Define function toString

[ruifigueira]

Calling toString on a function would return the source code of the interpreter instead of the actual function body as declared.

It's possible to extract the function code from the node itself, using acorn options like sourceFile.

[Siubaak]

The location and sourceFile options enormously reduce parse efficiency, leading to a low perf of evaluation. I think we should find a more efficient way to generate the string of a function

[ruifigueira]

I understand. I reverted the implicit parsing with locations: true, sourceFile: code.
But if the user explicitly includes the source file by provdiing a parser function, a function's .toString will be able to use that source.

Example:

  it('should serialize functions with toString', () => { 
    const parser =  (code) => parse(code, { ecmaVersion: 'latest', locations: true, sourceFile: code });
    const interpreter = new Sval()
    interpreter.import({ expect })
    const parsedCode = interpreter.parse(`
      expect((function x(a, b) { return a + b }).toString()).toEqual('function x(a, b) { return a + b }')
    `, parser);
    interpreter.run(parsedCode)
  })

[ruifigueira]

hi @Siubaak did you have a chance to look into my new proposal?