In binary mode, colorize letters, digits and whitespace

CHANGELOG.md

@@ -7,6 +7,9 @@ What changed in mapiproxy, per version
 
 - The use of colors can now be configured with --color=always|never|auto.
 
+- Colorize text, digits and whitespace in binary output. This makes it easier
+  to match the hex codes on the left to the characters on the right.
+
 - Raw IPv6 addresses are now allowed in LISTEN_ADDR and FORWARD_ADDR: `[::1]:50000`.
 
 - Clean up Unix sockets when Control-C is pressed.

src/mapi/mod.rs

@@ -379,7 +379,16 @@ impl Binary {
         }
     }
 
-    fn add(&mut self, byte: u8, style: Style, renderer: &mut Renderer) -> io::Result<()> {
+    fn add(&mut self, byte: u8, mut style: Style, renderer: &mut Renderer) -> io::Result<()> {
+        if style == Style::Normal {
+            style = match byte {
+                b'0'..=b'9' => Style::Digit,
+                b'a'..=b'z' | b'A'..=b'Z' => Style::Letter,
+                b' ' | b'\t' | b'\r' | b'\n' => Style::Whitespace,
+                _ => style,
+            }
+        }
+
         self.row[self.col] = (byte, style);
         self.col += 1;
 
@@ -472,7 +481,8 @@ impl Binary {
     fn readable(byte: &[u8; 1]) -> &[u8] {
         // note that the readable range does not include 0x7f (DEL)
         let s = match byte[0] {
-            b' '..=0x7e => return byte.as_ref(),
+            b' ' => "·",
+            0x21..=0x7e => return byte.as_ref(),
             b'\n' => "↵",
             b'\t' => "→",
             0 => "░",

src/render.rs

@@ -133,12 +133,18 @@ impl Renderer {
     }
 
     fn write_style(&mut self, style: Style) -> io::Result<()> {
+        // Black=30 Red=31 Green=32 Yellow=33 Blue=34 Magenta=35 Cyan=36 White=37
+
         let escape_sequence = match style {
-            Style::Normal => "\u{1b}[m",
-            Style::Header => "\u{1b}[1m",
-            Style::Frame => "\u{1b}[36m",
-            Style::Error => "\u{1b}[31m",
+            Style::Normal => "",
+            Style::Header => "\u{1b}[1m",          // bold
+            Style::Frame => "\u{1b}[36m",          // cyan
+            Style::Error => "\u{1b}[1m\u{1b}[31m", // bold red
+            Style::Whitespace => "\u{1b}[31m",     // red
+            Style::Digit => "\u{1b}[32m",          // green
+            Style::Letter => "\u{1b}[34m",         // blue
         };
+        self.out.write_all(b"\x1b[m")?; // NORMAL
         self.out.write_all(escape_sequence.as_bytes())?;
         Ok(())
     }
@@ -178,4 +184,7 @@ pub enum Style {
     Error,
     Frame,
     Header,
+    Whitespace,
+    Digit,
+    Letter,
 }