pkg/analyzer/tool/messages/error_code_info.dart - sdk.git - Git at Google

 // Copyright (c) 2021, 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.

 import 'dart:convert';
 import 'dart:io';

 import 'package:analyzer_utilities/package_root.dart' as pkg_root;
 import 'package:path/path.dart';
 import 'package:yaml/yaml.dart' show loadYaml;

 /// Information about all the classes derived from `ErrorCode` that are code
 /// generated based on the contents of the analyzer and front end
 /// `messages.yaml` files.
 const List<ErrorClassInfo> errorClasses = [
   ErrorClassInfo(
       filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
       name: 'AnalysisOptionsErrorCode',
       type: 'COMPILE_TIME_ERROR',
       severity: 'ERROR'),
   ErrorClassInfo(
       filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
       name: 'AnalysisOptionsHintCode',
       type: 'HINT',
       severity: 'INFO'),
   ErrorClassInfo(
       filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
       name: 'AnalysisOptionsWarningCode',
       type: 'STATIC_WARNING',
       severity: 'WARNING'),
   ErrorClassInfo(
       filePath: 'lib/src/error/codes.g.dart',
       name: 'CompileTimeErrorCode',
       superclass: 'AnalyzerErrorCode',
       type: 'COMPILE_TIME_ERROR',
       extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
   ErrorClassInfo(
       filePath: 'lib/src/error/codes.g.dart',
       name: 'LanguageCode',
       type: 'COMPILE_TIME_ERROR'),
   ErrorClassInfo(
       filePath: 'lib/src/error/codes.g.dart',
       name: 'StaticWarningCode',
       superclass: 'AnalyzerErrorCode',
       type: 'STATIC_WARNING',
       severity: 'WARNING',
       extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
   ErrorClassInfo(
       filePath: 'lib/src/dart/error/ffi_code.g.dart',
       name: 'FfiCode',
       superclass: 'AnalyzerErrorCode',
       type: 'COMPILE_TIME_ERROR',
       extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
   ErrorClassInfo(
       filePath: 'lib/src/dart/error/hint_codes.g.dart',
       name: 'HintCode',
       superclass: 'AnalyzerErrorCode',
       type: 'HINT',
       extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
   ErrorClassInfo(
       filePath: 'lib/src/dart/error/syntactic_errors.g.dart',
       name: 'ParserErrorCode',
       type: 'SYNTACTIC_ERROR',
       severity: 'ERROR',
       includeCfeMessages: true),
   ErrorClassInfo(
       filePath: 'lib/src/manifest/manifest_warning_code.g.dart',
       name: 'ManifestWarningCode',
       type: 'STATIC_WARNING',
       severity: 'WARNING'),
   ErrorClassInfo(
       filePath: 'lib/src/pubspec/pubspec_warning_code.g.dart',
       name: 'PubspecWarningCode',
       type: 'STATIC_WARNING',
       severity: 'WARNING'),
 ];

 /// Decoded messages from the analyzer's `messages.yaml` file.
 final Map<String, Map<String, AnalyzerErrorCodeInfo>> analyzerMessages =
     _loadAnalyzerMessages();

 /// The path to the `analyzer` package.
 final String analyzerPkgPath =
     normalize(join(pkg_root.packageRoot, 'analyzer'));

 /// A set of tables mapping between front end and analyzer error codes.
 final CfeToAnalyzerErrorCodeTables cfeToAnalyzerErrorCodeTables =
     CfeToAnalyzerErrorCodeTables._(frontEndMessages);

 /// Decoded messages from the front end's `messages.yaml` file.
 final Map<String, FrontEndErrorCodeInfo> frontEndMessages =
     _loadFrontEndMessages();

 /// The path to the `front_end` package.
 final String frontEndPkgPath =
     normalize(join(pkg_root.packageRoot, 'front_end'));

 /// Pattern used by the front end to identify placeholders in error message
 /// strings.  TODO(paulberry): share this regexp (and the code for interpreting
 /// it) between the CFE and analyzer.
 final RegExp _placeholderPattern =
     RegExp("#\([-a-zA-Z0-9_]+\)(?:%\([0-9]*\)\.\([0-9]+\))?");

 /// Convert a CFE template string (which uses placeholders like `#string`) to
 /// an analyzer template string (which uses placeholders like `{0}`).
 String convertTemplate(Map<String, int> placeholderToIndexMap, String entry) {
   return entry.replaceAllMapped(_placeholderPattern,
       (match) => '{${placeholderToIndexMap[match.group(0)!]}}');
 }

