1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
// Take a look at the license at the top of the repository in the LICENSE file.

mod boxed_derive;
mod clone;
mod closure;
mod downgrade_derive;
mod enum_derive;
mod error_domain_derive;
mod flags_attribute;
mod object_interface_attribute;
mod object_subclass_attribute;
mod shared_boxed_derive;
mod variant_derive;

mod utils;

use proc_macro::TokenStream;
use proc_macro_error::proc_macro_error;
use syn::{parse_macro_input, DeriveInput, NestedMeta};

/// Macro for passing variables as strong or weak references into a closure.
///
/// This macro can be useful in combination with closures, e.g. signal handlers, to reduce the
/// boilerplate required for passing strong or weak references into the closure. It will
/// automatically create the new reference and pass it with the same name into the closure.
///
/// If upgrading the weak reference to a strong reference inside the closure is failing, the
/// closure is immediately returning an optional default return value. If none is provided, `()` is
/// returned.
///
/// **⚠️ IMPORTANT ⚠️**
///
/// `glib` needs to be in scope, so unless it's one of the direct crate dependencies, you need to
/// import it because `clone!` is using it. For example:
///
/// ```rust,ignore
/// use gtk::glib;
/// ```
///
/// ### Debugging
///
/// In case something goes wrong inside the `clone!` macro, we use the [`g_debug`] macro. Meaning
/// that if you want to see these debug messages, you'll have to set the `G_MESSAGES_DEBUG`
/// environment variable when running your code (either in the code directly or when running the
/// binary) to either "all" or [`CLONE_MACRO_LOG_DOMAIN`]:
///
/// [`g_debug`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/macro.g_debug.html
/// [`CLONE_MACRO_LOG_DOMAIN`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/constant.CLONE_MACRO_LOG_DOMAIN.html
///
/// ```rust,ignore
/// use glib::CLONE_MACRO_LOG_DOMAIN;
///
/// std::env::set_var("G_MESSAGES_DEBUG", CLONE_MACRO_LOG_DOMAIN);
/// std::env::set_var("G_MESSAGES_DEBUG", "all");
/// ```
///
/// Or:
///
/// ```bash
/// $ G_MESSAGES_DEBUG=all ./binary
/// ```
///
/// ### Passing a strong reference
///
/// ```
/// use glib;
/// use glib_macros::clone;
/// use std::rc::Rc;
///
/// let v = Rc::new(1);
/// let closure = clone!(@strong v => move |x| {
///     println!("v: {}, x: {}", v, x);
/// });
///
/// closure(2);
/// ```
///
/// ### Passing a weak reference
///
/// ```
/// use glib;
/// use glib_macros::clone;
/// use std::rc::Rc;
///
/// let u = Rc::new(2);
/// let closure = clone!(@weak u => move |x| {
///     println!("u: {}, x: {}", u, x);
/// });
///
/// closure(3);
/// ```
///
/// #### Allowing a nullable weak reference
///
/// In some cases, even if the weak references can't be retrieved, you might want to still have
/// your closure called. In this case, you need to use `@weak-allow-none`:
///
/// ```
/// use glib;
/// use glib_macros::clone;
/// use std::rc::Rc;
///
/// let closure = {
///     // This `Rc` won't be available in the closure because it's dropped at the end of the
///     // current block
///     let u = Rc::new(2);
///     clone!(@weak-allow-none u => @default-return false, move |x| {
///         // We need to use a Debug print for `u` because it'll be an `Option`.
///         println!("u: {:?}, x: {}", u, x);
