isx 0.1.6

Traits for checking certain conditions of values
Documentation 
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//! Check if a value is the default.
//!
//! ```rust
//! use isx::IsDefault;
//!
//! fn test () {
//!   assert!(false.is_default());
//!   assert!(true.is_not_default());
//! }
//! ```
//!

#![cfg_attr(
    feature = "std",
    doc = r#"
You can also implement this using a derive for your own types:

```rust
use isx::IsDefault;

#[derive(Default, IsDefault)]
struct MyStruct {
  foo: String,
  bar: bool,
}

fn test() {
  assert!(MyStruct::default().is_default())
}
```
"#
)]

#[cfg(feature = "alloc")]
mod alloc;
#[cfg(feature = "bytes")]
mod bytes;
#[cfg(feature = "serde_json")]
mod serde_json;
#[cfg(feature = "std")]
mod std;

pub use isx_macros::IsDefault;

use ::core::marker::PhantomData;

/// Check if the value represents the default value.
pub trait IsDefault: Default {
    /// Return `true` if the current value is considered the default.
    fn is_default(&self) -> bool;

    /// Return `false` if the current value is considered the default.
    fn is_not_default(&self) -> bool {
        !self.is_default()
    }
}

macro_rules! default_impl {
    ($n:ty) => {
        impl $crate::IsDefault for $n {
            fn is_default(&self) -> bool {
                self == &<$n>::default()
            }
        }
    };
    ($n:ty, $v:expr) => {
        impl $crate::IsDefault for $n {
            fn is_default(&self) -> bool {
                self == &$v
            }
        }
    };
}

#[allow(unused_macros)]
macro_rules! empty_impl {
    ($n:ident) => {
        impl $crate::IsDefault for $n {
            fn is_default(&self) -> bool {
                self.is_empty()
            }
        }
    };
    ($n:ident<$($t:ident),+>) => {
        impl <$($t),+> $crate::IsDefault for $n<$($t),+> {
            fn is_default(&self) -> bool {
                self.is_empty()
            }
        }
    };
}

pub(crate) use default_impl;
#[allow(unused_imports)]
pub(crate) use empty_impl;

default_impl!(bool, false);
default_impl!(usize, 0usize);
default_impl!(isize, 0isize);
default_impl!(u8, 0u8);
default_impl!(u16, 0u16);
default_impl!(u32, 0u32);
default_impl!(u64, 0u64);
default_impl!(u128, 0u128);
default_impl!(i8, 0i8);
default_impl!(i16, 0i16);
default_impl!(i32, 0i32);
default_impl!(i64, 0i64);
default_impl!(i128, 0i128);

impl IsDefault for &str {
    fn is_default(&self) -> bool {
        self.is_empty()
    }
}

impl IsDefault for () {
    fn is_default(&self) -> bool {
        true
    }
}

impl<T> IsDefault for PhantomData<T> {
    fn is_default(&self) -> bool {
        true
    }
}

impl<T> IsDefault for Option<T> {
    fn is_default(&self) -> bool {
        self.is_none()
    }
}