## Description of Feature or Change
Zed currently lacks a built-in way to convert a file’s indentation style
on the fly. While it's possible to change indentation behavior via
global or language-specific settings, these changes are persistent and
broad in scope as they apply to all files or all files of a given
language. We believe this could be improved for quick one-off
adjustments to specific files.
This PR introduces two new editor commands:
`Editor::convert_indentation_to_spaces` and
`Editor::convert_indentation_to_tabs`. These commands allow users to
convert the indentation of either the entire buffer or a selection of
lines, to spaces or tabs. Indentation levels are preserved, and any
mixed whitespace lines are properly normalized.
This feature is inspired by VS Code’s "Convert Indentation to
Tabs/Spaces" commands, but offers faster execution and supports
selection-based conversion, making it more flexible for quick formatting
changes.
## Implementation Details
To enable selection-based indentation conversion, we initially
considered reusing the existing `Editor::manipulate_lines` function,
which handles selections for line-based manipulations. However, this
method was designed specifically for operations like sorting or
reversing lines, and does not allow modifications to the line contents
themselves.
To address this limitation, we refactored the method into a more
flexible version: `Editor::manipulate_generic_lines`. This new method
passes a reference to the selected text directly into a callback, giving
the callback full control over how to process and construct the
resulting lines. The callback returns a `String` containing the modified
text, as well as the number of lines before and after the
transformation. These counts are computed using `.len()` on the line
vectors during manipulation, which is more efficient than calculating
them after the fact.
```rust
fn manipulate_generic_lines<M>(
&mut self,
window: &mut Window,
cx: &mut Context<Self>,
mut manipulate: M,
) where
M: FnMut(&str) -> (String, usize, usize),
{
// ... Get text from buffer.text_for_range() ...
let (new_text, lines_before, lines_after) = manipulate(&text);
// ...
```
We now introduce two specialized methods:
`Editor::manipulate_mutable_lines` and
`Editor::manipulate_immutable_lines`. Each editor command selects the
appropriate method based on whether it needs to modify line contents or
simply reorder them. This distinction is important for performance: when
line contents remain unchanged, working with an immutable reference as
`&mut Vec<&str>` is both faster and more memory-efficient than using an
owned `&mut Vec<String>`.
## Demonstration
https://github.com/user-attachments/assets/e50b37ea-a128-4c2a-b252-46c3c4530d97
Release Notes:
- Added `editor::ConvertIndentationToSpaces` and
`editor::ConvertIndentationToTabs` actions to change editor indents
---------
Co-authored-by: Pedro Silveira <pedroruanosilveira@tecnico.ulisboa.pt>
c979452c2d