andrewjc2000 commented on a change in pull request #394: URL: https://github.com/apache/incubator-daffodil/pull/394#discussion_r456009313
########## File path: daffodil-core/src/main/scala/org/apache/daffodil/dsom/walker/AbstractDSOMWalker.scala ########## @@ -0,0 +1,174 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.daffodil.dsom.walker + +/** + * Below is a series of "View" Mixins defined such that particular simple attributes + * of the core DSOM classes are exposed as a Walk is performed. + * + * Several of them have a walkDSOM method. By default, this method is called as the walk is performed, + * but a user implementing AbstractDSOMWalker can override this behavior by overriding walkFromRoot + * and implementing their own event handlers for each of the DSOM types. + */ + +trait CommonContextView { + def namespaces: scala.xml.NamespaceBinding +} + +trait TermView extends CommonContextView { + def isArray: Boolean + def isOptional: Boolean +} + +trait TypeView +trait SimpleTypeView extends TypeView { + def primType: PrimTypeView +} +trait ComplexTypeView extends TypeView { + def group: ModelGroupView +} + +trait ModelGroupView extends TermView { + def groupMembers: Seq[TermView] +} + +trait ChoiceView extends ModelGroupView +trait SequenceView extends ModelGroupView +trait GroupRefView extends ModelGroupView { + def isHidden: Boolean Review comment: I think there is a solution to this, but it would break the current paradigm of every field in the `View`s referencing an existing field. We could replace the existing `group` element in `ComplexTypeView` with something like `optVisibleGroup`, and then the implementation for `optVisibleGroup` would pattern-match `group`; if it is hidden, return `None`, otherwise return the `group` wrapped in an option. Similarly, instead of `groupMembers` being in `TermView`, we would have `visisbleGroupMembers`, and in the implementation `visibleGroupMembers` would be a filtered list of the real `groupMembers`, excluding any `TermView` that is a `GroupRef` and is also hidden. However, my main concern with this is it would potentially cause more confusion, leading the end user to wonder why we're only allowed to see "visible" members, and might make traversal very annoying with having to constantly unpack Options. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
