🚚 Split Parser.cs (#318)

* Add ParseException.Create

* Move MethodData and IndexerData to their own files.

* Introduce TypeUtils to handle Type checks and operations

* Move _concatMethod and _toStringMethod to ReflectionExtensions

* Move InterpreterExpression to its own file

* Add MethodResolution class

* Introduce MemberFinder

* Extract LateBinders

src/DynamicExpresso.Core/Exceptions/ParseException.cs

@@ -26,7 +26,12 @@ public ParseException(string message, int position, Exception innerException)
 
 		public int Position { get; private set; }
 
-		#if !NETSTANDARD1_6
+		public static ParseException Create(int pos, string format, params object[] args)
+		{
+			return new ParseException(string.Format(format, args), pos);
+		}
+
+#if !NETSTANDARD1_6
 		protected ParseException(
 			SerializationInfo info,
 			StreamingContext context)

src/DynamicExpresso.Core/Parameter.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Linq.Expressions;
 
 namespace DynamicExpresso
@@ -49,4 +49,18 @@ public static Parameter Create<T>(string name, T value)
 
 		public ParameterExpression Expression { get; private set; }
 	}
+
+	/// <summary>
+	/// Parameter with its position in the expression.
+	/// </summary>
+	internal class ParameterWithPosition : Parameter
+	{
+		public ParameterWithPosition(int pos, string name, Type type)
+			: base(name, type)
+		{
+			Position = pos;
+		}
+
+		public int Position { get; }
+	}
 }

src/DynamicExpresso.Core/Parsing/InterpreterExpression.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using DynamicExpresso.Exceptions;
+using DynamicExpresso.Reflection;
+
+namespace DynamicExpresso.Parsing
+{
+	internal class InterpreterExpression : Expression
+	{
+		private readonly Interpreter _interpreter;
+		private readonly string _expressionText;
+		private readonly IList<Parameter> _parameters;
+		private Type _type;
+
+		public InterpreterExpression(ParserArguments parserArguments, string expressionText, params ParameterWithPosition[] parameters)
+		{
+			var settings = parserArguments.Settings.Clone();
+			_interpreter = new Interpreter(settings);
+			_expressionText = expressionText;
+			_parameters = parameters;
+
+			// Take the parent expression's parameters and set them as an identifier that
+			// can be accessed by any lower call
+			// note: this doesn't impact the initial settings, because they're cloned
+			foreach (var dp in parserArguments.DeclaredParameters)
+			{
+				// Have to mark the parameter as "Used" otherwise we can get a compilation error.
+				parserArguments.TryGetParameters(dp.Name, out var pe);
+				_interpreter.SetIdentifier(new Identifier(dp.Name, pe));
+			}
+
+			foreach (var myParameter in parameters)
+			{
+				if (settings.Identifiers.ContainsKey(myParameter.Name))
+				{
+					throw new ParseException($"A local or parameter named '{myParameter.Name}' cannot be declared in this scope because that name is used in an enclosing local scope to define a local or parameter", myParameter.Position);
+				}
+			}
+
+			// prior to evaluation, we don't know the generic arguments types
+			_type = ReflectionExtensions.GetFuncType(parameters.Length);
+		}
+
+		public IList<Parameter> Parameters
+		{
+			get { return _parameters; }
+		}
+
+		public override Type Type
+		{
+			get { return _type; }
+		}
+
+		internal LambdaExpression EvalAs(Type delegateType)
+		{
+			if (!IsCompatibleWithDelegate(delegateType))
+				return null;
+
+			var lambdaExpr = _interpreter.ParseAsExpression(delegateType, _expressionText, _parameters.Select(p => p.Name).ToArray());
+			_type = lambdaExpr.Type;
+			return lambdaExpr;
+		}
+
+		internal bool IsCompatibleWithDelegate(Type target)
+		{
+			if (!target.IsGenericType || target.BaseType != typeof(MulticastDelegate))
+				return false;
+
+			var genericTypeDefinition = target.GetGenericTypeDefinition();
+			return genericTypeDefinition == ReflectionExtensions.GetFuncType(_parameters.Count)
+				|| genericTypeDefinition == ReflectionExtensions.GetActionType(_parameters.Count);
+		}
+	}
+}