Rustのマクロを試し中。C++ライクなクラス構文を導入してみる

rust_macro_study.rs

macro_rules! defclass {
    (class $name:ident;) =>{struct $name;};
    (class $name:ident {$($contents:tt)*}) =>{defclass!{$name,,{},$($contents)*}};
    (struct $name:ident;) =>{struct $name;};
    (struct $name:ident {$($contents:tt)*}) =>{defclass!{$name,pub,{},$($contents)*}};
    ($name:ident,$($visible:ident)*,{$($field:tt)*},public:$($rest:tt)*) =>{
        defclass!{$name,pub,{$($field)*},$($rest)*}
    };
    ($name:ident,$($visible:ident)*,{$($field:tt)*},private:$($rest:tt)*) =>{
        defclass!{$name,,{$($field)*},$($rest)*}
    };
    // Field
    ($name:ident,pub,{$($field:tt)*},$($fname:ident),* : $ftype:ty;$($rest:tt)*) =>{
        defclass!{$name,pub,{$($field)*$(pub $fname:$ftype,)*},$($rest)*}
    };
    ($name:ident,,{$($field:tt)*},$($fname:ident),* : $ftype:ty;$($rest:tt)*) =>{
        defclass!{$name,,{$($field)*$($fname:$ftype,)*},$($rest)*}
    };
    // constructor
    ($name:ident,$($visible:ident)*,{$($field:tt)*},
     new($($arg:tt)*){$($body:tt)*}
     $($rest:tt)*) =>{
        defclass!{$name,$($visible)*,{$($field)*},$($rest)*}
        defmethod!{$($visible)*,$name,,new,($($arg)*),$name,$($body)*}
    };
    // function
    ($name:ident,$($visible:ident)*,{$($field:tt)*},
     $fname:ident($($arg:tt)*){$($body:tt)*}
     $($rest:tt)*) =>{
        defclass!{$name,$($visible)*,{$($field)*},$($rest)*}
        defmethod!{$($visible)*,$name,,$fname,($($arg)*),,$($body)*}
    };

    ($name:ident,$($visible:ident)*,{$($field:tt)*},
     $fname:ident($($arg:tt)*)->$ret:ty {$($body:tt)*}
     $($rest:tt)*) =>{
        defclass!{$name,$($visible)*,{$($field)*},$($rest)*}
        defmethod!{$($visible)*,$name,,$fname,($($arg)*),$ret,$($body)*}
    };

    ($name:ident,$($visible:ident)*,{$($field:tt)*},
     <$($t:tt)*> $fname:ident($($arg:tt)*)->$ret:ty {$($body:tt)*}
     $($rest:tt)*) =>{
        defclass!{$name,$($visible)*,{$($field)*},$($rest)*}
        defmethod!{$($visible)*,$name,($($t:tt)*),$fname,($($arg)*),$ret,$($body)*}
    };
    
    
    ($name:ident,$($visible:ident)*,{$($field:tt)*},) =>{
        struct $name{
            $($field)*
        }
    };
}

macro_rules! defmethod {
    ($($visible:ident)*,$clname:ident,($($t:tt)*),$name:ident,($($arg:tt)*),$ret:ty,$($body:tt)*) => {
        impl<$($t)*> $clname{
            $($visible)* fn $name($($arg)*)->$ret{$($body)*}
        }
    };
    ($($visible:ident)*,$clname:ident,($($t:tt)*),$name:ident,($($arg:tt)*),,$($body:tt)*) => {
        impl<$($t)*> $clname{
            $($visible)* fn $name($($arg)*){$($body)*}
        }
    };
    ($($visible:ident)*,$clname:ident,,$name:ident,($($arg:tt)*),$ret:ty,$($body:tt)*) => {
        impl $clname{
            $($visible)* fn $name($($arg)*)->$ret{$($body)*}
        }
    };
    ($($visible:ident)*,$clname:ident,,$name:ident,($($arg:tt)*),,$($body:tt)*) => {
        impl $clname{
            $($visible)* fn $name($($arg)*){$($body)*}
        }
    };
}

//----------------------------------------------------------------------------

defclass!{
  class Point {
    private:
    x,y,length:f64;

    public:

    new(x:f64,y:f64){
      Point{x:x,y:y,length:x.hypot(y)}
    }

    x(&self) -> f64{self.x}
    y(&self) -> f64{self.y}
    length(&self)->f64{self.length}    
  }
}

fn main() {
  let p = Point::new(1.0,20.0);
  println!("{},{},{}",p.x(),p.y(),p.length());
}