designer/src/com/android/tools/idea/uibuilder/handlers/relative/DependencyGraph.java - platform/tools/adt/idea - Git at Google

 /*
  * Copyright (C) 2015 The Android Open Source Project
  *
  * Licensed 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 com.android.tools.idea.uibuilder.handlers.relative;

 import com.android.annotations.NonNull;
 import com.android.annotations.Nullable;
 import com.android.tools.idea.rendering.AttributeSnapshot;
 import com.android.tools.idea.uibuilder.model.NlComponent;
 import com.android.tools.lint.detector.api.LintUtils;
 import com.intellij.util.containers.WeakHashMap;

 import java.util.*;

 import static com.android.SdkConstants.ANDROID_URI;
 import static com.android.SdkConstants.ATTR_LAYOUT_RESOURCE_PREFIX;
 import static com.android.SdkConstants.VALUE_TRUE;

 /**
  * Data structure about relative layout relationships which makes it possible to:
  * <ul>
  * <li> Quickly determine not just the dependencies on other nodes, but which nodes
  * depend on this node such that they can be visualized for the selection
  * <li> Determine if there are cyclic dependencies, and whether a potential move
  * would result in a cycle
  * <li> Determine the "depth" of a given node (in terms of how many connections it
  * is away from a parent edge) such that we can prioritize connections which
  * minimizes the depth
  * </ul>
  */
 public class DependencyGraph {
   /**
    * Format to chain constraint dependencies: button 1 above button2 etc
    */
   private static final String DEPENDENCY_FORMAT = "%1$s %2$s %3$s"; //$NON-NLS-1$

   /** Cache for {@link DependencyGraph} */
   private static final WeakHashMap<NlComponent, DependencyGraph> ourCache = new WeakHashMap<NlComponent, DependencyGraph>();

   private final Map<NlComponent, ViewData> myNodeToView = new HashMap<NlComponent, ViewData>();
   private final long myModelVersion;

   /**
    * Returns the {@link DependencyGraph} for the given relative layout widget
    *
    * @param layout the relative layout
    * @return a {@link DependencyGraph} for the layout
    */
   @NonNull
   public static DependencyGraph get(@NonNull NlComponent layout) {
     DependencyGraph dependencyGraph = ourCache.get(layout);
     if (dependencyGraph != null) {
       if (dependencyGraph.myModelVersion == layout.getModel().getModificationCount()) {
         return dependencyGraph;
       }
     }

     dependencyGraph = new DependencyGraph(layout);
     ourCache.put(layout, dependencyGraph);

     return dependencyGraph;
   }

   /**
    * Constructs a new {@link DependencyGraph} for the given relative layout
    */
   private DependencyGraph(NlComponent layout) {
     myModelVersion = layout.getModel().getModificationCount();

     // Parent view:
     String parentId = layout.getId();
     if (parentId != null) {
       parentId = LintUtils.stripIdPrefix(parentId);
     }
     else {
       parentId = "RelativeLayout"; // For display purposes; we never reference
       // the parent id from a constraint, only via parent-relative params
       // like centerInParent
     }
     ViewData parentView = new ViewData(layout, parentId);
     myNodeToView.put(layout, parentView);
     Map<String, ViewData> idToView = new HashMap<String, ViewData>();
     idToView.put(parentId, parentView);

     for (NlComponent child : layout.getChildren()) {
       String id = child.getId();
       if (id != null) {
         id = LintUtils.stripIdPrefix(id);
       }
       ViewData view = new ViewData(child, id);
       myNodeToView.put(child, view);
       if (id != null) {
         idToView.put(id, view);
       }
     }

     for (ViewData view : myNodeToView.values()) {
       for (AttributeSnapshot attribute : view.node.getAttributes()) {
         if (!ANDROID_URI.equals(attribute.namespace)) {
           continue;
         }
         String name = attribute.name;
         ConstraintType type = ConstraintType.fromAttribute(name);
         if (type != null) {
           String value = attribute.value;