///         true
///     })
/// };
///
/// assert_eq!(closure(3), true);
/// ```
///
/// ### Renaming variables
///
/// ```
/// use glib;
/// use glib_macros::clone;
/// use std::rc::Rc;
///
/// let v = Rc::new(1);
/// let u = Rc::new(2);
/// let closure = clone!(@strong v as y, @weak u => move |x| {
///     println!("v as y: {}, u: {}, x: {}", y, u, x);
/// });
///
/// closure(3);
/// ```
///
/// ### Providing a default return value if upgrading a weak reference fails
///
/// You can do it in two different ways:
///
/// Either by providing the value yourself using `@default-return`:
///
/// ```
/// use glib;
/// use glib_macros::clone;
/// use std::rc::Rc;
///
/// let v = Rc::new(1);
/// let closure = clone!(@weak v => @default-return false, move |x| {
///     println!("v: {}, x: {}", v, x);
///     true
/// });
///
/// // Drop value so that the weak reference can't be upgraded.
/// drop(v);
///
/// assert_eq!(closure(2), false);
/// ```
///
/// Or by using `@default-panic` (if the value fails to get upgraded, it'll panic):
///
/// ```should_panic
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// # let v = Rc::new(1);
/// let closure = clone!(@weak v => @default-panic, move |x| {
///     println!("v: {}, x: {}", v, x);
///     true
/// });
/// # drop(v);
/// # assert_eq!(closure(2), false);
/// ```
///
/// ### Errors
///
/// Here is a list of errors you might encounter:
///
/// **Missing `@weak` or `@strong`**:
///
/// ```compile_fail
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// let v = Rc::new(1);
///
/// let closure = clone!(v => move |x| println!("v: {}, x: {}", v, x));
/// # drop(v);
/// # closure(2);
/// ```
///
/// **Passing `self` as an argument**:
///
/// ```compile_fail
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// #[derive(Debug)]
/// struct Foo;
///
/// impl Foo {
///     fn foo(&self) {
///         let closure = clone!(@strong self => move |x| {
///             println!("self: {:?}", self);
///         });
///         # closure(2);
///     }
/// }
/// ```
///
/// If you want to use `self` directly, you'll need to rename it:
///
/// ```
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// #[derive(Debug)]
/// struct Foo;
///
/// impl Foo {
///     fn foo(&self) {
///         let closure = clone!(@strong self as this => move |x| {
///             println!("self: {:?}", this);
///         });
///         # closure(2);
///     }
/// }
/// ```
///
/// **Passing fields directly**
///
/// ```compile_fail
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// #[derive(Debug)]
/// struct Foo {
///     v: Rc<usize>,
/// }
///
/// impl Foo {
///     fn foo(&self) {
///         let closure = clone!(@strong self.v => move |x| {
///             println!("self.v: {:?}", v);
///         });
///         # closure(2);
///     }
/// }
/// ```
///
/// You can do it by renaming it:
///
/// ```
/// # use glib;
/// # use glib_macros::clone;
/// # use std::rc::Rc;
/// # struct Foo {
/// #     v: Rc<usize>,
/// # }
/// impl Foo {
///     fn foo(&self) {
///         let closure = clone!(@strong self.v as v => move |x| {
///             println!("self.v: {}", v);
///         });
///         # closure(2);
///     }
/// }
/// ```
#[proc_macro]
#[proc_macro_error]
pub fn clone(item: TokenStream) -> TokenStream {
    clone::clone_inner(item)
}

