simplified AngularJS Dependency Injection logic

gistfile1.js

function logProvider(){
  return function (){
    console.log.apply(console, arguments);
  }
}

function scopeProvider($dbAdapter){
 this.someVariable = $dbAdapter.getText();
 //this.someVariable = 'Some text';

}

function dbAdapterProvider(){
  this.getText = function(){
    return 'Some text'
  }
}


function DemoController($scope, $log) {
  $log($scope.someVariable);
}

function parseArguments(fnText){
  return fnText.slice(fnText.indexOf('(') + 1, fnText.indexOf(')')).match(/([^\s,]+)/g);
}

function getProviderMethod(provider){
  return window[provider.replace('$', '') + 'Provider']
}

function getInjectors(fn){

  if(!fn.length){
    //no injectors
    return [];
  }

  var args = parseArguments(fn.toString()) || [],
      injectors = [];

  args.forEach(function(arg){
    var provider = getProviderMethod(arg);
    injectors.push(ObjectFactory(provider, getInjectors(provider)));
  })

  return injectors;
}

function invoke(fn){
  fn.apply(window, getInjectors(fn));
}

invoke(window['DemoController']);

function ObjectFactory(Constructor, args) {

    var Temp = function(){},
        inst, ret;

    Temp.prototype = Constructor.prototype;
    inst = new Temp;

    ret = Constructor.apply(inst, args);

    return Object(ret) === ret ? ret : inst;

}