module javascript
imports libstrategolib signatures/- util

rules
  js: TopLevel(x) -> $[// Fostr preamble
  const _fostr_readline = require('readline');
  const _fostr_events = require('events');
  const _fostr_rl = _fostr_readline.createInterface({input: process.stdin});
  const Stdio = {
    gets:  v => { process.stdout.write(String(v)); return Stdio; },
    emit: async () => {
            const [line] = await _fostr_events.once(_fostr_rl, 'line');
            return line + "\n"; }
  }
  function to(data, strm) {
    strm.gets(data);
    return data;
  }

  const _fostr_body = async () => {
  // End of preamble

    [x]

  // Fostr coda
    _fostr_rl.close()
  }
  _fostr_body();
  ]
    with line := "[line]"

  js: Stream()     -> $[Stdio]
  js: Int(x)       -> x
  js: LitString(x) -> <javaLitString>x
  js: EscString(x) -> x
  js: Sum(x, y)    -> $[[x] + [y]]
  js: Concat(x, y) -> $[[x] + [y]]
  js: Gets(x, y)   -> $[[x].gets([y])]
  js: To(x, y)     -> $[to([x],[y])]
  js: Emits(x)     -> $[(await [x].emit())]
  js: Terminate(x) -> x
  js: Sequence(l)  -> <join(|";\n")>l

  /* Characters we need to escape in Javascript string constants */
  Jscape: ['\t' | cs ] -> ['\', 't'  | cs ]
  /* I think I can just use ASCII constants for characters... */
  Jscape: [ 0   | cs ] -> ['\', '0'  | cs ]
  Jscape: [ 8   | cs ] -> ['\', 'b'  | cs ] // Backspace
  Jscape: [ 11  | cs ] -> ['\', 'v'  | cs ] // Vertical tab
  Jscape: [ 12  | cs ] -> ['\', 'f'  | cs ] // Form feed

strategies
  javaLitString = un-single-quote
                ; string-as-chars(escape-chars(Escape <+ Jscape))
                ; single-quote

  javascript = bottomup(try(js))

  // Interface javascript code generation with editor services and file system
  to-javascript: (selected, _, _, path, project-path) -> (filename, result)
    with filename := <guarantee-extension(|"js")> path
       ; result   := <javascript> selected