 /// Decodes a YAML object (obtained from `pkg/analyzer/messages.yaml`) into a
 /// two-level map of [ErrorCodeInfo], indexed first by class name and then by
 /// error name.
 Map<String, Map<String, AnalyzerErrorCodeInfo>> decodeAnalyzerMessagesYaml(
     Object? yaml) {
   Never problem(String message) {
     throw 'Problem in pkg/analyzer/messages.yaml: $message';
   }

   var result = <String, Map<String, AnalyzerErrorCodeInfo>>{};
   if (yaml is! Map<Object?, Object?>) {
     problem('root node is not a map');
   }
   for (var classEntry in yaml.entries) {
     var className = classEntry.key;
     if (className is! String) {
       problem('non-string class key ${json.encode(className)}');
     }
     var classValue = classEntry.value;
     if (classValue is! Map<Object?, Object?>) {
       problem('value associated with class key $className is not a map');
     }
     for (var errorEntry in classValue.entries) {
       var errorName = errorEntry.key;
       if (errorName is! String) {
         problem('in class $className, non-string error key '
             '${json.encode(errorName)}');
       }
       var errorValue = errorEntry.value;
       if (errorValue is! Map<Object?, Object?>) {
         problem('value associated with error $className.$errorName is not a '
             'map');
       }
       try {
         (result[className] ??= {})[errorName] =
             AnalyzerErrorCodeInfo.fromYaml(errorValue);
       } catch (e) {
         problem('while processing '
             '$className.$errorName, $e');
       }
     }
   }
   return result;
 }

 /// Decodes a YAML object (obtained from `pkg/front_end/messages.yaml`) into a
 /// map from error name to [ErrorCodeInfo].
 Map<String, FrontEndErrorCodeInfo> decodeCfeMessagesYaml(Object? yaml) {
   Never problem(String message) {
     throw 'Problem in pkg/front_end/messages.yaml: $message';
   }

   var result = <String, FrontEndErrorCodeInfo>{};
   if (yaml is! Map<Object?, Object?>) {
     problem('root node is not a map');
   }
   for (var entry in yaml.entries) {
     var errorName = entry.key;
     if (errorName is! String) {
       problem('non-string error key ${json.encode(errorName)}');
     }
     var errorValue = entry.value;
     if (errorValue is! Map<Object?, Object?>) {
       problem('value associated with error $errorName is not a map');
     }
     result[errorName] = FrontEndErrorCodeInfo.fromYaml(errorValue);
   }
   return result;
 }

 /// Loads analyzer messages from the analyzer's `messages.yaml` file.
 Map<String, Map<String, AnalyzerErrorCodeInfo>> _loadAnalyzerMessages() {
   Object? messagesYaml =
       loadYaml(File(join(analyzerPkgPath, 'messages.yaml')).readAsStringSync());
   return decodeAnalyzerMessagesYaml(messagesYaml);
 }

 /// Loads front end messages from the front end's `messages.yaml` file.
 Map<String, FrontEndErrorCodeInfo> _loadFrontEndMessages() {
   Object? messagesYaml =
       loadYaml(File(join(frontEndPkgPath, 'messages.yaml')).readAsStringSync());
   return decodeCfeMessagesYaml(messagesYaml);
 }

 /// In-memory representation of error code information obtained from the
 /// analyzer's `messages.yaml` file.
 class AnalyzerErrorCodeInfo extends ErrorCodeInfo {
   AnalyzerErrorCodeInfo(
       {String? comment,
       String? correctionMessage,
       String? documentation,
       bool hasPublishedDocs = false,
       bool isUnresolvedIdentifier = false,
       required String problemMessage,
       String? sharedName})
       : super(
             comment: comment,
             correctionMessage: correctionMessage,
             documentation: documentation,
             hasPublishedDocs: hasPublishedDocs,
             isUnresolvedIdentifier: isUnresolvedIdentifier,
             problemMessage: problemMessage,
             sharedName: sharedName);

   AnalyzerErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
       : super.fromYaml(yaml);
 }

 /// Data tables mapping between CFE errors and their corresponding automatically
 /// generated analyzer errors.
 class CfeToAnalyzerErrorCodeTables {
   /// List of CFE errors for which analyzer errors should be automatically
   /// generated, organized by their `index` property.
   final List<ErrorCodeInfo?> indexToInfo = [];

   /// Map whose values are the CFE errors for which analyzer errors should be
   /// automatically generated, and whose keys are the corresponding analyzer
   /// error name.  (Names are simple identifiers; they are not prefixed by the
   /// class name `ParserErrorCode`)
   final Map<String, ErrorCodeInfo> analyzerCodeToInfo = {};

   /// Map whose values are the CFE errors for which analyzer errors should be
   /// automatically generated, and whose keys are the front end error name.
   final Map<String, ErrorCodeInfo> frontEndCodeToInfo = {};

   /// Map whose keys are the CFE errors for which analyzer errors should be
   /// automatically generated, and whose values are the corresponding analyzer
   /// error name.  (Names are simple identifiers; they are not prefixed by the
   /// class name `ParserErrorCode`)
   final Map<ErrorCodeInfo, String> infoToAnalyzerCode = {};

   /// Map whose keys are the CFE errors for which analyzer errors should be
   /// automatically generated, and whose values are the front end error name.
   final Map<ErrorCodeInfo, String> infoToFrontEndCode = {};

