implement stack-based interpreter to improve performance

currently sval is a tree-walking interpreter and has a ordinary performance. compile the code into some kinds of intermediate representation based on stack to improve performance.

I have a demo as followed. it may be difficult and take some time to migrate.

const { parse } = require('acorn')
const { simple } = require('acorn-walk')

const ast = parse('1 + 8 * 2 / 2 + 1')

const stack = []

simple(ast, {
  Literal(node) {
    stack.push(node.value)
  },
  BinaryExpression(node) {
    const right = stack.pop()
    const left = stack.pop()
    const binaryOps = {
      '+': () => left + right,
      '-': () => left - right,
      '*': () => left * right,
      '/': () => left / right
    }
    const handler = binaryOps[node.operator]
    if (handler) {
      stack.push(handler())
    } else {
      throw new SyntaxError(`Unexpected token ${node.operator}`)
    }
  }
})

console.log(stack[0])

[Siubaak]

When will this performance improvements reach master branch? Any ETA? I’m looking into moving from Interpreter-JS to Sval.

PD: Quite a nice job.

I will try to complete in August

[Siubaak]

fengari did a great job of running lua over js. mark for reference - Fengari

<script src="./fengari-web.js"></script>
<script type="application/lua">
  local start = os.time()
  for i=1, 10000000 do
  end
  print(os.time() - start) -- 0~1s cool :)
</script>
<script src="https://unpkg.com/sval"></script>
<script>
  const interpreter = new Sval()
  interpreter.run(`
    var start = Date.now()
    for (var i = 0; i < 10000000; i++) {}
    console.log((Date.now() - start) / 1000) // around 6s :(
  `)
</script>