Implement TupleExpression (#5021)

Resolves #5019

Implement TupleExpression and VariableTupleExpression

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/Expressions/TupleExpression.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+namespace Microsoft.Generator.CSharp.Expressions
+{
+    public record TupleExpression(params ValueExpression[] ValueExpressions) : ValueExpression
+    {
+        internal override void Write(CodeWriter writer)
+        {
+            writer.AppendRaw("(");
+            for (int i = 0; i < ValueExpressions.Length; i++)
+            {
+                ValueExpressions[i].Write(writer);
+                if (i < ValueExpressions.Length - 1)
+                {
+                    writer.AppendRaw(", ");
+                }
+            }
+            writer.AppendRaw(")");
+        }
+    }
+}

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/src/Expressions/VariableTupleExpression.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+namespace Microsoft.Generator.CSharp.Expressions
+{
+    public record VariableTupleExpression(bool IsRef = false, params VariableExpression[] Variables) : ValueExpression
+    {
+        internal override void Write(CodeWriter writer)
+        {
+            writer.AppendRawIf("ref ", IsRef);
+            writer.AppendRaw("(");
+            for (int i = 0; i < Variables.Length; i++)
+            {
+                var variable = Variables[i];
+                writer.Append($"{variable.Type} {variable.Declaration}");
+                if (i < Variables.Length - 1)
+                {
+                    writer.AppendRaw(", ");
+                }
+            }
+            writer.AppendRaw(")");
+        }
+    }
+}

packages/http-client-csharp/generator/Microsoft.Generator.CSharp/test/Expressions/TupleExpressionTests.cs

@@ -0,0 +1,47 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System.Threading;
+using Microsoft.Generator.CSharp.Expressions;
+using Microsoft.Generator.CSharp.Primitives;
+using Microsoft.Generator.CSharp.Providers;
+using NUnit.Framework;
+using static Microsoft.Generator.CSharp.Snippets.Snippet;
+
+namespace Microsoft.Generator.CSharp.Tests.Expressions
+{
+    internal class TupleExpressionTests
+    {
+        [Test]
+        public void VerifyTupleExpressionWrite()
+        {
+            var tupleExpression = new TupleExpression(Null, Static<CancellationToken>().Property("None"));
+            using CodeWriter writer = new CodeWriter();
+            tupleExpression.Write(writer);
+
+            Assert.AreEqual("(null, global::System.Threading.CancellationToken.None)", writer.ToString(false));
+        }
+
+        [Test]
+        public void VerifyTupleExpressionAssignment()
+        {
+            var item1 = new ParameterProvider("item1", FormattableStringHelpers.Empty, new CSharpType(typeof(int)));
+            var item2 = new ParameterProvider("item2", FormattableStringHelpers.Empty, new CSharpType(typeof(string)));
+            var variableTupleExpression = new VariableTupleExpression(false, item1, item2);
+            using CodeWriter writer = new CodeWriter();
+            variableTupleExpression.Assign(new TupleExpression(Literal(1), Literal("a"))).Write(writer);
+            Assert.AreEqual("(int item1, string item2) = (1, \"a\")", writer.ToString(false));
+        }
+
+        [Test]
+        public void VerifyTupleExpressionWithRef()
+        {
+            var item1 = new ParameterProvider("item1", FormattableStringHelpers.Empty, new CSharpType(typeof(int)));
+            var item2 = new ParameterProvider("item2", FormattableStringHelpers.Empty, new CSharpType(typeof(string)));
+            var tupleVariableExpression = new VariableTupleExpression(true, item1, item2);
+            using CodeWriter writer = new CodeWriter();
+            tupleVariableExpression.Write(writer);
+            Assert.AreEqual("ref (int item1, string item2)", writer.ToString(false));
+        }
+    }
+}