Use latest Dart Sass and release migrator 2.0.0 (#251)

- Deleted the obsolete `media-logic` migrator (breaking change bumps
  version to 2.0.0).
- Moved off of the tuple package to native Dart tuples.
- Fixed the `calc-interpolation` and `division` migrators to eliminate
  their use of the removed `CalculationExpression` AST node.
- Created a new `ScopedAstVisitor` that uses `Scope` to track Sass
  member declarations. `MigrationVisitor` and `_ReferenceVisitor`
  now extend this.
- Refactored the `division` migrator to use patterns.

CHANGELOG.md

@@ -1,21 +1,40 @@
-## 1.8.2
+## 2.0.0
+
+* **Breaking change**: The `media-logic` migrator has been removed as the
+  [corresponding breaking change][media logic] has been completed in Dart Sass.
+  If you still need to migrate legacy code, use migrator version 1.8.1.
+
+  [media logic]: https://sass-lang.com/documentation/breaking-changes/media-logic/
+
+* Update to be compatible with the latest version of the Dart Sass AST.
 
 ### Calc Functions Interpolation Migrator
 
-* Add parentheses in place of interpolation when necessary to preserve the evaluation order.
+* Add parentheses in place of interpolation when necessary to preserve the
+  evaluation order.
+
+### Division Migrator
+
+* `/` division should now be left untouched in all CSS calculation functions.
+  This was already the case for `calc`, `clamp`, `min`, and `max`, but it now
+  applies to the new functions that Dart Sass 1.67.0 added support for.
 
 ## 1.8.1
 
 ### Calc Functions Interpolation Migrator
 
-* Migration for more than one interpolation or expressions in a calc function parameter.
+* Migration for more than one interpolation or expressions in a calc function
+  parameter.
 
 ## 1.8.0
 
 ### Calc Functions Interpolation Migrator
 
-* Removes interpolation in calculation functions `calc()`, `clamp()`, `min()`, and `max()`. 
-  See the [scss/function-calculation-no-interpolation](https://github.com/stylelint-scss/stylelint-scss/tree/master/src/rules/function-calculation-no-interpolation) rule for more information.
+* Removes interpolation in calculation functions `calc()`, `clamp()`, `min()`,
+  and `max()`. See the [scss/function-calculation-no-interpolation] rule for
+  more information.
+
+  [scss/function-calculation-no-interpolation]: https://github.com/stylelint-scss/stylelint-scss/tree/master/src/rules/function-calculation-no-interpolation
 
 ## 1.7.3
 

lib/src/migration_visitor.dart

@@ -13,6 +13,8 @@ import 'package:source_span/source_span.dart';
 
 import 'exception.dart';
 import 'patch.dart';
+import 'util/scope.dart';
+import 'util/scoped_ast_visitor.dart';
 
 /// A visitor that migrates a stylesheet.
 ///
@@ -24,8 +26,7 @@ import 'patch.dart';
 /// If [migrateDependencies] is enabled, this visitor will construct and run a
 /// new instance of itself (using [newInstance]) each time it encounters an
 /// `@import` or `@use` rule.
-abstract class MigrationVisitor
-    with RecursiveStatementVisitor, RecursiveAstVisitor {
+abstract class MigrationVisitor extends ScopedAstVisitor {
   /// A mapping from URLs to migrated contents for stylesheets already migrated.
   final _migrated = <Uri, String>{};
 
@@ -117,26 +118,31 @@ abstract class MigrationVisitor
 
   /// Visits the stylesheet at [dependency], resolved based on the current
   /// stylesheet's URL and importer.
+  ///
+  /// When [forImport] is true, this preserves the [currentScope]. Otherwise,
+  /// the dependency is visited with a new global scope for the new module.
   @protected
   void visitDependency(Uri dependency, FileSpan context,
       {bool forImport = false}) {
     if (dependency.scheme == 'sass') return;
     var result = importCache.import(dependency,
         baseImporter: _importer, baseUrl: _currentUrl, forImport: forImport);
-    if (result != null) {
+    if (result case (var newImporter, var stylesheet)) {
       // If [dependency] comes from a non-relative import, don't migrate it,
       // because it's likely to be outside the user's repository and may even be
       // authored by a different person.
       //
       // TODO(nweiz): Add a flag to override this behavior for load paths
       // (#104).
-      if (result.item1 != _importer) return;
+      if (newImporter != _importer) return;
 
       var oldImporter = _importer;
-      _importer = result.item1;
-      var stylesheet = result.item2;
+      var oldScope = currentScope;
+      _importer = newImporter;
+      if (!forImport) currentScope = Scope();
       visitStylesheet(stylesheet);
       _importer = oldImporter;
+      currentScope = oldScope;
     } else {
       _missingDependencies.putIfAbsent(
           context.sourceUrl!.resolveUri(dependency), () => context);

lib/src/migrator.dart

@@ -93,7 +93,7 @@ abstract class Migrator extends Command<Map<Uri, String>> {
         throw MigrationException("Could not find Sass file at '$entrypoint'.");
       }
 
-      var migrated = migrateFile(importCache, tuple.item2, tuple.item1);
+      var migrated = migrateFile(importCache, tuple.$2, tuple.$1);
       migrated.forEach((file, contents) {
         if (allMigrated.containsKey(file) && contents != allMigrated[file]) {
           throw MigrationException(

lib/src/migrators/calc_interpolation.dart

@@ -33,12 +33,12 @@ class _CalculationInterpolationVisitor extends MigrationVisitor {
       : super(importCache, migrateDependencies);
 
   @override
-  void visitCalculationExpression(CalculationExpression node) {
+  void visitFunctionExpression(FunctionExpression node) {
     const calcFunctions = ['calc', 'clamp', 'min', 'max'];
     final interpolation = RegExp(r'\#{\s*[^}]+\s*}');
     final hasOperation = RegExp(r'[-+*/]+');
     if (calcFunctions.contains(node.name)) {
-      for (var arg in node.arguments) {
+      for (var arg in node.arguments.positional) {
         var newArg = arg.toString();
         for (var match in interpolation.allMatches(arg.toString())) {
           var noInterpolation =
@@ -58,6 +58,6 @@ class _CalculationInterpolationVisitor extends MigrationVisitor {
         }
       }
     }
-    super.visitCalculationExpression(node);
+    super.visitFunctionExpression(node);
   }
 }