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Diffstat (limited to 'third_party/rust/regex-automata/src/util/primitives.rs')
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diff --git a/third_party/rust/regex-automata/src/util/primitives.rs b/third_party/rust/regex-automata/src/util/primitives.rs new file mode 100644 index 0000000000..5c5d187b0e --- /dev/null +++ b/third_party/rust/regex-automata/src/util/primitives.rs @@ -0,0 +1,776 @@ +/*! +Lower level primitive types that are useful in a variety of circumstances. + +# Overview + +This list represents the principle types in this module and briefly describes +when you might want to use them. + +* [`PatternID`] - A type that represents the identifier of a regex pattern. +This is probably the most widely used type in this module (which is why it's +also re-exported in the crate root). +* [`StateID`] - A type the represents the identifier of a finite automaton +state. This is used for both NFAs and DFAs, with the notable exception of +the hybrid NFA/DFA. (The hybrid NFA/DFA uses a special purpose "lazy" state +identifier.) +* [`SmallIndex`] - The internal representation of both a `PatternID` and a +`StateID`. Its purpose is to serve as a type that can index memory without +being as big as a `usize` on 64-bit targets. The main idea behind this type +is that there are many things in regex engines that will, in practice, never +overflow a 32-bit integer. (For example, like the number of patterns in a regex +or the number of states in an NFA.) Thus, a `SmallIndex` can be used to index +memory without peppering `as` casts everywhere. Moreover, it forces callers +to handle errors in the case where, somehow, the value would otherwise overflow +either a 32-bit integer or a `usize` (e.g., on 16-bit targets). +* [`NonMaxUsize`] - Represents a `usize` that cannot be `usize::MAX`. As a +result, `Option<NonMaxUsize>` has the same size in memory as a `usize`. This +useful, for example, when representing the offsets of submatches since it +reduces memory usage by a factor of 2. It is a legal optimization since Rust +guarantees that slices never have a length that exceeds `isize::MAX`. +*/ + +use core::num::NonZeroUsize; + +#[cfg(feature = "alloc")] +use alloc::vec::Vec; + +use crate::util::int::{Usize, U16, U32, U64}; + +/// A `usize` that can never be `usize::MAX`. +/// +/// This is similar to `core::num::NonZeroUsize`, but instead of not permitting +/// a zero value, this does not permit a max value. +/// +/// This is useful in certain contexts where one wants to optimize the memory +/// usage of things that contain match offsets. Namely, since Rust slices +/// are guaranteed to never have a length exceeding `isize::MAX`, we can use +/// `usize::MAX` as a sentinel to indicate that no match was found. Indeed, +/// types like `Option<NonMaxUsize>` have exactly the same size in memory as a +/// `usize`. +/// +/// This type is defined to be `repr(transparent)` for +/// `core::num::NonZeroUsize`, which is in turn defined to be +/// `repr(transparent)` for `usize`. +#[derive(Clone, Copy, Eq, Hash, PartialEq, PartialOrd, Ord)] +#[repr(transparent)] +pub struct NonMaxUsize(NonZeroUsize); + +impl NonMaxUsize { + /// Create a new `NonMaxUsize` from the given value. + /// + /// This returns `None` only when the given value is equal to `usize::MAX`. + #[inline] + pub fn new(value: usize) -> Option<NonMaxUsize> { + NonZeroUsize::new(value.wrapping_add(1)).map(NonMaxUsize) + } + + /// Return the underlying `usize` value. The returned value is guaranteed + /// to not equal `usize::MAX`. + #[inline] + pub fn get(self) -> usize { + self.0.get().wrapping_sub(1) + } +} + +// We provide our own Debug impl because seeing the internal repr can be quite +// surprising if you aren't expecting it. e.g., 'NonMaxUsize(5)' vs just '5'. +impl core::fmt::Debug for NonMaxUsize { + fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result { + write!(f, "{:?