Impl iterator pattern: word iterator.

Author: ilopX

patterns/iterator/word_iterator/main.dart

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+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

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+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

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