           if (type.targetParent) {
             if (VALUE_TRUE.equals(value)) {
               Constraint constraint = new Constraint(type, view, parentView);
               view.dependsOn.add(constraint);
               parentView.dependedOnBy.add(constraint);
             }
           }
           else {
             // id-based constraint.
             // NOTE: The id could refer to some widget that is NOT a sibling!
             String targetId = LintUtils.stripIdPrefix(value);
             ViewData target = idToView.get(targetId);
             //noinspection StatementWithEmptyBody
             if (target != view) {
               if (target != null) {
                 Constraint constraint = new Constraint(type, view, target);
                 view.dependsOn.add(constraint);
                 target.dependedOnBy.add(constraint);
               }
             }
             else {
               // Self-reference. RelativeLayout ignores these so it's
               // not an error like a deeper cycle (where RelativeLayout
               // will throw an exception), but we might as well warn
               // the user about it.
               // TODO: Where do we emit this error?
             }
           }
         }
       }
     }
   }

   public ViewData getView(NlComponent node) {
     return myNodeToView.get(node);
   }

   /**
    * Returns the set of views that depend on the given node in either the horizontal or
    * vertical direction
    *
    * @param nodes    the set of nodes that we want to compute the transitive dependencies
    *                 for
    * @param vertical if true, look for vertical edge dependencies, otherwise look for
    *                 horizontal edge dependencies
    * @return the set of nodes that directly or indirectly depend on the given nodes in
    * the given direction
    */
   public Set<NlComponent> dependsOn(Collection<? extends NlComponent> nodes, boolean vertical) {
     List<ViewData> reachable = new ArrayList<ViewData>();

     // Traverse the graph of constraints and determine all nodes affected by
     // this node
     Set<ViewData> visiting = new HashSet<ViewData>();
     for (NlComponent node : nodes) {
       ViewData view = myNodeToView.get(node);
       if (view != null) {
         findBackwards(view, visiting, reachable, vertical, view);
       }
     }

     Set<NlComponent> dependents = new HashSet<NlComponent>(reachable.size());

     for (ViewData v : reachable) {
       dependents.add(v.node);
     }

     return dependents;
   }

   private void findBackwards(ViewData view, Set<ViewData> visiting, List<ViewData> reachable, boolean vertical, ViewData start) {
     visiting.add(view);
     reachable.add(view);

     for (Constraint constraint : view.dependedOnBy) {
       if (vertical && !constraint.type.verticalEdge || !vertical && !constraint.type.horizontalEdge) {
         continue;
       }

       assert constraint.to == view;
       ViewData from = constraint.from;
       if (visiting.contains(from)) {
         // Cycle - what do we do to highlight this?
         List<Constraint> path = getPathTo(start.node, view.node, vertical);
         if (path != null) {
           // TODO: display to the user somehow. We need log access for the
           // view rules.
           //System.out.println(Constraint.describePath(path, null, null));
         }
       }
       else {
         findBackwards(from, visiting, reachable, vertical, start);
       }
     }

     visiting.remove(view);
   }

   @Nullable
   public List<Constraint> getPathTo(NlComponent from, NlComponent to, boolean vertical) {
     // Traverse the graph of constraints and determine all nodes affected by
     // this node
     Set<ViewData> visiting = new HashSet<ViewData>();
     List<Constraint> path = new ArrayList<Constraint>();
     ViewData view = myNodeToView.get(from);
     if (view != null) {
       return findForwards(view, visiting, path, vertical, to);
     }

     return null;
   }

   @Nullable
   private static List<Constraint> findForwards(ViewData view,
                                                Set<ViewData> visiting,
                                                List<Constraint> path,
                                                boolean vertical,
                                                NlComponent target) {
     visiting.add(view);

     for (Constraint constraint : view.dependsOn) {
       if (vertical && !constraint.type.verticalEdge || !vertical && !constraint.type.horizontalEdge) {
         continue;
       }

       try {
         path.add(constraint);

         if (constraint.to.node == target) {
           return new ArrayList<Constraint>(path);
         }

         assert constraint.from == view;
         ViewData to = constraint.to;
         if (visiting.contains(to)) {
           // CYCLE!
           continue;
         }

