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+//! A punctuated sequence of syntax tree nodes separated by punctuation.
+//!
+//! Lots of things in Rust are punctuated sequences.
+//!
+//! - The fields of a struct are `Punctuated<Field, Token![,]>`.
+//! - The segments of a path are `Punctuated<PathSegment, Token![::]>`.
+//! - The bounds on a generic parameter are `Punctuated<TypeParamBound,
+//! Token![+]>`.
+//! - The arguments to a function call are `Punctuated<Expr, Token![,]>`.
+//!
+//! This module provides a common representation for these punctuated sequences
+//! in the form of the [`Punctuated<T, P>`] type. We store a vector of pairs of
+//! syntax tree node + punctuation, where every node in the sequence is followed
+//! by punctuation except for possibly the final one.
+//!
+//! [`Punctuated<T, P>`]: struct.Punctuated.html
+//!
+//! ```text
+//! a_function_call(arg1, arg2, arg3);
+//! ~~~~^ ~~~~^ ~~~~
+//! ```
+
+#[cfg(feature = "extra-traits")]
+use std::fmt::{self, Debug};
+#[cfg(any(feature = "full", feature = "derive"))]
+use std::iter;
+use std::iter::FromIterator;
+use std::ops::{Index, IndexMut};
+use std::option;
+use std::slice;
+use std::vec;
+
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream, Result};
+#[cfg(feature = "parsing")]
+use crate::token::Token;
+
+/// A punctuated sequence of syntax tree nodes of type `T` separated by
+/// punctuation of type `P`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+#[cfg_attr(feature = "extra-traits", derive(Eq, PartialEq, Hash))]
+#[cfg_attr(feature = "clone-impls", derive(Clone))]
+pub struct Punctuated<T, P> {
+ inner: Vec<(T, P)>,
+ last: Option<Box<T>>,
+}
+
+impl<T, P> Punctuated<T, P> {
+ /// Creates an empty punctuated sequence.
+ pub fn new() -> Punctuated<T, P> {
+ Punctuated {
+ inner: Vec::new(),
+ last: None,
+ }
+ }
+
+ /// Determines whether this punctuated sequence is empty, meaning it
+ /// contains no syntax tree nodes or punctuation.
+ pub fn is_empty(&self) -> bool {
+ self.inner.len() == 0 && self.last.is_none()
+ }
+
+ /// Returns the number of syntax tree nodes in this punctuated sequence.
+ ///
+ /// This is the number of nodes of type `T`, not counting the punctuation of
+ /// type `P`.
+ pub fn len(&self) -> usize {
+ self.inner.len() + if self.last.is_some() { 1 } else { 0 }
+ }
+
+ /// Borrows the first element in this sequence.
+ pub fn first(&self) -> Option<&T> {
+ self.iter().next()
+ }
+
+ /// Borrows the last element in this sequence.
+ pub fn last(&self) -> Option<&T> {
+ if self.last.is_some() {
+ self.last.as_ref().map(Box::as_ref)
+ } else {
+ self.inner.last().map(|pair| &pair.0)
+ }
+ }
+
+ /// Mutably borrows the last element in this sequence.
+ pub fn last_mut(&mut self) -> Option<&mut T> {
+ if self.last.is_some() {
+ self.last.as_mut().map(Box::as_mut)
+ } else {
+ self.inner.last_mut().map(|pair| &mut pair.0)
+ }
+ }
+
+ /// Returns an iterator over borrowed syntax tree nodes of type `&T`.
+ pub fn iter(&self) -> Iter<T> {
+ Iter {
+ inner: Box::new(PrivateIter {
+ inner: self.inner.iter(),
+ last: self.last.as_ref().map(Box::as_ref).into_iter(),
+ }),
+ }
+ }
+
+ /// Returns an iterator over mutably borrowed syntax tree nodes of type
+ /// `&mut T`.
+ pub fn iter_mut(&mut self) -> IterMut<T> {
+ IterMut {
+ inner: Box::new(PrivateIterMut {
+ inner: self.inner.iter_mut(),
+ last: self.last.as_mut().map(Box::as_mut).into_iter(),
+ }),
+ }
+ }
+
+ /// Returns an iterator over the contents of this sequence as borrowed
+ /// punctuated pairs.
