feat: Dart evaluation (#39)

Adds support for evaluation of Cedar policies in Dart.

Largely copied from https://github.com/cedar-policy/cedar-go

Author: dnys1

.github/workflows/cedar.yaml

@@ -0,0 +1,33 @@
+name: cedar
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/cedar.yaml"
+      - "packages/cedar/**"
+
+# Prevent duplicate runs due to Graphite
+# https://graphite.dev/docs/troubleshooting#why-are-my-actions-running-twice
+concurrency:
+  group: ${{ github.repository }}-${{ github.workflow }}-${{ github.ref }}-${{ github.ref == 'refs/heads/main' && github.sha || ''}}
+  cancel-in-progress: true
+
+defaults:
+  run:
+    shell: bash
+    working-directory: packages/cedar
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Git Checkout
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # 4.1.7
+        with:
+          submodules: true
+      - name: Setup Dart
+        uses: dart-lang/setup-dart@0a8a0fc875eb934c15d08629302413c671d3f672 # main
+      - name: Get Packages
+        run: dart pub get
+      - name: Test
+        run: dart test --fail-fast

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "dart.vmAdditionalArgs": [
+        "--enable-experiment=native-assets",
+    ],
+}

packages/cedar/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.0
+
+- feat: Add Dart evaluation
+
 ## 0.1.3
 
 - Update repository URL

packages/cedar/lib/ast.dart

@@ -0,0 +1 @@
+export 'src/ast.dart';

packages/cedar/lib/cedar.dart

@@ -14,13 +14,12 @@
 /// native assets of `package:cedar_ffi`.
 library;
 
-export 'src/ast/cedar_entity.dart';
-export 'src/ast/cedar_entity_id.dart';
-export 'src/ast/cedar_schema.dart';
 export 'src/authorization/cedar_authorization_request.dart';
 export 'src/authorization/cedar_authorization_response.dart';
 export 'src/authorization/cedar_authorizer.dart';
+export 'src/eval/errors.dart';
+export 'src/model/cedar_entity.dart';
+export 'src/model/cedar_schema.dart' hide CedarEntityType;
+export 'src/model/types/cedar_value.dart';
 export 'src/policy/cedar_policy.dart';
 export 'src/policy/cedar_policy_set.dart';
-export 'src/policy/json_expr.dart';
-export 'src/serializers.dart';

packages/cedar/lib/src/ast.dart

@@ -0,0 +1,10 @@
+export 'ast/annotation.dart';
+export 'ast/expr.dart';
+export 'ast/operator.dart';
+export 'ast/pattern.dart';
+export 'ast/value.dart';
+export 'ast/variable.dart';
+export 'ast/visitor.dart';
+export 'parser/position.dart';
+export 'policy/cedar_policy.dart';
+export 'policy/cedar_scope.dart';

packages/cedar/lib/src/ast/annotation.dart

@@ -0,0 +1,52 @@
+import 'dart:collection';
+
+import 'package:cedar/ast.dart';
+
+final class Annotations with IterableMixin<Annotation> {
+  Annotations(this.annotations);
+
+  factory Annotations.fromJson(Map<String, Object?> json) {
+    return Annotations(json.cast());
+  }
+
+  final Map<String, String> annotations;
+
+  operator [](String key) => annotations[key];
+  operator []=(String key, String value) => annotations[key] = value;
+
+  void add(Annotation annotation) {
+    annotations[annotation.key] = annotation.value;
+  }
+
+  Annotations annotation(String key, String value) {
+    return Annotations({
+      ...annotations,
+      key: value,
+    });
+  }
+
+  CedarPolicy permit() {
+    return CedarPolicy(effect: CedarEffect.permit, annotations: this);
+  }
+
+  CedarPolicy forbid() {
+    return CedarPolicy(effect: CedarEffect.forbid, annotations: this);
+  }
+
+  Iterable<Annotation> get iterable sync* {
+    for (final entry in annotations.entries) {
+      yield (key: entry.key, value: entry.value);
+    }
+  }
+
+  @override
+  Iterator<Annotation> get iterator => iterable.iterator;
+
+  Map<String, String> toJson() => annotations;
+}
+
+Annotations annotation(String key, String value) {
+  return Annotations({key: value});
+}
+
+typedef Annotation = ({String key, String value});