evaluate.js

const nodeTypes = require("./nodeTypes");

function evaluate(node) {
  let result;
  switch (node.type) {
    case nodeTypes.Program:
      for (let child of node.children) {
        result = evaluate(child);
      }
      break;
    case nodeTypes.Additive:
      result = evaluate(node.children[0]) + evaluate(node.children[1]);
      break;
    case nodeTypes.Minus:
      result = evaluate(node.children[0]) - evaluate(node.children[1]);
      break;
    case nodeTypes.Multiplicative:
      result = evaluate(node.children[0]) * evaluate(node.children[1]);
      break;
    case nodeTypes.Divide:
      result = evaluate(node.children[0]) / evaluate(node.children[1]);
      break;
    case nodeTypes.Numeric:
      result = parseFloat(node.value);
    default:
      break;
  }
  return result;
}

module.exports = evaluate;