Struct GapBuffer 

pub struct GapBuffer { /* private fields */ }

Gap buffer implementation for efficient text editing.

The buffer maintains text as a vector of characters with a gap at the current editing position. This makes insertions and deletions at the cursor position very efficient (O(1)), at the cost of having to move the gap when editing at different positions.

Example Structure

For text “Hello World” with gap after “Hello”:

['H', 'e', 'l', 'l', 'o', '\0', '\0', '\0', ' ', 'W', 'o', 'r', 'l', 'd']
                          ^gap_start      ^gap_end

Implementations

impl GapBuffer

pub fn new() -> Self

Create a new empty gap buffer

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

Create a gap buffer from text

pub fn from_lines(lines: Vec<String>) -> Self

Create a gap buffer from lines

pub fn len(&self) -> usize

Get the length of the content (excluding the gap)

pub fn move_gap_to(&mut self, position: usize)

Move the gap to a specific position in the text.

This is the core operation that enables efficient editing. When the gap is at the cursor position, insertions and deletions become O(1) operations.

Complexity

O(n) where n is the distance between the current gap position and the target position

pub fn insert_char(&mut self, position: usize, ch: char)

Insert a character at the specified position.

Moves the gap to the position first, then inserts the character by placing it at gap_start and incrementing gap_start.

pub fn insert(&mut self, position: usize, text: &str)

Insert text at the specified position

pub fn delete_backward(&mut self, position: usize)

Delete backward from the specified position

pub fn delete_forward(&mut self, position: usize)

Delete forward from the specified position

pub fn delete_range(&mut self, start: usize, end: usize)

Delete a range of text

pub fn to_string(&self) -> String

Convert the buffer to a string.

Reconstructs the text by concatenating the content before the gap with the content after the gap, skipping the gap itself.

Complexity

O(n) where n is the length of the text

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

Convert the buffer to lines

pub fn cursor_to_position(&self, row: usize, col: usize) -> usize

Convert cursor position (row, col) to buffer position.

Translates a 2D cursor position (line and column) to a linear position in the buffer. This is used to map editor cursor positions to buffer positions for editing operations.

Returns

The character index in the buffer corresponding to the cursor position

pub fn position_to_cursor(&self, position: usize) -> (usize, usize)

Convert buffer position to cursor position (row, col).

Translates a linear buffer position to a 2D cursor position (line and column). This is the inverse of cursor_to_position.

Returns

A tuple of (row, column) representing the cursor position

Trait Implementations

impl Clone for GapBuffer

fn clone(&self) -> GapBuffer

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for GapBuffer

fn default() -> Self

Returns the “default value” for a type.

impl TextBuffer for GapBuffer

fn line_count(&self) -> usize

Get the total number of lines in the buffer

fn get_line(&self, line_idx: usize) -> Option<String>

Get a specific line by index (0-based)

fn all_lines(&self) -> Vec<String>

Get all lines (for now, while we’re simple)

fn line_len(&self, line_idx: usize) -> usize

Get the length of a specific line in characters

fn insert_at(&mut self, row: usize, col: usize, text: &str)

Insert text at a specific position (row, col)

fn delete_at(&mut self, row: usize, col: usize)

Delete a character at a specific position (row, col)

fn backspace_at(&mut self, row: usize, col: usize)

Delete backwards from a specific position (row, col)