}", self.get()) + } +} + +/// A type that represents a "small" index. +/// +/// The main idea of this type is to provide something that can index memory, +/// but uses less memory than `usize` on 64-bit systems. Specifically, its +/// representation is always a `u32` and has `repr(transparent)` enabled. (So +/// it is safe to transmute between a `u32` and a `SmallIndex`.) +/// +/// A small index is typically useful in cases where there is no practical way +/// that the index will overflow a 32-bit integer. A good example of this is +/// an NFA state. If you could somehow build an NFA with `2^30` states, its +/// memory usage would be exorbitant and its runtime execution would be so +/// slow as to be completely worthless. Therefore, this crate generally deems +/// it acceptable to return an error if it would otherwise build an NFA that +/// requires a slice longer than what a 32-bit integer can index. In exchange, +/// we can use 32-bit indices instead of 64-bit indices in various places. +/// +/// This type ensures this by providing a constructor that will return an error +/// if its argument cannot fit into the type. This makes it much easier to +/// handle these sorts of boundary cases that are otherwise extremely subtle. +/// +/// On all targets, this type guarantees that its value will fit in a `u32`, +/// `i32`, `usize` and an `isize`. This means that on 16-bit targets, for +/// example, this type's maximum value will never overflow an `isize`, +/// which means it will never overflow a `i16` even though its internal +/// representation is still a `u32`. +/// +/// The purpose for making the type fit into even signed integer types like +/// `isize` is to guarantee that the difference between any two small indices +/// is itself also a small index. This is useful in certain contexts, e.g., +/// for delta encoding. +/// +/// # Other types +/// +/// The following types wrap `SmallIndex` to provide a more focused use case: +/// +/// * [`PatternID`] is for representing the identifiers of patterns. +/// * [`StateID`] is for representing the identifiers of states in finite +/// automata. It is used for both NFAs and DFAs. +/// +/// # Representation +/// +/// This type is always represented internally by a `u32` and is marked as +/// `repr(transparent)`. Thus, this type always has the same representation as +/// a `u32`. It is thus safe to transmute between a `u32` and a `SmallIndex`. +/// +/// # Indexing +/// +/// For convenience, callers may use a `SmallIndex` to index slices. +/// +/// # Safety +/// +/// While a `SmallIndex` is meant to guarantee that its value fits into `usize` +/// without using as much space as a `usize` on all targets, callers must +/// not rely on this property for safety. Callers may choose to rely on this +/// property for correctness however. For example, creating a `SmallIndex` with +/// an invalid value can be done in entirely safe code. This may in turn result +/// in panics or silent logical errors. +#[derive( + Clone, Copy, Debug, Default, Eq, Hash, PartialEq, PartialOrd, Ord, +)] +#[repr(transparent)] +pub struct SmallIndex(u32); + +impl SmallIndex { + /// The maximum index value. + #[cfg(any(target_pointer_width = "32", target_pointer_width = "64"))] + pub const MAX: SmallIndex = + // FIXME: Use as_usize() once const functions in traits are stable. + SmallIndex::new_unchecked(core::i32::MAX as usize - 1); + + /// The maximum index value. + #[cfg(target_pointer_width = "16")] + pub const MAX: SmallIndex = + SmallIndex::new_unchecked(core::isize::MAX - 1); + + /// The total number of values that can be represented as a small index. + pub const LIMIT: usize = SmallIndex::MAX.as_usize() + 1; + + /// The zero index value. + pub const ZERO: SmallIndex = SmallIndex::new_unchecked(0); + + /// The number of bytes that a single small index uses in memory. + pub const SIZE: usize = core::mem::size_of::<SmallIndex>(); + + /// Create a new small index. + /// + /// If the given index exceeds [`SmallIndex::MAX`], then this returns + /// an error. + #[inline] + pub fn new(index: usize) -> Result<SmallIndex, SmallIndexError> { + SmallIndex::try_from(index) + } + + /// Create a new small index without checking whether the given value + /// exceeds [`SmallIndex::MAX`]. + /// + /// Using this routine with an invalid index value will result in + /// unspecified behavior, but *not* undefined behavior. In particular, an + /// invalid index value