Support combining with/as and named arguments in render tag

Fluid.Tests/IncludeStatementTests.cs

@@ -614,5 +614,115 @@ public void IncludeTag_Caches_HandleFileSystemCasing()
                     // Ignore any exceptions
                 }
         }
+
+        [Fact]
+        public void RenderTag_With_And_NamedArguments()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("icon.liquid", "Icon: {{ icon }}, Class: {{ class }}");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            _parser.TryParse("{%- render 'icon' with 'rating-star', class: 'rating__star' -%}", out var template);
+            var result = template.Render(context);
+
+            Assert.Equal("Icon: rating-star, Class: rating__star", result);
+        }
+
+        [Fact]
+        public void RenderTag_With_As_And_NamedArguments()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("product.liquid", "Product: {{ p.title }}, Price: {{ price }}");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            context.SetValue("my_product", new { title = "Draft 151cm" });
+            _parser.TryParse("{% render 'product' with my_product as p, price: '$99' %}", out var template);
+            var result = template.Render(context);
+
+            Assert.Equal("Product: Draft 151cm, Price: $99", result);
+        }
+
+        [Fact]
+        public void RenderTag_With_MultipleNamedArguments()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("button.liquid", "Text: {{ button }}, Size: {{ size }}, Color: {{ color }}");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            _parser.TryParse("{% render 'button' with 'Click Me', size: 'large', color: 'blue' %}", out var template);
+            var result = template.Render(context);
+
+            Assert.Equal("Text: Click Me, Size: large, Color: blue", result);
+        }
+
+        [Fact]
+        public void RenderTag_For_And_NamedArguments()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("product.liquid", "Product: {{ product.title }}, Tag: {{ tag }} ");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            context.SetValue("products", new[] { new { title = "Draft 151cm" }, new { title = "Element 155cm" } });
+
+            var parseResult = _parser.TryParse("{% render 'product' for products, tag: 'sale' %}", out var template, out var error);
+            Assert.True(parseResult, $"Parse failed: {error}");
+
+            // Check the parsed statement
+            var statements = (template as Fluid.Parser.FluidTemplate).Statements;
+            var renderStmt = statements.FirstOrDefault() as RenderStatement;
+            Assert.NotNull(renderStmt);
+            Assert.NotNull(renderStmt.For);
+            Assert.Single(renderStmt.AssignStatements);
+            Assert.Equal("tag", renderStmt.AssignStatements[0].Identifier);
+
+            // Check that the For expression evaluates correctly
+            Assert.IsType<MemberExpression>(renderStmt.For);
+            var forValue = renderStmt.For.EvaluateAsync(context).GetAwaiter().GetResult();
+            var items = forValue.Enumerate(context).ToList();
+            Assert.Equal(2, items.Count);  // Should have 2 items
+
+            // Also check that For is really the "products" variable
+            var memberExpr = renderStmt.For as MemberExpression;
+            Assert.Single(memberExpr.Segments);
+            Assert.IsType<IdentifierSegment>(memberExpr.Segments[0]);
+            Assert.Equal("products", ((IdentifierSegment)memberExpr.Segments[0]).Identifier);
+
+            var result = template.Render(context);
+
+            Assert.Equal("Product: Draft 151cm, Tag: sale Product: Element 155cm, Tag: sale ", result);
+        }
+
+        [Fact]
+        public void RenderTag_For_As_And_NamedArguments()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("item.liquid", "Item: {{ i.name }}, Status: {{ status }} ");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            context.SetValue("items", new[] { new { name = "First" }, new { name = "Second" } });
+            _parser.TryParse("{% render 'item' for items as i, status: 'active' %}", out var template);
+            var result = template.Render(context);
+
+            Assert.Equal("Item: First, Status: active Item: Second, Status: active ", result);
+        }
+
+        [Fact]
+        public void RenderTag_NamedArguments_DoNotLeakToParentScope()
+        {
+            var fileProvider = new MockFileProvider();
+            fileProvider.Add("snippet.liquid", "{{ class }}");
+
+            var options = new TemplateOptions() { FileProvider = fileProvider, MemberAccessStrategy = UnsafeMemberAccessStrategy.Instance };
+            var context = new TemplateContext(options);
+            _parser.TryParse("{% render 'snippet', class: 'test' %}{{ class }}", out var template);
+            var result = template.Render(context);
+
+            Assert.Equal("test", result);
+        }
     }
 }

