yield in es3.js

// yield in es3

// original code
(function()
{
  var _gen = function(a)
  {
    var d = '';
    
    for(;;) {
      if(a == 'a') {  
        d += a + a + a;
        yield '1' + d;
        yield '_1' + d;
      } else if(a == 'b') {
        d = a + a;
        yield '2' + d;
      } else {
        d += a;
        return '3' + d;
      }
    }  
  };
  
  var _test = function()
  {
    console.log(_gen('a'));
    console.log(_gen('a'));
    console.log(_gen('b'));
    console.log(_gen('c'));
    console.log(_gen('a'));
  }
})();

// 'generated' code (was manualy written by myself but i'll planning a real generator)
(function()
{
  var _gen = (function()
  {
    var d, eip = -1; // context + eip
    
    return function(a) {for(;;) { switch(eip) {
    case -1:  d = '';
    case  0:  /*  for(;;) { */
              /*    if(a == 'a') { */ if(!(a == 'a')){ eip = 4; break; }
                      d += a + a + a;
    case  1:  /*      yield '1' + d; */ eip = 2; return '1' + d; 
    case  2:  /*      yield '_1' + d; */ eip = 3; return '_1' + d;
    case  3:        eip = 8; break;
    case  4:  /*    } else if(a == 'b') { */ if(!(a == 'b')){ eip = 7; break; }
                      d += a + a;
    case  5:  /*      yield '2' + d; */ eip = 6; return '2' + d; 
    case  6:        eip = 8; break;
    case  7:  /*    } else { */
                      d += a;
              /*      return '3' + d; */ eip = -1; return '3' + d; 
    case  8:  /*    } */ eip = 9; break;
    case  9:  /*  } */ eip = 0; break;
    }}};  
  })();
  
  var _test = function()
  {
    console.log(_gen('a'));
    console.log(_gen('a'));
    console.log(_gen('b'));
    console.log(_gen('c'));
    console.log(_gen('a'));
  };
  
  _test();
})();