private FieldValidatorCreator(
     PipeValidator <TModel> pipe,
     params Func <TModel, bool>[] ifConditions)
 {
     _pipe         = pipe;
     _current      = new ValidatorStruture <TField>();
     _ifConditions = ifConditions;
 }
 internal FieldValidatorCreator(
     PipeValidator <TModel> pipe,
     Expression <Func <TModel, TField> > field,
     params Func <TModel, bool>[] ifConditions)
     : this(pipe, ifConditions)
 {
     _field = field;
 }
 internal FieldValidatorCreator(
     PipeValidator <TModel> pipe,
     Expression <Func <TModel, IEnumerable <TField> > > field,
     params Func <TModel, bool>[] ifConditions)
     : this(pipe, ifConditions)
 {
     _collectionField   = field;
     _isCollectionField = true;
 }