/// <summary>Or操作</summary>
/// <param name="exp"></param>
/// <returns></returns>
public WhereExpression Or(Expression exp)
{
if (exp != null)
{
Expressions.Add(new ExpItem(false, exp));
}
return this;
}
/// <summary>And操作</summary>
/// <param name="exp"></param>
/// <returns></returns>
public WhereExpression And(Expression exp)
{
if (exp != null)
{
// 如果前面有Or，则整体推入下一层
if (Expressions.Any(e => !e.IsAnd))
{
var where = new WhereExpression();
where.Expressions.AddRange(Expressions);
Expressions.Clear();
Expressions.Add(new ExpItem(true, where));
}
Expressions.Add(new ExpItem(true, exp));
}
return this;
}
static WhereExpression And(Expression exp, Expression value)
{
// 如果exp为空，主要考虑右边
if (exp == null) CreateWhere(value);
// 左边构造条件表达式，自己是也好，新建立也好
var where = CreateWhere(exp);
if (value == null) return where;
// 如果右边为空，创建的表达式将会失败，直接返回左边
return where.And(value);
}
static WhereExpression CreateWhere(Expression value)
{
if (value == null) return new WhereExpression();
if (value is WhereExpression) return (value as WhereExpression);
return new WhereExpression(value);
}
/// <summary>把普通表达式包装为条件表达式表达式</summary>
/// <param name="exp"></param>
public WhereExpression(Expression exp) { And(exp); }
public ExpItem(Boolean isAnd, Expression exp)
{
IsAnd = isAnd;
Exp = exp;
}
/// <summary>有条件Or操作</summary>
/// <param name="condition"></param>
/// <param name="exp"></param>
/// <returns></returns>
public WhereExpression OrIf(Boolean condition, Expression exp) { return condition ? Or(exp) : this; }
/// <summary>有条件And操作</summary>
/// <param name="condition"></param>
/// <param name="exp"></param>
/// <returns></returns>
public WhereExpression AndIf(Boolean condition, Expression exp) { return condition ? And(exp) : this; }