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lib/livebook/text/selection.ex

defmodule Livebook.Text.Selection do
# A text selection holding one or more selection ranges.
#
# This is a minimal representation of an editor selection, specifically
# for the purpose of serialization and transformation. It does not
# perform any normalizations, such as deduplication and range merging,
# since this is already handled on the client during deserialization.
defstruct [:ranges]
@type t :: %__MODULE__{ranges: list(range())}
@type range :: {anchor :: non_neg_integer(), head :: non_neg_integer()}
def new(ranges) do
if ranges == [] do
raise ArgumentError, "text selection must have at least a single range"
end
%__MODULE__{ranges: ranges}
end
@doc """
Transforms `selection` against `delta`.
Selections are ultimately a group of positions, so each position is
transformed. See `Livebook.Text.Delta.transform_position/2` for more
details.
"""
@spec transform(t(), Livebook.Text.Delta.t()) :: t()
def transform(selection, delta) do
ranges =
for {anchor, head} <- selection.ranges do
{Livebook.Text.Delta.transform_position(delta, anchor),
Livebook.Text.Delta.transform_position(delta, head)}
end
%__MODULE__{ranges: ranges}
end
@doc """
Converts the given selection to a compact representation, suitable
for JSON serialization.
"""
@spec to_compressed(t()) :: list()
def to_compressed(selection) do
for {anchor, head} <- selection.ranges, do: [anchor, head]
end
@doc """
Builds a new selection from the given compact representation.
"""
@spec from_compressed(list()) :: t()
def from_compressed(list) do
ranges = for [anchor, head] <- list, do: {anchor, head}
%__MODULE__{ranges: ranges}
end
end