Add support for using and await using (#23)

* update to latest test suite

* create experimental flags

* port parsing logic

* Update src/Acornima/ExperimentalESFeatures.cs

* add configuration to allow top-level using

* fix line break test

* fix scope

* use localized messages

* Adjust IsLet

* Simplify IsUsingKeyword usage by removing redundant calls

* Update TryGetInternedString

* Update documentation of VariableDeclarator.Id

* Fix source gen tests

* Correct async function and await using lookaheads

* Disallow explicit resource management for ES versions not supporting async/await

* Improve AST to JSON conversion + remove the each property of for-of statements

* Port tests from acornjs

* Adjust implementation to match the error reporting behavior of V8

* Add tests for some edge cases + AllowTopLevelUsing

* Improve documentation of AllowTopLevelUsing

---------

Co-authored-by: adams85 <[email protected]>
Co-authored-by: Adam Simon <[email protected]>

Author: lahma

src/Acornima.Extras/AstToJsonConverter.cs

@@ -152,16 +152,41 @@ protected void Member(string name, int value)
         _writer.Number(value);
     }
 
-    private static readonly ConditionalWeakTable<Type, IDictionary> s_enumMap = new();
+    protected void Member(string name, SourceType sourceType)
+    {
+        var value = sourceType switch
+        {
+            SourceType.Script => "script",
+            SourceType.Module => "module",
+            _ => "unknown"
+        };
+
+        Member(name, value);
+    }
+
+    protected void Member(string name, PropertyKind propertyKind)
+    {
+        var value = propertyKind switch
+        {
+            PropertyKind.Init => "init",
+            PropertyKind.Get => "get",
+            PropertyKind.Set => "set",
+            PropertyKind.Constructor => "constructor",
+            PropertyKind.Method => "method",
+            PropertyKind.Property => "property",
+            _ => "unknown"
+        };
+
+        Member(name, value);
+    }
 
-    protected void Member<T>(string name, T value) where T : struct, Enum
+    protected void Member(string name, VariableDeclarationKind declarationKind)
     {
-        var map = (Dictionary<T, string>)s_enumMap.GetValue(value.GetType(), t =>
-            t.GetRuntimeFields()
-                .Where(f => f.IsStatic)
-                .ToDictionary(f => (T)f.GetValue(null)!, f => f.Name.ToLowerInvariant()));
+        var value = declarationKind is >= VariableDeclarationKind.Var and <= VariableDeclarationKind.AwaitUsing
+            ? VariableDeclaration.GetVariableDeclarationKindToken(declarationKind)
+            : "unknown";
 
-        Member(name, map[value]);
+        Member(name, value);
     }
 
     protected void Member<T>(string name, in NodeList<T> nodes) where T : Node?
@@ -514,7 +539,6 @@ private IClass VisitClass(IClass node)
             Member("left", node.Left);
             Member("right", node.Right);
             Member("body", node.Body);
-            Member("each", false);
         }
 
         return node;

src/Acornima/Ast/Property.cs

@@ -21,7 +21,7 @@ private protected Property(PropertyKind kind, Expression key, Node value, bool c
     public Expression Key { [MethodImpl(MethodImplOptions.AggressiveInlining)] get; }
 
     /// <remarks>
-    /// When property of an object literal: <see cref="Expression"/> (incl. <see cref="SpreadElement"/> and <see cref="FunctionExpression"/> for getters/setters/methods) <br />
+    /// When property of an object literal: <see cref="Expression"/> (incl. <see cref="SpreadElement"/> and <see cref="FunctionExpression"/> for getters/setters/methods)<br />
     /// When property of an object pattern: <see cref="Identifier"/> | <see cref="MemberExpression"/> (in assignment contexts only) | <see cref="ArrayPattern"/> | <see cref="ObjectPattern"/> | <see cref="AssignmentPattern"/> | <see cref="RestElement"/>
     /// </remarks>
     public Node Value { [MethodImpl(MethodImplOptions.AggressiveInlining)] get; }

src/Acornima/Ast/VariableDeclaration.cs

@@ -15,6 +15,8 @@ public static string GetVariableDeclarationKindToken(VariableDeclarationKind kin
             VariableDeclarationKind.Var => "var",
             VariableDeclarationKind.Let => "let",
             VariableDeclarationKind.Const => "const",
+            VariableDeclarationKind.Using => "using",
+            VariableDeclarationKind.AwaitUsing => "await using",
             _ => ThrowArgumentOutOfRangeException(nameof(kind), kind.ToString(), null)
         };
     }

src/Acornima/Ast/VariableDeclarationKind.cs

@@ -5,5 +5,7 @@ public enum VariableDeclarationKind
     Unknown,
     Var,
     Let,
-    Const
+    Const,
+    Using,
+    AwaitUsing
 }

src/Acornima/Ast/VariableDeclarator.cs

@@ -13,7 +13,8 @@ public VariableDeclarator(Node id, Expression? init)
     }
 
     /// <remarks>
-    /// <see cref="Identifier"/> | <see cref="ArrayPattern"/> | <see cref="ObjectPattern"/>
+    /// In the case of var, let or const variable declarations: <see cref="Identifier"/> | <see cref="ArrayPattern"/> | <see cref="ObjectPattern"/><br />
+    /// In the case of using and await using const variable declarations: <see cref="Identifier"/>
     /// </remarks>
     public Node Id { [MethodImpl(MethodImplOptions.AggressiveInlining)] get; }
     public Expression? Init { [MethodImpl(MethodImplOptions.AggressiveInlining)] get; }

src/Acornima/ExperimentalESFeatures.cs

@@ -22,5 +22,10 @@ public enum ExperimentalESFeatures
     /// </summary>
     RegExpDuplicateNamedCapturingGroups = 1 << 2,
 
-    All = Decorators | ImportAttributes | RegExpDuplicateNamedCapturingGroups
+    /// <summary>
+    /// Explicit resource management feature as specified by this <seealso href="https://github.com/tc39/proposal-explicit-resource-management">proposal</seealso>. Available only when <see cref="ParserOptions.EcmaVersion"/> >= ES2017.
+    /// </summary>
+    ExplicitResourceManagement = 1 << 3,
+
+    All = Decorators | ImportAttributes | RegExpDuplicateNamedCapturingGroups | ExplicitResourceManagement
 }

src/Acornima/Parser.State.cs

@@ -309,6 +309,18 @@ private bool AllowNewDotTarget
             || (CurrentThisScope._flags & (ScopeFlags.Function | ScopeFlags.ClassStaticBlock | ScopeFlags.InClassFieldInit)) != 0;
     }
 
+    private bool AllowUsing
+    {
+        // https://github.com/acornjs/acorn/blob/8.11.3/acorn/src/state.js > `get allowUsing`
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get
+        {
+            var flags = CurrentScope._flags;
+            return (flags & ScopeFlags.Switch) == 0 && (_inModule || (flags & ScopeFlags.Top) == 0 || _options._allowTopLevelUsing);
+        }
+    }
+
     private bool InClassStaticBlock
     {
         // https://github.com/acornjs/acorn/blob/8.11.3/acorn/src/state.js > `get inClassStaticBlock`