From 75cd953c30124b1a3d5e08da0c224395e3dfd386 Mon Sep 17 00:00:00 2001
From: Nikita Revenco <154856872+NikitaRevenco@users.noreply.github.com>
Date: Fri, 20 Dec 2024 09:38:48 +0000
Subject: [PATCH] feat: correct implementation for pascal_case and camel_case

---
 helix-core/src/case_conversion.rs | 144 +++++++++++++++++++++++-------
 1 file changed, 111 insertions(+), 33 deletions(-)

diff --git a/helix-core/src/case_conversion.rs b/helix-core/src/case_conversion.rs
index 35287d5be..f4f1a166b 100644
--- a/helix-core/src/case_conversion.rs
+++ b/helix-core/src/case_conversion.rs
@@ -71,23 +71,6 @@ pub fn to_alternate_case_with(text: impl Iterator<Item = char>, buf: &mut Tendri
     }
 }
 
-pub fn to_pascal_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
-    let mut at_word_start = true;
-    for c in text {
-        // we don't count _ as a word char here so case conversions work well
-        if !c.is_alphanumeric() {
-            at_word_start = true;
-            continue;
-        }
-        if at_word_start {
-            at_word_start = false;
-            buf.extend(c.to_uppercase());
-        } else {
-            buf.push(c)
-        }
-    }
-}
-
 pub fn to_title_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
     let mut capitalize_next = true;
     let mut prev_is_lowercase = false;
@@ -150,24 +133,119 @@ pub fn to_snake_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
     to_case_with_separator(text, buf, '_');
 }
 
-pub fn to_camel_case_with(mut text: impl Iterator<Item = char>, buf: &mut Tendril) {
-    for c in &mut text {
-        if c.is_alphanumeric() {
-            buf.extend(c.to_lowercase())
-        }
-    }
-    let mut at_word_start = false;
+pub fn to_camel_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
+    to_camel_or_pascal_case_with(text, buf, false);
+}
+
+pub fn to_pascal_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
+    to_camel_or_pascal_case_with(text, buf, true);
+}
+
+pub fn to_camel_or_pascal_case_with(
+    text: impl Iterator<Item = char>,
+    buf: &mut Tendril,
+    is_pascal: bool,
+) {
+    let mut capitalize_next = is_pascal;
+
     for c in text {
-        // we don't count _ as a word char here so case conversions work well
-        if !c.is_alphanumeric() {
-            at_word_start = true;
-            continue;
-        }
-        if at_word_start {
-            at_word_start = false;
-            buf.extend(c.to_uppercase());
+        if c.is_alphanumeric() {
+            if capitalize_next {
+                buf.extend(c.to_uppercase());
+                capitalize_next = false;
+            } else {
+                buf.extend(c.to_lowercase());
+            }
         } else {
-            buf.push(c)
+            capitalize_next = true;
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn case_tester<'a, F>(change_fn: F) -> impl Fn(&'a str, &'a str) + 'a
+    where
+        F: Fn(std::str::Chars<'a>) -> Tendril + 'a,
+    {
+        move |input: &str, expected: &str| {
+            let transformed = change_fn(input.chars());
+            let m = transformed.to_string();
+            dbg!(input);
+            assert_eq!(m.as_str(), expected)
+        }
+    }
+
+    #[test]
+    fn test_camel_case_conversion() {
+        let camel_test = case_tester(to_camel_case);
+        camel_test("hello world", "helloWorld");
+        camel_test("Hello World", "helloWorld");
+        camel_test("hello_world", "helloWorld");
+        camel_test("HELLO_WORLD", "helloWorld");
+    }
+
+    #[test]
+    fn test_lower_case_conversion() {
+        let lower_test = case_tester(to_lower_case);
+        lower_test("HelloWorld", "helloworld");
+        lower_test("HELLO WORLD", "hello world");
+        lower_test("hello_world", "hello_world");
+        lower_test("Hello-World", "hello-world");
+    }
+
+    #[test]
+    fn test_upper_case_conversion() {
+        let upper_test = case_tester(to_upper_case);
+        upper_test("helloWorld", "HELLOWORLD");
+        upper_test("hello world", "HELLO WORLD");
+        upper_test("hello_world", "HELLO_WORLD");
+        upper_test("Hello-World", "HELLO-WORLD");
+    }
+
+    #[test]
+    fn test_pascal_case_conversion() {
+        let pascal_test = case_tester(to_pascal_case);
+        pascal_test("hello world", "HelloWorld");
+        pascal_test("Hello World", "HelloWorld");
+        pascal_test("hello_world", "HelloWorld");
+        pascal_test("HELLO_WORLD", "HelloWorld");
+    }
+
+    #[test]
+    fn test_alternate_case_conversion() {
+        let alternate_test = case_tester(to_alternate_case);
+        alternate_test("hello world", "HELLO WORLD");
+        alternate_test("Hello World", "hELLO wORLD");
+        alternate_test("helLo_woRlD", "HELlO_WOrLd");
+    }
+
+    #[test]
+    fn test_title_case_conversion() {
+        let title_test = case_tester(to_title_case);
+        title_test("hello world", "Hello World");
+        title_test("Hello World", "Hello World");
+        title_test("hello_world", "Hello World");
+        title_test("HELLO_WORLD", "Hello World");
+    }
+
+    #[test]
+    fn test_kebab_case_conversion() {
+        let kebab_test = case_tester(to_kebab_case);
+        kebab_test("helloWorld", "hello-world");
+        kebab_test("HelloWorld", "hello-world");
+        kebab_test("hello_world", "hello-world");
+        kebab_test("HELLO_WORLD", "hello-world");
+    }
+
+    #[test]
+    fn test_snake_case_conversion() {
+        let snake_test = case_tester(to_snake_case);
+        snake_test("helloWorld", "hello_world");
+        snake_test("HelloWorld", "hello_world");
+        snake_test("hello world", "hello_world");
+        snake_test("HELLO WORLD", "hello_world");
+    }
+}