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//! [![github]](https://github.com/dtolnay/proc-macro2) [![crates-io]](https://crates.io/crates/proc-macro2) [![docs-rs]](crate)
//!
//!
//! <br>
//!
//! A wrapper around the procedural macro API of the compiler's [`proc_macro`]
//! crate. This library serves two purposes:
//!
//!
//! - **Bring proc-macro-like functionality to other contexts like build.rs and
//! main.rs.** Types from `proc_macro` are entirely specific to procedural
//! macros and cannot ever exist in code outside of a procedural macro.
//! Meanwhile `proc_macro2` types may exist anywhere including non-macro code.
//! By developing foundational libraries like [syn] and [quote] against
//! `proc_macro2` rather than `proc_macro`, the procedural macro ecosystem
//! becomes easily applicable to many other use cases and we avoid
//! reimplementing non-macro equivalents of those libraries.
//!
//! - **Make procedural macros unit testable.** As a consequence of being
//! specific to procedural macros, nothing that uses `proc_macro` can be
//! executed from a unit test. In order for helper libraries or components of
//! a macro to be testable in isolation, they must be implemented using
//! `proc_macro2`.
//!
//!
//! # Usage
//!
//! The skeleton of a typical procedural macro typically looks like this:
//!
//! ```
//! extern crate proc_macro;
//!
//! # const IGNORE: &str = stringify! {
//! #[proc_macro_derive(MyDerive)]
//! # };
//! # #[cfg(wrap_proc_macro)]
//! pub fn my_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
//! let input = proc_macro2::TokenStream::from(input);
//!
//! let output: proc_macro2::TokenStream = {
//! /* transform input */
//! # input
//! };
//!
//! proc_macro::TokenStream::from(output)
//! }
//! ```
//!
//! If parsing with [Syn], you'll use [`parse_macro_input!`] instead to
//! propagate parse errors correctly back to the compiler when parsing fails.
//!
//!
//! # Unstable features
//!
//! The default feature set of proc-macro2 tracks the most recent stable
//! compiler API. Functionality in `proc_macro` that is not yet stable is not
//! exposed by proc-macro2 by default.
//!
//! To opt into the additional APIs available in the most recent nightly
//! compiler, the `procmacro2_semver_exempt` config flag must be passed to
//! rustc. We will polyfill those nightly-only APIs back to Rust 1.56.0. As
//! these are unstable APIs that track the nightly compiler, minor versions of
//! proc-macro2 may make breaking changes to them at any time.
//!
//! ```sh
//! RUSTFLAGS='--cfg procmacro2_semver_exempt' cargo build
//! ```
//!
//! Note that this must not only be done for your crate, but for any crate that
//! depends on your crate. This infectious nature is intentional, as it serves
//! as a reminder that you are outside of the normal semver guarantees.
//!
//! Semver exempt methods are marked as such in the proc-macro2 documentation.
//!
//! # Thread-Safety
//!
//! Most types in this crate are `!Sync` because the underlying compiler
//! types make use of thread-local memory, meaning they cannot be accessed from
//! a different thread.
// Proc-macro2 types in rustdoc of other crates get linked to here.
#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.86")]
#![cfg_attr(any(proc_macro_span, super_unstable), feature(proc_macro_span))]
#![cfg_attr(super_unstable, feature(proc_macro_def_site))]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![deny(unsafe_op_in_unsafe_fn)]
#![allow(
clippy::cast_lossless,
clippy::cast_possible_truncation,
clippy::checked_conversions,
clippy::doc_markdown,
clippy::incompatible_msrv,
clippy::items_after_statements,
clippy::iter_without_into_iter,
clippy::let_underscore_untyped,
clippy::manual_assert,
clippy::manual_range_contains,
clippy::missing_safety_doc,
clippy::must_use_candidate,
clippy::needless_doctest_main,
clippy::new_without_default,
clippy::return_self_not_must_use,
clippy::shadow_unrelated,
clippy::trivially_copy_pass_by_ref,
clippy::unnecessary_wraps,
clippy::unused_self,
clippy::used_underscore_binding,
clippy::vec_init_then_push
)]
#[cfg(all(procmacro2_semver_exempt, wrap_proc_macro, not(super_unstable)))]
compile_error! {"\
Something is not right. If you've tried to turn on \
procmacro2_semver_exempt, you need to ensure that it \
is turned on for the compilation of the proc-macro2 \
build script as well.
