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update IQueryable provider

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28810
2020-04-10 11:58:47 +08:00
parent a958a64bd0
commit f9566af7d1
3 changed files with 166 additions and 9 deletions
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95
Extensions/FreeSql.Extensions.Linq/ExprHelper.cs Normal file
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using System;
using System.Collections.Generic;
using System.Text;
using System.Linq.Expressions;
using System.Linq;
using System.Reflection;
namespace FreeSql.Extensions.Linq
{
public static class ExprHelper
{
public static object GetConstExprValue(this Expression exp)
{
if (exp.IsParameter()) return null;
var expStack = new Stack<Expression>();
var exp2 = exp;
while (true)
{
switch (exp2?.NodeType)
{
case ExpressionType.Constant:
expStack.Push(exp2);
break;
case ExpressionType.MemberAccess:
expStack.Push(exp2);
exp2 = (exp2 as MemberExpression).Expression;
if (exp2 == null) break;
continue;
case ExpressionType.Call:
return Expression.Lambda(exp).Compile().DynamicInvoke();
case ExpressionType.TypeAs:
case ExpressionType.Convert:
var oper2 = (exp2 as UnaryExpression).Operand;
if (oper2.NodeType == ExpressionType.Parameter)
{
var oper2Parm = oper2 as ParameterExpression;
expStack.Push(exp2.Type.IsAbstract || exp2.Type.IsInterface ? oper2Parm : Expression.Parameter(exp2.Type, oper2Parm.Name));
}
else
expStack.Push(oper2);
break;
}
break;
}
object firstValue = null;
switch (expStack.First().NodeType)
{
case ExpressionType.Constant:
var expStackFirst = expStack.Pop() as ConstantExpression;
firstValue = expStackFirst?.Value;
break;
case ExpressionType.MemberAccess:
var expStackFirstMem = expStack.First() as MemberExpression;
if (expStackFirstMem.Expression?.NodeType == ExpressionType.Constant)
firstValue = (expStackFirstMem.Expression as ConstantExpression)?.Value;
else
return Expression.Lambda(exp).Compile().DynamicInvoke();
break;
}
while (expStack.Any())
{
var expStackItem = expStack.Pop();
switch (expStackItem.NodeType)
{
case ExpressionType.MemberAccess:
var memExp = expStackItem as MemberExpression;
if (memExp.Member.MemberType == MemberTypes.Property)
firstValue = ((PropertyInfo)memExp.Member).GetValue(firstValue, null);
else if (memExp.Member.MemberType == MemberTypes.Field)
firstValue = ((FieldInfo)memExp.Member).GetValue(firstValue);
break;
}
}
return firstValue;
}
public static bool IsParameter(this Expression exp)
{
var test = new TestParameterExpressionVisitor();
test.Visit(exp);
return test.Result;
}
internal class TestParameterExpressionVisitor : ExpressionVisitor
{
public bool Result { get; private set; }
protected override Expression VisitParameter(ParameterExpression node)
{
if (!Result) Result = true;
return node;
}
}
}
}