private Expression GetExpression(string methodName, params NodeInfo[] nodes)
{
var expressions = nodes.Select(x => new { Expression = InnerBuild(x.Node), Type = _expressionTypeResolver.GetTypeFor(x.Node, _type), x.ReturnIfNull });
var nullExpression = Expression.Constant(null);
Expression returnNullTest = Expression.Constant(false);
returnNullTest = expressions.Where(x => x.ReturnIfNull).Select(x => x.Expression).Aggregate(returnNullTest, (current, exp) => Expression.Or(current, Expression.ReferenceEqual(Expression.Convert(exp, typeof(object)), nullExpression)));
var method = CSharpExpressionHelperMethodResolver.GetMethod(methodName, expressions.Select(x => x.Type).ToArray());
if (method == null)
{
return(null);
}
var parameterTypes = method.GetParameters().Select(x => x.ParameterType).ToArray();
var arguments = expressions.Select((x, i) => GetArgument(x.Expression, parameterTypes[i])).ToArray();
var methodCall = Expression.Convert(Expression.Call(method, arguments), typeof(object));
return(Expression.Condition(returnNullTest, nullExpression, methodCall));
}
private Type Build(FunctionNode node)
{
var functionName = node.FunctionName.ToLower();
switch (functionName)
{
case "abs":
var parameterTypes = node.Arguments.Select(InnerBuild).ToArray();
var method = CSharpExpressionHelperMethodResolver.GetMethod("Abs", parameterTypes);
return(method.ReturnType);
case "ceiling":
case "floor":
return(typeof(decimal));
case "power":
return(typeof(double));
case "substring":
case "left":
case "right":
case "replace":
return(typeof(string));
case "contains":
return(typeof(bool));
case "len":
return(typeof(int));
default:
return(null);
}
}
private Type Build(MaxFunctionNode node)
{
var parameterTypes = node.Arguments.Select(InnerBuild).ToArray();
var method = CSharpExpressionHelperMethodResolver.GetMethod("Max", parameterTypes);
return(method.ReturnType);
}
private Type Build(IifFunctionNode node)
{
var ifTrueType = InnerBuild(node.IfTrue);
var ifFalseType = InnerBuild(node.IfFalse);
var method = CSharpExpressionHelperMethodResolver.GetMethod("Iif", typeof(bool), ifTrueType, ifFalseType);
return(GetUnderlyingType(method.ReturnType));
}
private Type Build(BinaryExpressionNode node)
{
string methodName;
if (!_methodNames.TryGetValue(node.Op, out methodName))
{
return(null);
}
var leftType = InnerBuild(node.Left);
var rightType = InnerBuild(node.Right);
var method = CSharpExpressionHelperMethodResolver.GetMethod(methodName, leftType, rightType);
return(method.ReturnType);
}
