expose strong checker API, for use by analyzer_cli

lib/strong_mode.dart

Index: lib/strong_mode.dart
diff --git a/lib/strong_mode.dart b/lib/strong_mode.dart
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+++ b/lib/strong_mode.dart
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+// Copyright (c) 2015, 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.
+
+/// Types needed to implement "strong" checking in the Dart analyzer.
+/// This is intended to be used by analyzer_cli and analysis_server packages.
+library dev_compiler.strong_mode;
+
+import 'package:analyzer/src/generated/engine.dart'
+    show AnalysisContextImpl, AnalysisErrorInfo, AnalysisErrorInfoImpl;
+import 'package:analyzer/src/generated/error.dart'
+    show
+        AnalysisError,
+        ErrorCode,
+        CompileTimeErrorCode,
+        StaticTypeWarningCode,
+        HintCode;
+import 'package:analyzer/src/generated/source.dart' show Source;
+import 'package:args/args.dart';
+import 'package:logging/logging.dart' show Level;
+
+import 'src/checker/checker.dart' show CodeChecker;
+import 'src/checker/resolver.dart' show LibraryResolverWithInference;
+import 'src/checker/rules.dart' show RestrictedRules;
+import 'src/report.dart' show CheckerReporter, Message;
+
+/// A type checker for Dart code that operates under stronger rules, and has
+/// the ability to do local type inference in some situations.
+class StrongChecker {
+  final AnalysisContextImpl _context;
+  final CodeChecker _checker;
+  final _ErrorReporter _reporter;
+  final StrongModeOptions _options;
+
+  StrongChecker._(this._context, this._options, this._checker, this._reporter);
+
+  factory StrongChecker(
+      AnalysisContextImpl context, StrongModeOptions options) {
+    // TODO(jmesserly): is there a cleaner way to plug this in?
+    if (context.libraryResolverFactory != null) {
+      throw new ArgumentError.value(context, 'context',
+          'Analysis context must not have libraryResolverFactory already set.');
+    }
+    context.libraryResolverFactory =
+        (c) => new LibraryResolverWithInference(c, options);
+
+    var rules = new RestrictedRules(context.typeProvider, options: options);
+    var reporter = new _ErrorReporter();
+    var checker = new CodeChecker(rules, reporter, options);
+    return new StrongChecker._(context, options, checker, reporter);
+  }
+
+  /// Computes and returns DDC errors for the [source].
+  AnalysisErrorInfo computeErrors(Source source) {
+    var errors = new List<AnalysisError>();
+
+    // TODO(jmesserly): change DDC to emit ErrorCodes directly.
+    _reporter._log = (Message msg) {
+      // Skip hints unless requested.
+      if (msg.level < Level.WARNING && !_options.hints) return;
+
+      var errorCodeFactory = _levelToErrorCode[msg.level];
+      var category = '${msg.runtimeType}';
+      var errorCode = errorCodeFactory(category, msg.message);
+      var len = msg.end - msg.begin;
+      errors.add(new AnalysisError.con2(source, msg.begin, len, errorCode));
+    };
+
+    for (Source librarySource in _context.getLibrariesContaining(source)) {
+      var resolved = _context.resolveCompilationUnit2(source, librarySource);
+      _checker.visitCompilationUnit(resolved);
+    }
+    _reporter._log = null;
+    return new AnalysisErrorInfoImpl(errors, _context.getLineInfo(source));
+  }
+}
+
+/// Maps a DDC log level to an analyzer ErrorCode subclass.
+final _levelToErrorCode = <Level, _ErrorCodeFactory>{
+  Level.SEVERE: (n, m) => new CompileTimeErrorCode(n, m),
+  Level.WARNING: (n, m) => new StaticTypeWarningCode(n, m),
+  Level.INFO: (n, m) => new HintCode(n, m)
+};
+
+class _ErrorReporter implements CheckerReporter {
+  _CheckerReporterLog _log;
+  void log(Message message) => _log(message);
+}
+
+class StrongModeOptions {
+
+  /// Whether to infer return types and field types from overridden members.
+  final bool inferFromOverrides;
+  static const inferFromOverridesDefault = true;
+
+  /// Whether to infer types for consts and fields by looking at initializers on
+  /// the RHS. For example, in a constant declaration like:
+  ///
+  ///      const A = B;
+  ///
+  /// We can infer the type of `A` based on the type of `B`.
+  ///
+  /// The inference algorithm determines what variables depend on others, and
+  /// computes types by visiting the variable dependency graph in topological
+  /// order. This ensures that the inferred type is deterministic when applying
+  /// inference on library cycles.
