web3-provider-engine/dist/es5/subproviders/provider.js

A JavaScript library for composing Ethereum provider objects using middleware modules

"use strict";

var inherits = require('util').inherits;
var Subprovider = require('./subprovider.js');

// wraps a provider in a subprovider interface

module.exports = ProviderSubprovider;
inherits(ProviderSubprovider, Subprovider);
function ProviderSubprovider(provider) {
  if (!provider) throw new Error('ProviderSubprovider - no provider specified');
  if (!provider.sendAsync) throw new Error('ProviderSubprovider - specified provider does not have a sendAsync method');
  this.provider = provider;
}
ProviderSubprovider.prototype.handleRequest = function (payload, next, end) {
  this.provider.sendAsync(payload, function (err, response) {
    if (err) return end(err);
    if (response.error) return end(new Error(response.error.message));
    end(null, response.result);
  });
};