editor: Improve range_to_utf16 and range_from_utf16 by use Rope. (#1268)

Now, we can work on 200K lines (editing).

--------

Now, all cost are on tree-sitter parse.

<img width="1091" height="672" alt="image"
src="https://github.com/user-attachments/assets/b111bc58-1334-40b2-9920-7006ad86bb3c"
/>

README.md

@@ -15,7 +15,8 @@ UI components for building fantastic desktop applications using [GPUI](https://g
 - **High Performance**: Virtualized Table and List components for smooth large-data rendering.
 - **Content Rendering**: Native support for Markdown and simple HTML.
 - **Charting**: Built-in charts for visualization your data.
-- **Code Highlighting**: Code Editor and Syntax highlighting.
+- **Editor**: High performance code editor (support up to 200K lines) with LSP (diagnostics, completion, hover, etc).
+- **Syntax Highlighting**: Syntax highlighting for editor and markdown components using Tree Sitter.
 - **Wef**: (Experimental) Offscreen rendering webview based on [CEF](https://github.com/chromiumembedded/cef).
 
 ## Showcase
@@ -87,7 +88,7 @@ Check out [CONTRIBUTING.md](CONTRIBUTING.md) for more details.
 | Syntax Highlight      | [Tree Sitter]                  | [Syntect]   | [Syntect]             | [QSyntaxHighlighter]           |
 | Markdown Rendering    | Yes                            | Yes         | Basic                 | No                             |
 | Markdown mix HTML     | Yes                            | No          | No                    | No                             |
-| HTML Rendering        | Basic                          | No          | No                    | Basic                            |
+| HTML Rendering        | Basic                          | No          | No                    | Basic                          |
 | Text Selection        | TextView                       | No          | Any Label             | No                             |
 | Themes                | Yes                            | No          | No                    | No                             |
 | I18n                  | Yes                            | Yes         | Yes                   | Yes                            |

crates/story/examples/editor.rs

@@ -200,12 +200,12 @@ impl CompletionProvider for ExampleLspStore {
             return Task::ready(Ok(vec![]));
         }
 
-        let _ = rope.to_string(); // Just to use the rope parameter.
-        let pos = rope.offset_to_position(offset);
-
         // Simulate to delay for fetching completions
+        let rope = rope.clone();
         let items = self.completions.clone();
         cx.background_spawn(async move {
+            let pos = rope.offset_to_position(offset);
+
             // Simulate a slow completion source, to test Editor async handling.
             smol::Timer::after(Duration::from_millis(20)).await;
 
@@ -940,7 +940,7 @@ fn main() {
         cx.activate(true);
 
         story::create_new_window_with_size(
-            "Code Editor",
+            "Editor",
             Some(size(px(1200.), px(960.))),
             |window, cx| cx.new(|cx| Example::new(name, window, cx)),
             cx,

crates/ui/src/input/state.rs

@@ -11,7 +11,7 @@ use gpui::{
     ScrollWheelEvent, SharedString, Styled as _, Subscription, Task, UTF16Selection, Window,
     WrappedLine,
 };
-use rope::Rope;
+use rope::{OffsetUtf16, Rope};
 use serde::Deserialize;
 use smallvec::SmallVec;
 use std::cell::RefCell;
@@ -1968,40 +1968,22 @@ impl InputState {
         cx.notify()
     }
 
+    #[inline]
     pub(super) fn offset_from_utf16(&self, offset: usize) -> usize {
-        let mut utf8_offset = 0;
-        let mut utf16_count = 0;
-
-        for ch in self.text.chars() {
-            if utf16_count >= offset {
-                break;
-            }
-            utf16_count += ch.len_utf16();
-            utf8_offset += ch.len_utf8();
-        }
-
-        utf8_offset
+        self.text.offset_utf16_to_offset(OffsetUtf16(offset))
     }
 
+    #[inline]
     pub(super) fn offset_to_utf16(&self, offset: usize) -> usize {
-        let mut utf16_offset = 0;
-        let mut utf8_count = 0;
-
-        for ch in self.text.chars() {
-            if utf8_count >= offset {
-                break;
-            }
-            utf8_count += ch.len_utf8();
-            utf16_offset += ch.len_utf16();
-        }
-
-        utf16_offset
+        self.text.offset_to_offset_utf16(offset).0
     }
 
+    #[inline]
     pub(super) fn range_to_utf16(&self, range: &Range<usize>) -> Range<usize> {
         self.offset_to_utf16(range.start)..self.offset_to_utf16(range.end)
     }
 
+    #[inline]
     pub(super) fn range_from_utf16(&self, range_utf16: &Range<usize>) -> Range<usize> {
         self.offset_from_utf16(range_utf16.start)..self.offset_from_utf16(range_utf16.end)
     }