         List<Constraint> chain = findForwards(to, visiting, path, vertical, target);
         if (chain != null) {
           return chain;
         }
       }
       finally {
         path.remove(constraint);
       }
     }

     visiting.remove(view);

     return null;
   }

   /**
    * Info about a specific widget child of a relative layout and its constraints. This
    * is a node in the dependency graph.
    */
   static class ViewData {
     @NonNull public final NlComponent node;
     @Nullable public final String id;
     @NonNull public final List<Constraint> dependsOn = new ArrayList<Constraint>(4);
     @NonNull public final List<Constraint> dependedOnBy = new ArrayList<Constraint>(8);

     ViewData(@NonNull NlComponent node, @Nullable String id) {
       this.node = node;
       this.id = id;
     }
   }

   /**
    * Info about a specific constraint between two widgets in a relative layout. This is
    * an edge in the dependency graph.
    */
   static class Constraint {
     @NonNull public final ConstraintType type;
     public final ViewData from;
     public final ViewData to;

     Constraint(@NonNull ConstraintType type, @NonNull ViewData from, @NonNull ViewData to) {
       this.type = type;
       this.from = from;
       this.to = to;
     }

     static String describePath(@NonNull List<Constraint> path, @Nullable String newName, @Nullable String newId) {
       String s = "";
       for (int i = path.size() - 1; i >= 0; i--) {
         Constraint constraint = path.get(i);
         String suffix = (i == path.size() - 1) ? constraint.to.id : s;
         s = String.format(DEPENDENCY_FORMAT, constraint.from.id, stripLayoutAttributePrefix(constraint.type.name), suffix);
       }

       if (newName != null) {
         s = String.format(DEPENDENCY_FORMAT, s, stripLayoutAttributePrefix(newName), newId != null ? LintUtils.stripIdPrefix(newId) : "?");
       }

       return s;
     }

     private static String stripLayoutAttributePrefix(String name) {
       if (name.startsWith(ATTR_LAYOUT_RESOURCE_PREFIX)) {
         return name.substring(ATTR_LAYOUT_RESOURCE_PREFIX.length());
       }

       return name;
     }
   }
 }
	/*
	* Copyright (C) 2015 The Android Open Source Project
	*
	* Licensed 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 com.android.tools.idea.uibuilder.handlers.relative;

	import com.android.annotations.NonNull;
	import com.android.annotations.Nullable;
	import com.android.tools.idea.rendering.AttributeSnapshot;
	import com.android.tools.idea.uibuilder.model.NlComponent;
	import com.android.tools.lint.detector.api.LintUtils;
	import com.intellij.util.containers.WeakHashMap;

	import java.util.*;

	import static com.android.SdkConstants.ANDROID_URI;
	import static com.android.SdkConstants.ATTR_LAYOUT_RESOURCE_PREFIX;
	import static com.android.SdkConstants.VALUE_TRUE;

	/**
	* Data structure about relative layout relationships which makes it possible to:
	* <ul>
	* <li> Quickly determine not just the dependencies on other nodes, but which nodes
	* depend on this node such that they can be visualized for the selection
	* <li> Determine if there are cyclic dependencies, and whether a potential move
	* would result in a cycle
	* <li> Determine the "depth" of a given node (in terms of how many connections it
	* is away from a parent edge) such that we can prioritize connections which
	* minimizes the depth
	* </ul>
	*/
	public class DependencyGraph {
	/**
	* Format to chain constraint dependencies: button 1 above button2 etc
	*/
	private static final String DEPENDENCY_FORMAT = "%1$s %2$s %3$s"; //$NON-NLS-1$

	/** Cache for {@link DependencyGraph} */
	private static final WeakHashMap<NlComponent, DependencyGraph> ourCache = new WeakHashMap<NlComponent, DependencyGraph>();

	private final Map<NlComponent, ViewData> myNodeToView = new HashMap<NlComponent, ViewData>();
	private final long myModelVersion;

