Generate methods for reporting problems.

pkg/front_end/tool/_fasta/generate_messages.dart

+// Copyright (c) 2017, 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:io';
+
+import 'dart:isolate';
+
+import 'dart:convert';
+
+import 'package:yaml/yaml.dart' show loadYaml;
+
+import 'package:front_end/src/fasta/parser/error_kind.dart' show ErrorKind;
+
+main(List<String> arguments) async {
+  var port = new ReceivePort();
+  Uri messagesFile = Platform.script.resolve("../../messages.yaml");
+  Map yaml = loadYaml(await new File.fromUri(messagesFile).readAsStringSync());
+  Set<String> names =
+      new Set<String>.from(yaml.keys.map((String s) => "ErrorKind.$s"));

[Siggi Cherem (dart-lang), 2017/03/17 21:57:52]

Oh, I see that you are trying to match error kinds and keys in the yaml file. Do
we ever expect to have more errors that are not covered by this enum? For
example, errors from the type-system or errors that we want to still collect in
our yaml file, but that are produced by other tools, like analyzer?

If so, it might be worth having a name that can be different than the
error-kind, for example:

some_error:
  frontend_kind: SomeError
  message: ...
  ...

[ahe, 2017/03/22 11:06:56]

Actually, I was hoping to replace ErrorKind with invocations of methods in this
CL.

+  Set<String> kinds =
+      new Set<String>.from(ErrorKind.values.map((kind) => "$kind"));
+  Set<String> difference = kinds.difference(names);
+  if (difference.isNotEmpty) {
+    Uri errorKindFile = await Isolate.resolvePackageUri(
+        Uri.parse('package:front_end/src/fasta/parser/error_kind.dart'));
+    throw "Mismatch between '${errorKindFile.toFilePath()}' and"
+        " '${messagesFile.toFilePath()}': ${difference.join(' ')}.";
+  }
+  StringBuffer sb = new StringBuffer();
+
+  sb.writeln("""
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// NOTE: THIS FILE IS GENERATED. DO NOT EDIT.
+//
+// Instead modify 'pkg/front_end/messages.yaml' and run
+// 'pkg/front_end/tool/_fasta/generate_messages.dart' to update.
+
+library fasta.problems;
+
+import 'package:front_end/src/fasta/scanner/token.dart' show Token;
+
+import 'package:front_end/src/fasta/parser/error_kind.dart' show ErrorKind;
+""");
+
+  yaml.forEach((String name, description) {
+    while (description is String) {
+      description = yaml[description];
+    }
+    Map map = description;
+    sb.writeln(compileTemplate(name, map['template'], map['tip']));
+  });
+
+  Uri problemsFile = await Isolate.resolvePackageUri(
+      Uri.parse('package:front_end/src/fasta/problems.dart'));
+  await new File.fromUri(problemsFile).writeAsString("$sb", flush: true);
+  port.close();
+}
+
+final RegExp placeholderPattern = new RegExp("#[a-zA-Z0-9_]+");
+
+String compileTemplate(String name, String template, String tip) {
+  var parameters = new Set<String>();
+  var conversions = new Set<String>();
+  var arguments = new Set<String>();
+  for (Match match in placeholderPattern.allMatches("$template$tip")) {
+    switch (match[0]) {
+      case "#character":
+        parameters.add("String character");
+        arguments.add("'character': character,");
+        break;
+
+      case "#unicode":
+        parameters.add("int codePoint");
+        conversions.add("String unicode = "
+            "\"(U+\${codePoint.toRadixString(16).padLeft(4, '0')})\";");
+        arguments.add("'codePoint': codePoint,");
+        break;
+
+      case "#name":
+        parameters.add("String name");
+        arguments.add("'name': name,");
+        break;
+
+      case "#lexeme":
+        parameters.add("Token token");
+        conversions.add("String lexeme = token.lexeme;");
+        arguments.add("'token': token,");
+        break;
+
+      case "#string":
+        parameters.add("String string");
+        arguments.add("'string': string,");
+        break;
+    }
+  }
+
+  String interpolate(String name, String text) {
+    if (text == null) return "";

[Siggi Cherem (dart-lang), 2017/03/17 21:57:52]

maybe generate a comment instead? e.g.:
  /* no $name provided. */

to avoid the empty line in the generated output?

[ahe, 2017/03/22 11:06:56]

I'll use a StringBuffer in a follow-up CL.

+    return "  '$name': "
+        "\"${text.replaceAll(r'$', r'\$').replaceAll('#', '\$')}\",";
+  }
+
+  return """
+problem$name(${parameters.join(', ')}) {
+  // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+  ${conversions.join('\n  ')}
+  return {
+  ${interpolate('message', template)}
+  ${interpolate('tip', tip)}
+    'code': ErrorKind.$name,
+    'arguments': {
+      ${arguments.join('\n      ')}
+    },
+  };
+}
+""";
+}