carmi/src/expr-hash.js

const objectHash = require('object-hash');
const {memoizeNonPrimitives} = require('./memoize');
const _ = require('lodash');

let strHash = {};
const hashString = str => {
  if (!strHash[str]) {
    strHash[str] = objectHash(str);
  }
  const res = strHash[str];
  return res;
};

const clearHashStrings = () => {
  strHash = {};
}
  
const exprHash = memoizeNonPrimitives(
  obj => {
    // console.log( Array.isArray(obj), _.isPlainObject(obj),JSON.stringify(obj, null,2))
    if (Array.isArray(obj)) {
      return objectHash(_.map(obj, val => exprHash(val)).join(','));
    } else if (_.isPlainObject(obj)) {
      const keys = Object.keys(obj).sort();
      return objectHash(_.map(keys, key => `${key}:${exprHash(obj[key])}`).join(','));
    } else if (_.isFunction(obj)) {
      throw new TypeError(`Trying to chain a function in carmi code: ${obj}`)
    } else {
      return hashString(JSON.stringify(obj));
    }
  },
  primitive => hashString(JSON.stringify(primitive))
);

module.exports = {exprHash, hashString, clearHashStrings};