   CfeToAnalyzerErrorCodeTables._(Map<String, FrontEndErrorCodeInfo> messages) {
     for (var entry in messages.entries) {
       var errorCodeInfo = entry.value;
       var index = errorCodeInfo.index;
       if (index == null || errorCodeInfo.analyzerCode.length != 1) {
         continue;
       }
       var frontEndCode = entry.key;
       if (index < 1) {
         throw '''
 $frontEndCode specifies index $index but indices must be 1 or greater.
 For more information run:
 pkg/front_end/tool/fasta generate-messages
 ''';
       }
       if (indexToInfo.length <= index) {
         indexToInfo.length = index + 1;
       }
       var previousEntryForIndex = indexToInfo[index];
       if (previousEntryForIndex != null) {
         throw 'Index $index used by both '
             '${infoToFrontEndCode[previousEntryForIndex]} and $frontEndCode';
       }
       indexToInfo[index] = errorCodeInfo;
       frontEndCodeToInfo[frontEndCode] = errorCodeInfo;
       infoToFrontEndCode[errorCodeInfo] = frontEndCode;
       var analyzerCodeLong = errorCodeInfo.analyzerCode.single;
       var expectedPrefix = 'ParserErrorCode.';
       if (!analyzerCodeLong.startsWith(expectedPrefix)) {
         throw 'Expected all analyzer error codes to be prefixed with '
             '${json.encode(expectedPrefix)}.  Found '
             '${json.encode(analyzerCodeLong)}.';
       }
       var analyzerCode = analyzerCodeLong.substring(expectedPrefix.length);
       infoToAnalyzerCode[errorCodeInfo] = analyzerCode;
       var previousEntryForAnalyzerCode = analyzerCodeToInfo[analyzerCode];
       if (previousEntryForAnalyzerCode != null) {
         throw 'Analyzer code $analyzerCode used by both '
             '${infoToFrontEndCode[previousEntryForAnalyzerCode]} and '
             '$frontEndCode';
       }
       analyzerCodeToInfo[analyzerCode] = errorCodeInfo;
     }
     for (int i = 1; i < indexToInfo.length; i++) {
       if (indexToInfo[i] == null) {
         throw 'Indices are not consecutive; no error code has index $i.';
       }
     }
   }
 }

 /// Information about a code generated class derived from `ErrorCode`.
 class ErrorClassInfo {
   /// A list of additional import URIs that are needed by the code generated
   /// for this class.
   final List<String> extraImports;

   /// The file path (relative to the root of `pkg/analyzer`) of the generated
   /// file containing this class.
   final String filePath;

   /// True if this class should contain error messages extracted from the front
   /// end's `messages.yaml` file.
   ///
   /// Note: at the moment we only support extracting front end error messages to
   /// a single error class.
   final bool includeCfeMessages;

   /// The name of this class.
   final String name;

   /// The severity of errors in this class, or `null` if the severity should be
   /// based on the [type] of the error.
   final String? severity;

   /// The superclass of this class.
   final String superclass;

   /// The type of errors in this class.
   final String type;

   const ErrorClassInfo(
       {this.extraImports = const [],
       required this.filePath,
       this.includeCfeMessages = false,
       required this.name,
       this.severity,
       this.superclass = 'ErrorCode',
       required this.type});

   /// Generates the code to compute the severity of errors of this class.
   String get severityCode {
     var severity = this.severity;
     if (severity == null) {
       return '$typeCode.severity';
     } else {
       return 'ErrorSeverity.$severity';
     }
   }

   /// Generates the code to compute the type of errors of this class.
   String get typeCode => 'ErrorType.$type';
 }

 /// In-memory representation of error code information obtained from either the
 /// analyzer or the front end's `messages.yaml` file.  This class contains the
 /// common functionality supported by both formats.
 abstract class ErrorCodeInfo {
   /// If present, a documentation comment that should be associated with the
   /// error in code generated output.
   final String? comment;

   /// If the error code has an associated correctionMessage, the template for
   /// it.
   final String? correctionMessage;

   /// If present, user-facing documentation for the error.
   final String? documentation;

   /// `true` if diagnostics with this code have documentation for them that has
   /// been published.
   final bool hasPublishedDocs;

   /// Indicates whether this error is caused by an unresolved identifier.
   final bool isUnresolvedIdentifier;

   /// The problemMessage for the error code.
   final String problemMessage;

   /// If present, indicates that this error code has a special name for
   /// presentation to the user, that is potentially shared with other error
   /// codes.
   final String? sharedName;

   /// If present, indicates that this error code has been renamed from
   /// [previousName] to its current name (or [sharedName]).
   final String? previousName;

   ErrorCodeInfo(
       {this.comment,
       this.documentation,
       this.hasPublishedDocs = false,
       this.isUnresolvedIdentifier = false,
       this.sharedName,
       required this.problemMessage,
       this.correctionMessage,
       this.previousName});