is likely to cause panics or possibly even silent + /// logical errors. + /// + /// Callers must never rely on a `SmallIndex` to be within a certain range + /// for memory safety. + #[inline] + pub const fn new_unchecked(index: usize) -> SmallIndex { + // FIXME: Use as_u32() once const functions in traits are stable. + SmallIndex(index as u32) + } + + /// Like [`SmallIndex::new`], but panics if the given index is not valid. + #[inline] + pub fn must(index: usize) -> SmallIndex { + SmallIndex::new(index).expect("invalid small index") + } + + /// Return this small index as a `usize`. This is guaranteed to never + /// overflow `usize`. + #[inline] + pub const fn as_usize(&self) -> usize { + // FIXME: Use as_usize() once const functions in traits are stable. + self.0 as usize + } + + /// Return this small index as a `u64`. This is guaranteed to never + /// overflow. + #[inline] + pub const fn as_u64(&self) -> u64 { + // FIXME: Use u64::from() once const functions in traits are stable. + self.0 as u64 + } + + /// Return the internal `u32` of this small index. This is guaranteed to + /// never overflow `u32`. + #[inline] + pub const fn as_u32(&self) -> u32 { + self.0 + } + + /// Return the internal `u32` of this small index represented as an `i32`. + /// This is guaranteed to never overflow an `i32`. + #[inline] + pub const fn as_i32(&self) -> i32 { + // This is OK because we guarantee that our max value is <= i32::MAX. + self.0 as i32 + } + + /// Returns one more than this small index as a usize. + /// + /// Since a small index has constraints on its maximum value, adding `1` to + /// it will always fit in a `usize`, `u32` and a `i32`. + #[inline] + pub fn one_more(&self) -> usize { + self.as_usize() + 1 + } + + /// Decode this small index from the bytes given using the native endian + /// byte order for the current target. + /// + /// If the decoded integer is not representable as a small index for the + /// current target, then this returns an error. + #[inline] + pub fn from_ne_bytes( + bytes: [u8; 4], + ) -> Result<SmallIndex, SmallIndexError> { + let id = u32::from_ne_bytes(bytes); + if id > SmallIndex::MAX.as_u32() { + return Err(SmallIndexError { attempted: u64::from(id) }); + } + Ok(SmallIndex::new_unchecked(id.as_usize())) + } + + /// Decode this small index from the bytes given using the native endian + /// byte order for the current target. + /// + /// This is analogous to [`SmallIndex::new_unchecked`] in that is does not + /// check whether the decoded integer is representable as a small index. + #[inline] + pub fn from_ne_bytes_unchecked(bytes: [u8; 4]) -> SmallIndex { + SmallIndex::new_unchecked(u32::from_ne_bytes(bytes).as_usize()) + } + + /// Return the underlying small index integer as raw bytes in native endian + /// format. + #[inline] + pub fn to_ne_bytes(&self) -> [u8; 4] { + self.0.to_ne_bytes() + } +} + +impl<T> core::ops::Index<SmallIndex> for [T] { + type Output = T; + + #[inline] + fn index(&self, index: SmallIndex) -> &T { + &self[index.as_usize()] + } +} + +impl<T> core::ops::IndexMut<SmallIndex> for [T] { + #[inline] + fn index_mut(&mut self, index: SmallIndex) -> &mut T { + &mut self[index.as_usize()] + } +} + +#[cfg(feature = "alloc")] +impl<T> core::ops::Index<SmallIndex> for Vec<T> { + type Output = T; + + #[inline] + fn index(&self, index: SmallIndex) -> &T { + &self[index.as_usize()] + } +} + +#[cfg(feature = "alloc")] +impl<T> core::ops::IndexMut<SmallIndex> for Vec<T> { + #[inline] + fn index_mut(&mut self, index: SmallIndex) -> &mut T { + &mut self[index.as_usize()] + } +} + +impl From<u8> for SmallIndex { + fn from(index: u8) -> SmallIndex { + SmallIndex::new_unchecked(usize::from(index)) + } +} + +impl TryFrom<u16> for SmallIndex { + type Error = SmallIndexError; + + fn try_from(index: u16) -> Result<SmallIndex, SmallIndexError> { + if u32::from(index) > SmallIndex::MAX.as_u32() { + return Err(SmallIndexError { attempted: u64::from(index) }); + } + Ok(SmallIndex::new_unchecked(index.as_usize())) + } +} + +impl TryFrom<u32> for SmallIndex { + type Error = SmallIndexError; + + fn try_from(index: u32) -> Result<SmallIndex, SmallIndexError> { + if index > SmallIndex::MAX.as_u32() { + return