"}
#[cfg(all(
procmacro2_nightly_testing,
feature = "proc-macro",
not(proc_macro_span)
))]
compile_error! {"\
Build script probe failed to compile.
"}
extern crate alloc;
#[cfg(feature = "proc-macro")]
extern crate proc_macro;
mod marker;
mod parse;
mod rcvec;
#[cfg(wrap_proc_macro)]
mod detection;
// Public for proc_macro2::fallback::force() and unforce(), but those are quite
// a niche use case so we omit it from rustdoc.
#[doc(hidden)]
pub mod fallback;
pub mod extra;
#[cfg(not(wrap_proc_macro))]
use crate::fallback as imp;
#[path = "wrapper.rs"]
#[cfg(wrap_proc_macro)]
mod imp;
#[cfg(span_locations)]
mod location;
use crate::extra::DelimSpan;
use crate::marker::{ProcMacroAutoTraits, MARKER};
use core::cmp::Ordering;
use core::fmt::{self, Debug, Display};
use core::hash::{Hash, Hasher};
#[cfg(span_locations)]
use core::ops::Range;
use core::ops::RangeBounds;
use core::str::FromStr;
use std::error::Error;
use std::ffi::CStr;
#[cfg(procmacro2_semver_exempt)]
use std::path::PathBuf;
#[cfg(span_locations)]
#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
pub use crate::location::LineColumn;
/// An abstract stream of tokens, or more concretely a sequence of token trees.
///
/// This type provides interfaces for iterating over token trees and for
/// collecting token trees into one stream.
///
/// Token stream is both the input and output of `#[proc_macro]`,
/// `#[proc_macro_attribute]` and `#[proc_macro_derive]` definitions.
#[derive(Clone)]
pub struct TokenStream {
inner: imp::TokenStream,
_marker: ProcMacroAutoTraits,
}
/// Error returned from `TokenStream::from_str`.
pub struct LexError {
inner: imp::LexError,
_marker: ProcMacroAutoTraits,
}
impl TokenStream {
fn _new(inner: imp::TokenStream) -> Self {
TokenStream {
inner,
_marker: MARKER,
}
}
fn _new_fallback(inner: fallback::TokenStream) -> Self {
TokenStream {
inner: inner.into(),
_marker: MARKER,
}
}
/// Returns an empty `TokenStream` containing no token trees.
pub fn new() -> Self {
TokenStream::_new(imp::TokenStream::new())
}
/// Checks if this `TokenStream` is empty.
pub fn is_empty(&self) -> bool {
self.inner.is_empty()
}
}
/// `TokenStream::default()` returns an empty stream,
/// i.e. this is equivalent with `TokenStream::new()`.
impl Default for TokenStream {
fn default() -> Self {
TokenStream::new()
}
}
/// Attempts to break the string into tokens and parse those tokens into a token
/// stream.
///
/// May fail for a number of reasons, for example, if the string contains
/// unbalanced delimiters or characters not existing in the language.
///
/// NOTE: Some errors may cause panics instead of returning `LexError`. We
/// reserve the right to change these errors into `LexError`s later.
impl FromStr for TokenStream {
type Err = LexError;
fn from_str(src: &str) -> Result<TokenStream, LexError> {
let e = src.parse().map_err(|e| LexError {
inner: e,
_marker: MARKER,
})?;
Ok(TokenStream::_new(e))
}
}
#[cfg(feature = "proc-macro")]
#[cfg_attr(docsrs, doc(cfg(feature = "proc-macro")))]
impl From<proc_macro::TokenStream> for TokenStream {
fn from(inner: proc_macro::TokenStream) -> Self {
TokenStream::_new(inner.into())
}
}
#[cfg(feature = "proc-macro")]
#[cfg_attr(docsrs, doc(cfg(feature = "proc-macro")))]
impl From<TokenStream> for proc_macro::TokenStream {
fn from(inner: TokenStream) -> Self {
inner.inner.into()
}
}
impl From<TokenTree> for TokenStream {
fn from(token: TokenTree) -> Self {
TokenStream::_new(imp::TokenStream::from(token))
}
}
impl Extend<TokenTree> for TokenStream {
fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
self.inner.extend(streams);
}
}
impl Extend<TokenStream> for TokenStream {
fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
self.inner
.extend(streams.into_iter().map(|stream| stream.inner));
}
}
/// Collects a number of token trees into a single stream.
