Convert newtype_index to a proc macro
The `macro_rules!` implementation was becomng excessively complicated, and difficult to modify. The new proc macro implementation should make it much easier to add new features (e.g. skipping certain `#[derive]`s)
This commit is contained in:
Aaron Hill
parent
4b043faba3
commit
339bbebbc1
4 changed files with 349 additions and 455 deletions
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@ -12,6 +12,8 @@ pub mod bit_set;
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pub mod interval;
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pub mod vec;
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pub use rustc_macros::newtype_index;
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/// Type size assertion. The first argument is a type and the second argument is its expected size.
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#[macro_export]
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macro_rules! static_assert_size {
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@ -49,461 +49,6 @@ impl Idx for u32 {
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}
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}
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/// Creates a struct type `S` that can be used as an index with
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/// `IndexVec` and so on.
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///
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/// There are two ways of interacting with these indices:
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///
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/// - The `From` impls are the preferred way. So you can do
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/// `S::from(v)` with a `usize` or `u32`. And you can convert back
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/// to an integer with `u32::from(s)`.
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///
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/// - Alternatively, you can use the methods `S::new(v)` and `s.index()`
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/// to create/return a value.
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///
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/// Internally, the index uses a u32, so the index must not exceed
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/// `u32::MAX`. You can also customize things like the `Debug` impl,
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/// what traits are derived, and so forth via the macro.
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#[macro_export]
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#[allow_internal_unstable(step_trait, rustc_attrs, trusted_step)]
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macro_rules! newtype_index {
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// ---- public rules ----
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// Use default constants
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($(#[$attrs:meta])* $v:vis struct $name:ident { .. }) => (
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$crate::newtype_index!(
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// Leave out derives marker so we can use its absence to ensure it comes first
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@attrs [$(#[$attrs])*]
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@type [$name]
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// shave off 256 indices at the end to allow space for packing these indices into enums
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@max [0xFFFF_FF00]
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@vis [$v]
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@debug_format ["{}"]);
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);
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// Define any constants
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($(#[$attrs:meta])* $v:vis struct $name:ident { $($tokens:tt)+ }) => (
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$crate::newtype_index!(
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// Leave out derives marker so we can use its absence to ensure it comes first
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@attrs [$(#[$attrs])*]
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@type [$name]
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// shave off 256 indices at the end to allow space for packing these indices into enums
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@max [0xFFFF_FF00]
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@vis [$v]
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@debug_format ["{}"]
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$($tokens)+);
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);
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// ---- private rules ----
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// Base case, user-defined constants (if any) have already been defined
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]) => (
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$(#[$attrs])*
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#[derive(Copy, PartialEq, Eq, Hash, PartialOrd, Ord, $($derives),*)]
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#[rustc_layout_scalar_valid_range_end($max)]
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$v struct $type {
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private: u32
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}
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impl Clone for $type {
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#[inline]
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fn clone(&self) -> Self {
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*self
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}
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}
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impl $type {
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/// Maximum value the index can take, as a `u32`.
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$v const MAX_AS_U32: u32 = $max;
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/// Maximum value the index can take.
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$v const MAX: Self = Self::from_u32($max);
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/// Creates a new index from a given `usize`.
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///
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/// # Panics
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///
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/// Will panic if `value` exceeds `MAX`.
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#[inline]
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$v const fn from_usize(value: usize) -> Self {
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assert!(value <= ($max as usize));
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// SAFETY: We just checked that `value <= max`.
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unsafe {
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Self::from_u32_unchecked(value as u32)
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}
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}
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/// Creates a new index from a given `u32`.
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///
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/// # Panics
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///
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/// Will panic if `value` exceeds `MAX`.
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#[inline]
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$v const fn from_u32(value: u32) -> Self {
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assert!(value <= $max);
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// SAFETY: We just checked that `value <= max`.
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unsafe {
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Self::from_u32_unchecked(value)
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}
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}
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/// Creates a new index from a given `u32`.
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///
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/// # Safety
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///
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/// The provided value must be less than or equal to the maximum value for the newtype.
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/// Providing a value outside this range is undefined due to layout restrictions.
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///
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/// Prefer using `from_u32`.
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#[inline]
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$v const unsafe fn from_u32_unchecked(value: u32) -> Self {
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Self { private: value }
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}
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/// Extracts the value of this index as a `usize`.
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#[inline]
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$v const fn index(self) -> usize {
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self.as_usize()
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}
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/// Extracts the value of this index as a `u32`.
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#[inline]
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$v const fn as_u32(self) -> u32 {
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self.private
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}
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/// Extracts the value of this index as a `usize`.
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#[inline]
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$v const fn as_usize(self) -> usize {
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self.as_u32() as usize
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}
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}
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impl std::ops::Add<usize> for $type {
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type Output = Self;
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fn add(self, other: usize) -> Self {
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Self::from_usize(self.index() + other)
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}
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}
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impl $crate::vec::Idx for $type {
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#[inline]
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fn new(value: usize) -> Self {
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Self::from_usize(value)
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}
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#[inline]
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fn index(self) -> usize {
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self.as_usize()
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}
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}
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impl ::std::iter::Step for $type {
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#[inline]
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fn steps_between(start: &Self, end: &Self) -> Option<usize> {
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<usize as ::std::iter::Step>::steps_between(
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&Self::index(*start),
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&Self::index(*end),
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)
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}
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#[inline]
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fn forward_checked(start: Self, u: usize) -> Option<Self> {
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Self::index(start).checked_add(u).map(Self::from_usize)
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}
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#[inline]
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fn backward_checked(start: Self, u: usize) -> Option<Self> {
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Self::index(start).checked_sub(u).map(Self::from_usize)
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}
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}
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// Safety: The implementation of `Step` upholds all invariants.
