✨ Placeholder Support

未指定檔案或測試。首先追蹤目前的文字編輯、語法醒目提示和 LSP 整合點，接著確定預留位置的辨識、呈現、編輯，以及使用 Tab/Shift+Tab 導覽應該放在哪裡。完成的標準是：預留位置在視覺上具有區別、可編輯、可導覽、可巢狀，並反映在編輯器狀態中，同時不破壞現有的醒目提示或 LSP 行為。

Description

Implement support for placeholders in CodeEdit, similar to Xcode’s <#placeholder#> feature. This would allow developers to insert and cycle through editable placeholders in their code, improving productivity and code clarity during development.

Use Case

This feature would be particularly useful for defining temporary or template-like code constructs, such as:

let <#name#> = <#value#>

Placeholders would:

1. Be highlighted visually.
2. Be navigable (e.g., via Tab key).
3. Allow inline editing to replace the placeholder text.

Expected Behavior

• When a placeholder is inserted (e.g., <#placeholder#>), it should:
• Appear visually distinct (e.g., highlighted with a subtle background color or outline).
• Be editable directly in the code editor.
• Allow navigation between placeholders using keyboard shortcuts like Tab and Shift+Tab.
• Placeholders should support nested constructs (e.g., let <#name#> = <#type#>(<#arguments#>)).

Technical Notes

• Integrate placeholder handling with the current text editing features.
• Consider compatibility with existing syntax highlighting and LSP integration.

Steps to Implement

1. Define a syntax for placeholders (e.g., <#placeholder#>).
2. Update the text editor to recognize and render placeholders.
3. Add keyboard navigation support for placeholders.
4. Ensure placeholder edits are reflected in the editor state.

Additional Context

This feature would align CodeEdit with Xcode’s behavior, making it a more familiar and seamless experience for developers who work on macOS. It also complements other code editing enhancements, such as autocompletion and LSP support.

Screenshots