#Milky2018/mproc_gen

• GenerationPlan stores the explicit input files and output target.
• parse_runner_cli parses positional input files plus the fixed -o <output> option.
• ParsedSource stores one successfully parsed MoonBit input.
• generate runs generation and writes the emitted source to the output target.
• generate_to_string parses the input sources and runs the callback into a builder.
• GenerationCallback emits generated MoonBit source into a runner-owned StringBuilder.
• ParseFailure reports runner-level read or parse failures.
• GenerationFailure reports callback-level failures with a message.

#Minimal downstream callback

///|
test "minimal downstream callback" {
  @fs.create_dir(".test-tmp") catch {
    _ => ()
  }
  @fs.create_dir(".test-tmp/mproc_gen") catch {
    _ => ()
  }
  let input_path = ".test-tmp/mproc_gen/readme_input.mbt"
  @fs.write_string_to_file(input_path, "fn source() -> Unit { () }\n")
  let plan = @mproc_gen.GenerationPlan::{
    input_paths: [input_path],
    output_path: ".test-tmp/mproc_gen/readme_output.g.mbt",
  }
  let generated = @mproc_gen.generate_to_string(plan, fn(sources, out) {
    match sources[:] {
      [source] => out.write_string("// generated from \{source.path}")
      _ => abort("expected one parsed source")
    }
  }) catch {
    @mproc_gen.ParseFailure(message) =>
      abort("unexpected parse failure: \{message}")
    @mproc_gen.GenerationFailure(message) =>
      abort("unexpected generation failure: \{message}")
    _ => abort("unexpected runner failure")
  }
  inspect(
    generated,
    content="// generated from .test-tmp/mproc_gen/readme_input.mbt",
  )
}