45 lines
1.1 KiB
Dart
45 lines
1.1 KiB
Dart
import 'package:flutter/services.dart';
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class RegExInputFormatter implements TextInputFormatter {
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final RegExp _regExp;
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RegExInputFormatter._(this._regExp);
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factory RegExInputFormatter.withRegex(String regexString) {
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try {
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final regex = RegExp(regexString);
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return RegExInputFormatter._(regex);
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} catch (e) {
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// Something not right with regex string.
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assert(false, e.toString());
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return RegExInputFormatter._("" as RegExp);
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}
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}
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@override
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TextEditingValue formatEditUpdate(
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TextEditingValue oldValue, TextEditingValue newValue) {
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final oldValueValid = _isValid(oldValue.text);
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final newValueValid = _isValid(newValue.text);
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if (oldValueValid && !newValueValid) {
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return oldValue;
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}
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return newValue;
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}
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bool _isValid(String value) {
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try {
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final matches = _regExp.allMatches(value);
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for (Match match in matches) {
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if (match.start == 0 && match.end == value.length) {
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return true;
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}
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}
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return false;
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} catch (e) {
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// Invalid regex
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assert(false, e.toString());
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return true;
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}
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}
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} |