+ pub fn pairs(&self) -> Pairs<T, P> {
+ Pairs {
+ inner: self.inner.iter(),
+ last: self.last.as_ref().map(Box::as_ref).into_iter(),
+ }
+ }
+
+ /// Returns an iterator over the contents of this sequence as mutably
+ /// borrowed punctuated pairs.
+ pub fn pairs_mut(&mut self) -> PairsMut<T, P> {
+ PairsMut {
+ inner: self.inner.iter_mut(),
+ last: self.last.as_mut().map(Box::as_mut).into_iter(),
+ }
+ }
+
+ /// Returns an iterator over the contents of this sequence as owned
+ /// punctuated pairs.
+ pub fn into_pairs(self) -> IntoPairs<T, P> {
+ IntoPairs {
+ inner: self.inner.into_iter(),
+ last: self.last.map(|t| *t).into_iter(),
+ }
+ }
+
+ /// Appends a syntax tree node onto the end of this punctuated sequence. The
+ /// sequence must previously have a trailing punctuation.
+ ///
+ /// Use [`push`] instead if the punctuated sequence may or may not already
+ /// have trailing punctuation.
+ ///
+ /// [`push`]: Punctuated::push
+ ///
+ /// # Panics
+ ///
+ /// Panics if the sequence does not already have a trailing punctuation when
+ /// this method is called.
+ pub fn push_value(&mut self, value: T) {
+ assert!(self.empty_or_trailing());
+ self.last = Some(Box::new(value));
+ }
+
+ /// Appends a trailing punctuation onto the end of this punctuated sequence.
+ /// The sequence must be non-empty and must not already have trailing
+ /// punctuation.
+ ///
+ /// # Panics
+ ///
+ /// Panics if the sequence is empty or already has a trailing punctuation.
+ pub fn push_punct(&mut self, punctuation: P) {
+ assert!(self.last.is_some());
+ let last = self.last.take().unwrap();
+ self.inner.push((*last, punctuation));
+ }
+
+ /// Removes the last punctuated pair from this sequence, or `None` if the
+ /// sequence is empty.
+ pub fn pop(&mut self) -> Option<Pair<T, P>> {
+ if self.last.is_some() {
+ self.last.take().map(|t| Pair::End(*t))
+ } else {
+ self.inner.pop().map(|(t, d)| Pair::Punctuated(t, d))
+ }
+ }
+
+ /// Determines whether this punctuated sequence ends with a trailing
+ /// punctuation.
+ pub fn trailing_punct(&self) -> bool {
+ self.last.is_none() && !self.is_empty()
+ }
+
+ /// Returns true if either this `Punctuated` is empty, or it has a trailing
+ /// punctuation.
+ ///
+ /// Equivalent to `punctuated.is_empty() || punctuated.trailing_punct()`.
+ pub fn empty_or_trailing(&self) -> bool {
+ self.last.is_none()
+ }
+
+ /// Appends a syntax tree node onto the end of this punctuated sequence.
+ ///
+ /// If there is not a trailing punctuation in this sequence when this method
+ /// is called, the default value of punctuation type `P` is inserted before
+ /// the given value of type `T`.
+ pub fn push(&mut self, value: T)
+ where
+ P: Default,
+ {
+ if !self.empty_or_trailing() {
+ self.push_punct(Default::default());
+ }
+ self.push_value(value);
+ }
+
+ /// Inserts an element at position `index`.
+ ///
+ /// # Panics
+ ///
+ /// Panics if `index` is greater than the number of elements previously in
+ /// this punctuated sequence.
+ pub fn insert(&mut self, index: usize, value: T)
+ where
+ P: Default,
+ {
+ assert!(index <= self.len());
+
+ if index == self.len() {
+ self.push(value);
+ } else {
+ self.inner.insert(index, (value, Default::default()));
+ }
+ }
+
+ /// Parses zero or more occurrences of `T` separated by punctuation of type
+ /// `P`, with optional trailing punctuation.
+ ///
+ /// Parsing continues until the end of this parse stream. The entire content
+ /// of this parse stream must consist of `T` and `P`.
+ ///
+ /// *This function is available if Syn is built with the `"parsing"`
+ /// feature.*
+ #[cfg(feature = "parsing")]
+ pub fn parse_terminated(input: ParseStream) -> Result<Self>
+ where
+ T: Parse,
+ P: Parse,
+ {
+ Self::parse_terminated_with(input, T::parse)
+ }
+
+ /// Parses zero or more occurrences of `T` using the given parse function,
+ /// separated by punctuation of type `P`, with optional trailing
+ /// punctuation.
