/// <summary>
/// 用指定的操作连接表达式
/// </summary>
/// <param name="expressions">表达式集合</param>
/// <param name="combineType">连接方式</param>
/// <returns>表达式</returns>
public Expression CombinExpressions(List <Expression> expressions, ExpressionCombineType combineType)
{
Expression where = Expression.Constant(true);
if (expressions.Count() > 0)
{
switch (combineType)
{
case ExpressionCombineType.And:
where = expressions[0];
for (int i = 1; i < expressions.Count(); i++)
{
where = Expression.And(where, expressions[i]);
}
break;
case ExpressionCombineType.Or:
where = expressions[0];
for (int i = 1; i < expressions.Count(); i++)
{
where = Expression.Or(where, expressions[i]);
}
break;
}
}
return(where);
}
public ExpressionGroup()
{
TupleList = new List <(string, object, ExpressionType)>();
ExpressionCombineType = new ExpressionCombineType();
ExpressionGroupsList = new List <ExpressionGroup <T> >();
}
/// <summary>
/// 组合lambda表达式
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="expressions"></param>
/// <returns></returns>
public LambdaExpression JoinLambdaExpression(List <LambdaExpression> expressions, ExpressionCombineType combineType)
{
if (expressions.Count() == 0)
{
return(null);
}
LambdaExpression lambda = expressions[0];
if (expressions.Count() > 0)
{
foreach (var ex in expressions)
{
var invokedExpr = Expression.Invoke(lambda, ex.Parameters.Cast <Expression>());
switch (combineType)
{
case ExpressionCombineType.And:
lambda = Expression.Lambda(Expression.And(ex.Body, invokedExpr), ex.Parameters);
break;
case ExpressionCombineType.Or:
lambda = Expression.Lambda(Expression.Or(ex.Body, invokedExpr), ex.Parameters);
break;
}
}
}
return(lambda);
}
