Module changeset 

Text editing changeset system

STATUS: The core types (TextChangeset, TextOperation, TextOp* structs) are actively used by window.rs, undo_redo.rs, event.rs, and platform code.

The live copy/cut/select-all/delete paths run through common/event.rs (SystemChange::CopyToClipboard/CutToClipboard, CallbackChange::SetSelectAllRange, LayoutWindow::delete_selection), not through changeset constructors. The earlier create_*_changeset helpers were a never-wired parallel implementation (with placeholder deleted_text, CursorPosition::Uninitialized cursors, and byte±1 UTF-8 deletion) and have been removed.

Architecture

This module implements a two-phase changeset system for all text editing operations:

1. Create changesets (pre-callback): Analyze what would change, don’t mutate yet
2. Apply changesets (post-callback): Actually mutate state if !preventDefault

This pattern enables:

• preventDefault support for ALL operations (not just text input)
• Undo/redo stack (record changesets before applying)
• Validation (check bounds, permissions before mutation)
• Inspection (user callbacks can see planned changes)

Structs

TextChangeset

A text editing changeset that can be inspected before application

TextOpClearSelection

Clear all selections

TextOpCopy

Copy selection to clipboard (no text change)

TextOpCut

Cut selection to clipboard (deletes text)

TextOpDeleteText

Delete text in range

TextOpExtendSelection

Extend selection in a direction

TextOpInsertText

Insert text at cursor position

TextOpMoveCursor

Move cursor to new position

TextOpPaste

Paste from clipboard (inserts text)

TextOpReplaceText

Replace text in range with new text

TextOpSelectAll

Select all text in node

TextOpSetSelection

Set selection to new range

Enums

CursorMovement

Type of cursor movement

SelectionDirection

Re-export from events module Direction of cursor movement or selection expansion.

TextOperation

Text editing operation (what will change)

Type Aliases

ChangesetId

Unique identifier for a changeset (for undo/redo)