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

use glib::translate::*;
use glib::{IsA, Object, Value};

glib::wrapper! {
    /// A `GObject` value in a [`Expression`][crate::Expression].
    #[derive(Debug)]
    #[doc(alias = "GtkObjectExpression")]
    pub struct ObjectExpression(Shared<ffi::GtkObjectExpression>);

    match fn {
        ref => |ptr| ffi::gtk_expression_ref(ptr as *mut ffi::GtkExpression),
        unref => |ptr| ffi::gtk_expression_unref(ptr as *mut ffi::GtkExpression),
    }
}

define_expression!(
    ObjectExpression,
    ffi::GtkObjectExpression,
    ffi::gtk_object_expression_get_type
);

impl ObjectExpression {
    /// Creates an expression evaluating to the given `object` with a weak reference.
    ///
    /// Once the `object` is disposed, it will fail to evaluate.
    ///
    /// This expression is meant to break reference cycles.
    ///
    /// If you want to keep a reference to `object`, use [``ConstantExpression::new()``][crate::`ConstantExpression::new()`].
    /// ## `object`
    /// object to watch
    ///
    /// # Returns
    ///
    /// a new [`Expression`][crate::Expression]
    #[doc(alias = "gtk_object_expression_new")]
    pub fn new<T: IsA<Object>>(object: &T) -> Self {
        assert_initialized_main_thread!();
        unsafe {
            from_glib_full(ffi::gtk_object_expression_new(
                object.as_ref().to_glib_none().0,
            ))
        }
    }

    /// Gets the object that the expression evaluates to.
    ///
    /// # Returns
    ///
    /// the object, or `NULL`
    #[doc(alias = "gtk_object_expression_get_object")]
    #[doc(alias = "get_object")]
    pub fn object(&self) -> Option<Object> {
        assert_initialized_main_thread!();
        unsafe { from_glib_none(ffi::gtk_object_expression_get_object(self.to_glib_none().0)) }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_synced;

    #[test]
    fn test_object_expression() {
        test_synced(move || {
            let obj = crate::IconTheme::new();
            let expr = ObjectExpression::new(&obj);
            assert_eq!(expr.object().unwrap(), obj);
        });
    }
}