   /// Decodes an [ErrorCodeInfo] object from its YAML representation.
   ErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
       : this(
             comment: yaml['comment'] as String?,
             correctionMessage: yaml['correctionMessage'] as String?,
             documentation: yaml['documentation'] as String?,
             hasPublishedDocs: yaml['hasPublishedDocs'] as bool? ?? false,
             isUnresolvedIdentifier:
                 yaml['isUnresolvedIdentifier'] as bool? ?? false,
             problemMessage: yaml['problemMessage'] as String,
             sharedName: yaml['sharedName'] as String?,
             previousName: yaml['previousName'] as String?);

   /// Given a messages.yaml entry, come up with a mapping from placeholder
   /// patterns in its message strings to their corresponding indices.
   Map<String, int> computePlaceholderToIndexMap() {
     var mapping = <String, int>{};
     for (var value in [problemMessage, correctionMessage]) {
       if (value is! String) continue;
       for (Match match in _placeholderPattern.allMatches(value)) {
         // CFE supports a bunch of formatting options that analyzer doesn't;
         // make sure none of those are used.
         if (match.group(0) != '#${match.group(1)}') {
           throw 'Template string ${json.encode(value)} contains unsupported '
               'placeholder pattern ${json.encode(match.group(0))}';
         }

         mapping[match.group(0)!] ??= mapping.length;
       }
     }
     return mapping;
   }

   /// Generates a dart declaration for this error code, suitable for inclusion
   /// in the error class [className].  [errorCode] is the name of the error code
   /// to be generated.
   String toAnalyzerCode(String className, String errorCode) {
     var out = StringBuffer();
     out.writeln('$className(');
     out.writeln("'${sharedName ?? errorCode}',");
     final placeholderToIndexMap = computePlaceholderToIndexMap();
     out.writeln(
         json.encode(convertTemplate(placeholderToIndexMap, problemMessage)) +
             ',');
     final correctionMessage = this.correctionMessage;
     if (correctionMessage is String) {
       out.write('correctionMessage: ');
       out.writeln(json.encode(
               convertTemplate(placeholderToIndexMap, correctionMessage)) +
           ',');
     }
     if (hasPublishedDocs) {
       out.writeln('hasPublishedDocs:true,');
     }
     if (isUnresolvedIdentifier) {
       out.writeln('isUnresolvedIdentifier:true,');
     }
     if (sharedName != null) {
       out.writeln("uniqueName: '$errorCode',");
     }
     out.write(');');
     return out.toString();
   }

   /// Generates dart comments for this error code.
   String toAnalyzerComments({String indent = ''}) {
     var out = StringBuffer();
     var comment = this.comment;
     if (comment != null) {
       out.writeln('$indent/**');
       for (var line in comment.split('\n')) {
         out.writeln('$indent *${line.isEmpty ? '' : ' '}$line');
       }
       out.writeln('$indent */');
     }
     var documentation = this.documentation;
     if (documentation != null) {
       for (var line in documentation.split('\n')) {
         out.writeln('$indent//${line.isEmpty ? '' : ' '}$line');
       }
     }
     return out.toString();
   }

   /// Encodes this object into a YAML representation.
   Map<Object?, Object?> toYaml() => {
         if (sharedName != null) 'sharedName': sharedName,
         'problemMessage': problemMessage,
         if (correctionMessage != null) 'correctionMessage': correctionMessage,
         if (isUnresolvedIdentifier) 'isUnresolvedIdentifier': true,
         if (hasPublishedDocs) 'hasPublishedDocs': true,
         if (comment != null) 'comment': comment,
         if (documentation != null) 'documentation': documentation,
       };
 }

 /// In-memory representation of error code information obtained from the front
 /// end's `messages.yaml` file.
 class FrontEndErrorCodeInfo extends ErrorCodeInfo {
   /// The set of analyzer error codes that corresponds to this error code, if
   /// any.
   final List<String> analyzerCode;

   /// The index of the error in the analyzer's `fastaAnalyzerErrorCodes` table.
   final int? index;

   FrontEndErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
       : analyzerCode = _decodeAnalyzerCode(yaml['analyzerCode']),
         index = yaml['index'] as int?,
         super.fromYaml(yaml);

   @override
   Map<Object?, Object?> toYaml() => {
         if (analyzerCode.isNotEmpty)
           'analyzerCode': _encodeAnalyzerCode(analyzerCode),
         if (index != null) 'index': index,
         ...super.toYaml(),
       };

   static List<String> _decodeAnalyzerCode(Object? value) {
     if (value == null) {
       return const [];
     } else if (value is String) {
       return [value];
     } else if (value is List) {
       return [for (var s in value) s as String];
     } else {
       throw 'Unrecognized analyzer code: $value';
     }
   }

   static Object _encodeAnalyzerCode(List<String> analyzerCode) {
     if (analyzerCode.length == 1) {
       return analyzerCode.single;
     } else {
       return analyzerCode;
     }
   }
 }
	// Copyright (c) 2021, 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.

