Struct Selection 

pub struct Selection {
    pub anchor: Position,
    pub active: bool,
    pub mode: SelectionMode,
}

Selection state within a buffer.

Tracks whether a selection is active, where it started (anchor), and what mode it’s in. The selection extends from the anchor to the current cursor position.

Selection Direction

The anchor is where selection started. The selection can extend in either direction from the anchor:

• Forward: cursor is after anchor
• Backward: cursor is before anchor

Use bounds() to get normalized (start, end) positions.

Fields

anchor: Position

The position where selection started.

active: bool

Whether selection is currently active.

mode: SelectionMode

The selection mode (character/block/line).

Implementations

impl Selection

pub const fn new() -> Self

Create a new inactive selection.

pub const fn start(&mut self, pos: Position, mode: SelectionMode)

Start a selection at the given position with the specified mode.

This sets the anchor and activates the selection.

Arguments

• pos - The anchor position (where selection starts)
• mode - The selection mode

pub const fn start_char(&mut self, pos: Position)

Start a character-wise selection at the given position.

Convenience method equivalent to start(pos, SelectionMode::Character).

pub const fn start_line(&mut self, pos: Position)

Start a line-wise selection at the given position.

Convenience method equivalent to start(pos, SelectionMode::Line).

pub const fn start_block(&mut self, pos: Position)

Start a block selection at the given position.

Convenience method equivalent to start(pos, SelectionMode::Block).

pub const fn clear(&mut self)

Clear (deactivate) the selection.

The anchor position is preserved but the selection becomes inactive.

pub const fn is_active(&self) -> bool

Check if selection is currently active.

pub const fn mode(&self) -> SelectionMode

Get the selection mode.

pub const fn set_mode(&mut self, mode: SelectionMode)

Change the selection mode without changing anchor or active state.

pub fn bounds(&self, cursor_pos: Position) -> Option<(Position, Position)>

Get selection bounds in document order (start <= end).

Returns None if selection is not active. The returned positions are always ordered so that start comes before or equals end in document order.

Arguments

• cursor_pos - The current cursor position (selection endpoint)

pub fn block_bounds(&self, cursor_pos: Position) -> Option<(Position, Position)>

Get block selection bounds (top-left, bottom-right).

For block selections, this returns the rectangle corners:

• Top-left: (min_line, min_column)
• Bottom-right: (max_line, max_column)

Returns None if selection is not active or not in block mode.

Arguments

• cursor_pos - The current cursor position

pub fn line_bounds(&self, cursor_pos: Position) -> Option<(usize, usize)>

Get line-wise selection bounds (start_line, end_line).

For line selections, this returns the range of selected lines. Returns None if selection is not active.

Arguments

• cursor_pos - The current cursor position

pub fn contains(&self, pos: Position, cursor_pos: Position) -> bool

Check if a position is within the selection.

The behavior depends on the selection mode:

• Character: position is between start and end
• Block: position is within the rectangle
• Line: position’s line is within the line range

Arguments

• pos - The position to check
• cursor_pos - The current cursor position (selection endpoint)

pub fn line_count(&self, cursor_pos: Position) -> usize

Get the number of lines in the selection.

Returns 0 if selection is not active.

Arguments

• cursor_pos - The current cursor position

Trait Implementations

impl Clone for Selection

fn clone(&self) -> Selection

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Selection

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

Formats the value using the given formatter.

impl Default for Selection

fn default() -> Selection

Returns the “default value” for a type.

impl PartialEq for Selection

fn eq(&self, other: &Selection) -> 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 Copy for Selection

impl Eq for Selection

impl StructuralPartialEq for Selection