Lidarr/Marr.Data/QGen/ExpressionVisitor.cs

150 lines
5.3 KiB
C#

/* This class was copied from Mehfuz's LinqExtender project, which is available from github.
* http://mehfuzh.github.com/LinqExtender/
*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
namespace Marr.Data.QGen
{
///<summary>
/// Expression visitor
///</summary>
public class ExpressionVisitor
{
/// <summary>
/// Visits expression and delegates call to different to branch.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression Visit(Expression expression)
{
if (expression == null)
return null;
switch (expression.NodeType)
{
case ExpressionType.Lambda:
return VisitLamda((LambdaExpression)expression);
case ExpressionType.ArrayLength:
case ExpressionType.Convert:
case ExpressionType.ConvertChecked:
case ExpressionType.Negate:
case ExpressionType.UnaryPlus:
case ExpressionType.NegateChecked:
case ExpressionType.Not:
case ExpressionType.Quote:
case ExpressionType.TypeAs:
return this.VisitUnary((UnaryExpression)expression);
case ExpressionType.Add:
case ExpressionType.AddChecked:
case ExpressionType.And:
case ExpressionType.AndAlso:
case ExpressionType.ArrayIndex:
case ExpressionType.Coalesce:
case ExpressionType.Divide:
case ExpressionType.Equal:
case ExpressionType.ExclusiveOr:
case ExpressionType.GreaterThan:
case ExpressionType.GreaterThanOrEqual:
case ExpressionType.LeftShift:
case ExpressionType.LessThan:
case ExpressionType.LessThanOrEqual:
case ExpressionType.Modulo:
case ExpressionType.Multiply:
case ExpressionType.MultiplyChecked:
case ExpressionType.NotEqual:
case ExpressionType.Or:
case ExpressionType.OrElse:
case ExpressionType.Power:
case ExpressionType.RightShift:
case ExpressionType.Subtract:
case ExpressionType.SubtractChecked:
return this.VisitBinary((BinaryExpression)expression);
case ExpressionType.Call:
return this.VisitMethodCall((MethodCallExpression)expression);
case ExpressionType.Constant:
return this.VisitConstant((ConstantExpression)expression);
case ExpressionType.MemberAccess:
return this.VisitMemberAccess((MemberExpression)expression);
case ExpressionType.Parameter:
return this.VisitParameter((ParameterExpression)expression);
}
throw new ArgumentOutOfRangeException("expression", expression.NodeType.ToString());
}
/// <summary>
/// Visits the constance expression. To be implemented by user.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression VisitConstant(ConstantExpression expression)
{
return expression;
}
/// <summary>
/// Visits the memeber access expression. To be implemented by user.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression VisitMemberAccess(MemberExpression expression)
{
return expression;
}
/// <summary>
/// Visits the method call expression. To be implemented by user.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression VisitMethodCall(MethodCallExpression expression)
{
throw new NotImplementedException();
}
/// <summary>
/// Visits the binary expression.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression VisitBinary(BinaryExpression expression)
{
this.Visit(expression.Left);
this.Visit(expression.Right);
return expression;
}
/// <summary>
/// Visits the unary expression.
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected virtual Expression VisitUnary(UnaryExpression expression)
{
this.Visit(expression.Operand);
return expression;
}
/// <summary>
/// Visits the lamda expression.
/// </summary>
/// <param name="lambdaExpression"></param>
/// <returns></returns>
protected virtual Expression VisitLamda(LambdaExpression lambdaExpression)
{
this.Visit(lambdaExpression.Body);
return lambdaExpression;
}
private Expression VisitParameter(ParameterExpression expression)
{
return expression;
}
}
}