feat: Lowercasing stage

Cargo.toml

@@ -31,12 +31,13 @@ regex = "1.9.5"
 
 [features]
 default = ["all"]
-all = ["german", "symbols", "deletion", "squeeze", "upper"]
+all = ["german", "symbols", "deletion", "squeeze", "upper", "lower"]
 german = []
 symbols = []
 deletion = []
 squeeze = []
 upper = []
+lower = []
 
 [dev-dependencies]
 assert_cmd = "2.0.12"

src/main.rs

@@ -3,6 +3,8 @@ use betterletters::apply;
 use betterletters::stages::DeletionStage;
 #[cfg(feature = "german")]
 use betterletters::stages::GermanStage;
+#[cfg(feature = "lower")]
+use betterletters::stages::LowerStage;
 #[cfg(feature = "squeeze")]
 use betterletters::stages::SqueezeStage;
 #[cfg(feature = "symbols")]
@@ -51,6 +53,11 @@ fn main() -> Result<(), Error> {
         debug!("Loaded stage: Upper");
     }
 
+    if args.lower {
+        stages.push(Box::<LowerStage>::default());
+        debug!("Loaded stage: Lower");
+    }
+
     let mut source = BufReader::new(io::stdin());
     let mut destination = io::stdout();
 
@@ -79,6 +86,9 @@ mod cli {
         /// Uppercase what was matched
         #[arg(short, long, env = "UPPER")]
         pub upper: bool,
+        /// Lowercase what was matched
+        #[arg(short, long, env = "LOWER")]
+        pub lower: bool,
         /// Perform substitutions on German words, such as 'Abenteuergruesse' to
         /// 'Abenteuergrüße'
         ///

src/stages/lower/mod.rs

@@ -0,0 +1,56 @@
+use crate::scoped::Scoped;
+
+use super::Stage;
+
+/// Renders in lowercase.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+#[allow(clippy::module_name_repetitions)]
+pub struct LowerStage {}
+
+impl Scoped for LowerStage {}
+
+impl Stage for LowerStage {
+    fn substitute(&self, input: &str) -> String {
+        input.to_lowercase()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use rstest::rstest;
+
+    use super::*;
+
+    #[rstest]
+    // German
+    #[case("A", "a")]
+    #[case("a", "a")]
+    #[case("Ä", "ä")]
+    #[case("ä", "ä")]
+    #[case("Ö", "ö")]
+    #[case("ö", "ö")]
+    #[case("Ü", "ü")]
+    #[case("ü", "ü")]
+    #[case("ẞ", "ß")]
+    #[case("ß", "ß")]
+    #[case("AaÄäÖöÜüẞß!", "aaääööüüßß!")]
+    #[case("SS", "ss")]
+    //
+    // Chinese
+    #[case("你好!", "你好!")]
+    //
+    // Japanese
+    #[case("こんにちは!", "こんにちは!")]
+    //
+    // Korean
+    #[case("안녕하세요!", "안녕하세요!")]
+    //
+    // Russian
+    #[case("ПРИВЕТ!", "привет!")]
+    //
+    // Emojis
+    #[case("👋\0", "👋\0")]
+    fn substitute(#[case] input: &str, #[case] expected: &str) {
+        assert_eq!(LowerStage {}.substitute(input), expected);
+    }
+}

src/stages/mod.rs

@@ -2,6 +2,8 @@
 mod deletion;
 #[cfg(feature = "german")]
 mod german;
+#[cfg(feature = "lower")]
+mod lower;
 #[cfg(feature = "squeeze")]
 mod squeeze;
 #[cfg(feature = "symbols")]
@@ -13,6 +15,7 @@ use std::fmt::Debug;
 
 pub use deletion::DeletionStage;
 pub use german::GermanStage;
+pub use lower::LowerStage;
 pub use squeeze::SqueezeStage;
 pub use symbols::SymbolsStage;
 pub use upper::UpperStage;