Merge pull request #78 from ilopX/add-conceptual-iterator-pttern

Add conceptual iterator pattern.

Author: ilopX

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.37.0
+- Add iterator pattern: Word Iterator.
+
 ## 0.36.0
 - Add iterator pattern: Github Commit.
 

README.md

@@ -13,7 +13,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
     - [x] **Chain of Responsibility** - [[Server Middleware](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/chain_of_responsibility/server_middleware)]
     - [x] **Command** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/command/conceptual)] [[Text Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/command/text_editor)] 
     - [x] **Interpreter**  - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/interpreter/conceptual)]
-    - [x] **Iterator** - [[Github Commit](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/iterator/github_commit)]
+    - [x] **Iterator** - [[Word Iterator](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/iterator/word_iterator)] [[Github Commit](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/iterator/github_commit)]
     - [x] **Mediator** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/mediator/conceptual)]
     - [x] **Memento** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/memento/conceptual)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) Memento Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/memento/memento_editor)] 
     - [x] **Observer** - [[Open-Close Editor Events](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/open_close_editor_events)] [[AppObserver](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/app_observer)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) Subscriber Flutter Widget](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/subscriber_flutter_widget)]

patterns/iterator/word_iterator/README.md

@@ -0,0 +1,47 @@
+# Iterator pattern
+Iterator is a behavioral design pattern that lets you traverse elements of a collection without
+exposing its underlying representation (list, stack, tree, etc.).
+
+Tutorial: [here](https://refactoring.guru/design-patterns/iterator).
+
+### Client code:
+```dart
+void main() {
+  final text = Text(
+    'Iterator is a behavioral design pattern that lets you traverse elements '
+        'of a collection without exposing its underlying representation '
+        '(list, stack, tree, etc.).',
+  );
+
+  for (final s in text) {
+    print(s);
+  }
+}
+```
+
+**Output:**
+```
+Iterator
+is
+a
+behavioral
+design
+pattern
+that
+lets
+you
+traverse
+elements
+of
+a
+collection
+without
+exposing
+its
+underlying
+representation
+list
+stack
+tree
+etc
+```

patterns/iterator/word_iterator/main.dart

@@ -0,0 +1,13 @@
+import 'text/text.dart';
+
+void main() {
+  final text = Text(
+    'Iterator is a behavioral design pattern that lets you traverse elements '
+    'of a collection without exposing its underlying representation '
+    '(list, stack, tree, etc.).',
+  );
+
+  for (final s in text) {
+    print(s);
+  }
+}

patterns/iterator/word_iterator/pattern/word_iterator.dart

@@ -0,0 +1,48 @@
+import '../text/text.dart';
+
+class WordIterator extends Iterator<String> {
+  WordIterator(this._text);
+
+  @override
+  String get current => _currWord!;
+
+  @override
+  bool moveNext() {
+    final start = _lastIndex;
+
+    while (_searchNextSpaceChar(' ')) {
+      // ++
+    }
+
+    _currWord = _getWord(start, _lastIndex);
+    return _currWord!.isNotEmpty;
+  }
+
+  final Text _text;
+  int _lastIndex = 0;
+  String? _currWord;
+
+  bool _searchNextSpaceChar(String char) {
+    final isTextEnd = _lastIndex >= _text.text.length;
+
+    if (isTextEnd) {
+      return false;
+    }
+
+    final isNotSpaceChar = _text.text[_lastIndex++] != char;
+    return isNotSpaceChar;
+  }
+
+  String _getWord(int start, int end) {
+    final noWordChars = RegExp(r'\W');
+    return _text.text
+        .substring(
+          start,
+          _lastIndex,
+        )
+        .replaceAll(
+          noWordChars,
+          '',
+        );
+  }
+}

patterns/iterator/word_iterator/text/text.dart

@@ -0,0 +1,10 @@
+import '../pattern/word_iterator.dart';
+
+class Text extends Iterable<String> {
+  final String text;
+
+  Text(this.text);
+
+  @override
+  Iterator<String> get iterator => WordIterator(this);
+}

pubspec.yaml

@@ -1,6 +1,6 @@
 name: design_patterns_dart
 description: Dart examples for all classic GoF design patterns.
-version: 0.36.0
+version: 0.37.0
 homepage: https://refactoring.guru/design-patterns
 repository: https://github.com/RefactoringGuru/design-patterns-dart
 issue_tracker: https://github.com/RefactoringGuru/design-patterns-dart/issue