Merge branch '__rultor'

src/main/java/org/cqfn/astranaut/core/algorithms/DifferenceTreeBuilder.java

@@ -27,6 +27,8 @@
 import java.util.Map;
 import org.cqfn.astranaut.core.DifferenceNode;
 import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.algorithms.mapping.Mapper;
+import org.cqfn.astranaut.core.algorithms.mapping.Mapping;
 
 /**
  * Builder of difference syntax tree, that is, one that stores changes between two trees.
@@ -48,13 +50,28 @@ public final class DifferenceTreeBuilder {
 
     /**
      * Constructor.
-     * @param prototype Root node of an 'ordinary', non-difference original tree before the changes
+     * @param before Root node of an 'ordinary', non-difference original tree before the changes
      */
-    public DifferenceTreeBuilder(final Node prototype) {
-        this.root = new DifferenceNode(prototype);
+    public DifferenceTreeBuilder(final Node before) {
+        this.root = new DifferenceNode(before);
         this.parents = DifferenceTreeBuilder.buildParentsMap(this.root);
     }
 
+    /**
+     * Builds a difference tree based on the original tree and the tree after changes.
+     * @param after Root node of tree before the changes
+     * @param mapper A mapper used for node mappings
+     * @return Result of operation, {@code true} if difference tree was built
+     */
+    public boolean build(final Node after, final Mapper mapper) {
+        final Mapping mapping = mapper.map(this.root.getPrototype(), after);
+        boolean result = true;
+        for (final Node deleted : mapping.getDeleted()) {
+            result = result & this.deleteNode(deleted);
+        }
+        return result;
+    }
+
     /**
      * Returns root of resulting difference tree.
      * @return Root node of difference tree

src/test/java/org/cqfn/astranaut/core/algorithms/mapping/TopDownMapperTest.java → src/main/java/org/cqfn/astranaut/core/algorithms/mapping/BottomUpMapper.java

@@ -24,26 +24,19 @@
 package org.cqfn.astranaut.core.algorithms.mapping;
 
 import org.cqfn.astranaut.core.Node;
-import org.cqfn.astranaut.core.example.LittleTrees;
-import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.Test;
 
 /**
- * Test for {@link TopDownMapper} class.
+ * Bottom-up mapper.
+ * Tries to match leaf nodes first, and then subtrees containing leaf nodes,
+ * gradually increasing the size of the matched subtrees.
  *
- * @since 1.0
+ * @since 1.1.0
  */
-class TopDownMapperTest {
-    /**
-     * A test.
-     */
-    @Test
-    void test() {
-        final Node first = LittleTrees.createTreeWithDeleteAction();
-        final Node second = LittleTrees.createTreeWithDeleteAction();
-        final Mapper mapper = new TopDownMapper();
-        final Mapping mapping = mapper.map(first, second);
-        Assertions.assertEquals(mapping.getRight(first), second);
-        Assertions.assertEquals(mapping.getLeft(second), first);
+public final class BottomUpMapper implements Mapper {
+    @Override
+    public Mapping map(final Node left, final Node right) {
+        final BottomUpMappingAlgorithm algorithm = new BottomUpMappingAlgorithm(left, right);
+        algorithm.execute();
+        return algorithm.getResult();
     }
 }

src/main/java/org/cqfn/astranaut/core/algorithms/mapping/BottomUpMappingAlgorithm.java

