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#[macro_export] macro_rules! const_eq { ($left:expr, $right:expr) => { match $crate::coerce_to_cmp!($left, $right) { (left, right) => left.const_eq(right), } }; } /// Compares two generic standard library types for equality. /// /// # Types /// /// This macro supports multiple types with different prefixes: /// /// - `slice`: for comparing `&[T]`. [example](#compare_slices_structs) /// /// - `option`: for comparing `Option<T>`. [example](#compare_options) /// /// - `range`: for comparing `Range<T>`. [example](#compare_ranges) /// /// - `range_inclusive`: for comparing `RangeInclusive<T>`. /// [example](#compare_ranges_incluside) /// /// # Arguments /// /// The arguments take this form /// /// ```text /// const_eq_for!(type; left_value, right_value <comparator> ) /// ``` /// /// ### Comparator argument /// /// The `<comparator>` argument can be any of: /// /// - ` `(passing nothing): Compares the item using the [`const_eq`] macro. /// [example](#compare_slices_structs) /// /// - `, |item| <expression>`: /// Converts the item with `<expression>` to a type that can be compared using the /// [`const_eq`] macro. /// [example](#compare_slices_fieldless_enums) /// /// - `, |left_item, right_item| <expression>`: /// Compares the items with `<expression>`, which must evaluate to a `bool`. /// [example](#compare_options) /// /// - `, path::to::function`: /// Compares the items using the passed function, which must evaluate to a `bool`. /// [example](#compare_ranges_incluside) /// /// /// /// # Exmaples /// /// <span id = "compare_slices_structs"></span> /// ### Comparing slices of structs /// /// ``` /// use const_cmp::{const_eq_for, eq_str}; /// /// #[derive(Debug, Copy, Clone, PartialEq, Eq)] /// pub struct Location { /// pub file: &'static str, /// pub column: u32, /// pub line: u32, /// } /// /// const_cmp::impl_cmp! { /// impl Location; /// /// pub const fn const_eq(&self, other: &Self) -> bool { /// eq_str(self.file, other.file) && /// self.column == other.column && /// self.line == other.line /// } /// } /// # /// # macro_rules! here { /// # () => { /// # $crate::Location{file: file!(), column: column!(), line: line!()} /// # } /// # } /// # /// /// # fn main () { /// const HERE: &[Location] = &[here!(), here!(), here!(), here!()]; /// /// const THERE: &[Location] = &[here!(), here!(), here!(), here!()]; /// /// const CMP_HERE: bool = const_eq_for!(slice; HERE, HERE); /// assert!( CMP_HERE ); /// /// const CMP_HERE_THERE: bool = const_eq_for!(slice; HERE, THERE); /// assert!( !CMP_HERE_THERE ); /// /// const CMP_THERE_THERE: bool = const_eq_for!(slice; THERE, THERE); /// assert!( CMP_THERE_THERE ); /// /// /// # } /// /// ``` /// /// <span id = "compare_slices_fieldless_enums"></span> /// ### Comparing slices of field-less enums /// /// ```rust /// #[derive(Copy, Clone)] /// enum Direction { /// Left, /// Right, /// Up, /// Down, /// } /// /// use Direction::*; /// /// const fn eq_slice_direction(left: &[Direction], right: &[Direction]) -> bool { /// const_cmp::const_eq_for!(slice; left, right, |&x| x as u8) /// } /// /// const CHEAT_CODE: &[Direction] = &[Up, Up, Down, Down, Left, Right, Left, Right]; /// /// const CLOCKWISE: &[Direction] = &[Up, Right, Down, Left]; /// /// /// const CMP_CHEAT: bool = eq_slice_direction(CHEAT_CODE, CHEAT_CODE); /// assert!( CMP_CHEAT ); /// /// const CMP_CHEAT_CLOCK: bool = eq_slice_direction(CHEAT_CODE, CLOCKWISE); /// assert!( !CMP_CHEAT_CLOCK ); /// /// const CMP_CLOCK_CLOCK: bool = eq_slice_direction(CLOCKWISE, CLOCKWISE); /// assert!( CMP_CLOCK_CLOCK ); /// /// ``` /// /// <span id = "compare_options"></span> /// ### Comparing `Option`s /// /// ```rust /// use const_cmp::const_eq_for; /// /// const SOME: Option<(u32, u32)> = Some((3, 5)); /// const NONE: Option<(u32, u32)> = None; /// /// const fn eq_opt_tuple(left: &Option<(u32, u32)>, right: &Option<(u32, u32)>) -> bool { /// const_eq_for!(option; left, right, |l, r| l.0 == r.0 && l.1 == r.1 ) /// } /// /// const SOME_SOME: bool = eq_opt_tuple(&SOME, &SOME); /// assert!