Catching compilation errors

README.md

@@ -15,37 +15,40 @@ Below is an example that fills a destination span with coordinates for the point
 with either a radius or a diameter as input. While reusing the same machine instance by modifying
 its source and variables, and re-evaluating the expression.
 ```cs
-public unsafe void GetCirclePositions(float value, bool isDiameter, USpan<Vector2> positions)
+public void GetCirclePositions(float radius, Span<Vector2> positions)
 {
     using Machine vm = new();
     vm.SetVariable("value", value);
-    vm.SetVariable("multiplier", isDiameter ? 2 : 1);
-    vm.SetFunction("cos", &Cos);
-    vm.SetFunction("sin", &Sin);
+    vm.SetFunction("cos", MathF.Cos);
+    vm.SetFunction("sin", MathF.Sin);
 
-    uint length = positions.Length;
+    int length = positions.Length;
     for (int i = 0; i < length; i++)
     {
         float t = i * MathF.PI / (length * 0.5f);
         vm.SetVariable("t", t);
-        vm.SetSource("cos(t) * (value * multiplier)");
+        vm.SetSource("cos(t) * radius");
         float x = vm.Evaluate();    
-        vm.SetSource("sin(t) * (value * multiplier)");
+        vm.SetSource("sin(t) * radius");
         float y = vm.Evaluate();
         positions[i] = new Vector2(x, y);
     }
+}
+```
 
-    [UnmanagedCallersOnly]
-    static float Cos(float value)
-    {
-        return MathF.Cos(value);
-    }
+### Checking for compilation issues
 
-    [UnmanagedCallersOnly]
-    static float Sin(float value)
-    {
-        return MathF.Sin(value);
-    }
+When a text source is assigned to the machine, it returns a compilation result.
+This result value can be used to check if there were issues. And can do so with the try-do pattern:
+```cs
+if (vm.TrySetSource("5 +", out Exception? exception))
+{
+    //success
+}
+else
+{
+    //error
+    throw exception;
 }
 ```
 

source/CompilationResult.cs

@@ -0,0 +1,60 @@
+using System;
+
+namespace ExpressionMachine
+{
+    /// <summary>
+    /// Represents the result of compilation.
+    /// </summary>
+    public readonly struct CompilationResult : IEquatable<CompilationResult>
+    {
+        /// <summary>
+        /// Success compilation result.
+        /// </summary>
+        public static CompilationResult Success => new(null);
+
+        /// <summary>
+        /// Compilation exception if there was one.
+        /// </summary>
+        public readonly Exception? exception;
+
+        /// <summary>
+        /// Checks if the compilation was successful.
+        /// </summary>
+        public readonly bool IsSuccess => exception is null;
+
+        internal CompilationResult(Exception? exception)
+        {
+            this.exception = exception;
+        }
+
+        /// <inheritdoc/>
+        public readonly override bool Equals(object? obj)
+        {
+            return obj is CompilationResult result && Equals(result);
+        }
+
+        /// <inheritdoc/>
+        public readonly bool Equals(CompilationResult other)
+        {
+            return exception == other.exception;
+        }
+
+        /// <inheritdoc/>
+        public readonly override int GetHashCode()
+        {
+            return exception?.GetHashCode() ?? 0;
+        }
+
+        /// <inheritdoc/>
+        public static bool operator ==(CompilationResult left, CompilationResult right)
+        {
+            return left.Equals(right);
+        }
+
+        /// <inheritdoc/>
+        public static bool operator !=(CompilationResult left, CompilationResult right)
+        {
+            return !(left == right);
+        }
+    }
+}

source/Exceptions/MissingTokenException.cs

@@ -0,0 +1,20 @@
+using System;
+
+namespace ExpressionMachine
+{
+    /// <summary>
+    /// Error when an expected token is missing.
+    /// </summary>
+    public class MissingTokenException : Exception
+    {
+
+    }
+
+    /// <summary>
+    /// Error when a token to close a group is missing.
+    /// </summary>
+    public class MissingGroupCloseToken : Exception
+    {
+
+    }
+}

source/ExpressionMachine.csproj

@@ -6,6 +6,12 @@
 		<Nullable>enable</Nullable>
 		<AllowUnsafeBlocks>True</AllowUnsafeBlocks>
 		<GenerateDocumentationFile>True</GenerateDocumentationFile>
+		<Title>Expression Machine</Title>
+		<Authors>popcron</Authors>
+		<Company>simulation-tree</Company>
+		<Description>Library for evaluating logic expressions at runtime.</Description>
+		<PackageReadmeFile>README.md</PackageReadmeFile>
+		<RepositoryUrl>https://github.com/simulation-tree/expression-machine</RepositoryUrl>
 	</PropertyGroup>
 
 	<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
@@ -23,6 +29,13 @@
 		<WarningLevel>7</WarningLevel>
 	</PropertyGroup>
 
+	<ItemGroup>
+	  <None Include="..\README.md">
+	    <Pack>True</Pack>
+	    <PackagePath>\</PackagePath>
+	  </None>
+	</ItemGroup>
+
 	<ItemGroup>
 		<ProjectReference Include="..\..\collections\source\Collections.csproj" />
 		<ProjectReference Include="..\..\unmanaged\core\Unmanaged.Core.csproj" />