+ ///
+ /// Like [`parse_terminated`], the entire content of this stream is expected
+ /// to be parsed.
+ ///
+ /// [`parse_terminated`]: Punctuated::parse_terminated
+ ///
+ /// *This function is available if Syn is built with the `"parsing"`
+ /// feature.*
+ #[cfg(feature = "parsing")]
+ pub fn parse_terminated_with(
+ input: ParseStream,
+ parser: fn(ParseStream) -> Result<T>,
+ ) -> Result<Self>
+ where
+ P: Parse,
+ {
+ let mut punctuated = Punctuated::new();
+
+ loop {
+ if input.is_empty() {
+ break;
+ }
+ let value = parser(input)?;
+ punctuated.push_value(value);
+ if input.is_empty() {
+ break;
+ }
+ let punct = input.parse()?;
+ punctuated.push_punct(punct);
+ }
+
+ Ok(punctuated)
+ }
+
+ /// Parses one or more occurrences of `T` separated by punctuation of type
+ /// `P`, not accepting trailing punctuation.
+ ///
+ /// Parsing continues as long as punctuation `P` is present at the head of
+ /// the stream. This method returns upon parsing a `T` and observing that it
+ /// is not followed by a `P`, even if there are remaining tokens in the
+ /// stream.
+ ///
+ /// *This function is available if Syn is built with the `"parsing"`
+ /// feature.*
+ #[cfg(feature = "parsing")]
+ pub fn parse_separated_nonempty(input: ParseStream) -> Result<Self>
+ where
+ T: Parse,
+ P: Token + Parse,
+ {
+ Self::parse_separated_nonempty_with(input, T::parse)
+ }
+
+ /// Parses one or more occurrences of `T` using the given parse function,
+ /// separated by punctuation of type `P`, not accepting trailing
+ /// punctuation.
+ ///
+ /// Like [`parse_separated_nonempty`], may complete early without parsing
+ /// the entire content of this stream.
+ ///
+ /// [`parse_separated_nonempty`]: Punctuated::parse_separated_nonempty
+ ///
+ /// *This function is available if Syn is built with the `"parsing"`
+ /// feature.*
+ #[cfg(feature = "parsing")]
+ pub fn parse_separated_nonempty_with(
+ input: ParseStream,
+ parser: fn(ParseStream) -> Result<T>,
+ ) -> Result<Self>
+ where
+ P: Token + Parse,
+ {
+ let mut punctuated = Punctuated::new();
+
+ loop {
+ let value = parser(input)?;
+ punctuated.push_value(value);
+ if !P::peek(input.cursor()) {
+ break;
+ }
+ let punct = input.parse()?;
+ punctuated.push_punct(punct);
+ }
+
+ Ok(punctuated)
+ }
+}
+
+#[cfg(feature = "extra-traits")]
+impl<T: Debug, P: Debug> Debug for Punctuated<T, P> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ let mut list = f.debug_list();
+ for (t, p) in &self.inner {
+ list.entry(t);
+ list.entry(p);
+ }
+ if let Some(last) = &self.last {
+ list.entry(last);
+ }
+ list.finish()
+ }
+}
+
+impl<T, P> FromIterator<T> for Punctuated<T, P>
+where
+ P: Default,
+{
+ fn from_iter<I: IntoIterator<Item = T>>(i: I) -> Self {
+ let mut ret = Punctuated::new();
+ ret.extend(i);
+ ret
+ }
+}
+
+impl<T, P> Extend<T> for Punctuated<T, P>
+where
+ P: Default,
+{
+ fn extend<I: IntoIterator<Item = T>>(&mut self, i: I) {
+ for value in i {
+ self.push(value);
+ }
+ }
+}
+
+impl<T, P> FromIterator<Pair<T, P>> for Punctuated<T, P> {
+ fn from_iter<I: IntoIterator<Item = Pair<T, P>>>(i: I) -> Self {
+ let mut ret = Punctuated::new();
+ ret.extend(i);
+ ret
+ }
+}
+
+impl<T, P> Extend<Pair<T, P>> for Punctuated<T, P> {
+ fn extend<I: IntoIterator<Item = Pair<T, P>>>(&mut self, i: I) {
+ assert!(self.empty_or_trailing());
+ let mut nomore = false;
+ for pair in i {
+ if nomore {
+ panic!("Punctuated extended with items after a Pair::End");
+ }
+ match pair {
+ Pair::Punctuated(a, b) => self.inner.push((a, b)),
+ Pair::End(a) => {
+ self.last = Some(Box::new(a));
+ nomore = true;
+ }
+ }
+ }
+ }
+}
+
+impl<T, P> IntoIterator for Punctuated<T, P> {
+ type Item = T;
+ type IntoIter = IntoIter<T>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ let mut elements = Vec::with_capacity(self.len());
+ elements.extend(self.inner.into_iter().map(|pair| pair.0));
+ elements.extend(self.last.map(|t| *t));
+
+ IntoIter {
+ inner: elements.into_iter(),
