Improve helper code

school/intro-crypto/uebung/01/u01/map

@@ -0,0 +1,28 @@
+Af
+Bä
+Cg
+Dj
+Eö
+Fx
+Gn
+Ji
+Km
+Lc
+Mß
+Nv
+Od
+Pr
+Qa
+Rl
+Se
+Tü
+Uh
+Vz
+Wt
+Xw
+Yp
+Zs
+Äo
+Öb
+Üu
+ßk

school/intro-crypto/uebung/01/u01/src/main.rs

@@ -2,13 +2,15 @@ extern crate countmap;
 
 use countmap::CountMap;
 use std::{
+    collections::HashMap,
     fs::File,
     io::{BufRead, BufReader},
+    path::Path,
 };
 
 fn count() {
     let args: Vec<_> = std::env::args().collect();
-    let file = args.get(1).unwrap();
+    let file = &args[1];
     let mut map: CountMap<char, u32> = CountMap::new();
     let read = BufReader::new(File::open(file).unwrap());
     for line in read.lines() {
@@ -30,51 +32,40 @@ fn count() {
             "{} &\\text{{:}}& {:3} \\to{{}} {:.2} \\\\",
             k,
             v,
-            v as f64 / sum as f64
+            f64::from(v) / f64::from(sum)
         )
     });
     println!("sum &\\text{{:}}& {}", sum);
 }
 
+fn create_map<P: AsRef<Path>>(path: P) -> std::io::Result<HashMap<char, char>> {
+    let read = BufReader::new(File::open(path)?);
+    let mut map = HashMap::new();
+    for line in read.lines() {
+        if let Ok(line) = line {
+            let chars: Vec<char> = line.chars().collect();
+            if chars.len() != 2 {
+                eprintln!("Invalid line {}", line);
+            } else {
+                map.insert(chars[0], chars[1]);
+            }
+        }
+    }
+    Ok(map)
+}
+
 fn main() {
+    count();
     let args: Vec<_> = std::env::args().collect();
-    let file = args.get(1).unwrap();
-    let read = BufReader::new(File::open(file).unwrap());
+    let target = &args[1];
+    let map = create_map(&args[2]).unwrap();
+    let read = BufReader::new(File::open(target).unwrap());
     for line in read.lines() {
         if let Ok(line) = line {
             let s: String = line
                 .chars()
-                .map(|c| match c {
-                    'A' => 'f',
-                    'B' => 'ä',
-                    'C' => 'g',
-                    'D' => 'j',
-                    'E' => 'ö',
-                    'F' => 'x',
-                    'G' => 'n',
-                    'J' => 'i',
-                    'K' => 'm',
-                    'L' => 'c',
-                    'M' => 'ß',
-                    'N' => 'v',
-                    'O' => 'd',
-                    'P' => 'r',
-                    'Q' => 'a',
-                    'R' => 'l',
-                    'S' => 'e',
-                    'T' => 'ü',
-                    'U' => 'h',
-                    'V' => 'z',
-                    'W' => 't',
-                    'X' => 'w',
-                    'Y' => 'p',
-                    'Z' => 's',
-                    'Ä' => 'o',
-                    'Ö' => 'b',
-                    'Ü' => 'u',
-                    'ß' => 'k',
-                    c => c,
-                }).collect();
+                .map(|c| map.get(&c).cloned().unwrap_or(c))
+                .collect();
             println!("{}", s);
         }
     }