BinaryExpressionHelper.cs

// This file is part of Core WF which is licensed under the MIT license.
// See LICENSE file in the project root for full license information.

using System.Activities.Runtime;
using System.Activities.Validation;
using System.Collections.ObjectModel;
using System.Linq.Expressions;

namespace System.Activities.Expressions;

internal static class BinaryExpressionHelper
{
    public static void OnGetArguments<TLeft, TRight>(CodeActivityMetadata metadata, InArgument<TLeft> left, InArgument<TRight> right)
    {
        RuntimeArgument rightArgument = new("Right", typeof(TRight), ArgumentDirection.In, true);
        metadata.Bind(right, rightArgument);

        RuntimeArgument leftArgument = new("Left", typeof(TLeft), ArgumentDirection.In, true);
        metadata.Bind(left, leftArgument);

        metadata.SetArgumentsCollection(
            new Collection<RuntimeArgument>
            {
                rightArgument,
                leftArgument
            });
    }

    public static bool TryGenerateLinqDelegate<TLeft, TRight, TResult>(ExpressionType operatorType, out Func<TLeft, TRight, TResult> function, out ValidationError validationError)
    {
        function = null;
        validationError = null;

        ParameterExpression leftParameter = Expression.Parameter(typeof(TLeft), "left");
        ParameterExpression rightParameter = Expression.Parameter(typeof(TRight), "right");

        try
        {
            BinaryExpression binaryExpression = Expression.MakeBinary(operatorType, leftParameter, rightParameter);
            Expression<Func<TLeft, TRight, TResult>> lambdaExpression = Expression.Lambda<Func<TLeft, TRight, TResult>>(binaryExpression, leftParameter, rightParameter);
            function = lambdaExpression.Compile();

            return true;
        }
        catch (Exception e)
        {
            if (Fx.IsFatal(e))
            {
                throw;
            }

            validationError = new ValidationError(e.Message);
            return false;
        }
    }
}