A simple B+Tree implementation.

pkg/analysis_server/test/index/btree_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.index.btree;
+
+import 'dart:math';
+
+import 'package:analysis_server/src/index/btree.dart';
+import 'package:unittest/unittest.dart';
+
+import '../reflective_tests.dart';
+
+
+main() {
+  groupSep = ' | ';
+  group('BTree', () {
+    runReflectiveTests(BTreeTest);
+  });
+}
+
+
+void _assertDebugString(BTree tree, String expected) {
+  String dump = _getDebugString(tree);
+//  print(dump);

[Brian Wilkerson, 2014/06/07 16:34:02]

Remove?

[scheglov, 2014/06/07 21:26:23]

Done.

+  expect(dump, expected);
+}
+
+
+String _getDebugString(BTree tree) {
+  StringBuffer buffer = new StringBuffer();
+  (tree as dynamic).debugPrint(buffer);
+  return buffer.toString();
+}
+
+
+int _intComparator(int a, int b) => a - b;
+
+
+@ReflectiveTestCase()
+class BTreeTest {
+  BTree<int, String> tree = new BTree<int, String>(4, 4, _intComparator);
+
+  test_NoSuchMethodError() {
+    expect(() {
+      (tree as dynamic).thereIsNoSuchMethod();
+    }, throwsA(new isInstanceOf<NoSuchMethodError>()));
+  }
+
+  void test_find() {
+    _insertValues(12);
+    expect(tree.find(-1), isNull);
+    expect(tree.find(1000), isNull);
+    for (int key = 0; key < 12; key++) {
+      expect(tree.find(key), 'V$key');
+    }
+  }
+
+  void test_insert_01() {
+    _insert(0, 'A');
+    _assertDebugString(tree, 'LNode {0: A}\n');
+  }
+
+  void test_insert_02() {
+    _insert(1, 'B');
+    _insert(0, 'A');
+    _assertDebugString(tree, 'LNode {0: A, 1: B}\n');
+  }
+
+  void test_insert_03() {
+    _insert(2, 'C');
+    _insert(0, 'A');
+    _insert(1, 'B');
+    _assertDebugString(tree, 'LNode {0: A, 1: B, 2: C}\n');
+  }
+
+  void test_insert_05() {
+    _insertValues(5);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3, 4: V4}
+}
+''');
+  }
+
+  void test_insert_09() {
+    _insertValues(9);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 8: V8}
+}
+''');
+  }
+
+  void test_insert_innerSplitLeft() {
+    // Prepare a tree with '0' key missing.
+    for (int i = 1; i < 12; i++) {
+      _insert(i, "V$i");
+    }
+    _assertDebugString(tree, '''
+INode {
+    LNode {1: V1, 2: V2}
+  3
+    LNode {3: V3, 4: V4}
+  5
+    LNode {5: V5, 6: V6}
+  7
+    LNode {7: V7, 8: V8}
+  9
+    LNode {9: V9, 10: V10, 11: V11}
+}
+''');
+    // Split and insert into the 'left' child.