+  ///
+  /// When this feature is turned off, we don't use the type of `B` to infer the
+  /// type of `A`, even if `B` has a declared type.
+  final bool inferTransitively;
+  static const inferTransitivelyDefault = true;
+
+  /// Restrict inference of fields and top-levels to those that are final and
+  /// const.
+  final bool onlyInferConstsAndFinalFields;
+  static const onlyInferConstAndFinalFieldsDefault = false;
+
+  /// Whether to infer types downwards from local context
+  final bool inferDownwards;
+  static const inferDownwardsDefault = true;
+
+  /// Whether to inject casts between Dart assignable types.
+  final bool relaxedCasts;
+
+  /// A list of non-nullable type names (e.g., 'int')
+  final List<String> nonnullableTypes;
+  static const List<String> NONNULLABLE_TYPES = const <String>[];
+
+  /// Whether to include hints about dynamic invokes and runtime checks.
+  // TODO(jmesserly): this option is not used yet by DDC server mode or batch
+  // compile to JS.
+  final bool hints;
+
+  const StrongModeOptions({this.hints: false,
+      this.inferFromOverrides: inferFromOverridesDefault,
+      this.inferTransitively: inferTransitivelyDefault,
+      this.onlyInferConstsAndFinalFields: onlyInferConstAndFinalFieldsDefault,
+      this.inferDownwards: inferDownwardsDefault, this.relaxedCasts: true,
+      this.nonnullableTypes: StrongModeOptions.NONNULLABLE_TYPES});
+
+  StrongModeOptions.fromArguments(ArgResults args, {String prefix: ''})
+      : relaxedCasts = args[prefix + 'relaxed-casts'],
+        inferDownwards = args[prefix + 'infer-downwards'],
+        inferFromOverrides = args[prefix + 'infer-from-overrides'],
+        inferTransitively = args[prefix + 'infer-transitively'],
+        onlyInferConstsAndFinalFields = args[prefix + 'infer-only-finals'],
+        nonnullableTypes = _optionsToList(args[prefix + 'nonnullable'],
+            defaultValue: StrongModeOptions.NONNULLABLE_TYPES),
+        hints = args[prefix + 'hints'];
+
+  static ArgParser addArguments(ArgParser parser,
+      {String prefix: '', bool hide: false}) {
+    return parser
+      ..addFlag(prefix + 'hints',
+          help: 'Display hints about dynamic casts and dispatch operations',
+          defaultsTo: false,
+          hide: hide)
+      ..addFlag(prefix + 'relaxed-casts',
+          help: 'Cast between Dart assignable types',
+          defaultsTo: true,
+          hide: hide)
+      ..addOption(prefix + 'nonnullable',
+          abbr: prefix == '' ? 'n' : null,
+          help: 'Comma separated string of non-nullable types',
+          defaultsTo: null,
+          hide: hide)
+      ..addFlag(prefix + 'infer-downwards',
+          help: 'Infer types downwards from local context',
+          defaultsTo: inferDownwardsDefault,
+          hide: hide)
+      ..addFlag(prefix + 'infer-from-overrides',
+          help: 'Infer unspecified types of fields and return types from\n'
+          'definitions in supertypes',
+          defaultsTo: inferFromOverridesDefault,
+          hide: hide)
+      ..addFlag(prefix + 'infer-transitively',
+          help: 'Infer consts/fields from definitions in other libraries',
+          defaultsTo: inferTransitivelyDefault,
+          hide: hide)
+      ..addFlag(prefix + 'infer-only-finals',
+          help: 'Do not infer non-const or non-final fields',
+          defaultsTo: onlyInferConstAndFinalFieldsDefault,
+          hide: hide);
+  }
+
+  bool operator ==(Object other) {
+    if (other is! StrongModeOptions) return false;
+    StrongModeOptions s = other;
+    return inferFromOverrides == s.inferFromOverrides &&
+        inferTransitively == s.inferTransitively &&
+        onlyInferConstsAndFinalFields == s.onlyInferConstsAndFinalFields &&
+        inferDownwards == s.inferDownwards &&
+        relaxedCasts == s.relaxedCasts &&
+        nonnullableTypes.length == s.nonnullableTypes.length &&
+        new Set.from(nonnullableTypes).containsAll(s.nonnullableTypes);
+  }
+}
+
+typedef void _CheckerReporterLog(Message message);
+typedef ErrorCode _ErrorCodeFactory(String name, String message);
+
+List<String> _optionsToList(String option,
+    {List<String> defaultValue: const <String>[]}) {
+  if (option == null) {
+    return defaultValue;
+  } else if (option.isEmpty) {
+    return <String>[];
+  } else {
+    return option.split(',');
+  }
+}