impl FromIterator<TokenTree> for TokenStream {
fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self {
TokenStream::_new(streams.into_iter().collect())
}
}
impl FromIterator<TokenStream> for TokenStream {
fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
TokenStream::_new(streams.into_iter().map(|i| i.inner).collect())
}
}
/// Prints the token stream as a string that is supposed to be losslessly
/// convertible back into the same token stream (modulo spans), except for
/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
/// numeric literals.
impl Display for TokenStream {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.inner, f)
}
}
/// Prints token in a form convenient for debugging.
impl Debug for TokenStream {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
impl LexError {
pub fn span(&self) -> Span {
Span::_new(self.inner.span())
}
}
impl Debug for LexError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
impl Display for LexError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.inner, f)
}
}
impl Error for LexError {}
/// The source file of a given `Span`.
///
/// This type is semver exempt and not exposed by default.
#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
#[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
#[derive(Clone, PartialEq, Eq)]
pub struct SourceFile {
inner: imp::SourceFile,
_marker: ProcMacroAutoTraits,
}
#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
impl SourceFile {
fn _new(inner: imp::SourceFile) -> Self {
SourceFile {
inner,
_marker: MARKER,
}
}
/// Get the path to this source file.
///
/// ### Note
///
/// If the code span associated with this `SourceFile` was generated by an
/// external macro, this may not be an actual path on the filesystem. Use
/// [`is_real`] to check.
///
/// Also note that even if `is_real` returns `true`, if
/// `--remap-path-prefix` was passed on the command line, the path as given
/// may not actually be valid.
///
/// [`is_real`]: #method.is_real
pub fn path(&self) -> PathBuf {
self.inner.path()
}
/// Returns `true` if this source file is a real source file, and not
/// generated by an external macro's expansion.
pub fn is_real(&self) -> bool {
self.inner.is_real()
}
}
#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
impl Debug for SourceFile {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
/// A region of source code, along with macro expansion information.
#[derive(Copy, Clone)]
pub struct Span {
inner: imp::Span,
_marker: ProcMacroAutoTraits,
}
impl Span {
fn _new(inner: imp::Span) -> Self {
Span {
inner,
_marker: MARKER,
}
}
fn _new_fallback(inner: fallback::Span) -> Self {
Span {
inner: inner.into(),
_marker: MARKER,
}
}
/// The span of the invocation of the current procedural macro.
///
/// Identifiers created with this span will be resolved as if they were
/// written directly at the macro call location (call-site hygiene) and
/// other code at the macro call site will be able to refer to them as well.
pub fn call_site() -> Self {
Span::_new(imp::Span::call_site())
}
/// The span located at the invocation of the procedural macro, but with
/// local variables, labels, and `$crate` resolved at the definition site
/// of the macro. This is the same hygiene behavior as `macro_rules`.
pub fn mixed_site() -> Self {
Span::_new(imp::Span::mixed_site())
}
/// A span that resolves at the macro definition site.
///
/// This method is semver exempt and not exposed by default.
#[cfg(procmacro2_semver_exempt)]
#[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
pub fn def_site() -> Self {
Span::_new(imp::Span::def_site())
}
/// Creates a new span with the same line/column information as `self` but
/// that resolves symbols as though it were at `other`.
pub fn resolved_at(&self, other: Span) -> Span {
Span::_new(self.inner.resolved_at(other.inner))
}
/// Creates a new span with the same name resolution behavior as `self` but
/// with the line/column information of `other`.
pub fn located_at(&self, other: Span) -> Span {
Span::_new(self.inner.located_at(other.inner))
}
/// Convert `proc_macro2::Span` to `proc_macro::Span`.