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unsafe impl ::std::iter::TrustedStep for $type {}
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impl From<$type> for u32 {
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#[inline]
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fn from(v: $type) -> u32 {
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v.as_u32()
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}
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}
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impl From<$type> for usize {
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#[inline]
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fn from(v: $type) -> usize {
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v.as_usize()
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}
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}
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impl From<usize> for $type {
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#[inline]
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fn from(value: usize) -> Self {
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Self::from_usize(value)
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}
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}
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impl From<u32> for $type {
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#[inline]
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fn from(value: u32) -> Self {
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Self::from_u32(value)
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}
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}
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$crate::newtype_index!(
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@handle_debug
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@derives [$($derives,)*]
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@type [$type]
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@debug_format [$debug_format]);
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);
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// base case for handle_debug where format is custom. No Debug implementation is emitted.
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(@handle_debug
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@derives [$($_derives:ident,)*]
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@type [$type:ident]
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@debug_format [custom]) => ();
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// base case for handle_debug, no debug overrides found, so use default
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(@handle_debug
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@derives []
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@type [$type:ident]
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@debug_format [$debug_format:tt]) => (
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impl ::std::fmt::Debug for $type {
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fn fmt(&self, fmt: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
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write!(fmt, $debug_format, self.as_u32())
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}
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}
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);
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// Debug is requested for derive, don't generate any Debug implementation.
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(@handle_debug
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@derives [Debug, $($derives:ident,)*]
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@type [$type:ident]
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@debug_format [$debug_format:tt]) => ();
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// It's not Debug, so just pop it off the front of the derives stack and check the rest.
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(@handle_debug
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@derives [$_derive:ident, $($derives:ident,)*]
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@type [$type:ident]
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@debug_format [$debug_format:tt]) => (
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$crate::newtype_index!(
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@handle_debug
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@derives [$($derives,)*]
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@type [$type]
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@debug_format [$debug_format]);
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);
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// Append comma to end of derives list if it's missing
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(@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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derive [$($derives:ident),*]
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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derive [$($derives,)*]
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$($tokens)*);
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);
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// By not including the @derives marker in this list nor in the default args, we can force it
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// to come first if it exists. When encodable is custom, just use the derives list as-is.
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(@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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derive [$($derives:ident,)+]
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ENCODABLE = custom
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@attrs [$(#[$attrs])*]
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@derives [$($derives,)+]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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);
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// By not including the @derives marker in this list nor in the default args, we can force it
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// to come first if it exists. When encodable isn't custom, add serialization traits by default.
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(@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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derive [$($derives:ident,)+]
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@derives [$($derives,)+]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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$crate::newtype_index!(@serializable $type);
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);
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// The case where no derives are added, but encodable is overridden. Don't
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// derive serialization traits
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(@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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ENCODABLE = custom
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@derives []
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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);
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// The case where no derives are added, add serialization derives by default
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(@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@derives []
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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$crate::newtype_index!(@serializable $type);
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);
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(@serializable $type:ident) => (
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impl<D: ::rustc_serialize::Decoder> ::rustc_serialize::Decodable<D> for $type {
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fn decode(d: &mut D) -> Self {
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Self::from_u32(d.read_u32())
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}
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}
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impl<E: ::rustc_serialize::Encoder> ::rustc_serialize::Encodable<E> for $type {
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fn encode(&self, e: &mut E) -> Result<(), E::Error> {
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e.emit_u32(self.private)
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}
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}
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);
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// Rewrite final without comma to one that includes comma
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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$name:ident = $constant:expr) => (
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$crate::newtype_index!(
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@derives [$($derives,)*]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$name = $constant,);
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);
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// Rewrite final const without comma to one that includes comma
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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$(#[doc = $doc:expr])*
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const $name:ident = $constant:expr) => (
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$crate::newtype_index!(
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@derives [$($derives,)*]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$(#[doc = $doc])* const $name = $constant,);
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);
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// Replace existing default for max
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$_max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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MAX = $max:expr,
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@derives [$($derives,)*]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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);
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// Replace existing default for debug_format
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$_debug_format:tt]
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DEBUG_FORMAT = $debug_format:tt,
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$($tokens:tt)*) => (
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$crate::newtype_index!(
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@derives [$($derives,)*]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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);
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// Assign a user-defined constant
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(@derives [$($derives:ident,)*]
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@attrs [$(#[$attrs:meta])*]
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@type [$type:ident]
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@max [$max:expr]
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@vis [$v:vis]
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@debug_format [$debug_format:tt]
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$(#[doc = $doc:expr])*
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const $name:ident = $constant:expr,
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$($tokens:tt)*) => (
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$(#[doc = $doc])*
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$v const $name: $type = $type::from_u32($constant);
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$crate::newtype_index!(
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@derives [$($derives,)*]
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@attrs [$(#[$attrs])*]
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@type [$type]
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@max [$max]
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@vis [$v]
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@debug_format [$debug_format]
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$($tokens)*);
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);
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}
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#[derive(Clone, PartialEq, Eq, Hash)]
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pub struct IndexVec<I: Idx, T> {
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pub raw: Vec<T>,
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