99 lines
3 KiB
Elixir
99 lines
3 KiB
Elixir
defmodule RecycledCloud.OpenNebula.Schema do
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@moduledoc """
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Helpers used to process OpenNebula's XSD schema.
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,.
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/,,;';;. ,;;;.. ,,;. '
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.','' `::;:' ``;;;;' `..'
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` ,,/' ,,//
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Here be dragons! We import the records from Erlang header files (.hrl)
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generated by erlsom as macros in the Records module. The only way I found to
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programatically call a macro (apply/3 only works with functions) is by
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playing around with the AST to template said call...
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I'm not fond of this as it makes things more complex than I would like them
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to be, but likely the easiest way to user erlsom's data binder from elixir
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(and it's not *that* bad). The ideal would be to generate elixir structs from
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source XSD files, but it would take much more work.
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Heavily inspired from Gary Poster's:
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http://codesinger.blogspot.com/2015/12/elixir-erlang-records-and-erlsom-xml.html
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I stole the dragon art from ASCII.co.uk.
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"""
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require Logger
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alias RecycledCloud.OpenNebula.Schema
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alias RecycledCloud.OpenNebula.Schema.Records
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@opennebula_release "5.12"
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##
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# Data-binding: access and extract XSD models.
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defp get_raw(type, object) do
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priv_dir = :code.priv_dir(:recycledcloud) |> to_string
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{data_dir, extension} = case type do
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:xsd -> {"xsd-src", ".xsd"}
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:hrl -> {"xsd-records", ".hrl"}
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end
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raw_path = [priv_dir, "opennebula", @opennebula_release, data_dir, object <> extension]
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raw_path |> Path.join()
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end
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def get_xsd_for(object), do: get_raw(:xsd, object)
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def get_hrl_for(object), do: get_raw(:hrl, object)
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def generate_model_for(object) do
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{:ok, model} = object
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|> get_xsd_for()
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|> :erlsom.compile_xsd_file()
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model
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end
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##
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# Data-binding: transform erlsom records to Elixir maps.
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def scan(raw, object_type) do
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{:ok, data, _rest} = :erlsom.scan(raw, Records.get_model_for(object_type))
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data
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end
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defp transform_value({k, l}) when is_list(l) do
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{k, Enum.map(l, fn v -> map_record(v) end)}
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end
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defp transform_value({k, v}), do: {k, map_record(v)}
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# Here be dragons! See moduledoc.
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def map_record(data) when is_tuple(data) do
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schema = elem(data, 0)
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if schema in Keyword.keys(Schema.Records.__info__(:macros)) do
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call = quote do
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require RecycledCloud.OpenNebula.Schema.Records
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RecycledCloud.OpenNebula.Schema.Records."XSD"(:data)
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end
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replace = fn
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:XSD, {model, data} -> {model, {model, data}}
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:data, {model, data} -> {data, {model, data}}
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node, stubs -> {node, stubs}
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end
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{{inserted, _raw}, []} = call
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|> Macro.prewalk({schema, Macro.escape(data)}, replace)
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|> Code.eval_quoted()
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Enum.into(inserted, Map.new, &transform_value/1)
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else
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Logger.debug("Ignoring unknown OpenNebula Model #{schema}.")
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data
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end
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end
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def map_record(data = [first | _rest]) when is_integer(first), do:
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List.to_string(data)
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def map_record(:undefined), do: nil
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def map_record(data), do: data
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end
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