Error code validation updates.

pkg/analyzer/lib/source/error_processor.dart

 // 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.
 
 library analyzer.source.error_processor;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/task/options.dart';
@@ skipping 36 matching lines @@
       });
     } else if (codes is Map) {
       codes.forEach((k, v) {
         if (k is String) {
           _process(k, v);
         }
       });
     }
   }
 
-  ErrorSeverity _toSeverity(String severity) {
-    switch (severity) {
-      case 'error':
-        return ErrorSeverity.ERROR;
-      case 'info':
-        return ErrorSeverity.INFO;
-      case 'warning':
-        return ErrorSeverity.WARNING;
-    }
-    return null;
-  }
+  ErrorSeverity _toSeverity(String severity) => severityMap[severity];
+}
 
-}
+/// String identifiers mapped to associated severities.
+const Map<String, ErrorSeverity> severityMap = const {
+  'error': ErrorSeverity.ERROR,
+  'info': ErrorSeverity.INFO,
+  'warning': ErrorSeverity.WARNING
+};
 
 /// Process errors by filtering or changing associated [ErrorSeverity].
 class ErrorProcessor {
   /// The code name of the associated error.
   final String code;
 
   /// The desired severity of the processed error.
   ///
   /// If `null`, this processor will "filter" the associated error code.
   final ErrorSeverity severity;
@@ skipping 16 matching lines @@
       AnalysisContext context, AnalysisError error) {
     if (context == null) {
       return null;
     }
     List<ErrorProcessor> processors =
         context.getConfigurationData(CONFIGURED_ERROR_PROCESSORS);
     return processors.firstWhere((ErrorProcessor p) => p.appliesTo(error),
         orElse: () => null);
   }
 }