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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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5.2 kB · 153 lines
Rust
at master
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154// SPDX-License-Identifier: Apache-2.0 OR MIT
//! Items which do not have a correspondence to any API in the proc_macro crate,//! but are necessary to include in proc-macro2.
use crate::fallback;use crate::imp;use crate::marker::{ProcMacroAutoTraits, MARKER};use crate::Span;use core::fmt::{self, Debug};
/// Invalidate any `proc_macro2::Span` that exist on the current thread.////// The implementation of `Span` uses thread-local data structures and this/// function clears them. Calling any method on a `Span` on the current thread/// created prior to the invalidation will return incorrect values or crash.////// This function is useful for programs that process more than 2<sup>32</sup>/// bytes of Rust source code on the same thread. Just like rustc, proc-macro2/// uses 32-bit source locations, and these wrap around when the total source/// code processed by the same thread exceeds 2<sup>32</sup> bytes (4/// gigabytes). After a wraparound, `Span` methods such as `source_text()` can/// return wrong data.////// # Example////// As of late 2023, there is 200 GB of Rust code published on crates.io./// Looking at just the newest version of every crate, it is 16 GB of code. So a/// workload that involves parsing it all would overflow a 32-bit source/// location unless spans are being invalidated.////// ```/// use flate2::read::GzDecoder;/// use std::ffi::OsStr;/// use std::io::{BufReader, Read};/// use std::str::FromStr;/// use tar::Archive;////// rayon::scope(|s| {/// for krate in every_version_of_every_crate() {/// s.spawn(move |_| {/// proc_macro2::extra::invalidate_current_thread_spans();////// let reader = BufReader::new(krate);/// let tar = GzDecoder::new(reader);/// let mut archive = Archive::new(tar);/// for entry in archive.entries().unwrap() {/// let mut entry = entry.unwrap();/// let path = entry.path().unwrap();/// if path.extension() != Some(OsStr::new("rs")) {/// continue;/// }/// let mut content = String::new();/// entry.read_to_string(&mut content).unwrap();/// match proc_macro2::TokenStream::from_str(&content) {/// Ok(tokens) => {/* ... */},/// Err(_) => continue,/// }/// }/// });/// }/// });/// #/// # fn every_version_of_every_crate() -> Vec<std::fs::File> {/// # Vec::new()/// # }/// ```////// # Panics////// This function is not applicable to and will panic if called from a/// procedural macro.#[cfg(span_locations)]#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]pub fn invalidate_current_thread_spans() { crate::imp::invalidate_current_thread_spans();}
/// An object that holds a [`Group`]'s `span_open()` and `span_close()` together/// in a more compact representation than holding those 2 spans individually.////// [`Group`]: crate::Group#[derive(Copy, Clone)]pub struct DelimSpan { inner: DelimSpanEnum, _marker: ProcMacroAutoTraits,}
#[derive(Copy, Clone)]enum DelimSpanEnum { #[cfg(wrap_proc_macro)] Compiler { join: proc_macro::Span, open: proc_macro::Span, close: proc_macro::Span, }, Fallback(fallback::Span),}
impl DelimSpan { pub(crate) fn new(group: &imp::Group) -> Self { #[cfg(wrap_proc_macro)] let inner = match group { imp::Group::Compiler(group) => DelimSpanEnum::Compiler { join: group.span(), open: group.span_open(), close: group.span_close(), }, imp::Group::Fallback(group) => DelimSpanEnum::Fallback(group.span()), };
#[cfg(not(wrap_proc_macro))] let inner = DelimSpanEnum::Fallback(group.span());
DelimSpan { inner, _marker: MARKER, } }
/// Returns a span covering the entire delimited group. pub fn join(&self) -> Span { match &self.inner { #[cfg(wrap_proc_macro)] DelimSpanEnum::Compiler { join, .. } => Span::_new(imp::Span::Compiler(*join)), DelimSpanEnum::Fallback(span) => Span::_new_fallback(*span), } }
/// Returns a span for the opening punctuation of the group only. pub fn open(&self) -> Span { match &self.inner { #[cfg(wrap_proc_macro)] DelimSpanEnum::Compiler { open, .. } => Span::_new(imp::Span::Compiler(*open)), DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.first_byte()), } }
/// Returns a span for the closing punctuation of the group only. pub fn close(&self) -> Span { match &self.inner { #[cfg(wrap_proc_macro)] DelimSpanEnum::Compiler { close, .. } => Span::_new(imp::Span::Compiler(*close)), DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.last_byte()), } }}
impl Debug for DelimSpan { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { Debug::fmt(&self.join(), f) }}