Enum CommandFilter 

pub enum CommandFilter {
    All,
    ReadOnly,
    ForwardOnly,
}

Command filter consulted before any cursor call in a surface’s keyboard layer.

Generic over the command vocabulary rather than duplicated per surface: the rule (“a read-only surface accepts everything that doesn’t mutate”) is the same for prose and for code, only the list of commands differs.

Variants

All

Every command accepted (editor preset).

ReadOnly

Mutating commands rejected; navigation and copy/select-all accepted (read-only preset).

ForwardOnly

Additive editing only: the document may grow anywhere, but nothing the writer already committed can be taken away from the keyboard.

Deletes, word-deletes, cut and undo/redo are rejected; typing, pasting, splitting blocks, formatting and every navigation command are accepted. Unlike ReadOnly the surface is still a real editor — caret, accessibility role and clipboard stay editable — so a host swapping this in at runtime changes what the keyboard may do and nothing else.

⚠ Rejecting commands is only half of the guarantee. Inserting over a selection deletes it one layer below any command vocabulary (in TextCursor::insert_text), so a surface honouring this filter must also collapse the selection before inserting — collapses_selection_before_insert is that question, and RichTextEditor answers it at every insert site.

Implementations

impl CommandFilter

pub fn accepts<C: EditorCommand>(&self, cmd: C) -> bool

pub fn collapses_selection_before_insert(&self) -> bool

Whether an insertion must first collapse the selection instead of replacing it.

True only for ForwardOnly. Type-over is a delete that never passes through a command filter, so the insert sites themselves ask this question and move the caret to the end of the selection first — the typed text lands after the selected passage rather than in place of it, and the keystroke is neither lost nor destructive.

pub fn allows_wholesale_replacement(&self) -> bool

Whether a command may replace document content wholesale (an assistive-technology SetValue, which swaps the entire document for a new string).

Only All permits it: under ReadOnly nothing may be written, and under ForwardOnly a whole-document replacement is the single most regressive edit there is, however additive the text arriving with it looks.

Trait Implementations

impl Clone for CommandFilter

fn clone(&self) -> CommandFilter

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for CommandFilter

impl Debug for CommandFilter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for CommandFilter

impl PartialEq for CommandFilter

fn eq(&self, other: &CommandFilter) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for CommandFilter