///
/// This method is available when building with a nightly compiler, or when
/// building with rustc 1.29+ *without* semver exempt features.
///
/// # Panics
///
/// Panics if called from outside of a procedural macro. Unlike
/// `proc_macro2::Span`, the `proc_macro::Span` type can only exist within
/// the context of a procedural macro invocation.
#[cfg(wrap_proc_macro)]
pub fn unwrap(self) -> proc_macro::Span {
self.inner.unwrap()
}
// Soft deprecated. Please use Span::unwrap.
#[cfg(wrap_proc_macro)]
#[doc(hidden)]
pub fn unstable(self) -> proc_macro::Span {
self.unwrap()
}
/// The original source file into which this span points.
///
/// This method is semver exempt and not exposed by default.
#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
#[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
pub fn source_file(&self) -> SourceFile {
SourceFile::_new(self.inner.source_file())
}
/// Returns the span's byte position range in the source file.
///
/// This method requires the `"span-locations"` feature to be enabled.
///
/// When executing in a procedural macro context, the returned range is only
/// accurate if compiled with a nightly toolchain. The stable toolchain does
/// not have this information available. When executing outside of a
/// procedural macro, such as main.rs or build.rs, the byte range is always
/// accurate regardless of toolchain.
#[cfg(span_locations)]
#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
pub fn byte_range(&self) -> Range<usize> {
self.inner.byte_range()
}
/// Get the starting line/column in the source file for this span.
///
/// This method requires the `"span-locations"` feature to be enabled.
///
/// When executing in a procedural macro context, the returned line/column
/// are only meaningful if compiled with a nightly toolchain. The stable
/// toolchain does not have this information available. When executing
/// outside of a procedural macro, such as main.rs or build.rs, the
/// line/column are always meaningful regardless of toolchain.
#[cfg(span_locations)]
#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
pub fn start(&self) -> LineColumn {
self.inner.start()
}
/// Get the ending line/column in the source file for this span.
///
/// This method requires the `"span-locations"` feature to be enabled.
///
/// When executing in a procedural macro context, the returned line/column
/// are only meaningful if compiled with a nightly toolchain. The stable
/// toolchain does not have this information available. When executing
/// outside of a procedural macro, such as main.rs or build.rs, the
/// line/column are always meaningful regardless of toolchain.
#[cfg(span_locations)]
#[cfg_attr(docsrs, doc(cfg(feature = "span-locations")))]
pub fn end(&self) -> LineColumn {
self.inner.end()
}
/// Create a new span encompassing `self` and `other`.
///
/// Returns `None` if `self` and `other` are from different files.
///
/// Warning: the underlying [`proc_macro::Span::join`] method is
/// nightly-only. When called from within a procedural macro not using a
/// nightly compiler, this method will always return `None`.
///
pub fn join(&self, other: Span) -> Option<Span> {
self.inner.join(other.inner).map(Span::_new)
}
/// Compares two spans to see if they're equal.
///
/// This method is semver exempt and not exposed by default.
#[cfg(procmacro2_semver_exempt)]
#[cfg_attr(docsrs, doc(cfg(procmacro2_semver_exempt)))]
pub fn eq(&self, other: &Span) -> bool {
self.inner.eq(&other.inner)
}
/// Returns the source text behind a span. This preserves the original
/// source code, including spaces and comments. It only returns a result if
/// the span corresponds to real source code.
///
/// Note: The observable result of a macro should only rely on the tokens
/// and not on this source text. The result of this function is a best
/// effort to be used for diagnostics only.
pub fn source_text(&self) -> Option<String> {
self.inner.source_text()
}
}
/// Prints a span in a form convenient for debugging.
impl Debug for Span {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
/// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
#[derive(Clone)]
pub enum TokenTree {
/// A token stream surrounded by bracket delimiters.
Group(Group),
/// An identifier.
Ident(Ident),
/// A single punctuation character (`+`, `,`, `$`, etc.).
