Struct Buffer 

pub struct Buffer { /* private fields */ }

Per-document state shared across all crate::View views of the same file. Wrap in Arc<Mutex<Buffer>> and pass to crate::View::new_view to create an additional window onto the same content.

Uses a ropey::Rope for O(log N) edits and O(1) byte-length queries. The rope always contains at least one logical line: a freshly constructed Buffer holds an empty rope (which ropey reports as 1 line) so cursor positions never need an “is the buffer empty?” branch.

Line semantics

ropey::Rope::len_lines() and split('\n').count() agree for all inputs:

• "" → 1 line
• "foo\n" → 2 lines (trailing empty line)
• "a\nb\n" → 3 lines

Rope::line(i) returns a RopeSlice that includes the trailing \n for non-final lines. Public accessors strip it before returning String.

Implementations

impl Buffer

pub fn new() -> Self

New empty content with one empty row.

pub fn from_str(text: &str) -> Self

Build content from a flat string. Splits on \n; a trailing \n produces a trailing empty line (matches ropey’s own convention).

pub fn undo_group_enter(&mut self)

Open (nest into) an undo group. On the outermost open (depth 0→1) record the current dirty_gen and disarm, so the group’s first mutating push_undo takes exactly one snapshot.

pub fn undo_group_exit(&mut self)

Close (unnest) an undo group. On the outermost close (depth 1→0), if the group armed a snapshot but dirty_gen is unchanged since it opened (nothing was mutated), pop that snapshot so a no-op group leaves zero undo entries. Resets the group flags.

pub fn undo_group_active(&self) -> bool

Whether an undo group is currently open (depth > 0).

pub fn undo_group_arm(&mut self) -> bool

Arm the open group’s single snapshot. Returns true if this call armed it (the first mutating push_undo in the group, which must take the snapshot), false if it was already armed (a later push to suppress).

Trait Implementations

impl Default for Buffer

fn default() -> Self

Returns the “default value” for a type.