Insert query generator macro

insert.rs

#![feature(inclusive_range_syntax)]

macro_rules! new_model {
    ($struct_name:ident {
        $( $arg:ident : $arg_type:ty ),*
    }, table: $table:expr) => (
        #[derive(Clone, Debug)]
        pub struct $struct_name {
            pub id: i32,
            $ (
                pub $arg: $arg_type,
            )*
        }

        impl $struct_name {
            
            pub fn new($($arg: $arg_type,)*) -> $struct_name {
                $struct_name {
                    id: 0,
                    $(
                        $arg : $arg,
                    )*
                }
            }

            
            pub fn insert_query() -> String {
                let cnt = count!($($arg)*);
                concat!("INSERT INTO ", $table, "(").to_owned()
                + &{ let mut s = String::new(); 
                     let mut i = 0;
                     $(
                         s.push_str(
                             &format!("{}{}", stringify!($arg), {
                                 i += 1; if i < cnt { ", " } else { "" }
                             })
                         );
                     )*
                     s    
                } + ")"
                + " VALUES("
                + &{ let mut s = String::new(); 
                     for i in 1...cnt { s += &format!("${}{}", i, {
                        if i < cnt { ", " } else { "" }
                     });} 
                     s 
                 } + ")"
            }

            pub fn batch_insert_query(object: Self) -> String {
                let cnt = count!($($arg)*);
                concat!("INSERT INTO ", $table, "(").to_owned()
                + &{ let mut s = String::new(); 
                     let mut i = 0;
                     $(
                         s.push_str(
                             &format!("{}{}", stringify!($arg), {
                                 i += 1; if i < cnt { ", " } else { "" }
                             })
                         );
                     )*
                     s    
                } + ")"
                + " VALUES("
                + &{ let mut s = String::new(); 
                     let mut i = 0;
                     $(
                         s.push_str(
                             &format!("{}{}", object.$arg, {
                                 i += 1; if i < cnt { ", " } else { "" }
                             })
                         );
                     )*
                     s 
                 } + ");"
            }
        }
    )
}

macro_rules! count {
    () => (0usize);
    ( $x:tt $($xs:tt)* ) => (1usize + count!($($xs)*));
}

new_model!(Args {
    flag_flat: bool,
    flag_all: bool,
    cmd_new: bool,
    cmd_done: bool,
    cmd_del: bool,
    cmd_clear: bool,
    arg_list: String,
    arg_task: String,
    arg_description: String,
    arg_num: i32
},  table: "args");

fn main() {
    println!("{}", Args::insert_query());
    // output:
    // INSERT INTO args(flag_flat, flag_all, cmd_new, cmd_done, cmd_del, cmd_clear, arg_list, arg_task, arg_description, arg_num) 
    //              VALUES($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
}