+ }
+ }
+}
+
+impl<'a, T, P> IntoIterator for &'a Punctuated<T, P> {
+ type Item = &'a T;
+ type IntoIter = Iter<'a, T>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ Punctuated::iter(self)
+ }
+}
+
+impl<'a, T, P> IntoIterator for &'a mut Punctuated<T, P> {
+ type Item = &'a mut T;
+ type IntoIter = IterMut<'a, T>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ Punctuated::iter_mut(self)
+ }
+}
+
+impl<T, P> Default for Punctuated<T, P> {
+ fn default() -> Self {
+ Punctuated::new()
+ }
+}
+
+/// An iterator over borrowed pairs of type `Pair<&T, &P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct Pairs<'a, T: 'a, P: 'a> {
+ inner: slice::Iter<'a, (T, P)>,
+ last: option::IntoIter<&'a T>,
+}
+
+impl<'a, T, P> Iterator for Pairs<'a, T, P> {
+ type Item = Pair<&'a T, &'a P>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner
+ .next()
+ .map(|(t, p)| Pair::Punctuated(t, p))
+ .or_else(|| self.last.next().map(Pair::End))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<'a, T, P> DoubleEndedIterator for Pairs<'a, T, P> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.last
+ .next()
+ .map(Pair::End)
+ .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+ }
+}
+
+impl<'a, T, P> ExactSizeIterator for Pairs<'a, T, P> {
+ fn len(&self) -> usize {
+ self.inner.len() + self.last.len()
+ }
+}
+
+// No Clone bound on T or P.
+impl<'a, T, P> Clone for Pairs<'a, T, P> {
+ fn clone(&self) -> Self {
+ Pairs {
+ inner: self.inner.clone(),
+ last: self.last.clone(),
+ }
+ }
+}
+
+/// An iterator over mutably borrowed pairs of type `Pair<&mut T, &mut P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct PairsMut<'a, T: 'a, P: 'a> {
+ inner: slice::IterMut<'a, (T, P)>,
+ last: option::IntoIter<&'a mut T>,
+}
+
+impl<'a, T, P> Iterator for PairsMut<'a, T, P> {
+ type Item = Pair<&'a mut T, &'a mut P>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner
+ .next()
+ .map(|(t, p)| Pair::Punctuated(t, p))
+ .or_else(|| self.last.next().map(Pair::End))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PairsMut<'a, T, P> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.last
+ .next()
+ .map(Pair::End)
+ .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+ }
+}
+
+impl<'a, T, P> ExactSizeIterator for PairsMut<'a, T, P> {
+ fn len(&self) -> usize {
+ self.inner.len() + self.last.len()
+ }
+}
+
+/// An iterator over owned pairs of type `Pair<T, P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+#[derive(Clone)]
+pub struct IntoPairs<T, P> {
+ inner: vec::IntoIter<(T, P)>,
+ last: option::IntoIter<T>,
+}
+
+impl<T, P> Iterator for IntoPairs<T, P> {
+ type Item = Pair<T, P>;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner
+ .next()
+ .map(|(t, p)| Pair::Punctuated(t, p))
+ .or_else(|| self.last.next().map(Pair::End))
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<T, P> DoubleEndedIterator for IntoPairs<T, P> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.last
+ .next()
+ .map(Pair::End)
+ .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+ }
+}
+
+impl<T, P> ExactSizeIterator for IntoPairs<T, P> {
+ fn len(&self) -> usize {
+ self.inner.len() + self.last.len()
+ }
+}
+
+/// An iterator over owned values of type `T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+#[derive(Clone)]
+pub struct IntoIter<T> {
+ inner: vec::IntoIter<T>,
+}
+
+impl<T> Iterator for IntoIter<T> {
+ type Item = T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner.next()
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<T> DoubleEndedIterator for IntoIter<T> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.inner.next_back()
+ }
+}
+
+impl<T> ExactSizeIterator for IntoIter<T> {
+ fn len(&self) -> usize {
+ self.inner.len()
+ }
+}
+
+/// An iterator over borrowed values of type `&T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct Iter<'a, T: 'a> {
+ // The `Item = &'a T` needs to be specified to support rustc 1.31 and older.