	import 'dart:convert';
	import 'dart:io';

	import 'package:analyzer_utilities/package_root.dart' as pkg_root;
	import 'package:path/path.dart';
	import 'package:yaml/yaml.dart' show loadYaml;

	/// Information about all the classes derived from `ErrorCode` that are code
	/// generated based on the contents of the analyzer and front end
	/// `messages.yaml` files.
	const List<ErrorClassInfo> errorClasses = [
	ErrorClassInfo(
	filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
	name: 'AnalysisOptionsErrorCode',
	type: 'COMPILE_TIME_ERROR',
	severity: 'ERROR'),
	ErrorClassInfo(
	filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
	name: 'AnalysisOptionsHintCode',
	type: 'HINT',
	severity: 'INFO'),
	ErrorClassInfo(
	filePath: 'lib/src/analysis_options/error/option_codes.g.dart',
	name: 'AnalysisOptionsWarningCode',
	type: 'STATIC_WARNING',
	severity: 'WARNING'),
	ErrorClassInfo(
	filePath: 'lib/src/error/codes.g.dart',
	name: 'CompileTimeErrorCode',
	superclass: 'AnalyzerErrorCode',
	type: 'COMPILE_TIME_ERROR',
	extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
	ErrorClassInfo(
	filePath: 'lib/src/error/codes.g.dart',
	name: 'LanguageCode',
	type: 'COMPILE_TIME_ERROR'),
	ErrorClassInfo(
	filePath: 'lib/src/error/codes.g.dart',
	name: 'StaticWarningCode',
	superclass: 'AnalyzerErrorCode',
	type: 'STATIC_WARNING',
	severity: 'WARNING',
	extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
	ErrorClassInfo(
	filePath: 'lib/src/dart/error/ffi_code.g.dart',
	name: 'FfiCode',
	superclass: 'AnalyzerErrorCode',
	type: 'COMPILE_TIME_ERROR',
	extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
	ErrorClassInfo(
	filePath: 'lib/src/dart/error/hint_codes.g.dart',
	name: 'HintCode',
	superclass: 'AnalyzerErrorCode',
	type: 'HINT',
	extraImports: ['package:analyzer/src/error/analyzer_error_code.dart']),
	ErrorClassInfo(
	filePath: 'lib/src/dart/error/syntactic_errors.g.dart',
	name: 'ParserErrorCode',
	type: 'SYNTACTIC_ERROR',
	severity: 'ERROR',
	includeCfeMessages: true),
	ErrorClassInfo(
	filePath: 'lib/src/manifest/manifest_warning_code.g.dart',
	name: 'ManifestWarningCode',
	type: 'STATIC_WARNING',
	severity: 'WARNING'),
	ErrorClassInfo(
	filePath: 'lib/src/pubspec/pubspec_warning_code.g.dart',
	name: 'PubspecWarningCode',
	type: 'STATIC_WARNING',
	severity: 'WARNING'),
	];

	/// Decoded messages from the analyzer's `messages.yaml` file.
	final Map<String, Map<String, AnalyzerErrorCodeInfo>> analyzerMessages =
	_loadAnalyzerMessages();

	/// The path to the `analyzer` package.
	final String analyzerPkgPath =
	normalize(join(pkg_root.packageRoot, 'analyzer'));

	/// A set of tables mapping between front end and analyzer error codes.
	final CfeToAnalyzerErrorCodeTables cfeToAnalyzerErrorCodeTables =
	CfeToAnalyzerErrorCodeTables._(frontEndMessages);

	/// Decoded messages from the front end's `messages.yaml` file.
	final Map<String, FrontEndErrorCodeInfo> frontEndMessages =
	_loadFrontEndMessages();

	/// The path to the `front_end` package.
	final String frontEndPkgPath =
	normalize(join(pkg_root.packageRoot, 'front_end'));

	/// Pattern used by the front end to identify placeholders in error message
	/// strings. TODO(paulberry): share this regexp (and the code for interpreting
	/// it) between the CFE and analyzer.
	final RegExp _placeholderPattern =
	RegExp("#\([-a-zA-Z0-9_]+\)(?:%\([0-9]*\)\.\([0-9]+\))?");

	/// Convert a CFE template string (which uses placeholders like `#string`) to
	/// an analyzer template string (which uses placeholders like `{0}`).
	String convertTemplate(Map<String, int> placeholderToIndexMap, String entry) {
	return entry.replaceAllMapped(_placeholderPattern,
	(match) => '{${placeholderToIndexMap[match.group(0)!]}}');
	}