+    _insert(0, 'V0');
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1, 2: V2}
+      3
+        LNode {3: V3, 4: V4}
+      5
+        LNode {5: V5, 6: V6}
+    }
+  7
+    INode {
+        LNode {7: V7, 8: V8}
+      9
+        LNode {9: V9, 10: V10, 11: V11}
+    }
+}
+''');
+  }
+
+  void test_insert_innerSplitRight() {
+    _insertValues(12);
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+    }
+  6
+    INode {
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9, 10: V10, 11: V11}
+    }
+}
+''');
+  }
+
+  void test_insert_replace() {
+    _insert(0, 'A');
+    _insert(1, 'B');
+    _insert(2, 'C');
+    _assertDebugString(tree, 'LNode {0: A, 1: B, 2: C}\n');
+    _insert(2, 'C2');
+    _insert(1, 'B2');
+    _insert(0, 'A2');
+    _assertDebugString(tree, 'LNode {0: A2, 1: B2, 2: C2}\n');
+  }
+
+  void test_remove_inner_borrowLeft() {
+    tree = new BTree<int, String>(10, 4, _intComparator);
+    for (int i = 100; i < 125; i++) {
+      _insert(i, 'V$i');
+    }
+    for (int i = 0; i < 10; i++) {
+      _insert(i, 'V$i');
+    }
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+      6
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9, 100: V100, 101: V101}
+      102
+        LNode {102: V102, 103: V103}
+      104
+        LNode {104: V104, 105: V105}
+      106
+        LNode {106: V106, 107: V107}
+      108
+        LNode {108: V108, 109: V109}
+      110
+        LNode {110: V110, 111: V111}
+    }
+  112
+    INode {
+        LNode {112: V112, 113: V113}
+      114
+        LNode {114: V114, 115: V115}
+      116
+        LNode {116: V116, 117: V117}
+      118
+        LNode {118: V118, 119: V119}
+      120
+        LNode {120: V120, 121: V121}
+      122
+        LNode {122: V122, 123: V123, 124: V124}
+    }
+}
+''');
+    expect(tree.remove(112), 'V112');
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+      6
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9, 100: V100, 101: V101}
+      102
+        LNode {102: V102, 103: V103}
+      104
+        LNode {104: V104, 105: V105}
+    }
+  106
+    INode {
+        LNode {106: V106, 107: V107}
+      108
+        LNode {108: V108, 109: V109}
+      110
+        LNode {110: V110, 111: V111}
+      112
+        LNode {113: V113, 114: V114, 115: V115}
+      116
+        LNode {116: V116, 117: V117}
+      118
+        LNode {118: V118, 119: V119}
+      120
+        LNode {120: V120, 121: V121}
+      122
+        LNode {122: V122, 123: V123, 124: V124}
+    }
+}
+''');
+  }
+
+  void test_remove_inner_borrowRight() {
+    tree = new BTree<int, String>(10, 4, _intComparator);
+    for (int i = 100; i < 135; i++) {
+      _insert(i, 'V$i');
+    }
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {100: V100, 101: V101}
+      102
+        LNode {102: V102, 103: V103}
+      104
+        LNode {104: V104, 105: V105}
+      106
+        LNode {106: V106, 107: V107}
+      108
+        LNode {108: V108, 109: V109}
+      110
+        LNode {110: V110, 111: V111}
+    }
+  112
+    INode {
+        LNode {112: V112, 113: V113}
+      114
+        LNode {114: V114, 115: V115}
+      116
+        LNode {116: V116, 117: V117}
+      118
+        LNode {118: V118, 119: V119}
+      120
+        LNode {120: V120, 121: V121}
+      122
+        LNode {122: V122, 123: V123}
+      124
+        LNode {124: V124, 125: V125}
+      126
+        LNode {126: V126, 127: V127}
+      128
+        LNode {128: V128, 129: V129}
+      130
+        LNode {130: V130, 131: V131}
+      132
+        LNode {132: V132, 133: V133, 134: V134}
+    }
+}
+''');
+    expect(tree.remove(100), 'V100');
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {101: V101, 102: V102, 103: V103}
+      104
+        LNode {104: V104, 105: V105}
