Add generalized method to parse expressions, refactoring

MathExpressionsNet.Tests/CodeDomTests.cs

@@ -13,10 +13,13 @@ public class CodeDomTests
 		[Test]
 		public void StringsToExpressionsTest()
 		{
+			var f0 = CodeDom.ParseExpression<Func<double>>("2+5*4").Compile();
+			Assert.That(f0(), Is.EqualTo(22));
+
 			var f1 = ((Expression<Func<double, double>>)CodeDom.GetExpressionFrom("x=>0")).Compile();
 			VerifyFunctions(f1, functions.LeftBoundCond);
 
-			f1 = ((Expression<Func<double, double>>)CodeDom.GetExpressionFrom("t=>t+3*t*t")).Compile();
+			f1 = CodeDom.ParseExpression<Func<double, double>>("t+3*t*t", "t").Compile();
 			VerifyFunctions(f1, functions.RightBoundCond);
 
 			var f2 = ((Expression<Func<double, double, double>>)CodeDom.GetExpressionFrom("(x,t)=>x*x*t+3*x*t*t")).Compile();
@@ -27,9 +30,6 @@ public void StringsToExpressionsTest()
 
 			var f3 = ((Expression<Func<double, double, double, double>>)CodeDom.GetExpressionFrom("(x,t,u)=>x*x*t+u*u")).Compile();
 			VerifyFunctions(f3, functions.K);
-
-			f3 = ((Expression<Func<double, double, double, double>>)CodeDom.GetExpressionFrom("(x,t,u)=>x*x+6*x*t-2*u*Math.Pow(2*x*t+3*t*t,2)-2*t*(x*x*t+u*u)")).Compile();
-			VerifyFunctions(f3, functions.g);
 		}
 
 		private void VerifyFunctions(Func<double, double> generatedFunc, Func<double, double> expectedFunc)
@@ -53,6 +53,22 @@ private void VerifyFunctions(Func<double, double, double, double> generatedFunc,
 			Assert.That(generatedFunc(a, b, c), Is.EqualTo(expectedFunc(a, b, c)));
 		}
 
+		[Test]
+		public void MakeNewFunction()
+		{
+			var exprU = CodeDom.ParseExpression<Func<double, double, double>>("x * x * t + 3 * x * t * t", "x", "t");
+			var exprK = CodeDom.ParseExpression<Func<double, double, double, double>>("x * x * t + u * u", "x", "t", "u");
+			string du_dt = exprU.Derive("t").Simplify().Body.ToString();
+			string dK_du = exprK.Derive("u").Simplify().Body.ToString();
+			var dudx = exprU.Derive("x").Simplify();
+			string du_dx = dudx.Body.ToString();
+			string d2u_dx2 = dudx.Derive("x").Simplify().Body.ToString();
+			string g = $"{du_dt}-{dK_du}*Math.Pow({du_dx},2)-{d2u_dx2}*{exprK.Simplify().Body}".Replace(" ", "");
+			Assert.That(g, Is.EqualTo("((x*x)+(6*(x*t)))-(2*u)*Math.Pow(((2*(x*t))+(3*(t*t))),2)-(2*t)*(((x*x)*t)+(u*u))"));
+			var gFunc = CodeDom.ParseExpression<Func<double, double, double, double>>(g, "x", "t", "u").Compile();
+			VerifyFunctions(gFunc, functions.g);
+		}
+
 		[Test]
 		public void ThrowingException()
 		{

MathExpressionsNet.Tests/Functions.cs

@@ -5,14 +5,10 @@ namespace MathExpressionsNet.Tests
 	public class Functions
 	{
 		public Func<double, double, double, double> K => (x, t, u) => x * x * t + u * u;
-		public Func<double, double, double, double> dK_du => (x, t, u) => 2 * u;
 		public Func<double, double, double, double> g => (x, t, u) => x * x + 6 * x * t - 2 * u * Math.Pow(2 * x * t + 3 * t * t, 2) - 2 * t * (x * x * t + u * u);
 		public Func<double, double> LeftBoundCond => t => 0;
 		public Func<double, double> RightBoundCond => t => t + 3 * t * t;
-
 		public Func<double, double, double> u => (x, t) => x * x * t + 3 * x * t * t;
 		public Func<double, double, double> du_dx => (x, t) => 2 * x * t + 3 * t * t;
-		public Func<double, double, double> d2u_dx2 => (x, t) => 2 * t;
-		public Func<double, double, double> du_dt => (x, t) => x * x + 6 * x * t;
 	}
 }

MathExpressionsNet.Tests/Properties/AssemblyInfo.cs

@@ -31,5 +31,5 @@
 // You can specify all the values or you can default the Build and Revision Numbers
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]
+[assembly: AssemblyVersion("1.0.1.0")]
+[assembly: AssemblyFileVersion("1.0.1.0")]

