path: root/core/src/lib.rs

//! The core library of [Iced].
//!
//! This library holds basic types that can be reused and re-exported in
//! different runtime implementations.
//!
//! ![The foundations of the Iced ecosystem](https://github.com/iced-rs/iced/blob/0525d76ff94e828b7b21634fa94a747022001c83/docs/graphs/foundations.png?raw=true)
//!
//! [Iced]: https://github.com/iced-rs/iced
#![doc(
    html_logo_url = "https://raw.githubusercontent.com/iced-rs/iced/9ab6923e943f784985e9ef9ca28b10278297225d/docs/logo.svg"
)]
pub mod alignment;
pub mod animation;
pub mod border;
pub mod clipboard;
pub mod event;
pub mod font;
pub mod gradient;
pub mod image;
pub mod input_method;
pub mod keyboard;
pub mod layout;
pub mod mouse;
pub mod overlay;
pub mod padding;
pub mod renderer;
pub mod svg;
pub mod text;
pub mod theme;
pub mod time;
pub mod touch;
pub mod widget;
pub mod window;

mod angle;
mod background;
mod color;
mod content_fit;
mod element;
mod length;
mod pixels;
mod point;
mod rectangle;
mod rotation;
mod settings;
mod shadow;
mod shell;
mod size;
mod transformation;
mod vector;

pub use alignment::Alignment;
pub use angle::{Degrees, Radians};
pub use animation::Animation;
pub use background::Background;
pub use border::Border;
pub use clipboard::Clipboard;
pub use color::Color;
pub use content_fit::ContentFit;
pub use element::Element;
pub use event::Event;
pub use font::Font;
pub use gradient::Gradient;
pub use image::Image;
pub use input_method::InputMethod;
pub use layout::Layout;
pub use length::Length;
pub use overlay::Overlay;
pub use padding::Padding;
pub use pixels::Pixels;
pub use point::Point;
pub use rectangle::Rectangle;
pub use renderer::Renderer;
pub use rotation::Rotation;
pub use settings::Settings;
pub use shadow::Shadow;
pub use shell::Shell;
pub use size::Size;
pub use svg::Svg;
pub use text::Text;
pub use theme::Theme;
pub use transformation::Transformation;
pub use vector::Vector;
pub use widget::Widget;

pub use smol_str::SmolStr;

/// A function that can _never_ be called.
///
/// This is useful to turn generic types into anything
/// you want by coercing them into a type with no possible
/// values.
pub fn never<T>(never: std::convert::Infallible) -> T {
    match never {}
}

/// A trait extension for binary functions (`Fn(A, B) -> O`).
///
/// It enables you to use a bunch of nifty functional programming paradigms
/// that work well with iced.
pub trait Function<A, B, O> {
    /// Applies the given first argument to a binary function and returns
    /// a new function that takes the other argument.
    ///
    /// This lets you partially "apply" a function—equivalent to currying,
    /// but it only works with binary functions. If you want to apply an
    /// arbitrary number of arguments, create a little struct for them.
    ///
    /// # When is this useful?
    /// Sometimes you will want to identify the source or target
    /// of some message in your user interface. This can be achieved through
    /// normal means by defining a closure and moving the identifier
    /// inside:
    ///
    /// ```rust
    /// # let element: Option<()> = Some(());
    /// # enum Message { ButtonPressed(u32, ()) }
    /// let id = 123;
    ///
    /// # let _ = {
    /// element.map(move |result| Message::ButtonPressed(id, result))
    /// # };
    /// ```
    ///
    /// That's quite a mouthful. [`with`](Self::with) lets you write:
    ///
    /// ```rust
    /// # use iced_core::Function;
    /// # let element: Option<()> = Some(());
    /// # enum Message { ButtonPressed(u32, ()) }
    /// let id = 123;
    ///
    /// # let _ = {
    /// element.map(Message::ButtonPressed.with(id))
    /// # };
    /// ```
    ///
    /// Effectively creating the same closure that partially applies
    /// the `id` to the message—but much more concise!
    fn with(self, prefix: A) -> impl Fn(B) -> O;
}

impl<F, A, B, O> Function<A, B, O> for F
where
    F: Fn(A, B) -> O,
    Self: Sized,
    A: Clone,
{
    fn with(self, prefix: A) -> impl Fn(B) -> O {
        move |result| self(prefix.clone(), result)
    }
}