Punct(Punct),
/// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
Literal(Literal),
}
impl TokenTree {
/// Returns the span of this tree, delegating to the `span` method of
/// the contained token or a delimited stream.
pub fn span(&self) -> Span {
match self {
TokenTree::Group(t) => t.span(),
TokenTree::Ident(t) => t.span(),
TokenTree::Punct(t) => t.span(),
TokenTree::Literal(t) => t.span(),
}
}
/// Configures the span for *only this token*.
///
/// Note that if this token is a `Group` then this method will not configure
/// the span of each of the internal tokens, this will simply delegate to
/// the `set_span` method of each variant.
pub fn set_span(&mut self, span: Span) {
match self {
TokenTree::Group(t) => t.set_span(span),
TokenTree::Ident(t) => t.set_span(span),
TokenTree::Punct(t) => t.set_span(span),
TokenTree::Literal(t) => t.set_span(span),
}
}
}
impl From<Group> for TokenTree {
fn from(g: Group) -> Self {
TokenTree::Group(g)
}
}
impl From<Ident> for TokenTree {
fn from(g: Ident) -> Self {
TokenTree::Ident(g)
}
}
impl From<Punct> for TokenTree {
fn from(g: Punct) -> Self {
TokenTree::Punct(g)
}
}
impl From<Literal> for TokenTree {
fn from(g: Literal) -> Self {
TokenTree::Literal(g)
}
}
/// Prints the token tree as a string that is supposed to be losslessly
/// convertible back into the same token tree (modulo spans), except for
/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
/// numeric literals.
impl Display for TokenTree {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
TokenTree::Group(t) => Display::fmt(t, f),
TokenTree::Ident(t) => Display::fmt(t, f),
TokenTree::Punct(t) => Display::fmt(t, f),
TokenTree::Literal(t) => Display::fmt(t, f),
}
}
}
/// Prints token tree in a form convenient for debugging.
impl Debug for TokenTree {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
// Each of these has the name in the struct type in the derived debug,
// so don't bother with an extra layer of indirection
match self {
TokenTree::Group(t) => Debug::fmt(t, f),
TokenTree::Ident(t) => {
let mut debug = f.debug_struct("Ident");
debug.field("sym", &format_args!("{}", t));
imp::debug_span_field_if_nontrivial(&mut debug, t.span().inner);
debug.finish()
}
TokenTree::Punct(t) => Debug::fmt(t, f),
TokenTree::Literal(t) => Debug::fmt(t, f),
}
}
}
/// A delimited token stream.
///
/// A `Group` internally contains a `TokenStream` which is surrounded by
/// `Delimiter`s.
#[derive(Clone)]
pub struct Group {
inner: imp::Group,
}
/// Describes how a sequence of token trees is delimited.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Delimiter {
/// `( ... )`
Parenthesis,
/// `{ ... }`
Brace,
/// `[ ... ]`
Bracket,
/// `∅ ... ∅`
///
/// An invisible delimiter, that may, for example, appear around tokens
/// coming from a "macro variable" `$var`. It is important to preserve
/// operator priorities in cases like `$var * 3` where `$var` is `1 + 2`.
/// Invisible delimiters may not survive roundtrip of a token stream through
/// a string.
///
/// <div class="warning">
///
/// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
/// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
/// of a proc_macro macro are preserved, and only in very specific circumstances.
/// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
/// operator priorities as indicated above. The other `Delimiter` variants should be used
/// instead in this context. This is a rustc bug. For details, see
/// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
///
/// </div>
None,
}
impl Group {
fn _new(inner: imp::Group) -> Self {
Group { inner }
}
fn _new_fallback(inner: fallback::Group) -> Self {
Group {
inner: inner.into(),
}
}
/// Creates a new `Group` with the given delimiter and token stream.
///
/// This constructor will set the span for this group to
/// `Span::call_site()`. To change the span you can use the `set_span`
/// method below.
pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
Group {
inner: imp::Group::new(delimiter, stream.inner),
}
}
/// Returns the punctuation used as the delimiter for this group: a set of
/// parentheses, square brackets, or curly braces.
pub fn delimiter(&self) -> Delimiter {
self.inner.delimiter()
}
/// Returns the `TokenStream` of tokens that are delimited in this `Group`.
