/src/NHibernate.Spatial/src/NHibernate.Spatial/Linq/Functions/SpatialMethodGenerator.cs

using System;

using System.Collections.ObjectModel;

using System.Linq;

using System.Linq.Expressions;

using System.Reflection;

using NHibernate.Hql.Ast;

using NHibernate.Linq;

using NHibernate.Linq.Functions;

using NHibernate.Linq.Visitors;

using NHibernate.Spatial.Dialect;



namespace NHibernate.Spatial.Linq.Functions

{

	public abstract class SpatialMethodGenerator<TSource, TResult> : BaseHqlGeneratorForMethod

	{

		private readonly string methodName;



		protected SpatialMethodGenerator(string methodName, params Expression<Action<TSource>>[] expressions)

		{

			this.methodName = methodName;

			SupportedMethods = expressions.Select(o => ReflectionHelper.GetMethodDefinition(o)).ToArray();

		}



		protected SpatialMethodGenerator(params Expression<Action<TSource>>[] expressions)

			: this(null, expressions)

		{

		}



		public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)

		{

			var isExtensionMethod = (targetObject == null);

			var expressions = isExtensionMethod ? arguments : new[] { targetObject }.Concat(arguments);

			var parameters = expressions.Select(o => visitor.Visit(o).AsExpression());

			var methodCall = treeBuilder.MethodCall(SpatialDialect.HqlPrefix + (methodName ?? method.Name), parameters);

			if (typeof(TResult) == typeof(bool))

			{

				return treeBuilder.Equality(methodCall, treeBuilder.True());

			}

			return methodCall;

		}

	}

}