defmodule Gettext.Interpolation do
@moduledoc """
Behaviour to provide Gettext string interpolation.
By default, Gettext uses `Gettext.Interpolation.Default` as the interpolation module.
"""
@typedoc since: "0.19.0"
@type translation_type() :: :translation | :plural_translation
@typedoc since: "0.22.0"
@type bindings() :: %{optional(atom()) => term()}
@doc """
Called to perform interpolation *at runtime*.
If successful, should return `{:ok, interpolated_string}`. If there
are missing bindings, should return `{:missing_bindings, partially_interpolated, missing}`
where `partially_interpolated` is a string with the available bindings interpolated.
"""
@doc since: "0.19.0"
@callback runtime_interpolate(message :: String.t(), bindings()) ::
{:ok, String.t()}
| {:missing_bindings, partially_interpolated_message :: String.t(),
missing_bindings :: [atom()]}
@doc """
Called to perform interpolation *at compile time*.
"""
@doc since: "0.19.0"
@macrocallback compile_interpolate(translation_type(), message :: String.t(), bindings()) ::
Macro.t()
@doc """
Defines the Gettext message format to be used when extracting.
The default interpolation module that ships with Gettext uses `"elixir-format"`.
See the [GNU Gettext
documentation](https://www.gnu.org/software/gettext/manual/html_node/PO-Files.html#index-msgstr).
"""
@doc since: "0.19.0"
@callback message_format() :: String.t()
end