- parentNodes 父节点 (HTMLNode) - name 子节点selector. - notAllChildren 仅查询一层子节点. 返回匹配到的元素集合.
function _matchElement(parentNodes, name, notAllChildren) {
    var elems;
    var tag = 0;  // 0-tag, 1-id, 2-class.
    var nameattr, nameattrVal;

    // :checked, :disabled
    var selector = name.split(':');
    name = selector[0];
    name = stringUtils.trim(name);
    selector = selector[1];
    if (selector) {
      if (selector != 'checked' && selector != 'disabled') {
        throw new Error('only support `:checked or :disabled` selector');
      }
    }

    // attri.
    if (name.indexOf('[') > 0) {
      var iblace = name.indexOf('[');
      nameattr = name.substring(iblace+1, name.length-1);
      nameattr = nameattr.split('=');
      if (nameattr.length != 2) {
        throw new Error('Syntax error, unrecognized expression: ' + name);
      }
      nameattrVal = nameattr[1];
      if (nameattrVal.indexOf('\'') >= 0 || nameattrVal.indexOf('"') >= 0)
        nameattrVal = nameattrVal.substring(1, nameattrVal.length-1);
      nameattr = nameattr[0];
      name = name.substr(0, iblace);
    }
    
    if (name[0] == '.') {
      tag = 2;
      name = name.substr(1);
    }
    else if (name[0] == '#') {
      tag = 1;
      name = name.substr(1);
    }

    if (!parentNodes || parentNodes.length == 0) {
      if (2 == tag) {
        elems = window.document.getElementsByClassName(name);
      }
      else if (1 == tag) {
        elems = window.document.getElementById(name);
        if (elems) elems = [elems];
        else elems = [];
      }
      else if (0 == tag) {
        elems = window.document.getElementsByTagName(name);
      }

      // attrvalue.
      if (nameattr) {
        var tt_elems = elems;
        elems = [];
        for (var i = 0; i < tt_elems.length; i++) {
          if (tt_elems[i].getAttribute(nameattr) === nameattrVal) {
            elems.push(tt_elems[i]);
          }
        }
      } // if.

      if (selector) {
        var tt_elems = elems;
        elems = [];
        for (var i = 0; i < tt_elems.length; i++) {
          if (selector == 'disabled') {
            if (tt_elems[i].disabled) {
              elems.push(tt_elems[i]);  
            }
          }
          else 
          if (selector == 'checked') {
            if (tt_elems[i].checked) {
              elems.push(tt_elems[i]);  
            }
          }
        }
      } // if.
    }
    else {
      elems = [];
      for (var i = 0; i < parentNodes.length; i++) {
        var node1 = parentNodes[i].childNodes;
        if (!node1) continue;
        var node = [];
        for (var j = 0; j < node1.length; j++) {
          node.push(node1[j]);
        }

        for (var j = 0; j < node.length; j++) {
          var add = true;

          if (selector) {
            if (selector == 'disabled') {
              if (!node[j].disabled) {
                add = false;
              }
            }
            else 
            if (selector == 'checked') {
              if (!node[j].checked) {
                add = false;
              }
            }
          } // if.

          // attrvalue.
          if (add && nameattr) {
            if (node[j].getAttribute(nameattr) !== nameattrVal) {
              add = false;
            }
          }

          if (add) {
            if (2 == tag) {
              if (_hasClass(node[j], name)) {
                elems.push(node[j]);
                continue;
              }
            }
            else if (1 == tag) {
              if (node[j].id == name) {
                elems.push(node[j]);
                continue;
              }
            }
            else if (0 == tag) {
              if (node[j].nodeName.toUpperCase() == name.toUpperCase()) {
                elems.push(node[j]);
                continue;
              }
            }
          } // if.

          if (!notAllChildren) {
            var nn = node[j].childNodes;
            if (nn && nn.length > 0) {
              for (var k = 0; k < nn.length; k++) {
                node.push(nn[k]);
              }
              if (j > 20) {
                node = node.slice(j+1);
                j = -1;
              }
            }
          }
        } // for.
      } // for.
    } // if..else.

    return elems;
  }