docs: function parseFilters (exp) {
  	  var inSingle = false;
  	  var inDouble = false;
  	  var curly = 0;
  	  var square = 0;
  	  var paren = 0;
  	  var lastFilterIndex = 0;
  	  var c, prev, i, expression, filters;
  	
  	  for (i = 0; i < exp.length; i++) {
  	    prev = c;
  	    c = exp.charCodeAt(i);
  	    if (inSingle) {
  	      // check single quote
  	      if (c === 0x27 && prev !== 0x5C) { inSingle = !inSingle; }
  	    } else if (inDouble) {
  	      // check double quote
  	      if (c === 0x22 && prev !== 0x5C) { inDouble = !inDouble; }
  	    } else if (
  	      c === 0x7C && // pipe
  	      exp.charCodeAt(i + 1) !== 0x7C &&
  	      exp.charCodeAt(i - 1) !== 0x7C &&
  	      !curly && !square && !paren
  	    ) {
  	      if (expression === undefined) {
  	        // first filter, end of expression
  	        lastFilterIndex = i + 1;
  	        expression = exp.slice(0, i).trim();
  	      } else {
  	        pushFilter();
  	      }
  	    } else {
  	      switch (c) {
  	        case 0x22: inDouble = true; break // "
  	        case 0x27: inSingle = true; break // '
  	        case 0x28: paren++; break         // (
  	        case 0x29: paren--; break         // )
  	        case 0x5B: square++; break        // [
  	        case 0x5D: square--; break        // ]
  	        case 0x7B: curly++; break         // {
  	        case 0x7D: curly--; break         // }
  	      }
  	    }
  	  }
  	
  	  if (expression === undefined) {
  	    expression = exp.slice(0, i).trim();
  	  } else if (lastFilterIndex !== 0) {
  	    pushFilter();
  	  }
  	
  	  function pushFilter () {
  	    (filters || (filters = [])).push(exp.slice(lastFilterIndex, i).trim());
  	    lastFilterIndex = i + 1;
  	  }
  	
  	  if (filters) {
  	    for (i = 0; i < filters.length; i++) {
  	      expression = wrapFilter(expression, filters[i]);
  	    }
  	  }
  	
  	  return expression
  	}