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require Logger
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defmodule ElixirStan do
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@moduledoc """
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Documentation for `ElixirStan`.
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"""
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@doc """
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Get the version of the stanc3 executable bundled with the library.
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"""
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@spec stanc_version :: String.t() | {:error, String.t()}
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def stanc_version() do
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case System.cmd(Application.app_dir(:elixir_stan, "/priv/bin/stanc"), ["--version"]) do
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{version_string, 0} -> String.trim(version_string)
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{error, _} -> {:error, error}
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end
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end
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@doc """
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Computes the hash of a file used for caching.
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Computes SHA256 of the file and truncates it to 8 bytes, then encodes it in a hex string.
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"""
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@spec hash_file(binary()) :: String.t()
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def hash_file(file) when is_binary(file) do
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<<hash::bitstring-size(64), _::binary>> = :crypto.hash(:sha256, file)
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Base.encode16 hash
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end
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@spec model_tmp_dir(Path.t()) :: binary | {:error, atom}
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def model_tmp_dir(path) do
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with {:ok, model_code} <- File.read(path) do
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model_name = Path.basename(path, ".stan")
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model_hash = hash_file(model_code)
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Path.join([
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System.tmp_dir(),
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"elixir_stan",
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model_name <> model_hash <> String.replace(stanc_version(), " ", "_")
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])
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end
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end
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@doc """
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Transpiles the model into C++ and stores it in a temporary directory.
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Temporary directory is based on `System.tmp_dir()`. An `elixir_stan` directory is created in the system temporary
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directory and the model is stored in a subdirectory of that. The model directory is based on the model name, the hash
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of the model code and the version of stanc used to compile it.
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"""
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@spec transpile_model(Path.t()) :: :ok | {:error, any()}
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def transpile_model(path) do
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with {:ok, model_code} <- File.read(path) do
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model_tmp_path = model_tmp_dir(path)
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# Create model dir
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:ok = File.mkdir_p(model_tmp_path)
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model_tmp_file = Path.join(model_tmp_path, Path.basename(path))
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# Write model code
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:ok = File.write(model_tmp_file, model_code)
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case System.cmd(Application.app_dir(:elixir_stan, "/priv/bin/stanc"), [model_tmp_file]) do
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{_, 0} -> :ok
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end
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end
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end
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@doc """
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Cleans the model tmp directory.
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"""
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@spec clean_model(Path.t()) :: :ok | {:error, String.t()}
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def clean_model(path) do
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model_tmp_path = model_tmp_dir(path)
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# Remove model dir
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case File.rm_rf(model_tmp_path) do
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{:ok, _} ->
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:ok
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{:error, error, file} ->
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Logger.error(
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"Could not clean model: #{path}\n\t Error: #{:file.format_error(error)}\n\t File: #{file}"
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)
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{:error, :file.format_error(error)}
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end
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end
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end
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