@@ -0,0 +1,307 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2024 Ivan Kniazkov
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.cqfn.astranaut.core.algorithms.mapping;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import org.cqfn.astranaut.core.Node;
+import org.cqfn.astranaut.core.algorithms.Depth;
+import org.cqfn.astranaut.core.algorithms.hash.AbsoluteHash;
+import org.cqfn.astranaut.core.algorithms.hash.Hash;
+
+/**
+ * Bottom-up mapping algorithm.
+ * Tries to match leaf nodes first, and then subtrees containing leaf nodes,
+ * gradually increasing the size of the matched subtrees.
+ *
+ * @since 1.1.0
+ */
+class BottomUpMappingAlgorithm {
+    /**
+     * Set of node hashes.
+     */
+    private final Hash hashes;
+
+    /**
+     * Set of node depths.
+     */
+    private final Depth depth;
+
+    /**
+     * Relationship of the nodes to their parents.
+     */
+    private final Map<Node, Node> parents;
+
+    /**
+     * Not yet processed nodes from the 'left' tree.
+     */
+    private final Set<Node> left;
+
+    /**
+     * Not yet processed nodes from the 'right' tree.
+     */
+    private final Set<Node> right;
+
+    /**
+     * Left-to-right mapping.
+     */
+    private final Map<Node, Node> ltr;
+
+    /**
+     * Right-to-left mapping.
+     */
+    private final Map<Node, Node> rtl;
+
+    /**
+     * Set of deleted nodes.
+     */
+    private final Set<Node> deleted;
+
+    /**
+     * Constructor.
+     * @param left Root node of the 'left' tree
+     * @param right Root node of the 'right' tree
+     */
+    BottomUpMappingAlgorithm(final Node left, final Node right) {
+        this.hashes = new AbsoluteHash();
+        this.depth = new Depth();
+        this.parents = new HashMap<>();
+        this.left = this.createNodeSet(left);
+        this.right = this.createNodeSet(right);
+        this.ltr = new HashMap<>();
+        this.rtl = new HashMap<>();
+        this.deleted = new HashSet<>();
+    }
+
+    /**
+     * Performs the mapping.
+     */
+    void execute() {
+        final Map<Node, List<Node>> draft = this.performInitialMapping();
+        this.absorbLargestSubtrees(draft);
+        Node node = this.findPartiallyMappedLeftNode();
+        while (node != null) {
+            node = this.mapPartiallyMappedLeftNode(node);
+            if (node == null) {
+                node = this.findPartiallyMappedLeftNode();
+            }
+        }
+    }
+
+    /**
+     * Returns result of mapping.
+     * @return Result of mapping
+     */
+    Mapping getResult() {
+        return new Mapping() {
+            @Override
+            public Node getRight(final Node node) {
+                return BottomUpMappingAlgorithm.this.ltr.get(node);
+            }
+
+            @Override
+            public Node getLeft(final Node node) {
+                return BottomUpMappingAlgorithm.this.rtl.get(node);
+            }
+
+            @Override
+            public Set<Node> getDeleted() {
+                return Collections.unmodifiableSet(BottomUpMappingAlgorithm.this.deleted);
+            }
+        };
+    }
+
+    /**
+     * Creates an initial set of nodes suitable for processing from the tree.
+     * @param root The root of the tree
+     * @return Set of nodes
+     */
+    private Set<Node> createNodeSet(final Node root) {
+        final Set<Node> set = new HashSet<>();
+        this.createNodeSet(root, null, set);
+        return set;
+    }
+
+    /**
+     * Creates an initial set of nodes suitable for processing from the tree (recursive method).
+     * @param node The current node
+     * @param parent The current node parent
+     * @param set The resulting set
+     */
+    private void createNodeSet(final Node node, final Node parent, final Set<Node> set) {
+        set.add(node);
+        this.parents.put(node, parent);
+        node.forEachChild(child -> this.createNodeSet(child, node, set));
+    }
+
+    /**
+     * Performs hash calculation of nodes from the 'right' set.
+     * @return The hash relation to the list of nodes that have such a hash
+     */
+    private Map<Integer, List<Node>> calculateRightHashes() {
+        final Map<Integer, List<Node>> result = new TreeMap<>();
+        for (final Node node : this.right) {
+            final int hash = this.hashes.calculate(node);
+            final List<Node> list =
+                result.computeIfAbsent(hash, k -> new ArrayList<>(1));
+            list.add(node);
+        }
+        return result;
+    }
+
+    /**
+     * Performs initial (draft) node mapping.
+     * @return Relationships of nodes to lists of nodes to which they can be mapped to
