/// <summary>
/// 重写Or函数
/// </summary>
/// <typeparam name="T">传入的实体类型</typeparam>
/// <param name="expression_left">表达式主体的左边</param>
/// <param name="expression_right">表达式主体的右边</param>
/// <returns>返回拼接的表达式</returns>
public static Expression <Func <T, bool> > Or <T>(this Expression <Func <T, bool> > expression_left, Expression <Func <T, bool> > expression_right)
{
var candidateExpr = Expression.Parameter(typeof(T), "candidate");
var parameterReplacer = new LambdaExpressionVisitor(candidateExpr);
var left = parameterReplacer.Replace(expression_left.Body);
var right = parameterReplacer.Replace(expression_right.Body);
var body = Expression.Or(left, right);
return(Expression.Lambda <Func <T, bool> >(body, candidateExpr));
}
/// <summary>
/// 重写And函数
/// </summary>
/// <typeparam name="T">传入的实体类型</typeparam>
/// <param name="expression_left">表达式主体的左边</param>
/// <param name="expression_right">表达式主体的右边</param>
/// <returns>返回拼接的表达式</returns>
public static Expression <Func <T, bool> > And <T>(this Expression <Func <T, bool> > expression_left, Expression <Func <T, bool> > expression_right)
{
var candidateExpr = Expression.Parameter(typeof(T), "candidate");
var parameterReplacer = new LambdaExpressionVisitor(candidateExpr);
var left = parameterReplacer.Replace(expression_left.Body); //例如这个我就只知道拿到左边的对象
var right = parameterReplacer.Replace(expression_right.Body); //拿到右边的对象
var body = Expression.And(left, right); //在这个里面进行合并
return(Expression.Lambda <Func <T, bool> >(body, candidateExpr));
}