From 2aaa4a65710e4f5b293d3682e09c02b70cd295ed Mon Sep 17 00:00:00 2001
From: "Adam T. Carpenter" <atc@53hor.net>
Date: Thu, 4 Mar 2021 21:44:24 -0500
Subject: faster exception lookups, slightly fuglier function signatures

---
 src/main.rs | 78 ++++++++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 54 insertions(+), 24 deletions(-)

(limited to 'src')

diff --git a/src/main.rs b/src/main.rs
index b060ed1..c9f03c3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,6 +1,9 @@
+use std::collections::HashSet;
 use std::env::args;
 use std::io::{stdin, BufRead, BufReader};
 
+const HELP_MSG: &str = "Title-Case Tool.\n-i | --ignore [word...]\tIgnores a list of words that should not be altered.";
+
 /// Words that will not be capitalized unless they are at the start or end of a title.
 const EXCEPTIONS: &[&str] = &[
     "vs", "above", "across", "against", "at", "between", "by", "along", "among", "down", "in",
@@ -28,7 +31,7 @@ fn main() {
                 break;
             }
             "--help" | "-h" => {
-                println!("Title-Case Tool.\n-i | --ignore [word...]\tIgnores a list of words that should not be altered.");
+                println!("{}", HELP_MSG);
             }
             unrecognized => {
                 panic!(format!("Unrecognized option: {}", unrecognized));
@@ -36,40 +39,54 @@ fn main() {
         }
     }
 
+    // gather exceptions
+    let exceptions: HashSet<&'static str> = EXCEPTIONS.iter().cloned().collect();
+
+    // read input and correct lines
     for line in BufReader::new(stdin()).lines() {
         let line = line.expect("IO error");
-        println!("{}", correct_line(&line, &ignorables));
+        println!("{}", correct_line(&line, &ignorables, &exceptions));
     }
 }
 
 /// Corrects a single line (title) based on placement and exceptions.
-fn correct_line(line: &str, ignorables: &[String]) -> String {
+fn correct_line(line: &str, ignorables: &[String], exceptions: &HashSet<&'static str>) -> String {
     let mut line = line.split_whitespace().peekable();
-    let mut result = Vec::new();
+    let mut result = String::new();
 
     if let Some(first) = line.next() {
         // always correct the first word
-        result.push(correct_word(first, true, ignorables));
+        result.push_str(&correct_word(first, true, ignorables, exceptions));
     } else {
-        // handle empty lines
-        return String::new();
+        // skip empty lines
+        return result;
     }
 
     // handle every other word
     while let Some(word) = line.next() {
-        result.push(correct_word(word, line.peek().is_none(), ignorables));
+        result.push(' ');
+        result.push_str(&correct_word(
+            word,
+            line.peek().is_none(),
+            ignorables,
+            exceptions,
+        ));
     }
 
-    // join words into title
-    result.join(" ")
+    result
 }
 
 /// Corrects a single word based on exceptions and ignorables.
-fn correct_word(word: &str, first_or_last: bool, ignorables: &[String]) -> String {
+fn correct_word(
+    word: &str,
+    first_or_last: bool,
+    ignorables: &[String],
+    exceptions: &HashSet<&'static str>,
+) -> String {
     if ignorables.iter().any(|s| s == word) {
         // leave ignorables untouched
         word.to_owned()
-    } else if first_or_last || !EXCEPTIONS.iter().any(|s| **s == word.to_lowercase()) {
+    } else if first_or_last || !exceptions.contains(&word.to_lowercase().as_str()) {
         // capitalize words that are first, last, or aren't exceptions
         capitalize_word(&word.to_lowercase())
     } else {
@@ -78,9 +95,6 @@ fn correct_word(word: &str, first_or_last: bool, ignorables: &[String]) -> Strin
     }
 }
 
-// correct with just ignorables
-// correct with ignorables and exceptions
-
 /// Capitalizes the first letter of a single word.
 fn capitalize_word(word: &str) -> String {
     let mut chars = word.chars();
@@ -100,12 +114,24 @@ mod tests {
 
     #[test]
     fn test_correct_word() {
-        assert_eq!(correct_word("Like", false, &[]), String::from("like"));
-        assert_eq!(correct_word("like", false, &[]), String::from("like"));
-        assert_eq!(correct_word("like", true, &[]), String::from("Like"));
-        assert_eq!(correct_word("liKe", false, &[]), String::from("like"));
         assert_eq!(
-            correct_word("computers", false, &[]),
+            correct_word("Like", false, &[], &EXCEPTIONS.iter().cloned().collect()),
+            String::from("like")
+        );
+        assert_eq!(
+            correct_word("like", false, &[], &EXCEPTIONS.iter().cloned().collect()),
+            String::from("like")
+        );
+        assert_eq!(
+            correct_word("like", true, &[], &EXCEPTIONS.iter().cloned().collect()),
+            String::from("Like")
+        );
+        assert_eq!(
+            correct_word("liKe", false, &[], &EXCEPTIONS.iter().cloned().collect()),
+            String::from("like")
+        );
+        assert_eq!(
+            correct_word("computers", false, &[], &HashSet::new()),
             String::from("Computers")
         );
     }
@@ -113,11 +139,15 @@ mod tests {
     #[test]
     fn test_correct_line() {
         assert_eq!(
-            correct_line("this is a test", &[]),
+            correct_line("this is a test", &[], &EXCEPTIONS.iter().cloned().collect()),
             String::from("This Is a Test")
         );
         assert_eq!(
-            correct_line("similEs: lIke Or As", &[]),
+            correct_line(
+                "similEs: lIke Or As",
+                &[],
+                &EXCEPTIONS.iter().cloned().collect()
+            ),
             String::from("Similes: like or As")
         );
     }
@@ -125,13 +155,13 @@ mod tests {
     #[test]
     fn test_proper_nouns_acronyms() {
         assert_eq!(
-            correct_line("FreeBSD", &[String::from("FreeBSD")]),
+            correct_line("FreeBSD", &[String::from("FreeBSD")], &HashSet::new()),
             String::from("FreeBSD")
         );
     }
 
     #[test]
     fn test_empty_lines() {
-        assert_eq!(correct_line("", &[]), String::from(""));
+        assert_eq!(correct_line("", &[], &HashSet::new()), String::from(""),);
     }
 }
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