+      106
+        LNode {106: V106, 107: V107}
+      108
+        LNode {108: V108, 109: V109}
+      110
+        LNode {110: V110, 111: V111}
+      112
+        LNode {112: V112, 113: V113}
+      114
+        LNode {114: V114, 115: V115}
+      116
+        LNode {116: V116, 117: V117}
+    }
+  118
+    INode {
+        LNode {118: V118, 119: V119}
+      120
+        LNode {120: V120, 121: V121}
+      122
+        LNode {122: V122, 123: V123}
+      124
+        LNode {124: V124, 125: V125}
+      126
+        LNode {126: V126, 127: V127}
+      128
+        LNode {128: V128, 129: V129}
+      130
+        LNode {130: V130, 131: V131}
+      132
+        LNode {132: V132, 133: V133, 134: V134}
+    }
+}
+''');
+  }
+
+  void test_remove_inner_mergeLeft() {
+    _insertValues(15);
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+    }
+  6
+    INode {
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9}
+      10
+        LNode {10: V10, 11: V11}
+      12
+        LNode {12: V12, 13: V13, 14: V14}
+    }
+}
+''');
+    expect(tree.remove(12), 'V12');
+    expect(tree.remove(13), 'V13');
+    expect(tree.remove(14), 'V14');
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+    }
+  6
+    INode {
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9}
+      10
+        LNode {10: V10, 11: V11}
+    }
+}
+''');
+    expect(tree.remove(8), 'V8');
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 9: V9}
+  10
+    LNode {10: V10, 11: V11}
+}
+''');
+  }
+
+  void test_remove_inner_mergeRight() {
+    _insertValues(12);
+    _assertDebugString(tree, '''
+INode {
+    INode {
+        LNode {0: V0, 1: V1}
+      2
+        LNode {2: V2, 3: V3}
+      4
+        LNode {4: V4, 5: V5}
+    }
+  6
+    INode {
+        LNode {6: V6, 7: V7}
+      8
+        LNode {8: V8, 9: V9, 10: V10, 11: V11}
+    }
+}
+''');
+    expect(tree.remove(0), 'V0');
+    _assertDebugString(tree, '''
+INode {
+    LNode {1: V1, 2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7}
+  8
+    LNode {8: V8, 9: V9, 10: V10, 11: V11}
+}
+''');
+  }
+
+  void test_remove_inner_notFound() {
+    _insertValues(20);
+    expect(tree.remove(100), isNull);
+  }
+
+  void test_remove_leafRoot_becomesEmpty() {
+    _insertValues(1);
+    _assertDebugString(tree, 'LNode {0: V0}\n');
+    expect(tree.remove(0), 'V0');
+    _assertDebugString(tree, 'LNode {}\n');
+  }
+
+  void test_remove_leafRoot_first() {
+    _insertValues(3);
+    _assertDebugString(tree, 'LNode {0: V0, 1: V1, 2: V2}\n');
+    expect(tree.remove(0), 'V0');
+    _assertDebugString(tree, 'LNode {1: V1, 2: V2}\n');
+  }
+
+  void test_remove_leafRoot_last() {
+    _insertValues(3);
+    _assertDebugString(tree, 'LNode {0: V0, 1: V1, 2: V2}\n');
+    expect(tree.remove(2), 'V2');
+    _assertDebugString(tree, 'LNode {0: V0, 1: V1}\n');
+  }
+
+  void test_remove_leafRoot_middle() {
+    _insertValues(3);
+    _assertDebugString(tree, 'LNode {0: V0, 1: V1, 2: V2}\n');
+    expect(tree.remove(1), 'V1');
+    _assertDebugString(tree, 'LNode {0: V0, 2: V2}\n');
+  }
+
+  void test_remove_leafRoot_notFound() {
+    _insertValues(1);
+    _assertDebugString(tree, 'LNode {0: V0}\n');
+    expect(tree.remove(10), null);
+    _assertDebugString(tree, 'LNode {0: V0}\n');
+  }
+
+  void test_remove_leaf_borrowLeft() {
+    tree = new BTree<int, String>(10, 10, _intComparator);
+    for (int i = 20; i < 40; i++) {
+      _insert(i, 'V$i');
+    }
+    for (int i = 0; i < 5; i++) {
+      _insert(i, 'V$i');
+    }
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1, 2: V2, 3: V3, 4: V4, 20: V20, 21: V21, 22: V22, 23: V23, 24: V24}
+  25
+    LNode {25: V25, 26: V26, 27: V27, 28: V28, 29: V29}
+  30
