private Expression ParseUnaryExpression(string s)
{
var relevantParser = UnaryExpressionParser.For(s);
if (relevantParser == null)
{
throw new Exception($"Unrecognized expression {s}.");
}
var expression = relevantParser.Parse(s);
var parameterExpression = expression as ParameterExpression;
if (parameterExpression != null)
{
Parameters.Add(parameterExpression);
}
else if (expression.NodeType == ExpressionType.Not)
{
Parameters.Add(((UnaryExpression)expression).Operand as ParameterExpression);
}
else if (expression.NodeType == ExpressionType.Call)
{
var methodCallExpression = expression as MethodCallExpression;
foreach (var param in methodCallExpression.Arguments)
{
var paramExpression = ((UnaryExpression)param).Operand as ParameterExpression ?? param as ParameterExpression;
Parameters.Add(paramExpression);
}
}
return(expression);
}
public Expression Parse(string s)
{
s = s.Trim();
var fullName = s.Substring(0, s.IndexOf("("));
var dotIndex = fullName.LastIndexOf(".");
if (dotIndex == -1)
{
throw new Exception($"You have to specify static type for function {fullName}, for example Math.Sin(30).");
}
var typeName = fullName.Substring(0, dotIndex);
var staticType = Type.GetType(typeName);
if (staticType == null)
{
throw new Exception($"Could not find type {typeName}.");
}
var methodName = fullName.Substring(dotIndex + 1, fullName.Length - dotIndex - 1);
var method = staticType.GetTypeInfo().GetDeclaredMethod(methodName);
if (method == null)
{
throw new Exception($"Could not find metehod {methodName} in type {typeName}.");
}
var unparsedParameters = s.Replace(fullName, "").Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries).Select(up => up.Trim()).ToArray();
var methodParameters = method.GetParameters();
var paramIndex = 0;
var parameters = unparsedParameters.Select(up =>
{
var parser = UnaryExpressionParser.For(up);
if (up == null)
{
throw new Exception($"Unrecognized expression {up} in parameters of function {fullName}.");
}
var parameterExpression = parser.Parse(up);
return(Expression.Convert(parameterExpression, methodParameters[paramIndex++].ParameterType));
}
).ToArray();
return(Expression.Call(method, parameters));
}