/// Macro for creating a [`Closure`] object. This is a wrapper around [`Closure::new`] that
/// automatically type checks its arguments at run-time.
///
/// A `Closure` takes [`Value`] objects as inputs and output. This macro will automatically convert
/// the inputs to Rust types when invoking its callback, and then will convert the output back to a
/// `Value`. All inputs must implement the [`FromValue`] trait, and outputs must either implement
/// the [`ToValue`] trait or be the unit type `()`. Type-checking of inputs is done at run-time; if
/// incorrect types are passed via [`Closure::invoke`] then the closure will panic. Note that when
/// passing input types derived from [`Object`] or [`Interface`], you must take care to upcast to
/// the exact object or interface type that is being received.
///
/// Similarly to [`clone!`](crate::clone!), this macro can be useful in combination with signal
/// handlers to reduce boilerplate when passing references. Unique to `Closure` objects is the
/// ability to watch an object using a the `@watch` directive. Only an [`Object`] value can be
/// passed to `@watch`, and only one object can be watched per closure. When an object is watched,
/// a weak reference to the object is held in the closure. When the object is destroyed, the
/// closure will become invalidated: all signal handlers connected to the closure will become
/// disconnected, and any calls to [`Closure::invoke`] on the closure will be silently ignored.
/// Internally, this is accomplished using [`Object::watch_closure`] on the watched object.
///
/// The `@weak-allow-none` and `@strong` captures are also supported and behave the same as in
/// [`clone!`](crate::clone!), as is aliasing captures with the `as` keyword. Notably, these
/// captures are able to reference `Rc` and `Arc` values in addition to `Object` values.
///
/// [`Closure`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/closure/struct.Closure.html
/// [`Closure::new`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/closure/struct.Closure.html#method.new
/// [`Closure::new_local`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/closure/struct.Closure.html#method.new_local
/// [`Closure::invoke`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/closure/struct.Closure.html#method.invoke
/// [`Value`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/value/struct.Value.html
/// [`FromValue`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/value/trait.FromValue.html
/// [`ToValue`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/value/trait.ToValue.html
/// [`Interface`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/object/struct.Interface.html
/// [`Object`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/object/struct.Object.html
/// [`Object::watch_closure`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/object/trait.ObjectExt.html#tymethod.watch_closure
/// **⚠️ IMPORTANT ⚠️**
///
/// `glib` needs to be in scope, so unless it's one of the direct crate dependencies, you need to
/// import it because `closure!` is using it. For example:
///
/// ```rust,ignore
/// use gtk::glib;
/// ```
///
/// ### Using as a closure object
///
/// ```
/// use glib_macros::closure;
///
/// let concat_str = closure!(|s: &str| s.to_owned() + " World");
/// let result = concat_str.invoke::<String>(&[&"Hello"]);
/// assert_eq!(result, "Hello World");
/// ```
///
/// ### Connecting to a signal
///
/// For wrapping closures that can't be sent across threads, the
/// [`closure_local!`](crate::closure_local!) macro can be used. It has the same syntax as
/// `closure!`, but instead uses [`Closure::new_local`] internally.
///
/// ```
/// use glib;
/// use glib::prelude::*;
/// use glib_macros::closure_local;
///
/// let obj = glib::Object::new::<glib::Object>(&[]).unwrap();
/// obj.connect_closure(
///     "notify", false,
///     closure_local!(|_obj: glib::Object, pspec: glib::ParamSpec| {
///         println!("property notify: {}", pspec.name());
///     }));
/// ```
///
/// ### Object Watching
///
/// ```
/// use glib;
/// use glib::prelude::*;
/// use glib_macros::closure_local;
///
/// let closure = {
///     let obj = glib::Object::new::<glib::Object>(&[]).unwrap();
///     let closure = closure_local!(@watch obj => move || {
///         obj.type_().name()
///     });
///     assert_eq!(closure.invoke::<String>(&[]), "GObject");
///     closure
/// };
/// // `obj` is dropped, closure invalidated so it always does nothing and returns None
/// closure.invoke::<()>(&[]);
/// ```
///
/// `@watch` has special behavior when connected to a signal:
///
/// ```
/// use glib;
/// use glib::prelude::*;
/// use glib_macros::closure_local;
///
/// let obj = glib::Object::new::<glib::Object>(&[]).unwrap();
/// {
///     let other = glib::Object::new::<glib::Object>(&[]).unwrap();
///     obj.connect_closure(
///         "notify", false,
///         closure_local!(@watch other as b => move |a: glib::Object, pspec: glib::ParamSpec| {
///             let value = a.property_value(pspec.name());
///             b.set_property(pspec.name(), &value);
///         }));
///     // The signal handler will disconnect automatically at the end of this
///     // block when `other` is dropped.
/// }
/// ```
///
/// ### Weak and Strong References
///
/// ```
/// use glib;
/// use glib::prelude::*;
/// use glib_macros::closure;
/// use std::sync::Arc;
///
/// let closure = {
///     let a = Arc::new(String::from("Hello"));
///     let b = Arc::new(String::from("World"));
///     let closure = closure!(@strong a, @weak-allow-none b => move || {
///         // `a` is Arc<String>, `b` is Option<Arc<String>>
///         format!("{} {}", a, b.as_ref().map(|b| b.as_str()).unwrap_or_else(|| "Moon"))
///     });
///     assert_eq!(closure.invoke::<String>(&[]), "Hello World");
///     closure
/// };
/// // `a` still kept alive, `b` is dropped
/// assert_eq!(closure.invoke::<String>(&[]), "Hello Moon");
/// ```
#[proc_macro]
#[proc_macro_error]
pub fn closure(item: TokenStream) -> TokenStream {
    closure::closure_inner(item, "new")
}