///
/// Note that the returned token stream does not include the delimiter
/// returned above.
pub fn stream(&self) -> TokenStream {
TokenStream::_new(self.inner.stream())
}
/// Returns the span for the delimiters of this token stream, spanning the
/// entire `Group`.
///
/// ```text
/// pub fn span(&self) -> Span {
/// ^^^^^^^
/// ```
pub fn span(&self) -> Span {
Span::_new(self.inner.span())
}
/// Returns the span pointing to the opening delimiter of this group.
///
/// ```text
/// pub fn span_open(&self) -> Span {
/// ^
/// ```
pub fn span_open(&self) -> Span {
Span::_new(self.inner.span_open())
}
/// Returns the span pointing to the closing delimiter of this group.
///
/// ```text
/// pub fn span_close(&self) -> Span {
/// ^
/// ```
pub fn span_close(&self) -> Span {
Span::_new(self.inner.span_close())
}
/// Returns an object that holds this group's `span_open()` and
/// `span_close()` together (in a more compact representation than holding
/// those 2 spans individually).
pub fn delim_span(&self) -> DelimSpan {
DelimSpan::new(&self.inner)
}
/// Configures the span for this `Group`'s delimiters, but not its internal
/// tokens.
///
/// This method will **not** set the span of all the internal tokens spanned
/// by this group, but rather it will only set the span of the delimiter
/// tokens at the level of the `Group`.
pub fn set_span(&mut self, span: Span) {
self.inner.set_span(span.inner);
}
}
/// Prints the group as a string that should be losslessly convertible back
/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
/// with `Delimiter::None` delimiters.
impl Display for Group {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.inner, formatter)
}
}
impl Debug for Group {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, formatter)
}
}
/// A `Punct` is a single punctuation character like `+`, `-` or `#`.
///
/// Multicharacter operators like `+=` are represented as two instances of
/// `Punct` with different forms of `Spacing` returned.
#[derive(Clone)]
pub struct Punct {
ch: char,
spacing: Spacing,
span: Span,
}
/// Whether a `Punct` is followed immediately by another `Punct` or followed by
/// another token or whitespace.
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Spacing {
/// E.g. `+` is `Alone` in `+ =`, `+ident` or `+()`.
Alone,
/// E.g. `+` is `Joint` in `+=` or `'` is `Joint` in `'#`.
///
/// Additionally, single quote `'` can join with identifiers to form
/// lifetimes `'ident`.
Joint,
}
impl Punct {
/// Creates a new `Punct` from the given character and spacing.
///
/// The `ch` argument must be a valid punctuation character permitted by the
/// language, otherwise the function will panic.
///
/// The returned `Punct` will have the default span of `Span::call_site()`
/// which can be further configured with the `set_span` method below.
pub fn new(ch: char, spacing: Spacing) -> Self {
Punct {
ch,
spacing,
span: Span::call_site(),
}
}
/// Returns the value of this punctuation character as `char`.
pub fn as_char(&self) -> char {
self.ch
}
/// Returns the spacing of this punctuation character, indicating whether
/// it's immediately followed by another `Punct` in the token stream, so
/// they can potentially be combined into a multicharacter operator
/// (`Joint`), or it's followed by some other token or whitespace (`Alone`)
/// so the operator has certainly ended.
pub fn spacing(&self) -> Spacing {
self.spacing
}
/// Returns the span for this punctuation character.
pub fn span(&self) -> Span {
self.span
}
/// Configure the span for this punctuation character.
pub fn set_span(&mut self, span: Span) {
self.span = span;
}
}
/// Prints the punctuation character as a string that should be losslessly
/// convertible back into the same character.
impl Display for Punct {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.ch, f)
}
}
impl Debug for Punct {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let mut debug = fmt.debug_struct("Punct");
debug.field("char", &self.ch);
debug.field("spacing", &self.spacing);
imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
debug.finish()
}
}
/// A word of Rust code, which may be a keyword or legal variable name.
///
/// An identifier consists of at least one Unicode code point, the first of
/// which has the XID_Start property and the rest of which have the XID_Continue
/// property.
///
/// - The empty string is not an identifier. Use `Option<Ident>`.
/// - A lifetime is not an identifier. Use `syn::Lifetime` instead.
