feat: `switch_to_title_case`

helix-core/src/case_conversion.rs

@@ -28,7 +28,11 @@ pub fn to_pascal_case(text: impl Iterator<Item = char>) -> Tendril {
 }
 
 pub fn to_alternate_case(text: impl Iterator<Item = char>) -> Tendril {
-    to_case(text, to_pascal_case_with)
+    to_case(text, to_alternate_case_with)
+}
+
+pub fn to_title_case(text: impl Iterator<Item = char>) -> Tendril {
+    to_case(text, to_title_case_with)
 }
 
 pub fn to_upper_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril) {
@@ -76,6 +80,24 @@ pub fn to_pascal_case_with(text: impl Iterator<Item = char>, buf: &mut Tendril)
     }
 }
 
+pub fn to_title_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.push(' ');
+            buf.extend(c.to_uppercase());
+        } else {
+            buf.push(c)
+        }
+    }
+}
+
 pub fn to_camel_case_with(mut text: impl Iterator<Item = char>, buf: &mut Tendril) {
     for c in &mut text {
         if c.is_alphanumeric() {

helix-term/src/commands.rs

@@ -19,7 +19,8 @@ pub use typed::*;
 
 use helix_core::{
     case_conversion::{
-        to_alternate_case, to_camel_case, to_lower_case, to_pascal_case, to_upper_case,
+        to_alternate_case, to_camel_case, to_lower_case, to_pascal_case, to_title_case,
+        to_upper_case,
     },
     char_idx_at_visual_offset,
     chars::char_is_word,
@@ -1806,6 +1807,10 @@ fn switch_to_alternate_case(cx: &mut Context) {
     switch_case_impl(cx, |chars| to_alternate_case(chars))
 }
 
+fn switch_to_title_case(cx: &mut Context) {
+    switch_case_impl(cx, |chars| to_title_case(chars))
+}
+
 // fn switch_to_snake_case(cx: &mut Context) {
 //     switch_heck_case_impl(cx, |str| str.to_snake_case())
 // }