/// The same as [`closure!`](crate::closure!) but uses [`Closure::new_local`] as a constructor.
/// This is useful for closures which can't be sent across threads. See the documentation of
/// [`closure!`](crate::closure!) for details.
///
/// [`Closure::new_local`]: https://gtk-rs.org/gtk-rs-core/stable/latest/docs/glib/closure/struct.Closure.html#method.new_local
#[proc_macro]
#[proc_macro_error]
pub fn closure_local(item: TokenStream) -> TokenStream {
    closure::closure_inner(item, "new_local")
}

/// Derive macro for register a rust enum in the glib type system and derive the
/// the [`glib::Value`] traits.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
/// use glib::subclass::prelude::*;
///
/// #[derive(Debug, Copy, Clone, PartialEq, Eq, glib::Enum)]
/// #[enum_type(name = "MyEnum")]
/// enum MyEnum {
///     Val,
///     #[enum_value(name = "My Val")]
///     ValWithCustomName,
///     #[enum_value(name = "My Other Val", nick = "other")]
///     ValWithCustomNameAndNick,
/// }
/// ```
#[proc_macro_derive(Enum, attributes(enum_type, enum_value))]
#[proc_macro_error]
pub fn enum_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let gen = enum_derive::impl_enum(&input);
    gen.into()
}

/// Attribute macro for defining flags using the `bitflags` crate.
/// This macro will also define a `GFlags::type_` function and
/// the [`glib::Value`] traits.
///
/// The expected `GType` name has to be passed as macro attribute.
/// The name and nick of each flag can also be optionally defined.
/// Default name is the flag identifier in CamelCase and default nick
/// is the identifier in kebab-case.
/// Combined flags should not be registered with the `GType` system
/// and so needs to be tagged with the `#[flags_value(skip)]` attribute.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
/// use glib::subclass::prelude::*;
///
/// #[glib::flags(name = "MyFlags")]
/// enum MyFlags {
///     #[flags_value(name = "Flag A", nick = "nick-a")]
///     A = 0b00000001,
///     #[flags_value(name = "Flag B")]
///     B = 0b00000010,
///     #[flags_value(skip)]
///     AB = Self::A.bits() | Self::B.bits(),
///     C = 0b00000100,
/// }
/// ```
///
/// [`glib::Value`]: value/struct.Value.html
#[proc_macro_attribute]
#[proc_macro_error]
pub fn flags(attr: TokenStream, item: TokenStream) -> TokenStream {
    let attr_meta = parse_macro_input!(attr as NestedMeta);
    let input = parse_macro_input!(item as DeriveInput);
    let gen = flags_attribute::impl_flags(&attr_meta, &input);
    gen.into()
}

/// Derive macro for defining a GLib error domain and its associated
/// [`ErrorDomain`] trait.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
/// use glib::subclass::prelude::*;
///
/// #[derive(Debug, Copy, Clone, glib::ErrorDomain)]
/// #[error_domain(name = "ExFoo")]
/// enum Foo {
///     Blah,
///     Baaz,
/// }
/// ```
///
/// [`ErrorDomain`]: error/trait.ErrorDomain.html
#[proc_macro_derive(ErrorDomain, attributes(error_domain))]
#[proc_macro_error]
pub fn error_domain_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let gen = error_domain_derive::impl_error_domain(&input);
    gen.into()
}

