core/pkgs/build-support/writers/data.nix

{ lib, pkgs, formats, runCommand }:
let inherit (lib) last optionalString types;
in {
  /* *
     Creates a transformer function that writes input data to disk, transformed
     by both the `input` and `output` arguments.

     # Example

     ```nix
     writeJSON = makeDataWriter { input = builtins.toJSON; output = "cp $inputPath $out"; };
     myConfig = writeJSON "config.json" { hello = "world"; }
     ```

     # Type

     ```
     makeDataWriter :: input -> output -> nameOrPath -> data -> (any -> string) -> string -> string -> any -> derivation

     input :: T -> string: function that takes the nix data and returns a string
     output :: string: script that takes the $inputFile and write the result into $out
     nameOrPath :: string: if the name contains a / the files gets written to a sub-folder of $out. The derivation name is the basename of this argument.
     data :: T: the data that will be converted.
     ```
  */
  makeDataWriter = lib.warn
    "pkgs.writers.makeDataWriter is deprecated. Use pkgs.writeTextFile."
    ({ input ? lib.id, output ? "cp $inputPath $out" }:
      nameOrPath: data:
      assert (types.path.check nameOrPath)
        || (builtins.match "([0-9A-Za-z._])[0-9A-Za-z._-]*" nameOrPath != null);
      let name = last (builtins.split "/" nameOrPath);
      in runCommand name {
        input = input data;
        passAsFile = [ "input" ];
      } ''
        ${output}

        ${optionalString (types.path.check nameOrPath) ''
          mv $out tmp
          mkdir -p $out/$(dirname "${nameOrPath}")
          mv tmp $out/${nameOrPath}
        ''}
      '');

  inherit (pkgs) writeText;

  /* *
     Writes the content to a JSON file.

     # Example

     ```nix
     writeJSON "data.json" { hello = "world"; }
     ```
  */
  writeJSON = (pkgs.formats.json { }).generate;

  /* *
     Writes the content to a TOML file.

     # Example

     ```nix
     writeTOML "data.toml" { hello = "world"; }
     ```
  */
  writeTOML = (pkgs.formats.toml { }).generate;

  /* *
     Writes the content to a YAML file.

     # Example

     ```nix
     writeYAML "data.yaml" { hello = "world"; }
     ```
  */
  writeYAML = (pkgs.formats.yaml { }).generate;
}