101 lines
2.6 KiB
Elixir
101 lines
2.6 KiB
Elixir
defmodule Behaviour do
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@moduledoc """
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This module has been deprecated.
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Instead of `defcallback`, one can simply use `@callback`.
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Instead of `defmacrocallback`, one can simply use `@macrocallback`.
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Instead of `__behaviour__(:callbacks)`, one can simply use `behaviour_info(:callbacks)`.
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"""
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# TODO: Deprecate by 1.4
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# TODO: Remove by 2.0
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@doc """
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Defines a function callback according to the given type specification.
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"""
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defmacro defcallback(spec) do
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do_defcallback(:def, split_spec(spec, quote(do: term)))
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end
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@doc """
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Defines a macro callback according to the given type specification.
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"""
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defmacro defmacrocallback(spec) do
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do_defcallback(:defmacro, split_spec(spec, quote(do: Macro.t)))
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end
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defp split_spec({:when, _, [{:::, _, [spec, return]}, guard]}, _default) do
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{spec, return, guard}
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end
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defp split_spec({:when, _, [spec, guard]}, default) do
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{spec, default, guard}
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end
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defp split_spec({:::, _, [spec, return]}, _default) do
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{spec, return, []}
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end
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defp split_spec(spec, default) do
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{spec, default, []}
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end
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defp do_defcallback(kind, {spec, return, guards}) do
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case Macro.decompose_call(spec) do
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{name, args} ->
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do_callback(kind, name, args, return, guards)
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_ ->
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raise ArgumentError, "invalid syntax in #{kind}callback #{Macro.to_string(spec)}"
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end
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end
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defp do_callback(kind, name, args, return, guards) do
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:lists.foreach fn
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{:::, _, [left, right]} ->
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ensure_not_default(left)
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ensure_not_default(right)
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left
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other ->
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ensure_not_default(other)
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other
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end, args
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spec =
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quote do
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unquote(name)(unquote_splicing(args)) :: unquote(return) when unquote(guards)
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end
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case kind do
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:def -> quote(do: @callback unquote(spec))
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:defmacro -> quote(do: @macrocallback unquote(spec))
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end
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end
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defp ensure_not_default({:\\, _, [_, _]}) do
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raise ArgumentError, "default arguments \\\\ not supported in defcallback/defmacrocallback"
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end
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defp ensure_not_default(_), do: :ok
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@doc false
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defmacro __using__(_) do
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quote do
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@doc false
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def __behaviour__(:callbacks) do
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__MODULE__.behaviour_info(:callbacks)
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end
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def __behaviour__(:docs) do
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for {tuple, line, kind, docs} <- Code.get_docs(__MODULE__, :callback_docs) do
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case kind do
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:callback -> {tuple, line, :def, docs}
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:macrocallback -> {tuple, line, :defmacro, docs}
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end
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end
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end
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import unquote(__MODULE__)
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end
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end
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end
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