/// Derive macro for defining a [`BoxedType`]`::type_` function and
/// the [`glib::Value`] traits.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
/// use glib::subclass::prelude::*;
///
/// #[derive(Clone, Debug, PartialEq, Eq, glib::Boxed)]
/// #[boxed_type(name = "MyBoxed")]
/// struct MyBoxed(String);
/// ```
///
/// [`BoxedType`]: subclass/boxed/trait.BoxedType.html
/// [`glib::Value`]: value/struct.Value.html
#[proc_macro_derive(Boxed, attributes(boxed_type))]
#[proc_macro_error]
pub fn boxed_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let gen = boxed_derive::impl_boxed(&input);
    gen.into()
}

/// Derive macro for defining a [`SharedType`]`::get_type` function and
/// the [`glib::Value`] traits.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
/// use glib::subclass::prelude::*;
///
/// #[derive(Clone, Debug, PartialEq, Eq)]
/// struct MySharedInner {
///   foo: String,
/// }
/// #[derive(Clone, Debug, PartialEq, Eq, glib::SharedBoxed)]
/// #[shared_boxed_type(name = "MySharedBoxed")]
/// struct MyShared(std::sync::Arc<MySharedInner>);
/// ```
///
/// [`SharedType`]: subclass/shared/trait.SharedType.html
/// [`glib::Value`]: value/struct.Value.html
#[proc_macro_derive(SharedBoxed, attributes(shared_boxed_type))]
#[proc_macro_error]
pub fn shared_boxed_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let gen = shared_boxed_derive::impl_shared_boxed(&input);
    gen.into()
}

/// Macro for boilerplate of [`ObjectSubclass`] implementations.
///
/// This adds implementations for the `type_data()` and `type_()` methods,
/// which should probably never be defined differently.
///
/// It provides default values for the `Instance`, `Class`, and `Interfaces`
/// type parameters. If these are present, the macro will use the provided value
/// instead of the default.
///
/// Usually the defaults for `Instance` and `Class` will work. `Interfaces` is
/// necessary for types that implement interfaces.
///
/// ```ignore
/// type Instance = glib::subclass::simple::InstanceStruct<Self>;
/// type Class = glib::subclass::simple::ClassStruct<Self>;
/// type Interfaces = ();
/// ```
///
/// If no `new()` or `with_class()` method is provide, the macro adds a `new()`
/// implementation calling `Default::default()`. So the type needs to implement
/// `Default`, or this should be overridden.
///
/// ```ignore
/// fn new() -> Self {
///     Default::default()
/// }
/// ```
///
/// [`ObjectSubclass`]: subclass/types/trait.ObjectSubclass.html
#[proc_macro_attribute]
#[proc_macro_error]
pub fn object_subclass(_attr: TokenStream, item: TokenStream) -> TokenStream {
    use proc_macro_error::abort_call_site;
    match syn::parse::<syn::ItemImpl>(item) {
        Ok(input) => object_subclass_attribute::impl_object_subclass(&input).into(),
        Err(_) => abort_call_site!(object_subclass_attribute::WRONG_PLACE_MSG),
    }
}

/// Macro for boilerplate of [`ObjectInterface`] implementations.
///
/// This adds implementations for the `get_type()` method, which should probably never be defined
/// differently.
///
/// It provides default values for the `Prerequisites` type parameter. If this present, the macro
/// will use the provided value instead of the default.
///
/// `Prerequisites` is interfaces for types that require a specific base class or interfaces.
///
/// ```ignore
/// type Prerequisites = ();
/// ```
///
/// [`ObjectInterface`]: interface/types/trait.ObjectInterface.html
#[proc_macro_attribute]
#[proc_macro_error]
pub fn object_interface(_attr: TokenStream, item: TokenStream) -> TokenStream {
    use proc_macro_error::abort_call_site;
    match syn::parse::<syn::ItemImpl>(item) {
        Ok(input) => object_interface_attribute::impl_object_interface(&input).into(),
        Err(_) => abort_call_site!(object_interface_attribute::WRONG_PLACE_MSG),
    }
}