Err(SmallIndexError { attempted: u64::from(index) }); + } + Ok(SmallIndex::new_unchecked(index.as_usize())) + } +} + +impl TryFrom<u64> for SmallIndex { + type Error = SmallIndexError; + + fn try_from(index: u64) -> Result<SmallIndex, SmallIndexError> { + if index > SmallIndex::MAX.as_u64() { + return Err(SmallIndexError { attempted: index }); + } + Ok(SmallIndex::new_unchecked(index.as_usize())) + } +} + +impl TryFrom<usize> for SmallIndex { + type Error = SmallIndexError; + + fn try_from(index: usize) -> Result<SmallIndex, SmallIndexError> { + if index > SmallIndex::MAX.as_usize() { + return Err(SmallIndexError { attempted: index.as_u64() }); + } + Ok(SmallIndex::new_unchecked(index)) + } +} + +#[cfg(test)] +impl quickcheck::Arbitrary for SmallIndex { + fn arbitrary(gen: &mut quickcheck::Gen) -> SmallIndex { + use core::cmp::max; + + let id = max(i32::MIN + 1, i32::arbitrary(gen)).abs(); + if id > SmallIndex::MAX.as_i32() { + SmallIndex::MAX + } else { + SmallIndex::new(usize::try_from(id).unwrap()).unwrap() + } + } +} + +/// This error occurs when a small index could not be constructed. +/// +/// This occurs when given an integer exceeding the maximum small index value. +/// +/// When the `std` feature is enabled, this implements the `Error` trait. +#[derive(Clone, Debug, Eq, PartialEq)] +pub struct SmallIndexError { + attempted: u64, +} + +impl SmallIndexError { + /// Returns the value that could not be converted to a small index. + pub fn attempted(&self) -> u64 { + self.attempted + } +} + +#[cfg(feature = "std")] +impl std::error::Error for SmallIndexError {} + +impl core::fmt::Display for SmallIndexError { + fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result { + write!( + f, + "failed to create small index from {:?}, which exceeds {:?}", + self.attempted(), + SmallIndex::MAX, + ) + } +} + +#[derive(Clone, Debug)] +pub(crate) struct SmallIndexIter { + rng: core::ops::Range<usize>, +} + +impl Iterator for SmallIndexIter { + type Item = SmallIndex; + + fn next(&mut self) -> Option<SmallIndex> { + if self.rng.start >= self.rng.end { + return None; + } + let next_id = self.rng.start + 1; + let id = core::mem::replace(&mut self.rng.start, next_id); + // new_unchecked is OK since we asserted that the number of + // elements in this iterator will fit in an ID at construction. + Some(SmallIndex::new_unchecked(id)) + } +} + +macro_rules! index_type_impls { + ($name:ident, $err:ident, $iter:ident, $withiter:ident) => { + impl $name { + /// The maximum value. + pub const MAX: $name = $name(SmallIndex::MAX); + + /// The total number of values that can be represented. + pub const LIMIT: usize = SmallIndex::LIMIT; + + /// The zero value. + pub const ZERO: $name = $name(SmallIndex::ZERO); + + /// The number of bytes that a single value uses in memory. + pub const SIZE: usize = SmallIndex::SIZE; + + /// Create a new value that is represented by a "small index." + /// + /// If the given index exceeds the maximum allowed value, then this + /// returns an error. + #[inline] + pub fn new(value: usize) -> Result<$name, $err> { + SmallIndex::new(value).map($name).map_err($err) + } + + /// Create a new value without checking whether the given argument + /// exceeds the maximum. + /// + /// Using this routine with an invalid value will result in + /// unspecified behavior, but *not* undefined behavior. In + /// particular, an invalid ID value is likely to cause panics or + /// possibly even silent logical errors. + /// + /// Callers must never rely on this type to be within a certain + /// range for memory safety. + #[inline] + pub const fn new_unchecked(value: usize) -> $name { + $name(SmallIndex::new_unchecked(value)) + } + + /// Like `new`, but panics if the given value is not valid. + #[inline] + pub fn must(value: usize) -> $name { + $name::new(value).expect(concat!( + "invalid ", + stringify!