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////////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2018, the Perspective Authors.
//
// This file is part of the Perspective library, distributed under the terms
// of the Apache License 2.0.  The full license can be found in the LICENSE
// file.

/// A helper to for the pattern `let x2 = x;` necessary to clone structs
/// destined for an `async` or `'static` closure stack.  This is like `move || {
/// .. }` or `move async { .. }`, but for clone semantics.  `clone!()` works
/// with symbols as well as properties and methods, using the last symbol name
/// in the method chain, or an alias via `x = ...` syntax.
///
/// # Examples
///
/// ```
/// clone!(my_struct.option_method(), alias = my_struct.prop1.my_rc);
/// println!("These bindings exist: {:?} {:?}", option_method, alias);
/// ```
#[macro_export]
macro_rules! clone {
    (impl @bind $i:tt { $($orig:tt)* } { }) => {
        let $i = $($orig)*.clone();
    };

    (impl @bind $i:tt { $($orig:tt)* } { $binder:tt }) => {
        let $binder = $($orig)*.clone();
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt) => {
        $crate::clone!(impl @bind $i { $($orig)* $i } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt ()) => {
        $crate::clone!(impl @bind $i { $($orig)* $i () } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt . 0) => {
        $crate::clone!(impl @bind $i { $($orig)* $i . 0 } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt . 1) => {
        $crate::clone!(impl @bind $i { $($orig)* $i . 1 } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt . 2) => {
        $crate::clone!(impl @bind $i { $($orig)* $i . 2 } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt . 3) => {
        $crate::clone!(impl @bind $i { $($orig)* $i . 3 } { $($binder)* });
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt = $($tail:tt)+) => {
        $crate::clone!(impl @expand { $($orig)* } { $i } $($tail)+);
    };

    (impl @expand { $($orig:tt)* } { $($binder:tt)* } $i:tt $($tail:tt)+) => {
        $crate::clone!(impl @expand { $($orig)* $i } { $($binder)* } $($tail)+);
    };

    (impl @context { $($orig:tt)* } $tail:tt) => {
        $crate::clone!(impl @expand { } { } $($orig)* $tail);
    };

    (impl @context { $($orig:tt)* } , $($tail:tt)+) => {
        $crate::clone!(impl @expand { } { } $($orig)*);
        $crate::clone!(impl @context { } $($tail)+);
    };

    (impl @context { $($orig:tt)* } $i:tt $($tail:tt)+) => {
        $crate::clone!(impl @context { $($orig)* $i } $($tail)+);
    };

    ($($tail:tt)+) => {
        $crate::clone!(impl @context { } $($tail)+);
    }
}