add firstWhere to ListCopyWith

Author: schultek

packages/dart_mappable/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 4.6.5
+
+- Added `firstWhere` to `ListCopyWith` for chaining copyWith calls on a list element based on a predicate function.
+
 # 4.6.1
 
 - Record mappers now correctly uses hooks specified on the `@MappableRecord` annotation.

packages/dart_mappable/lib/src/copywith/list_copy_with.dart

@@ -20,6 +20,9 @@ abstract class ListCopyWith<Result, Elem, Copy> {
   /// Access the copyWith interface for the item at [index]
   Copy at(int index);
 
+  /// Access the copyWith interface for the first item that passes [test]
+  Copy firstWhere(bool Function(Elem) test);
+
   /// Returns a new list with the item added to the end of the list
   Result add(Elem v);
 
@@ -70,6 +73,15 @@ class _ListCopyWith<Result, Elem, Copy>
   @override
   Copy at(int index) => _item($value[index], (v) => replace(index, v));
 
+  @override
+  Copy firstWhere(bool Function(Elem) test) {
+    final index = $value.indexWhere(test);
+    if (index == -1) {
+      throw StateError('No element found matching the predicate');
+    }
+    return at(index);
+  }
+
   @override
   Result add(Elem v) => addAll([v]);
 

packages/dart_mappable/pubspec.yaml

@@ -25,7 +25,7 @@ dependencies:
 
 dev_dependencies:
   build_runner: ^2.4.14
-  dart_mappable_builder: ^4.6.3
+  dart_mappable_builder: ^4.6.5
   lints: ^5.0.0
   test: ^1.25.10