[WIP] Start handling inline expressions

libs/UIX.DecompXml/Mock/IReturnValueProvider.cs

@@ -0,0 +1,8 @@
+using Microsoft.Iris.Markup;
+
+namespace Microsoft.Iris.DecompXml.Mock;
+
+internal interface IReturnValueProvider
+{
+    TypeSchema ReturnType { get; }
+}

libs/UIX.DecompXml/Mock/IrisConstantExpression.cs

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+using Microsoft.Iris.Markup;
+using System.Linq.Expressions;
+
+namespace Microsoft.Iris.DecompXml.Mock;
+
+internal class IrisConstantExpression : IrisExpression, IReturnValueProvider
+{
+    public IrisConstantExpression(object value, TypeSchema typeSchema)
+    {
+        Value = value;
+        TypeSchema = typeSchema;
+    }
+
+    public sealed override ExpressionType NodeType => ExpressionType.Constant;
+    
+    public object Value { get; }
+
+    public TypeSchema TypeSchema { get; }
+
+    public TypeSchema ReturnType => TypeSchema;
+
+    public override string Decompile(Decompiler decompiler)
+    {
+        if (TypeSchema.IsEnum)
+            return $"{decompiler.GetQualifiedName(TypeSchema)}.{Value}";
+
+        return Value switch
+        {
+            string str => str,
+            IStringEncodable strEnc => strEnc.EncodeString(),
+            _ => Value?.ToString() ?? "null",
+        };
+    }
+}

libs/UIX.DecompXml/Mock/IrisExpression.cs

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+using System.Linq.Expressions;
+
+namespace Microsoft.Iris.DecompXml.Mock;
+
+internal class IrisExpression : Expression
+{
+    public virtual string Decompile(Decompiler decompiler) => ToString();
+}

libs/UIX.DecompXml/Mock/IrisMethodCallExpression.cs

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+using Microsoft.Iris.Markup;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+
+namespace Microsoft.Iris.DecompXml.Mock;
+
+internal class IrisMethodCallExpression : IrisExpression, IArgumentProvider, IReturnValueProvider
+{
+    private readonly Expression[] _arguments;
+
+    public IrisMethodCallExpression(MethodSchema method, Expression? target, IEnumerable<Expression> arguments)
+    {
+        Method = method;
+        Target = target;
+        _arguments = arguments.ToArray();
+    }
+
+    public MethodSchema Method { get; }
+    
+    public sealed override ExpressionType NodeType => ExpressionType.Call;
+    
+    public Expression? Target { get; }
+
+    public int ArgumentCount => _arguments.Length;
+
+    public TypeSchema ReturnType => Method.ReturnType;
+
+    public Expression GetArgument(int index) => _arguments[index];
+
+    public override string Decompile(Decompiler decompiler)
+    {
+        StringBuilder sb = new();
+
+        var qfn = decompiler.GetQualifiedName(Method.Owner);
+        sb.Append(qfn);
+        sb.Append('.');
+        sb.Append(Method.Name);
+        sb.Append('(');
+
+        sb.Append(string.Join(", ", _arguments.Select(exprToString)));
+
+        sb.Append(')');
+        return sb.ToString();
+
+        string exprToString(Expression x)
+        {
+            return x is IrisExpression irisExpr
+                ? irisExpr.Decompile(decompiler)
+                : x.ToString();
+        }
+    }
+}