MathExpressionsNet/CodeDom.cs

@@ -11,9 +11,10 @@ namespace MathExpressionsNet
 {
 	public class CodeDom
 	{
-		const string TYPE_NAME = "TemporaryNamespace.Temporary";
-		const string METHOD_NAME = "Get";
-		const string CODE_HEADER = @"
+		private const string TypeName = "TemporaryNamespace.Temporary";
+		private const string MethodName = "Get";
+
+		private const string CodeHeader = @"
 namespace TemporaryNamespace
 {
 	using System;
@@ -25,10 +26,12 @@ public Expression Get()
 		{
 			return New(
 ";
-		const string CODE_FOOTER = @"
+
+		private const string CodeFooter = @"
 				);
 		}
 
+		static Expression New(Expression<Func<double>> e) { return e; }
 		static Expression New(Expression<Func<double, double>> e) { return e; }
 		static Expression New(Expression<Func<double, double, double>> e) { return e; }
 		static Expression New(Expression<Func<double, double, double, double>> e) { return e; }
@@ -37,29 +40,28 @@ public Expression Get()
 }
 ";
 
-		static CompilerResults Compile(string source)
+		private static CompilerResults Compile(string source)
 		{
 			CodeDomProvider provider = new CSharpCodeProvider(
 				new Dictionary<string, string> { { "CompilerVersion", "v3.5" } });
 
-			CompilerParameters cp = new CompilerParameters();
-			cp.GenerateInMemory = true;
+			var cp = new CompilerParameters { GenerateInMemory = true };
 			cp.ReferencedAssemblies.Add("System.Core.dll");
 
 			CompilerResults cr = provider.CompileAssemblyFromSource(
 				cp,
-				CODE_HEADER + source + CODE_FOOTER
+				CodeHeader + source + CodeFooter
 			);
 
 			return cr;
 		}
 
-		static Expression Execute(CompilerResults cr)
+		private static Expression Execute(CompilerResults cr)
 		{
 			Assembly asm = cr.CompiledAssembly;
-			Type myClass = asm.GetType(TYPE_NAME);
+			Type myClass = asm.GetType(TypeName);
 			Object o = Activator.CreateInstance(myClass);
-			MethodInfo mi = myClass.GetMethod(METHOD_NAME);
+			MethodInfo mi = myClass.GetMethod(MethodName);
 			return (Expression)mi.Invoke(o, null);
 		}
 
@@ -69,9 +71,9 @@ public static Expression GetExpressionFrom(string source)
 
 			if (cr.Errors.HasErrors)
 			{
-				StringBuilder sb = new StringBuilder();
+				var sb = new StringBuilder();
 				sb.Append("Compilation failed: ");
-				Regex reg = new Regex(@":\serror\s(?<reason>.*)$");
+				var reg = new Regex(@":\serror\s(?<reason>.*)$");
 
 				foreach (var error in cr.Errors)
 				{
@@ -87,6 +89,12 @@ public static Expression GetExpressionFrom(string source)
 
 			return Execute(cr);
 		}
+
+		public static Expression<T> ParseExpression<T>(string func, params string[] variables)
+		{
+			var expr = (Expression<T>)GetExpressionFrom($"({string.Join(",", variables)}) => {func}");
+			return expr.Simplify();
+		}
 	}
 
 	public class ExpressionCodeDomException : Exception

MathExpressionsNet/DifferentialOperator.cs

@@ -5,7 +5,7 @@ namespace MathExpressionsNet
 {
 	public class DifferentialOperator
 	{
-		Expression characteristic;
+		private Expression characteristic;
 
 		#region init
 
@@ -16,7 +16,7 @@ public class DifferentialOperator
 		/// <param name="paramName">parameter name</param>
 		public DifferentialOperator(string paramName)
 		{
-			this.characteristic = Expression.Parameter(typeof(double), paramName);
+			characteristic = Expression.Parameter(typeof(double), paramName);
 		}
 
 		/// <summary>
@@ -25,7 +25,7 @@ public DifferentialOperator(string paramName)
 		/// Laplacian = (∂/∂x)^2 + (∂/∂y)^2
 		/// </summary>
 		/// <param name="characteristic"></param>
-		DifferentialOperator(Expression characteristic)
+		private DifferentialOperator(Expression characteristic)
 		{
 			this.characteristic = characteristic;
 		}
@@ -55,6 +55,7 @@ public DifferentialOperator(
 			: this((Expression)e) { }
 
 		#endregion
+
 		#region apply operator
 
 		/// <summary>
@@ -65,7 +66,7 @@ public DifferentialOperator(
 		/// <returns>derivative</returns>
 		public Expression<T> Apply<T>(Expression<T> e)
 		{
-			return Apply(this.characteristic, e);
+			return Apply(characteristic, e);
 		}
 
 		/// <summary>
@@ -128,6 +129,7 @@ static public Expression<T> Apply<T>(Expression characteristic, Expression<T> e)
 		}
 
 		#endregion
+
 		#region operator
 
 		/// <summary>