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code_transformers/lib/messages/messages.dart

-// Copyright (c) 2014, 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 messages templates and an adapter for TransformLogger to be able
-/// report error messages from transformers and refer to them in a consistent
-/// manner long term.
-library code_transformers.messages;
-
-// Note: this library purposely doesn't depend on dart:io, dart:html, or barback
-// so it can easily be used both in the transformers and in client-side apps
-// (for example in the log_injector).
-import 'dart:collection' show LinkedHashMap;
-import 'package:source_span/source_span.dart';
-
-/// A globally unique identifier for an error message. This identifier should be
-/// stable, that is, it should never change after it is asigned to a particular
-/// message. That allows us to document our error messages and make them
-/// searchable for prosperity.
-class MessageId implements Comparable {
-  /// Name of the package that declares this message.
-  final String package;
-
-  /// Message identifier number, unique within the package.
-  final int id;
-
-  const MessageId(this.package, this.id);
-
-  static const MessageId NOT_SPECIFIED = const MessageId('unknown', 0);
-
-  /// Serialize this message. We use a string and not a map to encode ids so
-  /// they can be used as keys in JSON maps.
-  String toJson() => toString();
-
-  toString() => '${package}#$id';
-
-  int compareTo(MessageId other) {
-    var res = package.compareTo(other.package);
-    if (res != 0) return res;
-    return id.compareTo(other.id);
-  }
-
-  /// Creates a new [MessageId] from an encoded value produced via [toJson].
-  factory MessageId.fromJson(data) {
-    var index = data.lastIndexOf('#');
-    if (index == -1) throw 'Invalid message id: $data';
-    return new MessageId(
-        data.substring(0, index), int.parse(data.substring(index + 1)));
-  }
-
-  operator ==(MessageId other) => package == other.package && id == other.id;
-  int get hashCode => 31 * package.hashCode + id;
-}
-
-/// An instance of an error message. These are typically produced from a
-/// [MessageTemplate].
-class Message {
-  /// A globally unique identifier for this message.
-  final MessageId id;
-
-  /// A snippet message that is presented to the user.
-  final String snippet;
-
-  const Message(this.id, this.snippet);
-
-  const Message.unknown(this.snippet) : id = MessageId.NOT_SPECIFIED;
-
-  /// Serializes this message to JSON.
-  Map toJson() => {'id': id.toJson(), 'snippet': snippet};
-  String toString() => 'id: $id, snippet: $snippet';
-
-  /// Creates a new [Message] from an encoded value produced via [toJson].
-  factory Message.fromJson(data) =>
-      new Message(new MessageId.fromJson(data['id']), data['snippet']);
-}
-
-/// Template for a message. Templates can include placeholders to indicate
-/// values that are different for each instance of the error. Calling [create]
-/// will generate the actual message, with the placeholders replaced with
-/// values. If there are no placeholders, an instance of [MessageTemplate] is a
-/// valid instance of [Message] as well.
-class MessageTemplate implements Message {
-  /// Unique and stable id for the message.
-  final MessageId id;
-
-  /// Template message with placeholders of the form `%-name-%`.
-  final String snippetTemplate;
-
-  /// This returns the message snippet, only if it the template has no
-  /// placeholders, otherwise this throws an exception. Most messages have no
-  /// placeholder arguments, in those cases, the snippet  can be computed
-  /// without specifying any arguments (exactly like calling `create()` with no
-  /// arguments).
-  String get snippet => _createSnippet();
-
-  /// Short description of the error message, typically used as a title of the
-  /// error message in autogenerated documentation. This should be a single
-  /// phrase, and cannot use placeholders.
-  final String description;
-
-  /// Additional details about this error message. These are used to
-  /// automatically generate documentation.
