hls.js

'use strict';

const esprima = require('esprima');
const escodegen = require('escodegen');
const estraverse = require('estraverse');
const fhyper = require('./fhyper');

const ops = {
  '+': {
    name: 'add',
    fn: (a, b) => a + b
  },
  '-': {
    name: 'sub',
    fn: (a, b) => a - b
  }
};

function opGen(g, lut) {
  const res = {};
  Object.keys(lut).forEach(function(key) {
    const e = lut[key];
    res[e.name] = function(a, b) {
      if (typeof a === 'number' && typeof b === 'number') {
        return e.fn(a, b);
      }
      const aEdge = (typeof a === 'function') ? a : g(a)({});
      const bEdge = (typeof b === 'function') ? b : g(b)({});
      const resNode = g(e.name);
      aEdge(resNode);
      bEdge(resNode);
      return resNode({});
    };
  });
  // console.log(res);
  return res;
}

function hls(fn) {
  const fnText = fn.toString();
  // console.log(fnText);
  const ast = esprima.parse(fnText);
  // console.log(JSON.stringify(ast, null, 4));
  const newAst = estraverse.replace(ast, {
    leave: function(node) {
      if (node.type === 'BinaryExpression') {
        return {
          type: 'CallExpression',
          callee: {
            type: 'Identifier',
            name: ops[node.operator].name
          },
          arguments: [node.left, node.right]
        };
      }
    }
  });
  // console.log(JSON.stringify(newAst, null, 4));
  const newFnText = escodegen.generate(newAst);
  // console.log(newFnText);
  const _g = fhyper();
  const {
    add,
    sub
  } = opGen(_g, ops);
  let _res;
  eval('_res = ' + newFnText);
  return _res;
}

module.exports = hls;
/* eslint no-unused-vars: 0 */