+    LNode {30: V30, 31: V31, 32: V32, 33: V33, 34: V34, 35: V35, 36: V36, 37: V37, 38: V38, 39: V39}
+}
+''');
+    expect(tree.remove(25), 'V25');
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1, 2: V2, 3: V3, 4: V4, 20: V20, 21: V21}
+  22
+    LNode {22: V22, 23: V23, 24: V24, 26: V26, 27: V27, 28: V28, 29: V29}
+  30
+    LNode {30: V30, 31: V31, 32: V32, 33: V33, 34: V34, 35: V35, 36: V36, 37: V37, 38: V38, 39: V39}
+}
+''');
+  }
+
+  void test_remove_leaf_borrowRight() {
+    tree = new BTree<int, String>(10, 10, _intComparator);
+    _insertValues(15);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1, 2: V2, 3: V3, 4: V4}
+  5
+    LNode {5: V5, 6: V6, 7: V7, 8: V8, 9: V9, 10: V10, 11: V11, 12: V12, 13: V13, 14: V14}
+}
+''');
+    expect(tree.remove(0), 'V0');
+    _assertDebugString(tree, '''
+INode {
+    LNode {1: V1, 2: V2, 3: V3, 4: V4, 5: V5, 6: V6, 7: V7}
+  8
+    LNode {8: V8, 9: V9, 10: V10, 11: V11, 12: V12, 13: V13, 14: V14}
+}
+''');
+  }
+
+  void test_remove_leaf_mergeLeft() {
+    _insertValues(9);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 8: V8}
+}
+''');
+    expect(tree.remove(2), 'V2');
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 8: V8}
+}
+''');
+  }
+
+  void test_remove_leaf_mergeRight() {
+    _insertValues(9);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 8: V8}
+}
+''');
+    expect(tree.remove(1), 'V1');
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 2: V2, 3: V3}
+  4
+    LNode {4: V4, 5: V5}
+  6
+    LNode {6: V6, 7: V7, 8: V8}
+}
+''');
+  }
+
+  void test_remove_leaf_noReorder() {
+    _insertValues(5);
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 3: V3, 4: V4}
+}
+''');
+    expect(tree.remove(3), 'V3');
+    _assertDebugString(tree, '''
+INode {
+    LNode {0: V0, 1: V1}
+  2
+    LNode {2: V2, 4: V4}
+}
+''');
+  }
+
+  void test_stress_evenOdd() {
+    int count = 1000;
+    // insert odd, forward
+    for (int i = 1; i < count; i += 2) {
+      _insert(i, 'V$i');
+    }
+    // insert even, backward
+    for (int i = count - 2; i >= 0; i -= 2) {
+      _insert(i, 'V$i');
+    }
+    // find every
+    for (int i = 0; i < count; i++) {
+      expect(tree.find(i), 'V$i');
+    }
+    // remove odd, backward
+    for (int i = count - 1; i >= 1; i -= 2) {
+      expect(tree.remove(i), 'V$i');
+    }
+    for (int i = 0; i < count; i++) {
+      if (i.isEven) {
+        expect(tree.find(i), 'V$i');
+      } else {
+        expect(tree.find(i), isNull);
+      }
+    }
+    // remove even, forward
+    for (int i = 0; i < count; i += 2) {
+      tree.remove(i);
+    }
+    for (int i = 0; i < count; i++) {
+      expect(tree.find(i), isNull);
+    }
+  }
+
+  void test_stress_random() {
+    tree = new BTree<int, String>(10, 10, _intComparator);
+    int maxKey = 1000000;
+    int tryCount = 1000;
+    Set<int> keys = new Set<int>();
+    {
+      Random random = new Random();
+      for (int i = 0; i < tryCount; i++) {
+        int key = random.nextInt(maxKey);
+        keys.add(key);
+        _insert(key, 'V$key');
+      }
+    }
+    // find every
+    for (int key in keys) {
+      expect(tree.find(key), 'V$key');
+    }
+    // remove random keys
+    {
+      Random random = new Random();
+      for (int key in new Set<int>.from(keys)) {
+        if (random.nextBool()) {
+          keys.remove(key);
+          expect(tree.remove(key), 'V$key');
+        }
+      }
+    }
+    // find every remaining key
+    for (int key in keys) {
+      expect(tree.find(key), 'V$key');
+    }
+  }
+
+  void _insert(int key, String value) {
+    tree.insert(key, value);
+  }
+
+  void _insertValues(int count) {
+    for (int i = 0; i < count; i++) {
+      _insert(i, 'V$i');
+//      print('----------------------');
+//      print(_getDump(tree));
+    }
+  }
+}