+ // On modern compilers we would be able to write just IterTrait<'a, T> where
+ // Item can be inferred unambiguously from the supertrait.
+ inner: Box<dyn IterTrait<'a, T, Item = &'a T> + 'a>,
+}
+
+trait IterTrait<'a, T: 'a>:
+ DoubleEndedIterator<Item = &'a T> + ExactSizeIterator<Item = &'a T>
+{
+ fn clone_box(&self) -> Box<dyn IterTrait<'a, T, Item = &'a T> + 'a>;
+}
+
+struct PrivateIter<'a, T: 'a, P: 'a> {
+ inner: slice::Iter<'a, (T, P)>,
+ last: option::IntoIter<&'a T>,
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+pub(crate) fn empty_punctuated_iter<'a, T>() -> Iter<'a, T> {
+ Iter {
+ inner: Box::new(iter::empty()),
+ }
+}
+
+// No Clone bound on T.
+impl<'a, T> Clone for Iter<'a, T> {
+ fn clone(&self) -> Self {
+ Iter {
+ inner: self.inner.clone_box(),
+ }
+ }
+}
+
+impl<'a, T> Iterator for Iter<'a, T> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner.next()
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.inner.next_back()
+ }
+}
+
+impl<'a, T> ExactSizeIterator for Iter<'a, T> {
+ fn len(&self) -> usize {
+ self.inner.len()
+ }
+}
+
+impl<'a, T, P> Iterator for PrivateIter<'a, T, P> {
+ type Item = &'a T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner
+ .next()
+ .map(|pair| &pair.0)
+ .or_else(|| self.last.next())
+ }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PrivateIter<'a, T, P> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.last
+ .next()
+ .or_else(|| self.inner.next_back().map(|pair| &pair.0))
+ }
+}
+
+impl<'a, T, P> ExactSizeIterator for PrivateIter<'a, T, P> {
+ fn len(&self) -> usize {
+ self.inner.len() + self.last.len()
+ }
+}
+
+// No Clone bound on T or P.
+impl<'a, T, P> Clone for PrivateIter<'a, T, P> {
+ fn clone(&self) -> Self {
+ PrivateIter {
+ inner: self.inner.clone(),
+ last: self.last.clone(),
+ }
+ }
+}
+
+impl<'a, T: 'a, I: 'a> IterTrait<'a, T> for I
+where
+ I: DoubleEndedIterator<Item = &'a T> + ExactSizeIterator<Item = &'a T> + Clone,
+{
+ fn clone_box(&self) -> Box<dyn IterTrait<'a, T, Item = &'a T> + 'a> {
+ Box::new(self.clone())
+ }
+}
+
+/// An iterator over mutably borrowed values of type `&mut T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct IterMut<'a, T: 'a> {
+ inner: Box<dyn IterMutTrait<'a, T, Item = &'a mut T> + 'a>,
+}
+
+trait IterMutTrait<'a, T: 'a>:
+ DoubleEndedIterator<Item = &'a mut T> + ExactSizeIterator<Item = &'a mut T>
+{
+}
+
+struct PrivateIterMut<'a, T: 'a, P: 'a> {
+ inner: slice::IterMut<'a, (T, P)>,
+ last: option::IntoIter<&'a mut T>,
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+pub(crate) fn empty_punctuated_iter_mut<'a, T>() -> IterMut<'a, T> {
+ IterMut {
+ inner: Box::new(iter::empty()),
+ }
+}
+
+impl<'a, T> Iterator for IterMut<'a, T> {
+ type Item = &'a mut T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner.next()
+ }
+
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ (self.len(), Some(self.len()))
+ }
+}
+
+impl<'a, T> DoubleEndedIterator for IterMut<'a, T> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.inner.next_back()
+ }
+}
+
+impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
+ fn len(&self) -> usize {
+ self.inner.len()
+ }
+}
+
+impl<'a, T, P> Iterator for PrivateIterMut<'a, T, P> {
+ type Item = &'a mut T;
+
+ fn next(&mut self) -> Option<Self::Item> {
+ self.inner
+ .next()
+ .map(|pair| &mut pair.0)
