Rework go to line infrastructure (#23654)

Closes https://github.com/zed-industries/zed/issues/12024


https://github.com/user-attachments/assets/60ea3dbd-b594-4bf5-a44d-4bff925b815f

* Fixes incorrect line selection for certain corner cases

Before:

<img width="1728" alt="image"
src="https://github.com/user-attachments/assets/35aaee6c-c120-4bf1-9355-448a29d1b9b5"
/>

After:

<img width="1728" alt="image"
src="https://github.com/user-attachments/assets/abd97339-4594-4e8e-8605-50d74581ae86"
/>


* Reworks https://github.com/zed-industries/zed/pull/16420 to display
selection length with less performance overhead.
Improves the performance more, doing a single selections loop instead of
two.

* Fixes incorrect caret position display when text contains UTF-8 chars
with size > 1
Also fixes tooltop values for this case

* Fixes go to line to treat UTF-8 chars with size > 1 properly when
navigating

* Adds a way to fill go to line text editor with its tooltip on `Tab`

Release Notes:

- Fixed incorrect UTF-8 characters handling in `GoToLine` and caret
position

crates/rope/src/chunk.rs

@@ -162,9 +162,11 @@ impl<'a> ChunkSlice<'a> {
 
     #[inline(always)]
     pub fn text_summary(&self) -> TextSummary {
-        let (longest_row, longest_row_chars) = self.longest_row();
+        let mut chars = 0;
+        let (longest_row, longest_row_chars) = self.longest_row(&mut chars);
         TextSummary {
             len: self.len(),
+            chars,
             len_utf16: self.len_utf16(),
             lines: self.lines(),
             first_line_chars: self.first_line_chars(),
@@ -229,16 +231,19 @@ impl<'a> ChunkSlice<'a> {
     }
 
     /// Get the longest row in the chunk and its length in characters.
+    /// Calculate the total number of characters in the chunk along the way.
     #[inline(always)]
-    pub fn longest_row(&self) -> (u32, u32) {
+    pub fn longest_row(&self, total_chars: &mut usize) -> (u32, u32) {
         let mut chars = self.chars;
         let mut newlines = self.newlines;
+        *total_chars = 0;
         let mut row = 0;
         let mut longest_row = 0;
         let mut longest_row_chars = 0;
         while newlines > 0 {
             let newline_ix = newlines.trailing_zeros();
             let row_chars = (chars & ((1 << newline_ix) - 1)).count_ones() as u8;
+            *total_chars += usize::from(row_chars);
             if row_chars > longest_row_chars {
                 longest_row = row;
                 longest_row_chars = row_chars;
@@ -249,9 +254,11 @@ impl<'a> ChunkSlice<'a> {
             chars >>= newline_ix;
             chars >>= 1;
             row += 1;
+            *total_chars += 1;
         }
 
         let row_chars = chars.count_ones() as u8;
+        *total_chars += usize::from(row_chars);
         if row_chars > longest_row_chars {
             (row, row_chars as u32)
         } else {
@@ -908,7 +915,7 @@ mod tests {
         }
 
         // Verify longest row
-        let (longest_row, longest_chars) = chunk.longest_row();
+        let (longest_row, longest_chars) = chunk.longest_row(&mut 0);
         let mut max_chars = 0;
         let mut current_row = 0;
         let mut current_chars = 0;

crates/rope/src/rope.rs

@@ -965,8 +965,10 @@ impl sum_tree::Summary for ChunkSummary {
 /// Summary of a string of text.
 #[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
 pub struct TextSummary {
-    /// Length in UTF-8
+    /// Length in bytes.
     pub len: usize,
+    /// Length in UTF-8.
+    pub chars: usize,
     /// Length in UTF-16 code units
     pub len_utf16: OffsetUtf16,
     /// A point representing the number of lines and the length of the last line
@@ -994,6 +996,7 @@ impl TextSummary {
     pub fn newline() -> Self {
         Self {
             len: 1,
+            chars: 1,
             len_utf16: OffsetUtf16(1),
             first_line_chars: 0,
             last_line_chars: 0,
@@ -1022,7 +1025,9 @@ impl<'a> From<&'a str> for TextSummary {
         let mut last_line_len_utf16 = 0;
         let mut longest_row = 0;
         let mut longest_row_chars = 0;
+        let mut chars = 0;
         for c in text.chars() {
+            chars += 1;
             len_utf16.0 += c.len_utf16();
 
             if c == '\n' {
@@ -1047,6 +1052,7 @@ impl<'a> From<&'a str> for TextSummary {
 
         TextSummary {
             len: text.len(),
+            chars,
             len_utf16,
             lines,
             first_line_chars,
@@ -1103,6 +1109,7 @@ impl<'a> ops::AddAssign<&'a Self> for TextSummary {
             self.last_line_len_utf16 = other.last_line_len_utf16;
         }
 
+        self.chars += other.chars;
         self.len += other.len;
         self.len_utf16 += other.len_utf16;
         self.lines += other.lines;