AbstractCatalogVisitor.java

/*
 * Portions of this software was developed by employees of the National Institute
 * of Standards and Technology (NIST), an agency of the Federal Government and is
 * being made available as a public service. Pursuant to title 17 United States
 * Code Section 105, works of NIST employees are not subject to copyright
 * protection in the United States. This software may be subject to foreign
 * copyright. Permission in the United States and in foreign countries, to the
 * extent that NIST may hold copyright, to use, copy, modify, create derivative
 * works, and distribute this software and its documentation without fee is hereby
 * granted on a non-exclusive basis, provided that this notice and disclaimer
 * of warranty appears in all copies.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
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 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
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 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
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package gov.nist.secauto.oscal.lib.profile.resolver.support;

import gov.nist.secauto.metaschema.model.common.metapath.item.IDocumentNodeItem;
import gov.nist.secauto.metaschema.model.common.metapath.item.IRequiredValueModelNodeItem;
import gov.nist.secauto.metaschema.model.common.util.ObjectUtils;

import edu.umd.cs.findbugs.annotations.NonNull;

/**
 * Used to visit a catalog containing groups and controls.
 *
 * @param <T>
 *          the type of the state object used to pass calling context
 *          information
 * @param <R>
 *          the type of the result for visiting a collection of groups and/or
 *          controls
 */
public abstract class AbstractCatalogVisitor<T, R> implements ICatalogVisitor<T, R> {

  protected abstract R newDefaultResult(T state);

  protected abstract R aggregateResults(R first, R second, T state);

  protected R visitCatalog(@NonNull IDocumentNodeItem catalogDocument, T state) {
    return visitGroupContainer(catalogDocument.getRootAssemblyNodeItem(), newDefaultResult(state), state);
  }

  /**
   * Visit the child groups and controls (in that order) of a given catalog or
   * group container.
   *
   * @param catalogOrGroup
   *          the catalog or group Metapath item currently being visited
   * @param initialResult
   *          the initial result value to use when aggregating child results
   * @param state
   *          the current visitor state
   * @return a meaningful result of the given type
   */
  protected R visitGroupContainer(
      @NonNull IRequiredValueModelNodeItem catalogOrGroup,
      R initialResult,
      T state) {
    R result = catalogOrGroup.getModelItemsByName("group").stream()
        .map(groupItem -> {
          return visitGroupItem(ObjectUtils.requireNonNull(groupItem), state);
        })
        .reduce(initialResult, (first, second) -> aggregateResults(first, second, state));
    return visitControlContainer(catalogOrGroup, result, state);
  }

  /**
   * Called when visiting a group.
   * <p>
   * This method will first visit the group's children, then the group itself.
   *
   * @param item
   *          the group Metapath item to visit
   * @param state
   *          the current visitor state
   * @return a meaningful result of the given type
   */
  protected R visitGroupItem(@NonNull IRequiredValueModelNodeItem item, T state) {
    R childResult = visitGroupContainer(item, newDefaultResult(state), state);
    return visitGroupInternal(item, childResult, state);
  }

  /**
   * Called when visiting a group after visiting it's children.
   *
   * @param item
   *          the group Metapath item currently being visited
   * @param childResult
   *          the result of visiting the group's children
   * @param state
   *          the current visitor state
   * @return a meaningful result of the given type
   */
  protected R visitGroupInternal(
      @NonNull IRequiredValueModelNodeItem item,
      R childResult,
      T state) {
    return visitGroup(item, childResult, state);
  }

  /**
   * Visit the child controls (in that order) of a given catalog, group, or
   * control container.
   *
   * @param catalogOrGroupOrControl
   *          the catalog, group, or control Metapath item currently being visited
   * @param initialResult
   *          the initial result value to use when aggregating child results
   * @param state
   *          the current visitor state
   * @return a meaningful result of the given type
   */
  protected R visitControlContainer(
      @NonNull IRequiredValueModelNodeItem catalogOrGroupOrControl,
      R initialResult,
      T state) {
    return catalogOrGroupOrControl.getModelItemsByName("control").stream()
        .map(controlItem -> {
          return visitControlItem(ObjectUtils.requireNonNull(controlItem), state);
        })
        .reduce(initialResult, (first, second) -> aggregateResults(first, second, state));
  }

  /**
   * Called when visiting a control.
   * <p>
   * This method will first visit the control's children, then the control itself.
   *
   * @param item
   *          the group Metapath item to visit
   * @param state
   *          the current visitor state
   * @return a meaningful result of the given type
   */
  protected R visitControlItem(@NonNull IRequiredValueModelNodeItem item, T state) {
    R childResult = visitControlContainer(item, newDefaultResult(state), state);
    return visitControlInternal(item, childResult, state);
  }

  /**
   * Called when visiting a control after visiting it's children.
   *
   * @param controlItem
   *          the Metapath item for the control currently being visited
   * @param childResult
   *          the result of visiting the control's children
   * @param state
   *          the calling context information
   * @return a meaningful result of the given type
   */
  protected R visitControlInternal(@NonNull IRequiredValueModelNodeItem controlItem, R childResult, T state) {
    return visitControl(controlItem, childResult, state);
  }
}