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// Take a look at the license at the top of the repository in the LICENSE file.

mod attribute_parser;
mod composite_template_derive;
mod util;

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

/// Derive macro for using a composite template in a widget.
///
/// The `template` attribute specifies where the template should be loaded
/// from;  it can be a `file`, a `resource`, or a `string`.
///
/// The `template_child` attribute is used to mark all internal widgets
/// we need to have programmatic access to.
///
/// # Example
///
/// Specify that `MyWidget` is using a composite template and load the
/// template file the `composite_template.ui` file.
///
/// Then, in the [`ObjectSubclass`] implementation you will need to call
/// [`bind_template`] in the [`class_init`] function, and [`init_template`] in
/// [`instance_init`] function.
///
/// [`ObjectSubclass`]: ../glib/subclass/types/trait.ObjectSubclass.html
/// [`bind_template`]: ../gtk/subclass/widget/trait.CompositeTemplate.html#tymethod.bind_template
/// [`class_init`]: ../glib/subclass/types/trait.ObjectSubclass.html#method.class_init
/// [`init_template`]: ../gtk/prelude/trait.InitializingWidgetExt.html#tymethod.init_template
/// [`instance_init`]: ../glib/subclass/types/trait.ObjectSubclass.html#method.instance_init
///
/// ```no_run
/// use gtk::prelude::*;
/// use gtk::glib;
/// use gtk::subclass::prelude::*;
///
/// mod imp {
///     use super::*;
///
///     #[derive(Debug, Default, gtk::CompositeTemplate)]
///     #[template(file = "composite_template.ui")]
///     pub struct MyWidget {
///         #[template_child]
///         pub label: TemplateChild<gtk::Label>,
///         #[template_child(id = "my_button_id")]
///         pub button: TemplateChild<gtk::Button>,
///     }
///
///     #[glib::object_subclass]
///     impl ObjectSubclass for MyWidget {
///         const NAME: &'static str = "MyWidget";
///         type Type = super::MyWidget;
///         type ParentType = gtk::Box;
///
///         fn class_init(klass: &mut Self::Class) {
///             Self::bind_template(klass);
///         }
///
///         fn instance_init(obj: &glib::subclass::InitializingObject<Self>) {
///             obj.init_template();
///         }
///     }
///
///     impl ObjectImpl for MyWidget {}
///     impl WidgetImpl for MyWidget {}
///     impl ContainerImpl for MyWidget {}
///     impl BoxImpl for MyWidget {}
/// }
///
/// glib::wrapper! {
///     pub struct MyWidget(ObjectSubclass<imp::MyWidget>) @extends gtk::Widget, gtk::Container, gtk::Box;
/// }
///
/// impl MyWidget {
///     pub fn new() -> Self {
///         glib::Object::new(&[]).expect("Failed to create an instance of MyWidget")
///     }
/// }
/// # fn main() {}
/// ```
#[proc_macro_derive(CompositeTemplate, attributes(template, template_child))]
#[proc_macro_error]
pub fn composite_template_derive(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let gen = composite_template_derive::impl_composite_template(&input);
    gen.into()
}