	/// Decodes a YAML object (obtained from `pkg/analyzer/messages.yaml`) into a
	/// two-level map of [ErrorCodeInfo], indexed first by class name and then by
	/// error name.
	Map<String, Map<String, AnalyzerErrorCodeInfo>> decodeAnalyzerMessagesYaml(
	Object? yaml) {
	Never problem(String message) {
	throw 'Problem in pkg/analyzer/messages.yaml: $message';
	}

	var result = <String, Map<String, AnalyzerErrorCodeInfo>>{};
	if (yaml is! Map<Object?, Object?>) {
	problem('root node is not a map');
	}
	for (var classEntry in yaml.entries) {
	var className = classEntry.key;
	if (className is! String) {
	problem('non-string class key ${json.encode(className)}');
	}
	var classValue = classEntry.value;
	if (classValue is! Map<Object?, Object?>) {
	problem('value associated with class key $className is not a map');
	}
	for (var errorEntry in classValue.entries) {
	var errorName = errorEntry.key;
	if (errorName is! String) {
	problem('in class $className, non-string error key '
	'${json.encode(errorName)}');
	}
	var errorValue = errorEntry.value;
	if (errorValue is! Map<Object?, Object?>) {
	problem('value associated with error $className.$errorName is not a '
	'map');
	}
	try {
	(result[className] ??= {})[errorName] =
	AnalyzerErrorCodeInfo.fromYaml(errorValue);
	} catch (e) {
	problem('while processing '
	'$className.$errorName, $e');
	}
	}
	}
	return result;
	}

	/// Decodes a YAML object (obtained from `pkg/front_end/messages.yaml`) into a
	/// map from error name to [ErrorCodeInfo].
	Map<String, FrontEndErrorCodeInfo> decodeCfeMessagesYaml(Object? yaml) {
	Never problem(String message) {
	throw 'Problem in pkg/front_end/messages.yaml: $message';
	}

	var result = <String, FrontEndErrorCodeInfo>{};
	if (yaml is! Map<Object?, Object?>) {
	problem('root node is not a map');
	}
	for (var entry in yaml.entries) {
	var errorName = entry.key;
	if (errorName is! String) {
	problem('non-string error key ${json.encode(errorName)}');
	}
	var errorValue = entry.value;
	if (errorValue is! Map<Object?, Object?>) {
	problem('value associated with error $errorName is not a map');
	}
	result[errorName] = FrontEndErrorCodeInfo.fromYaml(errorValue);
	}
	return result;
	}

	/// Loads analyzer messages from the analyzer's `messages.yaml` file.
	Map<String, Map<String, AnalyzerErrorCodeInfo>> _loadAnalyzerMessages() {
	Object? messagesYaml =
	loadYaml(File(join(analyzerPkgPath, 'messages.yaml')).readAsStringSync());
	return decodeAnalyzerMessagesYaml(messagesYaml);
	}

	/// Loads front end messages from the front end's `messages.yaml` file.
	Map<String, FrontEndErrorCodeInfo> _loadFrontEndMessages() {
	Object? messagesYaml =
	loadYaml(File(join(frontEndPkgPath, 'messages.yaml')).readAsStringSync());
	return decodeCfeMessagesYaml(messagesYaml);
	}

	/// In-memory representation of error code information obtained from the
	/// analyzer's `messages.yaml` file.
	class AnalyzerErrorCodeInfo extends ErrorCodeInfo {
	AnalyzerErrorCodeInfo(
	{String? comment,
	String? correctionMessage,
	String? documentation,
	bool hasPublishedDocs = false,
	bool isUnresolvedIdentifier = false,
	required String problemMessage,
	String? sharedName})
	: super(
	comment: comment,
	correctionMessage: correctionMessage,
	documentation: documentation,
	hasPublishedDocs: hasPublishedDocs,
	isUnresolvedIdentifier: isUnresolvedIdentifier,
	problemMessage: problemMessage,
	sharedName: sharedName);

	AnalyzerErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
	: super.fromYaml(yaml);
	}

	/// Data tables mapping between CFE errors and their corresponding automatically
	/// generated analyzer errors.
	class CfeToAnalyzerErrorCodeTables {
	/// List of CFE errors for which analyzer errors should be automatically
	/// generated, organized by their `index` property.
	final List<ErrorCodeInfo?> indexToInfo = [];

	/// Map whose values are the CFE errors for which analyzer errors should be
	/// automatically generated, and whose keys are the corresponding analyzer
	/// error name. (Names are simple identifiers; they are not prefixed by the
	/// class name `ParserErrorCode`)
	final Map<String, ErrorCodeInfo> analyzerCodeToInfo = {};

	/// Map whose values are the CFE errors for which analyzer errors should be
	/// automatically generated, and whose keys are the front end error name.
	final Map<String, ErrorCodeInfo> frontEndCodeToInfo = {};

	/// Map whose keys are the CFE errors for which analyzer errors should be
	/// automatically generated, and whose values are the corresponding analyzer
	/// error name. (Names are simple identifiers; they are not prefixed by the
	/// class name `ParserErrorCode`)
	final Map<ErrorCodeInfo, String> infoToAnalyzerCode = {};

	/// Map whose keys are the CFE errors for which analyzer errors should be
	/// automatically generated, and whose values are the front end error name.
	final Map<ErrorCodeInfo, String> infoToFrontEndCode = {};

