PieceTable

The PieceTable module provides a naive implementation of the piece-table data structure for efficient text editing operations.

A piece-table represents an editable buffer of text as a sequence of non-overlapping pieces, allowing efficient inserts, deletes, and modifications.

This structure allows virtually infinite undo/redo, as long as we can keep the complete list of changes.

If a change is attempted when there unapplied changes (result of applying PieceTable.redo or PieceTable.redo!) it will return an error.

Usage

iex> table = PieceTable.new!("Hello, world!")
%PieceTable{
  original: "Hello, world!",
  result: "Hello, world!",
  edited: [keep: 13],
  index: 0
}

iex> table = PieceTable.insert!(table, "you ", 7)
%PieceTable{
  original: "Hello, world!",
  result: "Hello, you world!",
  edited: [{:add, "you ", 7}, {:keep, 13}],
  index: 0
}

iex> table = PieceTable.delete!(table, 10, 6)
%PieceTable{
  original: "Hello, world!",
  result: "Hello, you!",
  edited: [{:remove, " world", 10}, {:add, "you ", 7}, {:keep, 13}],
  index: 0
}

iex> table = PieceTable.undo!(table)
%PieceTable{
  original: "Hello, world!",
  result: "Hello, you world!",
  edited: [{:remove, " world", 10}, {:add, "you ", 7}, {:keep, 13}],
  index: 1
}

iex> table = PieceTable.redo!(table)
%PieceTable{
  original: "Hello, world!",
  result: "Hello, you!",
  edited: [{:remove, " world", 10}, {:add, "you ", 7}, {:keep, 13}],
  index: 0
}

iex> PieceTable.get_text(table)
"Hello, you!"

Installation

If available in Hex, the package can be installed by adding piece_table to your list of dependencies in mix.exs:

def deps do
  [
    {:piece_table, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/piece_table.