	/**
	* Returns the {@link DependencyGraph} for the given relative layout widget
	*
	* @param layout the relative layout
	* @return a {@link DependencyGraph} for the layout
	*/
	@NonNull
	public static DependencyGraph get(@NonNull NlComponent layout) {
	DependencyGraph dependencyGraph = ourCache.get(layout);
	if (dependencyGraph != null) {
	if (dependencyGraph.myModelVersion == layout.getModel().getModificationCount()) {
	return dependencyGraph;
	}
	}

	dependencyGraph = new DependencyGraph(layout);
	ourCache.put(layout, dependencyGraph);

	return dependencyGraph;
	}

	/**
	* Constructs a new {@link DependencyGraph} for the given relative layout
	*/
	private DependencyGraph(NlComponent layout) {
	myModelVersion = layout.getModel().getModificationCount();

	// Parent view:
	String parentId = layout.getId();
	if (parentId != null) {
	parentId = LintUtils.stripIdPrefix(parentId);
	}
	else {
	parentId = "RelativeLayout"; // For display purposes; we never reference
	// the parent id from a constraint, only via parent-relative params
	// like centerInParent
	}
	ViewData parentView = new ViewData(layout, parentId);
	myNodeToView.put(layout, parentView);
	Map<String, ViewData> idToView = new HashMap<String, ViewData>();
	idToView.put(parentId, parentView);

	for (NlComponent child : layout.getChildren()) {
	String id = child.getId();
	if (id != null) {
	id = LintUtils.stripIdPrefix(id);
	}
	ViewData view = new ViewData(child, id);
	myNodeToView.put(child, view);
	if (id != null) {
	idToView.put(id, view);
	}
	}

	for (ViewData view : myNodeToView.values()) {
	for (AttributeSnapshot attribute : view.node.getAttributes()) {
	if (!ANDROID_URI.equals(attribute.namespace)) {
	continue;
	}
	String name = attribute.name;
	ConstraintType type = ConstraintType.fromAttribute(name);
	if (type != null) {
	String value = attribute.value;

	if (type.targetParent) {
	if (VALUE_TRUE.equals(value)) {
	Constraint constraint = new Constraint(type, view, parentView);
	view.dependsOn.add(constraint);
	parentView.dependedOnBy.add(constraint);
	}
	}
	else {
	// id-based constraint.
	// NOTE: The id could refer to some widget that is NOT a sibling!
	String targetId = LintUtils.stripIdPrefix(value);
	ViewData target = idToView.get(targetId);
	//noinspection StatementWithEmptyBody
	if (target != view) {
	if (target != null) {
	Constraint constraint = new Constraint(type, view, target);
	view.dependsOn.add(constraint);
	target.dependedOnBy.add(constraint);
	}
	}
	else {
	// Self-reference. RelativeLayout ignores these so it's
	// not an error like a deeper cycle (where RelativeLayout
	// will throw an exception), but we might as well warn
	// the user about it.
	// TODO: Where do we emit this error?
	}
	}
	}
	}
	}
	}

	public ViewData getView(NlComponent node) {
	return myNodeToView.get(node);
	}

	/**
	* Returns the set of views that depend on the given node in either the horizontal or
	* vertical direction
	*
	* @param nodes the set of nodes that we want to compute the transitive dependencies
	* for
	* @param vertical if true, look for vertical edge dependencies, otherwise look for
	* horizontal edge dependencies
	* @return the set of nodes that directly or indirectly depend on the given nodes in
	* the given direction
	*/
	public Set<NlComponent> dependsOn(Collection<? extends NlComponent> nodes, boolean vertical) {
	List<ViewData> reachable = new ArrayList<ViewData>();

	// Traverse the graph of constraints and determine all nodes affected by
	// this node
	Set<ViewData> visiting = new HashSet<ViewData>();
	for (NlComponent node : nodes) {
	ViewData view = myNodeToView.get(node);
	if (view != null) {
	findBackwards(view, visiting, reachable, vertical, view);
	}
	}

