A package for creating, parsing, comparing, and sharing Dart language versions.

Installation

To use package:language_version and access its language version support, first add it as a dependency in your pubspec.yaml file:

dart pub add language_version

Usage

The package contains two built-in libraries:

• package:language_version/language_version.dart

  Provides the LanguageVersion type for creating and comparing language versions, as well as for sharing between libraries and packages.

• package:language_version/parse.dart

  Provides the parseLanguageVersion and tryParseLanguageVersion functions for parsing language version strings into LanguageVersion objects.

Create language versions

You can manually create a LanguageVersion by specifying a major and minor version number pair.

import 'package:language_version/language_version.dart';

// Create a language version for Dart 3.5:
final version = LanguageVersion(3, 5);

// Access the major and minor version numbers and the string representation:
print('Major version number: ${version.major}'); // Major version number: 3
print('Minor version number: ${version.minor}'); // Minor version number: 5
print('Language version: $version'); // Language version: 3.5

Compare language versions

Language versions can be compared using the standard equality and comparison operators:

final version2_12 = LanguageVersion(2, 12);
final version3_0 = LanguageVersion(3, 0);
final version3_5 = LanguageVersion(3, 5);

// Check for equality:
if (version2_12 != currentLanguageVersion) {
  print('$version2_12 is not the current language version.');
} else if (version2_12 == previousLanguageVersion) {
  print('$version2_12 was the previous language version.');
}

// Compare different language versions:
if (version3_0 > version2_12) {
  print('Language version $version3_0 is newer than $version2_12.');
}

if (version3_5 >= version3_0) {
  print('Language version $version3_5 is at least as new as $version3_0.');
}

// Check if a language version meets a minimum requirement:
final nullAwareElementsLanguageVersion = LanguageVersion(3, 8);
final currentLanguageVersion = LanguageVersion(3, 9);

if (currentLanguageVersion >= nullAwareElementsLanguageVersion) {
  print('Null-aware collection elements are supported!');
}

// Sort language versions with the compareTo function:
final versions = [version3_5, version2_12, version3_0];
versions.sort((a, b) => a.compareTo(b));
print(versions); // [2.12, 3.0, 3.5]

Parse language version strings

To parse a language version from a string, use the parseLanguageVersion function:

import 'package:language_version/parse.dart';

// Parse a valid version string.
final version = parseLanguageVersion('3.5');
print('Parsed language version: $version'); // Parsed version: 3.5

// An invalid format or invalid version numbers results
// in an exception being throw.
try {
  final invalidVersion = parseLanguageVersion('3.5.1');
} on LanguageVersionFormatException catch (e) {
  print('Invalid format: ${e.message}');
}

If you don't care about the reason for a parse failure, you can use tryParseLanguageVersion which instead returns null if the input is invalid:

import 'package:language_version/parse.dart';

final validVersionString = '2.19';
final validVersion = tryParseLanguageVersion(validVersionString);
if (validVersion != null) {
  print('Successfully parsed language version: "$validVersion".');
}

final invalidVersionString = 'invalid';
final invalidVersion = tryParseLanguageVersion(invalidVersionString);
if (invalidVersion == null) {
  print('Failed to parse language version from "$invalidVersionString".');
}

if (tryParseLanguageVersion('3.0') case final languageVersion?) {
  print('Parsed language version: $languageVersion');
} else {
  print('Failed to parse language version.');
}

Combined example

Here's a larger example that demonstrates extracting a language version from the current SDK, then parsing and checking for language feature support:

import 'dart:io' show Platform;

import 'package:language_version/language_version.dart';
import 'package:language_version/parse.dart';

void main() {
  // Extract language version from the current SDK.
  final currentSdkVersion = Platform.version;
  final extractedLanguageVersion = currentSdkVersion
      .split('.')
      .take(2)
      .join('.');

  if (tryParseLanguageVersion(extractedLanguageVersion)
      case final languageVersion?) {
    print('Latest supported language version by this SDK: $languageVersion');

    // Check for null safety support.
    const nullSafetyVersion = LanguageVersion(2, 12);
    if (languageVersion >= nullSafetyVersion) {
      print('This SDK supports Dart code with null safety!');
    }

    // Check for other features.
    const wildcardsVersion = LanguageVersion(3, 7);
    if (languageVersion < wildcardsVersion) {
      print('This SDK does not support Dart code with wildcard variables.');
    }
  }
}