\x19' |
+                    '\x7f' => {
+                        write!(f, "\\x{:02x}", ch as u32)?;
+                    }
+                    '\n' | '\r' | '\t' | _ => {
+                        write!(f, "{}", ch.escape_debug())?;
+                    }
+               }
             }
             write!(f, "\"")?;
             Ok(())
@@ -759,3 +768,12 @@ mod bstring_arbitrary {
         }
     }
 }
+
+#[test]
+fn test_debug() {
+    use crate::ByteSlice;
+    assert_eq!(
+        r#""\0\0\0 ftypisom\0\0\x02\0isomiso2avc1mp""#,
+        format!("{:?}", b"\0\0\0 ftypisom\0\0\x02\0isomiso2avc1mp".as_bstr()));
+}
+