+     */
+    private Map<Node, List<Node>> performInitialMapping() {
+        final Map<Node, List<Node>> result = new HashMap<>();
+        final Map<Integer, List<Node>> relation = this.calculateRightHashes();
+        for (final Node node : this.left) {
+            final int hash = this.hashes.calculate(node);
+            final List<Node> list = relation.get(hash);
+            if (list != null) {
+                result.put(node, list);
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Selects the largest size subtrees from the initial node relation and maps them.
+     * @param draft Initial node relation
+     */
+    private void absorbLargestSubtrees(final Map<Node, List<Node>> draft) {
+        final List<Node> sorted = new ArrayList<>(draft.keySet());
+        sorted.sort(
+            (first, second) -> -Integer.compare(
+                this.depth.calculate(first),
+                this.depth.calculate(second)
+            )
+        );
+        for (final Node node : sorted) {
+            final List<Node> related = draft.get(node);
+            if (related != null && related.size() == 1 && !this.ltr.containsKey(node)) {
+                this.mapSubtreesWithTheSameHash(node, related.get(0), draft);
+            }
+            if (draft.isEmpty()) {
+                break;
+            }
+        }
+    }
+
+    /**
+     * Maps subtrees with the same hash, adding the corresponding nodes to the resulting
+     * collections and removing them from the initial mapping.
+     * @param node Left node
+     * @param related Related node to the left node
+     * @param draft Initial node relation
+     */
+    private void mapSubtreesWithTheSameHash(
+        final Node node,
+        final Node related,
+        final Map<Node, List<Node>> draft) {
+        assert this.hashes.calculate(node) == this.hashes.calculate(related);
+        draft.remove(node);
+        this.left.remove(node);
+        this.right.remove(related);
+        this.ltr.put(node, related);
+        this.rtl.put(related, node);
+        final int count = node.getChildCount();
+        for (int index = 0; index < count; index = index + 1) {
+            final Node first = node.getChild(index);
+            final Node second = related.getChild(index);
+            this.mapSubtreesWithTheSameHash(first, second, draft);
+        }
+    }
+
+    /**
+     * Finds a partially mapped node from the 'left' set, that is, one that has some children
+     * mapped and some not.
+     * @return A node or {@code null} if such node not found
+     */
+    private Node findPartiallyMappedLeftNode() {
+        Node result = null;
+        final Iterator<Node> iterator = this.left.iterator();
+        while (result == null && iterator.hasNext()) {
+            final Node node = iterator.next();
+            final int count = node.getChildCount();
+            for (int index = 0; index < count; index = index + 1) {
+                final Node child = node.getChild(index);
+                if (this.ltr.containsKey(child)) {
+                    result = node;
+                    break;
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Tries to map a partially mapped 'left' node to another node.
+     * @param node A node to be mapped
+     * @return Next partially mapped node to be processed
+     */
+    private Node mapPartiallyMappedLeftNode(final Node node) {
+        final Set<Node> ancestors = new HashSet<>();
+        Node next = null;
+        node.forEachChild(
+            child -> {
+                final Node mapped = this.ltr.get(child);
+                if (mapped != null) {
+                    ancestors.add(this.parents.get(mapped));
+                }
+            }
+        );
+        do {
+            if (ancestors.size() != 1) {
+                break;
+            }
+            final Node related = ancestors.iterator().next();
+            if (!node.getTypeName().equals(related.getTypeName())
+                || !node.getData().equals(related.getData())) {
+                break;
+            }
+            this.right.remove(related);
+            this.ltr.put(node, related);
+            this.rtl.put(related, node);
+            final int count = node.getChildCount();
+            for (int index = 0; index < count; index = index + 1) {
+                final Node child = node.getChild(index);
+                if (!this.ltr.containsKey(child)) {
+                    this.deleted.add(child);
+                }
+            }
+            next = this.parents.get(node);
+        } while (false);
+        this.left.remove(node);
+        return next;
+    }
+}