blob: 311ce2e992c91ecc34c105a963e6691a956df0fe [file] [log] [blame]
// Copyright 2014 The Flutter Authors. 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:async';
import 'package:file/file.dart';
import 'package:package_config/package_config.dart';
import '../base/version.dart';
final RegExp _languageVersion = RegExp(r'\/\/\s*@dart\s*=\s*([0-9])\.([0-9]+)');
final RegExp _declarationEnd = RegExp('(import)|(library)|(part)');
const String _blockCommentStart = '/*';
const String _blockCommentEnd = '*/';
/// The first language version where null safety was available by default.
final LanguageVersion nullSafeVersion = LanguageVersion(2, 12);
LanguageVersion? _currentLanguageVersion;
/// Lookup the current Dart language version.
LanguageVersion currentLanguageVersion(FileSystem fileSystem, String flutterRoot) {
if (_currentLanguageVersion != null) {
return _currentLanguageVersion!;
}
// Either reading the file or parsing the version could fail on a corrupt Dart SDK.
// let it crash so it shows up in crash logging.
final File versionFile = fileSystem.file(fileSystem.path.join(flutterRoot, 'bin', 'cache', 'dart-sdk', 'version'));
if (!versionFile.existsSync() && _inUnitTest()) {
return LanguageVersion(2, 12);
}
final Version version = Version.parse(versionFile.readAsStringSync())!;
return _currentLanguageVersion = LanguageVersion(version.major, version.minor);
}
// Whether the tool is executing in a unit test.
bool _inUnitTest() {
return Zone.current[#test.declarer] != null;
}
/// Attempts to read the language version of a dart [file].
///
/// If this is not present, falls back to the language version defined in
/// [package]. If [package] is not provided and there is no
/// language version header, returns 2.12. This does not specifically check
/// for language declarations other than library, part, or import.
///
/// The specification for the language version tag is defined at:
/// https://github.com/dart-lang/language/blob/master/accepted/future-releases/language-versioning/feature-specification.md#individual-library-language-version-override
LanguageVersion determineLanguageVersion(File file, Package? package, String flutterRoot) {
int blockCommentDepth = 0;
// If reading the file fails, default to a null-safe version. The
// command will likely fail later in the process with a better error
// message.
List<String> lines;
try {
lines = file.readAsLinesSync();
} on FileSystemException {
return currentLanguageVersion(file.fileSystem, flutterRoot);
}
for (final String line in lines) {
final String trimmedLine = line.trim();
if (trimmedLine.isEmpty) {
continue;
}
// Check for the start or end of a block comment. Within a block
// comment, all language version declarations are ignored. Block
// comments can be nested, and the start or end may occur on
// the same line. This does not handle the case of invalid
// block comment combinations like `*/ /*` since that will cause
// a compilation error anyway.
bool sawBlockComment = false;
final int startMatches = _blockCommentStart.allMatches(trimmedLine).length;
final int endMatches = _blockCommentEnd.allMatches(trimmedLine).length;
if (startMatches > 0) {
blockCommentDepth += startMatches;
sawBlockComment = true;
}
if (endMatches > 0) {
blockCommentDepth -= endMatches;
sawBlockComment = true;
}
if (blockCommentDepth != 0 || sawBlockComment) {
continue;
}
// Check for a match with the language version.
final Match? match = _languageVersion.matchAsPrefix(trimmedLine);
if (match != null) {
final String rawMajor = match.group(1) ?? '';
final String rawMinor = match.group(2) ?? '';
try {
final int major = int.parse(rawMajor);
final int minor = int.parse(rawMinor);
return LanguageVersion(major, minor);
} on FormatException {
// Language comment was invalid in a way that the regexp did not
// anticipate.
break;
}
}
// Check for a declaration which ends the search for a language
// version.
if (_declarationEnd.matchAsPrefix(trimmedLine) != null) {
break;
}
}
// If the language version cannot be found, use the package version.
if (package != null) {
return package.languageVersion ?? currentLanguageVersion(file.fileSystem, flutterRoot);
}
// Default to current version.
return currentLanguageVersion(file.fileSystem, flutterRoot);
}