	Set<NlComponent> dependents = new HashSet<NlComponent>(reachable.size());

	for (ViewData v : reachable) {
	dependents.add(v.node);
	}

	return dependents;
	}

	private void findBackwards(ViewData view, Set<ViewData> visiting, List<ViewData> reachable, boolean vertical, ViewData start) {
	visiting.add(view);
	reachable.add(view);

	for (Constraint constraint : view.dependedOnBy) {
	if (vertical && !constraint.type.verticalEdge \|\| !vertical && !constraint.type.horizontalEdge) {
	continue;
	}

	assert constraint.to == view;
	ViewData from = constraint.from;
	if (visiting.contains(from)) {
	// Cycle - what do we do to highlight this?
	List<Constraint> path = getPathTo(start.node, view.node, vertical);
	if (path != null) {
	// TODO: display to the user somehow. We need log access for the
	// view rules.
	//System.out.println(Constraint.describePath(path, null, null));
	}
	}
	else {
	findBackwards(from, visiting, reachable, vertical, start);
	}
	}

	visiting.remove(view);
	}

	@Nullable
	public List<Constraint> getPathTo(NlComponent from, NlComponent to, boolean vertical) {
	// Traverse the graph of constraints and determine all nodes affected by
	// this node
	Set<ViewData> visiting = new HashSet<ViewData>();
	List<Constraint> path = new ArrayList<Constraint>();
	ViewData view = myNodeToView.get(from);
	if (view != null) {
	return findForwards(view, visiting, path, vertical, to);
	}

	return null;
	}

	@Nullable
	private static List<Constraint> findForwards(ViewData view,
	Set<ViewData> visiting,
	List<Constraint> path,
	boolean vertical,
	NlComponent target) {
	visiting.add(view);

	for (Constraint constraint : view.dependsOn) {
	if (vertical && !constraint.type.verticalEdge \|\| !vertical && !constraint.type.horizontalEdge) {
	continue;
	}

	try {
	path.add(constraint);

	if (constraint.to.node == target) {
	return new ArrayList<Constraint>(path);
	}

	assert constraint.from == view;
	ViewData to = constraint.to;
	if (visiting.contains(to)) {
	// CYCLE!
	continue;
	}

	List<Constraint> chain = findForwards(to, visiting, path, vertical, target);
	if (chain != null) {
	return chain;
	}
	}
	finally {
	path.remove(constraint);
	}
	}

	visiting.remove(view);

	return null;
	}

	/**
	* Info about a specific widget child of a relative layout and its constraints. This
	* is a node in the dependency graph.
	*/
	static class ViewData {
	@NonNull public final NlComponent node;
	@Nullable public final String id;
	@NonNull public final List<Constraint> dependsOn = new ArrayList<Constraint>(4);
	@NonNull public final List<Constraint> dependedOnBy = new ArrayList<Constraint>(8);

	ViewData(@NonNull NlComponent node, @Nullable String id) {
	this.node = node;
	this.id = id;
	}
	}

	/**
	* Info about a specific constraint between two widgets in a relative layout. This is
	* an edge in the dependency graph.
	*/
	static class Constraint {
	@NonNull public final ConstraintType type;
	public final ViewData from;
	public final ViewData to;

	Constraint(@NonNull ConstraintType type, @NonNull ViewData from, @NonNull ViewData to) {
	this.type = type;
	this.from = from;
	this.to = to;
	}

	static String describePath(@NonNull List<Constraint> path, @Nullable String newName, @Nullable String newId) {
	String s = "";
	for (int i = path.size() - 1; i >= 0; i--) {
	Constraint constraint = path.get(i);
	String suffix = (i == path.size() - 1) ? constraint.to.id : s;
	s = String.format(DEPENDENCY_FORMAT, constraint.from.id, stripLayoutAttributePrefix(constraint.type.name), suffix);
	}

	if (newName != null) {
	s = String.format(DEPENDENCY_FORMAT, s, stripLayoutAttributePrefix(newName), newId != null ? LintUtils.stripIdPrefix(newId) : "?");
	}

	return s;
	}

	private static String stripLayoutAttributePrefix(String name) {
	if (name.startsWith(ATTR_LAYOUT_RESOURCE_PREFIX)) {
	return name.substring(ATTR_LAYOUT_RESOURCE_PREFIX.length());
	}

	return name;
	}
	}
	}