From 96079e5c48789af0b0dbbb8a1058fd414f7ac337 Mon Sep 17 00:00:00 2001
From: Vladimir Koshelev <Vladimir.Koshelev@jetbrains.com>
Date: Mon, 12 Mar 2018 12:31:19 +0300
Subject: [PATCH] GraphAlgorithmsImpl#collectOutsRecursively: use non-recursive
 traversal

add tests for GraphAlgorithms#collectOutsRecursively

(cherry picked from commit 02398dc)

IDEA-CR-30465
---
 .../util/graph/impl/GraphAlgorithmsImpl.java  | 16 +++--
 .../com/intellij/util/graph/CollectTest.java  | 71 +++++++++++++++++++
 2 files changed, 83 insertions(+), 4 deletions(-)
 create mode 100644 platform/platform-tests/testSrc/com/intellij/util/graph/CollectTest.java

diff --git a/platform/core-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java b/platform/core-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
index 397b905ab023..90a512ba31bd 100644
--- a/platform/core-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
+++ b/platform/core-impl/src/com/intellij/util/graph/impl/GraphAlgorithmsImpl.java
@@ -3,6 +3,7 @@ package com.intellij.util.graph.impl;
 
 import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.util.Chunk;
+import com.intellij.util.containers.Stack;
 import com.intellij.util.graph.*;
 import org.jetbrains.annotations.NotNull;
 
@@ -96,10 +97,17 @@ public class GraphAlgorithmsImpl extends GraphAlgorithms {
     if (!set.add(start)) {
       return;
     }
-    Iterator<Node> iterator = graph.getOut(start);
-    while (iterator.hasNext()) {
-      Node node = iterator.next();
-      collectOutsRecursively(graph, node, set);
+    final Stack<Node> stack = new Stack<>();
+    stack.push(start);
+    while (!stack.empty()) {
+      final Node currentNode = stack.pop();
+      final Iterator<Node> successorIterator = graph.getOut(currentNode);
+      while (successorIterator.hasNext()) {
+        Node successor = successorIterator.next();
+        if (set.add(successor)) {
+          stack.push(successor);
+        }
+      }
     }
   }
 
diff --git a/platform/platform-tests/testSrc/com/intellij/util/graph/CollectTest.java b/platform/platform-tests/testSrc/com/intellij/util/graph/CollectTest.java
new file mode 100644
index 000000000000..84bf763b1ed5
--- /dev/null
+++ b/platform/platform-tests/testSrc/com/intellij/util/graph/CollectTest.java
@@ -0,0 +1,71 @@
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.util.graph;
+
+import com.intellij.util.ArrayUtil;
+import gnu.trove.THashMap;
+import gnu.trove.THashSet;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class CollectTest extends GraphTestCase {
+
+  @Test
+  public void testSimple() {
+    Map<String, String> graph = new THashMap<>();
+    graph.put("a", "b");
+    graph.put("b", "c");
+    graph.put("c", "c");
+    doTest(graph, "b", "b", "c");
+  }
+
+  @Test
+  public void testFull() {
+    Map<String, String> graph = new THashMap<>();
+    graph.put("a", "bcd");
+    graph.put("b", "acd");
+    graph.put("c", "abd");
+    graph.put("d", "abc");
+    doTest(graph, "a", "a", "b", "c", "d");
+  }
+
+  @Test
+  public void testVisitedNode() {
+    Map<String, String> graph = new THashMap<>();
+    graph.put("a", "bcd");
+    graph.put("b", "acd");
+    graph.put("c", "abd");
+    graph.put("d", "abc");
+    Set<String> nodes = new THashSet<>();
+    nodes.add("a");
+    getAlgorithmsInstance().collectOutsRecursively(initGraph(graph), "a", nodes);
+    assertThat(nodes.size()).isEqualTo(1);
+  }
+
+  @Test
+  public void testBigGraph() {
+    Map<String, String> graph = new THashMap<>();
+    List<String> answer = new ArrayList<>();
+    for (int i = 0; i < 10000; ++i) {
+      graph.put(String.valueOf((char)i), String.valueOf((char)(i + 1)));
+      answer.add(String.valueOf((char)i));
+    }
+    graph.put(String.valueOf((char)10000), String.valueOf((char)0));
+    answer.add(String.valueOf((char)10000));
+    doTest(graph, "0", ArrayUtil.toStringArray(answer));
+  }
+
+  private static void doTest(final @NotNull Map<String, String> graph,
+                             final @NotNull String node,
+                             final @NotNull String... expected) {
+    Set<String> nodes = new THashSet<>();
+    getAlgorithmsInstance().collectOutsRecursively(initGraph(graph), node, nodes);
+    assertThat(nodes).containsExactlyInAnyOrder(expected);
+  }
+}