	CfeToAnalyzerErrorCodeTables._(Map<String, FrontEndErrorCodeInfo> messages) {
	for (var entry in messages.entries) {
	var errorCodeInfo = entry.value;
	var index = errorCodeInfo.index;
	if (index == null \|\| errorCodeInfo.analyzerCode.length != 1) {
	continue;
	}
	var frontEndCode = entry.key;
	if (index < 1) {
	throw '''
	$frontEndCode specifies index $index but indices must be 1 or greater.
	For more information run:
	pkg/front_end/tool/fasta generate-messages
	''';
	}
	if (indexToInfo.length <= index) {
	indexToInfo.length = index + 1;
	}
	var previousEntryForIndex = indexToInfo[index];
	if (previousEntryForIndex != null) {
	throw 'Index $index used by both '
	'${infoToFrontEndCode[previousEntryForIndex]} and $frontEndCode';
	}
	indexToInfo[index] = errorCodeInfo;
	frontEndCodeToInfo[frontEndCode] = errorCodeInfo;
	infoToFrontEndCode[errorCodeInfo] = frontEndCode;
	var analyzerCodeLong = errorCodeInfo.analyzerCode.single;
	var expectedPrefix = 'ParserErrorCode.';
	if (!analyzerCodeLong.startsWith(expectedPrefix)) {
	throw 'Expected all analyzer error codes to be prefixed with '
	'${json.encode(expectedPrefix)}. Found '
	'${json.encode(analyzerCodeLong)}.';
	}
	var analyzerCode = analyzerCodeLong.substring(expectedPrefix.length);
	infoToAnalyzerCode[errorCodeInfo] = analyzerCode;
	var previousEntryForAnalyzerCode = analyzerCodeToInfo[analyzerCode];
	if (previousEntryForAnalyzerCode != null) {
	throw 'Analyzer code $analyzerCode used by both '
	'${infoToFrontEndCode[previousEntryForAnalyzerCode]} and '
	'$frontEndCode';
	}
	analyzerCodeToInfo[analyzerCode] = errorCodeInfo;
	}
	for (int i = 1; i < indexToInfo.length; i++) {
	if (indexToInfo[i] == null) {
	throw 'Indices are not consecutive; no error code has index $i.';
	}
	}
	}
	}

	/// Information about a code generated class derived from `ErrorCode`.
	class ErrorClassInfo {
	/// A list of additional import URIs that are needed by the code generated
	/// for this class.
	final List<String> extraImports;

	/// The file path (relative to the root of `pkg/analyzer`) of the generated
	/// file containing this class.
	final String filePath;

	/// True if this class should contain error messages extracted from the front
	/// end's `messages.yaml` file.
	///
	/// Note: at the moment we only support extracting front end error messages to
	/// a single error class.
	final bool includeCfeMessages;

	/// The name of this class.
	final String name;

	/// The severity of errors in this class, or `null` if the severity should be
	/// based on the [type] of the error.
	final String? severity;

	/// The superclass of this class.
	final String superclass;

	/// The type of errors in this class.
	final String type;

	const ErrorClassInfo(
	{this.extraImports = const [],
	required this.filePath,
	this.includeCfeMessages = false,
	required this.name,
	this.severity,
	this.superclass = 'ErrorCode',
	required this.type});

	/// Generates the code to compute the severity of errors of this class.
	String get severityCode {
	var severity = this.severity;
	if (severity == null) {
	return '$typeCode.severity';
	} else {
	return 'ErrorSeverity.$severity';
	}
	}

	/// Generates the code to compute the type of errors of this class.
	String get typeCode => 'ErrorType.$type';
	}

	/// In-memory representation of error code information obtained from either the
	/// analyzer or the front end's `messages.yaml` file. This class contains the
	/// common functionality supported by both formats.
	abstract class ErrorCodeInfo {
	/// If present, a documentation comment that should be associated with the
	/// error in code generated output.
	final String? comment;

	/// If the error code has an associated correctionMessage, the template for
	/// it.
	final String? correctionMessage;

	/// If present, user-facing documentation for the error.
	final String? documentation;

	/// `true` if diagnostics with this code have documentation for them that has
	/// been published.
	final bool hasPublishedDocs;

	/// Indicates whether this error is caused by an unresolved identifier.
	final bool isUnresolvedIdentifier;

	/// The problemMessage for the error code.
	final String problemMessage;

	/// If present, indicates that this error code has a special name for
	/// presentation to the user, that is potentially shared with other error
	/// codes.
	final String? sharedName;

	/// If present, indicates that this error code has been renamed from
	/// [previousName] to its current name (or [sharedName]).
	final String? previousName;

	ErrorCodeInfo(
	{this.comment,
	this.documentation,
	this.hasPublishedDocs = false,
	this.isUnresolvedIdentifier = false,
	this.sharedName,
	required this.problemMessage,
	this.correctionMessage,
	this.previousName});

