Server custom error severity support (#24452).

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';
+import 'package:yaml/yaml.dart';
+
+/// Error processor configuration derived from analysis (or embedder) options.
+class ErrorConfig {
+  /// The processors in this config.
+  final List<ErrorProcessor> processors = <ErrorProcessor>[];
+
+  /// Create an error config for the given error code map.
+  /// For example:
+  ///     new ErrorConfig({'missing_return' : 'error'});
+  /// will create a processor config that turns `missing_return` hints into
+  /// errors.
+  ErrorConfig(Object codeMap) {
+    _processMap(codeMap);
+  }
+
+  void _process(String code, Object action) {
+    action = toLowerCase(action);
+    code = toUpperCase(code);
+    if (AnalyzerOptions.ignoreSynonyms.contains(action)) {
+      processors.add(new ErrorProcessor.ignore(code));
+    } else {
+      ErrorSeverity severity = _toSeverity(action);
+      if (severity != null) {
+        processors.add(new ErrorProcessor(code, severity));
+      }
+    }
+  }
+
+  void _processMap(Object codes) {
+    if (codes is YamlMap) {
+      // TODO(pq): stop traversing nodes and unify w/ standard map handling
+      codes.nodes.forEach((k, v) {
+        if (k is YamlScalar && v is YamlScalar) {
+          _process(k.value, v.value);
+        }
+      });
+    } 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;
+  }
+
+}
+
+/// 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;
+
+  /// Create an error processor that assigns errors with this [code] the
+  /// given [severity].
+  ///
+  /// If [severity] is `null`, matching errors will be filtered.
+  ErrorProcessor(this.code, [this.severity]);
+
+  /// Create an error processor that ignores the given error by [code].
+  factory ErrorProcessor.ignore(String code) => new ErrorProcessor(code);
+
+  /// Check if this processor applies to the given [error].
+  bool appliesTo(AnalysisError error) => code == error.errorCode.name;
+
+  /// Return an error processor associated with this [context] for the given
+  /// [error], or `null` if none is found.
+  static ErrorProcessor getProcessor(
+      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);
+  }
+}