Preliminary checked mirrors (not ready for review yet)

pkg/checked_mirrors/lib/src/checker.dart

Index: pkg/checked_mirrors/lib/src/checker.dart
diff --git a/pkg/checked_mirrors/lib/src/checker.dart b/pkg/checked_mirrors/lib/src/checker.dart
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+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Defines rules and a chacker to determine if MirrorsUsed was used correctly.
+library checked_mirrors.src.checker;
+
+import "dart:mirrors";
+import "dart:async";
+
+import 'package:checked_mirrors/control.dart';
+import 'package:logging/logging.dart';
+
+import 'utils.dart';
+
+/// Controller used to log warnings detected by this checker.
+var _warnings = new StreamController<MirrorsUsedWarning>.broadcast(sync: true);
+var _logger = new Logger('checked_mirrors');
+
+/// Stream of warnings detected by this checker.
+Stream<MirrorsUsedWarning> get onWarning => _warnings.stream;
+
+/// A singleton checker used by the checked_mirrors system.
+MirrorsUsedChecker checker = new MirrorsUsedChecker();
+
+/// Symbol used to search for the MirrorUsed annotation. One dartbug.com/10360
+/// is fixed, we can just put the annotation directly in the checked_mirrors
+/// import.
+const _MIRROR_USED_LOCATION = #checked_mirrors_workaround_for_issue_10360;
+
+
+/// A warning generated by the checked_mirrors system.
+class MirrorsUsedWarning {
+
+  /// The kind of warning (undeclared symbol, target not marked).
+  final MirrorsUsedWarningKind kind;
+
+  /// The target of the mirror system that was not marked correctly. Or the
+  /// object containing the target (if symbol is not null).
+  final object;
+
+  final symbol;
+
+  MirrorsUsedWarning(this.kind, this.object, this.symbol);
+}
+
+/// Enumeration of warning kinds.
+class MirrorsUsedWarningKind {
+  final int _value;
+  const MirrorsUsedWarningKind(this._value);
+
+  /// Warning when reading a symbol that was not declared via
+  /// @MirrorUsed(symbols: ...)
+  static const UNDECLARED_SYMBOL = const MirrorsUsedWarningKind(1);
+
+  /// Warning when accesing a target that was not declared via
+  /// @MirrorUsed(targets: ...) or @MirrorUsed(metaTargets: ...)
+  static const TARGET_NOT_MARKED = const MirrorsUsedWarningKind(2);
+}
+
+/// Contains rules to check when mirrors are used, but they are not annotated
+/// appropriately.
+class MirrorsUsedChecker {
+  bool isInitialized = false;
+  bool _throwOnWarning = false;
+
+  Set symbols = new Set();
+  List globalRules = [];
+
+  Map<Uri, List> libraryRules = new Map<Uri, List>();
+
+  void init({throwOnWarning}) {
+    if (isInitialized) return;
+    _throwOnWarning = throwOnWarning;
+    var system = currentMirrorSystem();
+    system.libraries.forEach((uri, lib) {
+      if (uri.scheme == 'dart') return;
+      // TODO(sigmund): this should lookup the import instead. dartbug.com/10360
+      var target = lib.declarations[_MIRROR_USED_LOCATION];
+      if (target == null) return;
+      for (var metaMirror in target.metadata) {
+        var meta = metaMirror.reflectee;
+        if (meta is MirrorsUsed) {
+          addRule(uri, meta);
+        }
+      }
+    });
+    isInitialized = true;
+  }
+
+  /// Add a [rule] that was seen in [location].
+  void addRule(Uri location, MirrorsUsed annotation) {
+
+    // Symbols are handled separately since they are always global.
+    _loadSymbols(annotation.symbols);
+
+    // Direct target rules to specific libraries, if that's how they are
+    // declared.