	/// Decodes an [ErrorCodeInfo] object from its YAML representation.
	ErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
	: this(
	comment: yaml['comment'] as String?,
	correctionMessage: yaml['correctionMessage'] as String?,
	documentation: yaml['documentation'] as String?,
	hasPublishedDocs: yaml['hasPublishedDocs'] as bool? ?? false,
	isUnresolvedIdentifier:
	yaml['isUnresolvedIdentifier'] as bool? ?? false,
	problemMessage: yaml['problemMessage'] as String,
	sharedName: yaml['sharedName'] as String?,
	previousName: yaml['previousName'] as String?);

	/// Given a messages.yaml entry, come up with a mapping from placeholder
	/// patterns in its message strings to their corresponding indices.
	Map<String, int> computePlaceholderToIndexMap() {
	var mapping = <String, int>{};
	for (var value in [problemMessage, correctionMessage]) {
	if (value is! String) continue;
	for (Match match in _placeholderPattern.allMatches(value)) {
	// CFE supports a bunch of formatting options that analyzer doesn't;
	// make sure none of those are used.
	if (match.group(0) != '#${match.group(1)}') {
	throw 'Template string ${json.encode(value)} contains unsupported '
	'placeholder pattern ${json.encode(match.group(0))}';
	}

	mapping[match.group(0)!] ??= mapping.length;
	}
	}
	return mapping;
	}

	/// Generates a dart declaration for this error code, suitable for inclusion
	/// in the error class [className]. [errorCode] is the name of the error code
	/// to be generated.
	String toAnalyzerCode(String className, String errorCode) {
	var out = StringBuffer();
	out.writeln('$className(');
	out.writeln("'${sharedName ?? errorCode}',");
	final placeholderToIndexMap = computePlaceholderToIndexMap();
	out.writeln(
	json.encode(convertTemplate(placeholderToIndexMap, problemMessage)) +
	',');
	final correctionMessage = this.correctionMessage;
	if (correctionMessage is String) {
	out.write('correctionMessage: ');
	out.writeln(json.encode(
	convertTemplate(placeholderToIndexMap, correctionMessage)) +
	',');
	}
	if (hasPublishedDocs) {
	out.writeln('hasPublishedDocs:true,');
	}
	if (isUnresolvedIdentifier) {
	out.writeln('isUnresolvedIdentifier:true,');
	}
	if (sharedName != null) {
	out.writeln("uniqueName: '$errorCode',");
	}
	out.write(');');
	return out.toString();
	}

	/// Generates dart comments for this error code.
	String toAnalyzerComments({String indent = ''}) {
	var out = StringBuffer();
	var comment = this.comment;
	if (comment != null) {
	out.writeln('$indent/**');
	for (var line in comment.split('\n')) {
	out.writeln('$indent *${line.isEmpty ? '' : ' '}$line');
	}
	out.writeln('$indent */');
	}
	var documentation = this.documentation;
	if (documentation != null) {
	for (var line in documentation.split('\n')) {
	out.writeln('$indent//${line.isEmpty ? '' : ' '}$line');
	}
	}
	return out.toString();
	}

	/// Encodes this object into a YAML representation.
	Map<Object?, Object?> toYaml() => {
	if (sharedName != null) 'sharedName': sharedName,
	'problemMessage': problemMessage,
	if (correctionMessage != null) 'correctionMessage': correctionMessage,
	if (isUnresolvedIdentifier) 'isUnresolvedIdentifier': true,
	if (hasPublishedDocs) 'hasPublishedDocs': true,
	if (comment != null) 'comment': comment,
	if (documentation != null) 'documentation': documentation,
	};
	}

	/// In-memory representation of error code information obtained from the front
	/// end's `messages.yaml` file.
	class FrontEndErrorCodeInfo extends ErrorCodeInfo {
	/// The set of analyzer error codes that corresponds to this error code, if
	/// any.
	final List<String> analyzerCode;

	/// The index of the error in the analyzer's `fastaAnalyzerErrorCodes` table.
	final int? index;

	FrontEndErrorCodeInfo.fromYaml(Map<Object?, Object?> yaml)
	: analyzerCode = _decodeAnalyzerCode(yaml['analyzerCode']),
	index = yaml['index'] as int?,
	super.fromYaml(yaml);

	@override
	Map<Object?, Object?> toYaml() => {
	if (analyzerCode.isNotEmpty)
	'analyzerCode': _encodeAnalyzerCode(analyzerCode),
	if (index != null) 'index': index,
	...super.toYaml(),
	};

	static List<String> _decodeAnalyzerCode(Object? value) {
	if (value == null) {
	return const [];
	} else if (value is String) {
	return [value];
	} else if (value is List) {
	return [for (var s in value) s as String];
	} else {
	throw 'Unrecognized analyzer code: $value';
	}
	}

	static Object _encodeAnalyzerCode(List<String> analyzerCode) {
	if (analyzerCode.length == 1) {
	return analyzerCode.single;
	} else {
	return analyzerCode;
	}
	}
	}