/// Macro for deriving implementations of [`glib::clone::Downgrade`] and
/// [`glib::clone::Upgrade`] traits and a weak type.
///
/// # Examples
///
/// ## New Type Idiom
///
/// ```rust,ignore
/// #[derive(glib::Downgrade)]
/// pub struct FancyLabel(gtk::Label);
///
/// impl FancyLabel {
///     pub fn new(label: &str) -> Self {
///         Self(gtk::LabelBuilder::new().label(label).build())
///     }
///
///     pub fn flip(&self) {
///         self.0.set_angle(180.0 - self.0.angle());
///     }
/// }
///
/// let fancy_label = FancyLabel::new("Look at me!");
/// let button = gtk::ButtonBuilder::new().label("Click me!").build();
/// button.connect_clicked(clone!(@weak fancy_label => move || fancy_label.flip()));
/// ```
///
/// ## Generic New Type
///
/// ```rust,ignore
/// #[derive(glib::Downgrade)]
/// pub struct TypedEntry<T>(gtk::Entry, std::marker::PhantomData<T>);
///
/// impl<T: ToString + FromStr> for TypedEntry<T> {
///     // ...
/// }
/// ```
///
/// ## Structures and Enums
///
/// ```rust,ignore
/// #[derive(Clone, glib::Downgrade)]
/// pub struct ControlButtons {
///     pub up: gtk::Button,
///     pub down: gtk::Button,
///     pub left: gtk::Button,
///     pub right: gtk::Button,
/// }
///
/// #[derive(Clone, glib::Downgrade)]
/// pub enum DirectionButton {
///     Left(gtk::Button),
///     Right(gtk::Button),
///     Up(gtk::Button),
///     Down(gtk::Button),
/// }
/// ```
///
/// [`glib::clone::Downgrade`]: clone/trait.Downgrade.html
/// [`glib::clone::Upgrade`]: clone/trait.Upgrade.html
#[proc_macro_derive(Downgrade)]
pub fn downgrade(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    downgrade_derive::impl_downgrade(input)
}

/// Derive macro for serializing/deserializing custom structs as [`glib::Variant`]s.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
///
/// #[derive(Debug, PartialEq, Eq, glib::Variant)]
/// struct Foo {
///     some_string: String,
///     some_int: i32,
/// }
///
/// let v = Foo { some_string: String::from("bar"), some_int: 1 };
/// let var = v.to_variant();
/// assert_eq!(var.get::<Foo>(), Some(v));
/// ```
///
/// When storing `Vec`s of fixed size types it is a good idea to wrap these in
/// `glib::FixedSizeVariantArray` as serialization/deserialization will be more efficient.
///
/// # Example
///
/// ```
/// use glib::prelude::*;
///
/// #[derive(Debug, PartialEq, Eq, glib::Variant)]
/// struct Foo {
///     some_vec: glib::FixedSizeVariantArray<Vec<u32>, u32>,
///     some_int: i32,
/// }
///
/// let v = Foo { some_vec: vec![1u32, 2u32].into(), some_int: 1 };
/// let var = v.to_variant();
/// assert_eq!(var.get::<Foo>(), Some(v));
/// ```
///
/// [`glib::Variant`]: variant/struct.Variant.html
#[proc_macro_derive(Variant)]
pub fn variant_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    variant_derive::impl_variant(input)
}

#[proc_macro]
pub fn cstr_bytes(item: TokenStream) -> TokenStream {
    syn::parse::Parser::parse2(
        |stream: syn::parse::ParseStream<'_>| {
            let literal = stream.parse::<syn::LitStr>()?;
            stream.parse::<syn::parse::Nothing>()?;
            let bytes = std::ffi::CString::new(literal.value())
                .map_err(|e| syn::Error::new_spanned(&literal, format!("{}", e)))?
                .into_bytes_with_nul();
            let bytes = proc_macro2::Literal::byte_string(&bytes);
            Ok(quote::quote! { #bytes }.into())
        },
        item.into(),
    )
    .unwrap_or_else(|e| e.into_compile_error().into())
}