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#[macro_export]
/// 从SQL中查找指定标记,返回用于查询的SQL跟待绑定的字段列表
/// 示例请查看单元测试
macro_rules! sql_bind {
    ($db:ty,$sql:expr)=>{
        {
            let mut prev=None;
            let mut push_start=false;
            let mut key=vec![];
            let mut keys=vec![];
            let mut new_sql=vec![];
            for mstr in $sql.chars() {
                let mut is_r=false;
                if let Some(_prev)=prev {
                    if _prev!='\\'{is_r=true;}
                }else{ is_r=true;}
                prev=Some(mstr);
                if is_r {
                    if  mstr=='{'{
                        push_start=true;
                        key=vec![];
                        continue;
                    }else if mstr=='}' && push_start{
                        push_start=false;
                        keys.push(key.iter().collect::<String>());
                        key.clear();
                        new_sql.push('?');
                        continue;
                    }
                }
                if push_start {
                    key.push(mstr);
                }else{
                    new_sql.push(mstr);
                }
            }
            (new_sql.into_iter().collect::<String>(),keys)
        }
    };
}
#[macro_export]
/// 简化sql_bind返回的待绑定列表的绑定变量操作
/// 可以自行实现此过程
macro_rules! sql_bind_vars {
    ($bind_res:expr,$res:expr,{$($key:literal:$bind:expr),+$(,)?})=>{
        {
            for key in $bind_res.iter() {
                match key.as_str(){
                    $(
                        $key=>{$res=$res.bind($bind)},
                    )+
                    _=>{},
                }
            }
            $res
        }
    };
}



#[test]
fn test_sql_bind_macro(){
    let (sql,bind_res)=crate::sql_bind!(
        sqlx::MySql,
        r#"
            select * from (SELECT {nickname} as nickname,{gender} as gender,1 as gender_group,{nickname} as nickname1,{gender} as gender1 ) as t where gender in (1) and gender_group in ({gender_group})
        "#
    );
    assert_eq!(
        "select * from (SELECT ? as nickname,? as gender,1 as gender_group,? as nickname1,? as gender1 ) as t where gender in (1) and gender_group in (?)",
        sql.as_str().trim()
    );
    assert_eq!(bind_res.len(),5);
    struct Res{}
    impl Res{
        fn bind<T>(self,_:T)->Self{self}
    }
    let mut res=Res{};
    crate::sql_bind_vars!(bind_res,res,{
        "nickname":1,
        "gender":"ddd",
        "gender_group":3
    });
}