($name), + " value" + )) + } + + /// Return the internal value as a `usize`. This is guaranteed to + /// never overflow `usize`. + #[inline] + pub const fn as_usize(&self) -> usize { + self.0.as_usize() + } + + /// Return the internal value as a `u64`. This is guaranteed to + /// never overflow. + #[inline] + pub const fn as_u64(&self) -> u64 { + self.0.as_u64() + } + + /// Return the internal value as a `u32`. This is guaranteed to + /// never overflow `u32`. + #[inline] + pub const fn as_u32(&self) -> u32 { + self.0.as_u32() + } + + /// Return the internal value as a i32`. This is guaranteed to + /// never overflow an `i32`. + #[inline] + pub const fn as_i32(&self) -> i32 { + self.0.as_i32() + } + + /// Returns one more than this value as a usize. + /// + /// Since values represented by a "small index" have constraints + /// on their maximum value, adding `1` to it will always fit in a + /// `usize`, `u32` and a `i32`. + #[inline] + pub fn one_more(&self) -> usize { + self.0.one_more() + } + + /// Decode this value from the bytes given using the native endian + /// byte order for the current target. + /// + /// If the decoded integer is not representable as a small index + /// for the current target, then this returns an error. + #[inline] + pub fn from_ne_bytes(bytes: [u8; 4]) -> Result<$name, $err> { + SmallIndex::from_ne_bytes(bytes).map($name).map_err($err) + } + + /// Decode this value from the bytes given using the native endian + /// byte order for the current target. + /// + /// This is analogous to `new_unchecked` in that is does not check + /// whether the decoded integer is representable as a small index. + #[inline] + pub fn from_ne_bytes_unchecked(bytes: [u8; 4]) -> $name { + $name(SmallIndex::from_ne_bytes_unchecked(bytes)) + } + + /// Return the underlying integer as raw bytes in native endian + /// format. + #[inline] + pub fn to_ne_bytes(&self) -> [u8; 4] { + self.0.to_ne_bytes() + } + + /// Returns an iterator over all values from 0 up to and not + /// including the given length. + /// + /// If the given length exceeds this type's limit, then this + /// panics. + pub(crate) fn iter(len: usize) -> $iter { + $iter::new(len) + } + } + + // We write our own Debug impl so that we get things like PatternID(5) + // instead of PatternID(SmallIndex(5)). + impl core::fmt::Debug for $name { + fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result { + f.debug_tuple(stringify!($name)).field(&self.as_u32()).finish() + } + } + + impl<T> core::ops::Index<$name> for [T] { + type Output = T; + + #[inline] + fn index(&self, index: $name) -> &T { + &self[index.as_usize()] + } + } + + impl<T> core::ops::IndexMut<$name> for [T] { + #[inline] + fn index_mut(&mut self, index: $name) -> &mut T { + &mut self[index.as_usize()] + } + } + + #[cfg(feature = "alloc")] + impl<T> core::ops::Index<$name> for Vec<T> { + type Output = T; + + #[inline] + fn index(&self, index: $name) -> &T { + &self[index.as_usize()] + } + } + + #[cfg(feature = "alloc")] + impl<T> core::ops::IndexMut<$name> for Vec<T> { + #[inline] + fn index_mut(&mut self, index: $name) -> &mut T { + &mut self[index.as_usize()] + } + } + + impl From<u8> for $name { + fn from(value: u8) -> $name { + $name(SmallIndex::from(value)) + } + } + + impl TryFrom<u16> for $name { + type Error = $err; + + fn try_from(value: u16) -> Result<$name, $err> { + SmallIndex::try_from(value).map($name).map_err($err) + } + } + + impl TryFrom<u32> for $name { + type Error = $err; + + fn try_from(value: u32) -> Result<$name, $err> { + SmallIndex::try_from(value).map($name).map_err($err) + } + } + + impl TryFrom<u64> for $name { + type Error = $err; + + fn try_from(value: u64) -> Result<$name, $err> { + SmallIndex::try_from(value).map($name).map_err($err) + } + } + + impl TryFrom<usize> for $name { + type Error = $err; + + fn try_from(value: usize) -> Result<$name, $err> { + SmallIndex::try_from(value).map($name).map_err($err) + } + } + + #[cfg(test)] + impl quickcheck::Arbitrary for $name { + fn arbitrary(gen: &mut quickcheck::Gen) -> $name { + $name(SmallIndex::arbitrary(gen)) + } + } + + /// This error occurs when a value could not be constructed. + /// + /// This occurs when given an integer exceeding the maximum allowed + /// value. + /// + /// When the `std` feature is enabled, this implements the `Error` + /// trait. + #[derive(Clone, Debug, Eq, PartialEq)] + pub struct $err(SmallIndexError); + + impl $err { + /// Returns the value that could not be converted to an ID. + pub fn attempted(&self) -> u64 { + self.0.attempted() + } + } + + #[cfg(feature = "std")] + impl std::error::Error for $err {} + + impl core::fmt::Display for $err { + fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result { + write!