From c61ebb37d153d3090e768b975524bd8c4f9258de Mon Sep 17 00:00:00 2001
From: Toby Vincent <tobyv13@gmail.com>
Date: Fri, 2 Dec 2022 23:55:46 -0600
Subject: refactor: simplify nonprintable parsing

---
 src/lib.rs | 40 ++++++++++++++++------------------------
 1 file changed, 16 insertions(+), 24 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 0d45606..c3665da 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -28,6 +28,8 @@ Examples:
   cat f - g  Output f's contents, then standard input, then g's contents.
   cat        Copy standard input to standard output."#;
 
+const UNKNOWN_CHAR: &[u8; 2] = b"^?";
+
 pub fn run(cli: Cli) -> Result<()> {
     use std::io::{BufReader, Read, Write};
 
@@ -49,10 +51,10 @@ pub fn run(cli: Cli) -> Result<()> {
             let mut line = Vec::new();
             for c in arr {
                 let parsed = match *c {
-                    b'\t' if cli.opts.show_tabs => vec![b'^', b'I'],
-                    b'\t' => vec![b'\t'],
+                    b'\t' if cli.opts.show_tabs => b"^I".to_vec(),
+                    b'\t' => b"\t".to_vec(),
                     c if cli.opts.show_nonprinting => parse_nonprinting_char(c),
-                    c => vec![c],
+                    c => [c].to_vec(),
                 };
                 line.extend(parsed)
             }
@@ -79,29 +81,19 @@ pub fn run(cli: Cli) -> Result<()> {
     Ok(())
 }
 
-fn parse_nonprinting_char(c: u8) -> Vec<u8> {
-    match c {
-        c @ 0..=31 => into_ctrl_char(c),
-        c @ 32..=126 => vec![c],
-        127 => into_unknown_char(),
-        c @ 128.. => into_meta_char(c),
-    }
-}
+fn parse_nonprinting_char(mut c: u8) -> Vec<u8> {
+    let mut buf = Vec::new();
 
-fn into_ctrl_char(c: u8) -> Vec<u8> {
-    vec![b'^', c + 64]
-}
+    if c >= 128 {
+        c -= 128;
+        buf.extend(b"M-");
+    }
 
-fn into_meta_char(c: u8) -> Vec<u8> {
-    let mut buf = "M-^".as_bytes().to_vec();
-    match c - 128 {
-        c @ 0..=31 => buf.extend(vec![b'^', c + 64]),
-        c @ 32..=127 => buf.push(c),
-        128.. => buf.extend(into_unknown_char()),
+    match c {
+        c @ 0..=31 => buf.extend([b'^', c + 64]),
+        c @ 32..=126 => buf.push(c),
+        127.. => buf.extend(UNKNOWN_CHAR),
     };
-    buf
-}
 
-fn into_unknown_char() -> Vec<u8> {
-    vec![b'^', b'?']
+    buf
 }
-- 
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