Fluid/Ast/RenderStatement.cs

@@ -82,19 +82,17 @@ public override async ValueTask<Completion> WriteToAsync(TextWriter writer, Text
                     previousScope.CopyTo(context.LocalScope);
 
                     context.SetValue(Alias ?? identifier, with);
-                    await template.RenderAsync(writer, encoder, context);
-                }
-                else if (AssignStatements.Count > 0)
-                {
-                    var length = AssignStatements.Count;
-                    for (var i = 0; i < length; i++)
+
+                    // Evaluate assign statements in the new scope if present
+                    if (AssignStatements.Count > 0)
                     {
-                        await AssignStatements[i].WriteToAsync(writer, encoder, context);
+                        var length = AssignStatements.Count;
+                        for (var i = 0; i < length; i++)
+                        {
+                            await AssignStatements[i].WriteToAsync(writer, encoder, context);
+                        }
                     }
 
-                    context.LocalScope = new Scope(context.RootScope);
-                    previousScope.CopyTo(context.LocalScope);
-
                     await template.RenderAsync(writer, encoder, context);
                 }
                 else if (For != null)
@@ -108,6 +106,16 @@ public override async ValueTask<Completion> WriteToAsync(TextWriter writer, Text
                         context.LocalScope = new Scope(context.RootScope);
                         previousScope.CopyTo(context.LocalScope);
 
+                        // Evaluate assign statements in the new scope before the loop if present
+                        if (AssignStatements.Count > 0)
+                        {
+                            var assignLength = AssignStatements.Count;
+                            for (var j = 0; j < assignLength; j++)
+                            {
+                                await AssignStatements[j].WriteToAsync(writer, encoder, context);
+                            }
+                        }
+
                         var length = forloop.Length = list.Count;
 
                         context.SetValue("forloop", forloop);
@@ -140,6 +148,19 @@ public override async ValueTask<Completion> WriteToAsync(TextWriter writer, Text
                         context.LocalScope.Delete("forloop");
                     }
                 }
+                else if (AssignStatements.Count > 0)
+                {
+                    var length = AssignStatements.Count;
+                    for (var i = 0; i < length; i++)
+                    {
+                        await AssignStatements[i].WriteToAsync(writer, encoder, context);
+                    }
+
+                    context.LocalScope = new Scope(context.RootScope);
+                    previousScope.CopyTo(context.LocalScope);
+
+                    await template.RenderAsync(writer, encoder, context);
+                }
                 else
                 {
                     context.LocalScope = new Scope(context.RootScope);

Fluid/FluidParser.cs

@@ -366,9 +366,9 @@ public FluidParser(FluidParserOptions parserOptions)
             FromTag.Name = "FromTag";
 
             var RenderTag = OneOf(
+                        String.AndSkip(Terms.Text("with")).And(Primary).And(ZeroOrOne(Terms.Text("as").SkipAnd(Identifier))).And(ZeroOrOne(Comma.SkipAnd(Separated(Comma, Identifier.AndSkip(Colon).And(Primary).Then(static x => new AssignStatement(x.Item1, x.Item2)))))).Then(x => new RenderStatement(this, x.Item1.ToString(), with: x.Item2, alias: x.Item3, assignStatements: x.Item4 ?? [])),
+                        String.AndSkip(Terms.Text("for")).And(Primary).And(ZeroOrOne(Terms.Text("as").SkipAnd(Identifier))).And(ZeroOrOne(Comma.SkipAnd(Separated(Comma, Identifier.AndSkip(Colon).And(Primary).Then(static x => new AssignStatement(x.Item1, x.Item2)))))).Then(x => new RenderStatement(this, x.Item1.ToString(), @for: x.Item2, alias: x.Item3, assignStatements: x.Item4 ?? [])),
                         String.AndSkip(Comma).And(Separated(Comma, Identifier.AndSkip(Colon).And(Primary).Then(static x => new AssignStatement(x.Item1, x.Item2)))).Then(x => new RenderStatement(this, x.Item1.ToString(), null, null, null, x.Item2)),
-                        String.AndSkip(Terms.Text("with")).And(Primary).And(ZeroOrOne(Terms.Text("as").SkipAnd(Identifier))).Then(x => new RenderStatement(this, x.Item1.ToString(), with: x.Item2, alias: x.Item3)),
-                        String.AndSkip(Terms.Text("for")).And(Primary).And(ZeroOrOne(Terms.Text("as").SkipAnd(Identifier))).Then(x => new RenderStatement(this, x.Item1.ToString(), @for: x.Item2, alias: x.Item3)),
                         String.Then(x => new RenderStatement(this, x.ToString()))
                         ).ElseError(ErrorMessages.ExpectedStringRender).AndSkip(TagEnd)
                         .Then<Statement>(x => x)