( + f, + "failed to create {} from {:?}, which exceeds {:?}", + stringify!($name), + self.attempted(), + $name::MAX, + ) + } + } + + #[derive(Clone, Debug)] + pub(crate) struct $iter(SmallIndexIter); + + impl $iter { + fn new(len: usize) -> $iter { + assert!( + len <= $name::LIMIT, + "cannot create iterator for {} when number of \ + elements exceed {:?}", + stringify!($name), + $name::LIMIT, + ); + $iter(SmallIndexIter { rng: 0..len }) + } + } + + impl Iterator for $iter { + type Item = $name; + + fn next(&mut self) -> Option<$name> { + self.0.next().map($name) + } + } + + /// An iterator adapter that is like std::iter::Enumerate, but attaches + /// small index values instead. It requires `ExactSizeIterator`. At + /// construction, it ensures that the index of each element in the + /// iterator is representable in the corresponding small index type. + #[derive(Clone, Debug)] + pub(crate) struct $withiter<I> { + it: I, + ids: $iter, + } + + impl<I: Iterator + ExactSizeIterator> $withiter<I> { + fn new(it: I) -> $withiter<I> { + let ids = $name::iter(it.len()); + $withiter { it, ids } + } + } + + impl<I: Iterator + ExactSizeIterator> Iterator for $withiter<I> { + type Item = ($name, I::Item); + + fn next(&mut self) -> Option<($name, I::Item)> { + let item = self.it.next()?; + // Number of elements in this iterator must match, according + // to contract of ExactSizeIterator. + let id = self.ids.next().unwrap(); + Some((id, item)) + } + } + }; +} + +/// The identifier of a regex pattern, represented by a [`SmallIndex`]. +/// +/// The identifier for a pattern corresponds to its relative position among +/// other patterns in a single finite state machine. Namely, when building +/// a multi-pattern regex engine, one must supply a sequence of patterns to +/// match. The position (starting at 0) of each pattern in that sequence +/// represents its identifier. This identifier is in turn used to identify and +/// report matches of that pattern in various APIs. +/// +/// See the [`SmallIndex`] type for more information about what it means for +/// a pattern ID to be a "small index." +/// +/// Note that this type is defined in the +/// [`util::primitives`](crate::util::primitives) module, but it is also +/// re-exported at the crate root due to how common it is. +#[derive(Clone, Copy, Default, Eq, Hash, PartialEq, PartialOrd, Ord)] +#[repr(transparent)] +pub struct PatternID(SmallIndex); + +/// The identifier of a finite automaton state, represented by a +/// [`SmallIndex`]. +/// +/// Most regex engines in this crate are built on top of finite automata. Each +/// state in a finite automaton defines transitions from its state to another. +/// Those transitions point to other states via their identifiers, i.e., a +/// `StateID`. Since finite automata tend to contain many transitions, it is +/// much more memory efficient to define state IDs as small indices. +/// +/// See the [`SmallIndex`] type for more information about what it means for +/// a state ID to be a "small index." +#[derive(Clone, Copy, Default, Eq, Hash, PartialEq, PartialOrd, Ord)] +#[repr(transparent)] +pub struct StateID(SmallIndex); + +index_type_impls!(PatternID, PatternIDError, PatternIDIter, WithPatternIDIter); +index_type_impls!(StateID, StateIDError, StateIDIter, WithStateIDIter); + +/// A utility trait that defines a couple of adapters for making it convenient +/// to access indices as "small index" types. We require ExactSizeIterator so +/// that iterator construction can do a single check to make sure the index of +/// each element is representable by its small index type. +pub(crate) trait IteratorIndexExt: Iterator { + fn with_pattern_ids(self) -> WithPatternIDIter<Self> + where + Self: Sized + ExactSizeIterator, + { + WithPatternIDIter::new(self) + } + + fn with_state_ids(self) -> WithStateIDIter<Self> + where + Self: Sized + ExactSizeIterator, + { + WithStateIDIter::new(self) + } +} + +impl<I: Iterator> IteratorIndexExt for I {} |