72 lines
1.9 KiB
Elixir
72 lines
1.9 KiB
Elixir
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defmodule GeoTherminator.TypedStruct do
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@doc """
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Create typed struct with a type, default values, and enforced keys.
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Input should be a map where the key names are names of the struct keys and values are the
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field information. The value can be a typespec, in which case the field will be enforced, or
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a 2-tuple of `{typespec, default_value}`, making the field unenforced.
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To prevent ambiguity, a value of `{typespec, :ts_enforced}` will be interpreted as enforced,
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this will allow you to typespec a 2-tuple.
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NOTE: Due to the ambiguity removal technique above, `:ts_enforced` is not allowed as a default
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value.
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Example:
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```elixir
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deftypedstruct(%{
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# Enforced with simple type
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foo: integer(),
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# Enforced 2-tuple typed field, written like this to remove ambiguity
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bar: {{String.t(), integer()}, :ts_enforced},
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# Non-enforced field with default value
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baz: {any(), ""}
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})
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```
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"""
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defmacro deftypedstruct(fields) do
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fields_list =
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case fields do
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{:%{}, _, flist} -> flist
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_ -> raise ArgumentError, "Fields must be a map!"
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end
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enforced_list =
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fields_list
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|> Enum.filter(fn
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{_, {_, :ts_enforced}} -> true
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{_, {_, _}} -> false
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{_, _} -> true
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end)
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|> Enum.map(&elem(&1, 0))
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field_specs =
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Enum.map(fields_list, fn
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{field, {typespec, :ts_enforced}} ->
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{field, typespec}
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{field, {typespec, _}} ->
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{field, typespec}
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{field, typespec} ->
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{field, typespec}
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end)
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field_vals =
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Enum.map(fields_list, fn
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{field, {_, :ts_enforced}} -> field
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{field, {_, default}} -> {field, default}
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{field, _} -> field
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end)
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quote do
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@type t :: %__MODULE__{unquote_splicing(field_specs)}
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@enforce_keys unquote(enforced_list)
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defstruct unquote(field_vals)
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end
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end
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end
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