Remove repeated Regex compilation

src/choice.rs

@@ -219,22 +219,13 @@ impl Choice {
         &self,
         line: &String,
         opt: &Opt,
+        re: &Regex,
         handle: &mut BufWriter<std::io::StdoutLock>,
     ) {
-        write!(handle, "{}", self.get_choice_slice(line, opt).join(" "));
+        write!(handle, "{}", self.get_choice_slice(line, opt, re).join(" "));
     }
 
-    fn get_choice_slice<'a>(&self, line: &'a String, opt: &Opt) -> Vec<&'a str> {
+    fn get_choice_slice<'a>(&self, line: &'a String, opt: &Opt, re: &Regex) -> Vec<&'a str> {
-        let re = Regex::new(match &opt.field_separator {
-            Some(s) => s,
-            None => "[[:space:]]",
-        })
-        .unwrap_or_else(|e| {
-            eprintln!("Failed to compile regular expression: {}", e);
-            // Exit code of 1 means failed to compile field_separator regex
-            process::exit(1);
-        });
-
         let words = re
             .split(line)
             .into_iter()

src/main.rs

@@ -1,5 +1,7 @@
+use regex::Regex;
 use std::fs::File;
 use std::io::{self, BufRead, BufReader, Read, Write};
+use std::process;
 use structopt::StructOpt;
 
 mod choice;
@@ -18,12 +20,22 @@ fn main() {
     let lock = stdout.lock();
     let mut handle = io::BufWriter::new(lock);
 
+    let re = Regex::new(match &opt.field_separator {
+        Some(s) => s,
+        None => "[[:space:]]",
+    })
+    .unwrap_or_else(|e| {
+        eprintln!("Failed to compile regular expression: {}", e);
+        // Exit code of 1 means failed to compile field_separator regex
+        process::exit(1);
+    });
+
     let lines = buf.lines();
     for line in lines {
         match line {
             Ok(l) => {
                 for choice in &opt.choice {
-                    choice.print_choice(&l, &opt, &mut handle);
+                    choice.print_choice(&l, &opt, &re, &mut handle);
                 }
                 writeln!(handle, "");
             }