-  final String details;
-
-  const MessageTemplate(
-      this.id, this.snippetTemplate, this.description, this.details);
-
-  static final _placeholderPattern = new RegExp(r"%-(\w*)-%");
-
-  _createSnippet([Map args = const {}, bool fillUnknowns = false]) {
-    var snippet = snippetTemplate.replaceAllMapped(_placeholderPattern, (m) {
-      var arg = m.group(1);
-      var value = args[arg];
-      if (value != null) return '$value';
-      if (fillUnknowns) return '';
-      throw "missing argument $arg, for error message: $snippetTemplate";
-    });
-    return snippet;
-  }
-
-  create([Map args = const {}, bool fillUnknowns = false]) =>
-      new Message(id, _createSnippet(args, fillUnknowns));
-
-  /// Serializes this message to JSON.
-  Map toJson() => create().toJson();
-  String toString() => '${toJson()}';
-}
-
-/// Represents an actual log entry for a build error message. Including the
-/// actual message, its severity level (warning, error, etc), and a source span
-/// for a code location that is revelant to the message.
-class BuildLogEntry {
-  /// The actual message.
-  final Message message;
-
-  /// Severity level.
-  final String level;
-
-  /// Location associated with this message, if any.
-  final SourceSpan span;
-
-  BuildLogEntry(this.message, this.span, this.level);
-
-  /// Creates a new [BuildLogEntry] from an encoded value produced via [toJson].
-  factory BuildLogEntry.fromJson(Map data) {
-    var spanData = data['span'];
-    var span = null;
-    if (spanData != null) {
-      var locData = spanData['start'];
-      var start = new SourceLocation(locData['offset'],
-          sourceUrl: Uri.parse(locData['url']),
-          line: locData['line'],
-          column: locData['column']);
-      locData = spanData['end'];
-      var end = new SourceLocation(locData['offset'],
-          sourceUrl: Uri.parse(locData['url']),
-          line: locData['line'],
-          column: locData['column']);
-      span = new SourceSpan(start, end, spanData['text']);
-    }
-    return new BuildLogEntry(
-        new Message.fromJson(data['message']), span, data['level']);
-  }
-
-  /// Serializes this log entry to JSON.
-  Map toJson() {
-    var data = {'level': level, 'message': message.toJson(),};
-    if (span != null) {
-      data['span'] = {
-        'start': {
-          'url': span.start.sourceUrl.toString(),
-          'offset': span.start.offset,
-          'line': span.start.line,
-          'column': span.start.column,
-        },
-        'end': {
-          'url': span.end.sourceUrl.toString(),
-          'offset': span.end.offset,
-          'line': span.end.line,
-          'column': span.end.column,
-        },
-        'text': span.text,
-      };
-    }
-    return data;
-  }
-  String toString() => '${toJson()}';
-}
-
-/// A table of entries, that clusters error messages by id.
-class LogEntryTable {
-  final Map<MessageId, List<BuildLogEntry>> entries;
-
-  LogEntryTable() : entries = new LinkedHashMap();
-
-  /// Creates a new [LogEntryTable] from an encoded value produced via [toJson].
-  factory LogEntryTable.fromJson(Map json) {
-    var res = new LogEntryTable();
-    for (String key in json.keys) {
-      var id = new MessageId.fromJson(key);
-      res.entries[id] =
-          json[key].map((v) => new BuildLogEntry.fromJson(v)).toList();
-    }
-    return res;
-  }
-
-  /// Serializes this entire table as JSON.
-  Map toJson() {
-    var res = {};
-    entries.forEach((key, value) {
-      res['$key'] = value.map((e) => e.toJson()).toList();
-    });
-    return res;
-  }
-  String toString() => '${toJson()}';
-
-  void add(BuildLogEntry entry) {
-    entries.putIfAbsent(entry.message.id, () => []).add(entry);
-  }
-  void addAll(LogEntryTable other) {
-    for (var key in other.entries.keys) {
-      var values = entries.putIfAbsent(key, () => []);
-      values.addAll(other.entries[key]);
-    }
-  }
-}