Struct BufferSnapshot 

pub struct BufferSnapshot {
    pub id: BufferId,
    pub cursor: Cursor,
    pub file_path: Option<String>,
    pub modified: bool,
    /* private fields */
}

Read-only snapshot of buffer state.

A BufferSnapshot captures the complete state of a buffer at a point in time. Clone is O(1) via Arc structural sharing.

Cursor Isolation (#471)

Cursor is passed explicitly to from_buffer() - get it from Window.

Immutability

All methods are read-only. The snapshot cannot be modified after creation, ensuring thread safety without locks.

Fields Captured

• id: Buffer identifier
• text: Text content (rope clone, O(1))
• cursor: Cursor state (passed from Window)
• file_path: Associated file path (if any)
• modified: Whether buffer had unsaved changes

Note: Selection removed in Phase 8 (#465) - it now lives in Window. Note: Cursor removed from Buffer in #471 - it now lives in Window.

Fields

id: BufferId

Buffer identifier.

cursor: Cursor

Cursor state (from Window, not Buffer).

file_path: Option<String>

File path (if buffer is associated with a file).

modified: bool

Whether buffer has unsaved modifications.

Implementations

impl BufferSnapshot

pub fn from_buffer(buffer: &Buffer, cursor: Cursor) -> Self

Create a snapshot from a buffer.

Cursor must be passed explicitly - get it from Window. This is O(1) — the rope is cloned via Arc sharing.

pub fn new( id: BufferId, lines: &[String], cursor: Cursor, file_path: Option<String>, modified: bool, ) -> Self

Create a snapshot from individual components.

This is useful for testing or when constructing a snapshot without a buffer.

pub fn line_count(&self) -> usize

Get the number of lines.

pub fn is_empty(&self) -> bool

Check if the snapshot is empty.

pub fn line(&self, idx: usize) -> Option<&str>

Get a specific line by index.

Returns None if index is out of bounds.

pub fn line_len(&self, idx: usize) -> Option<usize>

Get the length of a line in characters.

pub fn lines(&self) -> Vec<String>

Collect all lines as a Vec<String>.

This allocates — prefer line(idx) for individual access.

pub fn content(&self) -> String

Get the full content as a string (lines joined with newlines).

pub fn text_in_range(&self, start: Position, end: Position) -> String

Extract text within a range.

Returns the text between start and end positions. Positions are clamped to valid bounds.

pub const fn position(&self) -> Position

Get the cursor position.

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

Check if a position is valid within this snapshot.

Trait Implementations

impl Clone for BufferSnapshot

fn clone(&self) -> BufferSnapshot

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BufferSnapshot

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

Formats the value using the given formatter.