+    var rule = new _Rule(annotation);
+    if (annotation.override == '*') {
+      globalRules.add(rule);
+      return;
+    }
+
+    if (annotation.override == null) {
+      _addToLibrary(location, rule);
+      return;
+    }
+
+    for (var name in annotation.override.split(',')) {
+      var symbol = MirrorSystem.getSymbol(name);
+      for (var lib in currentMirrorSystem().libraries.values) {
+        if (lib.simpleName == symbol) _addToLibrary(lib.uri, rule);
+      }
+    }
+  }
+
+  void _loadSymbols(value) {
+    if (value == null) return;
+    if (value is String) {
+      for (var s in value.split(',')) {
+        symbols.add(MirrorSystem.getSymbol(s));
+      }
+    } else if (value is Symbol) {
+      symbols.add(value);
+    } else if (value is List) {
+      for (var s in value) _loadSymbols(s);
+    } else {
+      _logger.warning('MirrorsUsed symbol not understood: $value');
+    }
+  }
+
+
+  void _addToLibrary(uri, rule) {
+    var rules = libraryRules[uri];
+    if (rules == null) {
+      rules = [];
+      libraryRules[uri] = rules;
+    }
+    rules.add(rule);
+  }
+
+  void useSymbol(Symbol symbol) {
+    if (!isInitialized || symbols.contains(symbol)) return;
+    var warning = new MirrorsUsedWarning(
+        MirrorsUsedWarningKind.UNDECLARED_SYMBOL, null, symbol);
+    _warnings.add(warning);
+    if (_throwOnWarning) throw warning;
+  }
+
+  void access(Mirror object, Symbol symbol) {
+    if (!isInitialized) return;
+
+    for (var rule in globalRules) {
+      if (rule.access(object, symbol)) return;
+    }
+
+    var uri = getLibraryUriOf(object);
+    var rules = libraryRules[uri];
+    if (rules != null) {
+      for (var rule in rules) {
+        if (rule.access(object, symbol)) return;
+      }
+    }
+
+    // No rule determined that it's ok to access [symbol]. Report an error.
+    var warning = new MirrorsUsedWarning(
+          MirrorsUsedWarningKind.TARGET_NOT_MARKED, object, symbol);
+    _warnings.add(warning);
+    if (_throwOnWarning) throw warning;
+  }
+}
+
+/// Contains a single rule, which is derived from a [MirrorsUsed] annotation.
+/// The information here is very similar to that of [MirrorsUsed] except it's
+/// normalized to make it easy to use and apply in the checker logic.
+class _Rule {
+  List<Mirror> targets = [];
+  List<Type> metaTargets = [];
+
+  _Rule(MirrorsUsed annotation) {
+    _loadTargets(annotation.targets);
+    _loadMetaTargets(annotation.metaTargets);
+  }
+
+  void _loadTargets(value) {
+    if (value == null) return;
+    if (value is Type) {
+      targets.add(value);
+    } else if (value is List) {
+      for (var t in value) _loadTargets(t);
+    } else {
+      _logger.warning('MirrorsUsed target not understood: $value');
+    }
+  }
+  void _loadMetaTargets(value) {
+    if (value == null) return;
+    if (value is Type) {
+      metaTargets.add(value);
+    } else if (value is List) {
+      for (var t in value) _loadMetaTargets(t);
+    } else {
+      _logger.warning('MirrorsUsed metaTarget not understood: $value');
+    }
+  }
+
+  bool access(object, Symbol symbol) {
+    // Explicitly declared targets/types
+    var declaration = getDeclarationOf(object);
+    if (declaration == null) return false;
+    if (targets.contains(declaration.reflectedType)) return true;
+
+    // Meta-targets on classes
+    for (var meta in declaration.metadata) {
+      var type = meta.type.reflectedType;
+      if (metaTargets.contains(type)) return true;
+    }
+
+    if (symbol == null) return false;
+
+    // Meta-targets on fields
+    var symbolDeclaration = declaration.declarations[symbol];
+    if (symbolDeclaration == null) return false;
+    for (var meta in symbolDeclaration.metadata) {
+      var type = meta.type.reflectedType;
+      if (metaTargets.contains(type)) return true;
+    }
+  }
+}