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Add a new trait proc_macro::ToTokens 
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‎library/proc_macro/src/lib.rs

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@@ -32,6 +32,8 @@
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#![feature(restricted_std)]
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#![feature(rustc_attrs)]
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#![feature(min_specialization)]
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#![feature(strict_provenance)]
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#![feature(extend_one)]
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#![recursion_limit = "256"]
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#![allow(internal_features)]
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#![deny(ffi_unwind_calls)]
@@ -43,6 +45,7 @@ pub mod bridge;
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mod diagnostic;
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mod escape;
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mod to_tokens;
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use std::ffi::CStr;
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use std::ops::{Range, RangeBounds};
@@ -52,6 +55,8 @@ use std::{error, fmt};
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#[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
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pub use diagnostic::{Diagnostic, Level, MultiSpan};
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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pub use to_tokens::ToTokens;
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use crate::escape::{EscapeOptions, escape_bytes};
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‎library/proc_macro/src/to_tokens.rs

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use std::borrow::Cow;
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use std::ffi::{CStr, CString};
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use std::rc::Rc;
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use crate::{ConcatTreesHelper, Group, Ident, Literal, Punct, Span, TokenStream, TokenTree};
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/// Types that can be interpolated inside a [`quote!`] invocation.
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///
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/// [`quote!`]: crate::quote!
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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pub trait ToTokens {
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/// Write `self` to the given `TokenStream`.
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///
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/// # Example
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///
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/// Example implementation for a struct representing Rust paths like
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/// `std::cmp::PartialEq`:
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///
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/// ```
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/// #![feature(proc_macro_totokens)]
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///
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/// use std::iter;
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/// use proc_macro::{Spacing, Punct, TokenStream, TokenTree, ToTokens};
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///
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/// pub struct Path {
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/// pub global: bool,
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/// pub segments: Vec<PathSegment>,
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/// }
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///
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/// impl ToTokens for Path {
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/// fn to_tokens(&self, tokens: &mut TokenStream) {
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/// for (i, segment) in self.segments.iter().enumerate() {
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/// if i > 0 || self.global {
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/// // Double colon `::`
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/// tokens.extend(iter::once(TokenTree::from(Punct::new(':', Spacing::Joint))));
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/// tokens.extend(iter::once(TokenTree::from(Punct::new(':', Spacing::Alone))));
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/// }
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/// segment.to_tokens(tokens);
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/// }
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/// }
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/// }
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/// #
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/// # pub struct PathSegment;
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/// #
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/// # impl ToTokens for PathSegment {
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/// # fn to_tokens(&self, tokens: &mut TokenStream) {
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/// # unimplemented!()
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/// # }
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/// # }
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/// ```
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fn to_tokens(&self, tokens: &mut TokenStream);
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/// Convert `self` directly into a `TokenStream` object.
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///
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/// This method is implicitly implemented using `to_tokens`, and acts as a
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/// convenience method for consumers of the `ToTokens` trait.
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fn to_token_stream(&self) -> TokenStream {
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let mut tokens = TokenStream::new();
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self.to_tokens(&mut tokens);
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tokens
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}
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/// Convert `self` directly into a `TokenStream` object.
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///
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/// This method is implicitly implemented using `to_tokens`, and acts as a
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/// convenience method for consumers of the `ToTokens` trait.
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fn into_token_stream(self) -> TokenStream
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where
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Self: Sized,
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{
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self.to_token_stream()
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for TokenTree {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend_one(self.clone());
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}
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fn into_token_stream(self) -> TokenStream {
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let mut builder = ConcatTreesHelper::new(1);
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builder.push(self);
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builder.build()
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for TokenStream {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend(self.clone());
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}
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fn into_token_stream(self) -> TokenStream {
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self
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for Literal {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend_one(TokenTree::from(self.clone()));
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for Ident {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend_one(TokenTree::from(self.clone()));
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for Punct {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend_one(TokenTree::from(self.clone()));
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for Group {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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tokens.extend_one(TokenTree::from(self.clone()));
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens + ?Sized> ToTokens for &T {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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(**self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens + ?Sized> ToTokens for &mut T {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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(**self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens + ?Sized> ToTokens for Box<T> {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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(**self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens + ?Sized> ToTokens for Rc<T> {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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(**self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens + ToOwned + ?Sized> ToTokens for Cow<'_, T> {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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(**self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl<T: ToTokens> ToTokens for Option<T> {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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if let Some(t) = self {
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t.to_tokens(tokens);
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}
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for u8 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::u8_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for u16 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::u16_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for u32 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::u32_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for u64 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::u64_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for u128 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::u128_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for i8 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::i8_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for i16 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::i16_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for i32 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::i32_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for i64 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::i64_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for i128 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::i128_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for f32 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::f32_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for f64 {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::f64_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for usize {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::usize_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for isize {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::isize_suffixed(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for bool {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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let word = if *self { "true" } else { "false" };
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Ident::new(word, Span::call_site()).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for char {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::character(*self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for str {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::string(self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for String {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::string(self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for CStr {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::c_string(self).to_tokens(tokens)
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}
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}
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#[unstable(feature = "proc_macro_totokens", issue = "130977")]
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impl ToTokens for CString {
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fn to_tokens(&self, tokens: &mut TokenStream) {
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Literal::c_string(self).to_tokens(tokens)
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}
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}

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