( SOME_SOME ); /// /// const SOME_NONE: bool = eq_opt_tuple(&SOME, &NONE); /// assert!( !SOME_NONE ); /// /// const NONE_NONE: bool = eq_opt_tuple(&NONE, &NONE); /// assert!( NONE_NONE ); /// /// ``` /// /// /// <span id = "compare_ranges"></span> /// ### Comparing `Range`s /// /// ```rust /// use const_cmp::{const_eq_for, impl_cmp}; /// /// use std::ops::Range; /// /// #[derive(Copy, Clone)] /// pub enum Month { /// January, /// February, /// March, /// April, /// May, /// June, /// July, /// August, /// September, /// October, /// November, /// December, /// } /// /// use Month::*; /// /// const_cmp::impl_cmp! { /// impl Month; /// /// pub const fn const_eq(&self, other: &Self) -> bool { /// *self as u8 == *other as u8 /// } /// } /// /// const FOO: Range<Month> = January..April; /// const BAR: Range<Month> = October..December; /// /// const FOO_FOO: bool = const_eq_for!(range; FOO, FOO); /// assert!( FOO_FOO ); /// /// const FOO_BAR: bool = const_eq_for!(range; FOO, BAR); /// assert!( !FOO_BAR ); /// /// const BAR_BAR: bool = const_eq_for!(range; BAR, BAR); /// assert!( BAR_BAR ); /// /// ``` /// /// <span id = "compare_ranges_incluside"></span> /// ### Comparing `RangeInclusive`s /// /// ```rust /// use const_cmp::{const_eq_for, impl_cmp}; /// /// use std::ops::RangeInclusive; /// /// #[derive(Copy, Clone)] /// pub enum WeekDay { /// Monday, /// Tuesday, /// Wednesday, /// Thursday, /// Friday, /// Saturday, /// Sunday, /// } /// /// use WeekDay::*; /// /// const_cmp::impl_cmp! { /// impl WeekDay; /// /// pub const fn const_eq(&self, other: &Self) -> bool { /// *self as u8 == *other as u8 /// } /// } /// /// const FOO: RangeInclusive<WeekDay> = Monday..=Thursday; /// const BAR: RangeInclusive<WeekDay> = Friday..=Sunday; /// /// const FOO_FOO: bool = const_eq_for!(range_inclusive; FOO, FOO); /// assert!( FOO_FOO ); /// /// const FOO_BAR: bool = const_eq_for!(range_inclusive; FOO, BAR, WeekDay::const_eq); /// assert!( !FOO_BAR ); /// /// const BAR_BAR: bool = const_eq_for!(range_inclusive; BAR, BAR, WeekDay::const_eq); /// assert!( BAR_BAR ); /// /// ``` /// #[macro_export] macro_rules! const_eq_for { ( slice; $left_slice:expr, $right_slice:expr $(, $($comparison:tt)* )? ) => { match ($left_slice, $right_slice) { (left_slice, right_slice) => { let mut returned = left_slice.len() == right_slice.len(); if returned { let mut i = 0; while i != left_slice.len() { let are_eq = $crate::__priv_const_eq_for!( left_slice[i], right_slice[i], $( $($comparison)* )? ); if !are_eq { returned = false; break; } i += 1; } } returned } } }; ( option; $left_opt:expr, $right_opt:expr $(, $($comparison:tt)* )? ) => { match (&$left_opt, &$right_opt) { (Some(l), Some(r)) => $crate::__priv_const_eq_for!(*l, *r, $( $($comparison)* )?), (None, None) => true, _ => false, } }; ( range; $left_range:expr, $right_range:expr $(, $($comparison:tt)* )? ) => { match (&$left_range, &$right_range) { (left_range, right_range) => { $crate::__priv_const_eq_for!( left_range.start, right_range.start, $( $($comparison)* )? ) && $crate::__priv_const_eq_for!( left_range.end, right_range.end, $( $($comparison)* )? ) } } }; ( range_inclusive; $left_range:expr, $right_range:expr $(, $($comparison:tt)* )? ) => { match (&$left_range, &$right_range) { (left_range, right_range) => { $crate::__priv_const_eq_for!( left_range.start(), right_range.start(), $( $($comparison)* )? ) && $crate::__priv_const_eq_for!( left_range.end(), right_range.end(), $( $($comparison)* )? ) } } }; } #[doc(hidden)] #[macro_export] macro_rules! __priv_const_eq_for { ($left:expr, $right:expr, ) => { $crate::coerce_to_cmp!($left).const_eq(&$right) }; ($left:expr, $right:expr, |$l: pat| $key_expr:expr $(,)*) => { $crate::coerce_to_cmp!({ let $l = &$left; $key_expr }) .const_eq(&{ let $l = &$right; $key_expr }) }; ($left:expr, $right:expr, |$l: pat, $r: pat| $eq_expr:expr $(,)*) => {{ let $l = &$left; let $r = &$right; $eq_expr }}; ($left:expr, $right:expr, $func:path $(,)*) => { $func(&$left, &$right) }; }