+ .or_else(|| self.last.next())
+ }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PrivateIterMut<'a, T, P> {
+ fn next_back(&mut self) -> Option<Self::Item> {
+ self.last
+ .next()
+ .or_else(|| self.inner.next_back().map(|pair| &mut pair.0))
+ }
+}
+
+impl<'a, T, P> ExactSizeIterator for PrivateIterMut<'a, T, P> {
+ fn len(&self) -> usize {
+ self.inner.len() + self.last.len()
+ }
+}
+
+impl<'a, T: 'a, I: 'a> IterMutTrait<'a, T> for I where
+ I: DoubleEndedIterator<Item = &'a mut T> + ExactSizeIterator<Item = &'a mut T>
+{
+}
+
+/// A single syntax tree node of type `T` followed by its trailing punctuation
+/// of type `P` if any.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+#[cfg_attr(feature = "clone-impls", derive(Clone))]
+pub enum Pair<T, P> {
+ Punctuated(T, P),
+ End(T),
+}
+
+impl<T, P> Pair<T, P> {
+ /// Extracts the syntax tree node from this punctuated pair, discarding the
+ /// following punctuation.
+ pub fn into_value(self) -> T {
+ match self {
+ Pair::Punctuated(t, _) | Pair::End(t) => t,
+ }
+ }
+
+ /// Borrows the syntax tree node from this punctuated pair.
+ pub fn value(&self) -> &T {
+ match self {
+ Pair::Punctuated(t, _) | Pair::End(t) => t,
+ }
+ }
+
+ /// Mutably borrows the syntax tree node from this punctuated pair.
+ pub fn value_mut(&mut self) -> &mut T {
+ match self {
+ Pair::Punctuated(t, _) | Pair::End(t) => t,
+ }
+ }
+
+ /// Borrows the punctuation from this punctuated pair, unless this pair is
+ /// the final one and there is no trailing punctuation.
+ pub fn punct(&self) -> Option<&P> {
+ match self {
+ Pair::Punctuated(_, d) => Some(d),
+ Pair::End(_) => None,
+ }
+ }
+
+ /// Creates a punctuated pair out of a syntax tree node and an optional
+ /// following punctuation.
+ pub fn new(t: T, d: Option<P>) -> Self {
+ match d {
+ Some(d) => Pair::Punctuated(t, d),
+ None => Pair::End(t),
+ }
+ }
+
+ /// Produces this punctuated pair as a tuple of syntax tree node and
+ /// optional following punctuation.
+ pub fn into_tuple(self) -> (T, Option<P>) {
+ match self {
+ Pair::Punctuated(t, d) => (t, Some(d)),
+ Pair::End(t) => (t, None),
+ }
+ }
+}
+
+impl<T, P> Index<usize> for Punctuated<T, P> {
+ type Output = T;
+
+ fn index(&self, index: usize) -> &Self::Output {
+ if index == self.len() - 1 {
+ match &self.last {
+ Some(t) => t,
+ None => &self.inner[index].0,
+ }
+ } else {
+ &self.inner[index].0
+ }
+ }
+}
+
+impl<T, P> IndexMut<usize> for Punctuated<T, P> {
+ fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+ if index == self.len() - 1 {
+ match &mut self.last {
+ Some(t) => t,
+ None => &mut self.inner[index].0,
+ }
+ } else {
+ &mut self.inner[index].0
+ }
+ }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+ use super::*;
+ use proc_macro2::TokenStream;
+ use quote::{ToTokens, TokenStreamExt};
+
+ impl<T, P> ToTokens for Punctuated<T, P>
+ where
+ T: ToTokens,
+ P: ToTokens,
+ {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.pairs())
+ }
+ }
+
+ impl<T, P> ToTokens for Pair<T, P>
+ where
+ T: ToTokens,
+ P: ToTokens,
+ {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ match self {
+ Pair::Punctuated(a, b) => {
+ a.to_tokens(tokens);
+ b.to_tokens(tokens);
+ }
+ Pair::End(a) => a.to_tokens(tokens),
+ }
+ }
+ }
+}
generated by cgit v1.2.1 (git 2.18.0) at 2024-05-19 00:17:52 +0000