/// Define and reexport submodules.
#[macro_export] macro_rules! modules(
    ($($($feat:literal?)? $name:ident),* $(,)?) => { $(
        $(#[cfg(feature=$feat)])? mod $name;
        $(#[cfg(feature=$feat)])? pub use self::$name::*;
    )* };
    ($($($feat:literal?)? $name:ident $body:block),* $(,)?) => { $(
        $(#[cfg(feature=$feat)])? mod $name $body
        $(#[cfg(feature=$feat)])? pub use self::$name::*;
    )* };
);

/// Define a trait an implement it for read-only wrapper types. */
#[macro_export] macro_rules! flex_trait (
    ($Trait:ident $(<$($A:ident:$T:ident),+>)? $(:$dep:ident $(<$dtt:tt>)? $(+$dep2:ident $(<$dtt2:tt>)?)*)? {
        $(fn $fn:ident (&$self:ident $(, $arg:ident:$ty:ty)*) -> $ret:ty $body:block)*
    }) => {
        pub trait $Trait $(<$($A: $T),+>)? $(:$dep $(<$dtt>)? $(+$dep2 $(<$dtt2>)?)*)? {
            $(fn $fn (&$self $(,$arg:$ty)*) -> $ret $body)*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for &_T_ {
            $(fn $fn (&$self $(,$arg:$ty)*) -> $ret { (*$self).$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for &mut _T_ {
            $(fn $fn (&$self $(,$arg:$ty)*) -> $ret { (**$self).$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Arc<_T_> {
            $(fn $fn (&$self $(,$arg:$ty)*) -> $ret { (*$self).$fn($($arg),*) })*
        }
        //impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for Option<_T_> {
            //$(fn $fn (&$self $(,$arg:$ty)*) -> $ret {
                //if let Some(this) = $self { this.$fn($($arg),*) } else { Ok(None) }
            //})*
        //}
        //impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Mutex<_T_> {
            //$(fn $fn (&$self $(,$arg:$ty)*) -> $ret { (*$self).lock().unwrap().$fn($($arg),*) })*
        //}
        //impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::RwLock<_T_> {
            //$(fn $fn (&$self $(,$arg:$ty)*) -> $ret { $self.read().unwrap().$fn($($arg),*) })*
        //}
    });

/// Define a trait an implement it for various mutation-enabled wrapper types. */
#[macro_export] macro_rules! flex_trait_mut (
    ($Trait:ident $(<$($A:ident:$T:ident),+>)? {
        $(fn $fn:ident (&mut $self:ident $(, $arg:ident:$ty:ty)*) -> $ret:ty $body:block)*
    })=>{
        pub trait $Trait $(<$($A: $T),+>)? {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret $body)*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for &mut _T_ {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { (*$self).$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for Option<_T_> {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret {
                if let Some(this) = $self { this.$fn($($arg),*) } else { Ok(None) }
            })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Mutex<_T_> {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.get_mut().unwrap().$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Arc<::std::sync::Mutex<_T_>> {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.lock().unwrap().$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::RwLock<_T_> {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.write().unwrap().$fn($($arg),*) })*
        }
        impl<$($($A: $T,)+)? _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Arc<::std::sync::RwLock<_T_>> {
            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.write().unwrap().$fn($($arg),*) })*
        }
    };
);

/// Implement [`Debug`] in bulk.
#[macro_export] macro_rules! impl_debug(($($S:ty|$self:ident,$w:ident|$body:block)*)=>{
    $(impl std::fmt::Debug for $S {
        fn fmt (&$self, $w: &mut std::fmt::Formatter) -> std::fmt::Result $body
    })* });

/// Implement [`From`] in bulk.
#[macro_export] macro_rules! from(
    ($(<$($lt:lifetime),+>)?|$state:ident:$Source:ty|$Target:ty=$cb:expr) => {
        impl $(<$($lt),+>)? From<$Source> for $Target {
            fn from ($state:$Source) -> Self { $cb }}};
    ($($Struct:ty { $(
        $(<$($l:lifetime),* $($T:ident$(:$U:ident)?),*>)? ($source:ident: $From:ty) $expr:expr
    );+ $(;)? })*) => { $(
        $(impl $(<$($l),* $($T$(:$U)?),*>)? From<$From> for $Struct {
            fn from ($source: $From) -> Self { $expr } })+ )* }; );

/// Implement [Has].
#[macro_export] macro_rules! has(($T:ty: |$self:ident : $S:ty| $x:expr) => {
    impl Has<$T> for $S {
        fn get (&$self) -> &$T { &$x }
        fn get_mut (&mut $self) -> &mut $T { &mut $x } } };);

/// Implement [MaybeHas].
#[macro_export] macro_rules! maybe_has(
    ($T:ty: |$self:ident : $S:ty| $x:block; $y:block $(;)?) => {
        impl MaybeHas<$T> for $S {
            fn get (&$self) -> Option<&$T> $x
            fn get_mut (&mut $self) -> Option<&mut $T> $y } };);