///
/// An identifier constructed with `Ident::new` is permitted to be a Rust
/// keyword, though parsing one through its [`Parse`] implementation rejects
/// Rust keywords. Use `input.call(Ident::parse_any)` when parsing to match the
/// behaviour of `Ident::new`.
///
///
/// # Examples
///
/// A new ident can be created from a string using the `Ident::new` function.
/// A span must be provided explicitly which governs the name resolution
/// behavior of the resulting identifier.
///
/// ```
/// use proc_macro2::{Ident, Span};
///
/// fn main() {
/// let call_ident = Ident::new("calligraphy", Span::call_site());
///
/// println!("{}", call_ident);
/// }
/// ```
///
/// An ident can be interpolated into a token stream using the `quote!` macro.
///
/// ```
/// use proc_macro2::{Ident, Span};
/// use quote::quote;
///
/// fn main() {
/// let ident = Ident::new("demo", Span::call_site());
///
/// // Create a variable binding whose name is this ident.
/// let expanded = quote! { let #ident = 10; };
///
/// // Create a variable binding with a slightly different name.
/// let temp_ident = Ident::new(&format!("new_{}", ident), Span::call_site());
/// let expanded = quote! { let #temp_ident = 10; };
/// }
/// ```
///
/// A string representation of the ident is available through the `to_string()`
/// method.
///
/// ```
/// # use proc_macro2::{Ident, Span};
/// #
/// # let ident = Ident::new("another_identifier", Span::call_site());
/// #
/// // Examine the ident as a string.
/// let ident_string = ident.to_string();
/// if ident_string.len() > 60 {
/// println!("Very long identifier: {}", ident_string)
/// }
/// ```
#[derive(Clone)]
pub struct Ident {
inner: imp::Ident,
_marker: ProcMacroAutoTraits,
}
impl Ident {
fn _new(inner: imp::Ident) -> Self {
Ident {
inner,
_marker: MARKER,
}
}
/// Creates a new `Ident` with the given `string` as well as the specified
/// `span`.
///
/// The `string` argument must be a valid identifier permitted by the
/// language, otherwise the function will panic.
///
/// Note that `span`, currently in rustc, configures the hygiene information
/// for this identifier.
///
/// As of this time `Span::call_site()` explicitly opts-in to "call-site"
/// hygiene meaning that identifiers created with this span will be resolved
/// as if they were written directly at the location of the macro call, and
/// other code at the macro call site will be able to refer to them as well.
///
/// Later spans like `Span::def_site()` will allow to opt-in to
/// "definition-site" hygiene meaning that identifiers created with this
/// span will be resolved at the location of the macro definition and other
/// code at the macro call site will not be able to refer to them.
///
/// Due to the current importance of hygiene this constructor, unlike other
/// tokens, requires a `Span` to be specified at construction.
///
/// # Panics
///
/// Panics if the input string is neither a keyword nor a legal variable
/// name. If you are not sure whether the string contains an identifier and
/// need to handle an error case, use
/// style="padding-right:0;">syn::parse_str</code></a><code
/// style="padding-left:0;">::&lt;Ident&gt;</code>
/// rather than `Ident::new`.
#[track_caller]
pub fn new(string: &str, span: Span) -> Self {
Ident::_new(imp::Ident::new_checked(string, span.inner))
}
/// Same as `Ident::new`, but creates a raw identifier (`r#ident`). The
/// `string` argument must be a valid identifier permitted by the language
/// (including keywords, e.g. `fn`). Keywords which are usable in path
/// segments (e.g. `self`, `super`) are not supported, and will cause a
/// panic.
#[track_caller]
pub fn new_raw(string: &str, span: Span) -> Self {
Ident::_new(imp::Ident::new_raw_checked(string, span.inner))
}
/// Returns the span of this `Ident`.
pub fn span(&self) -> Span {
Span::_new(self.inner.span())
}
/// Configures the span of this `Ident`, possibly changing its hygiene
/// context.
pub fn set_span(&mut self, span: Span) {
self.inner.set_span(span.inner);
}
}
impl PartialEq for Ident {
fn eq(&self, other: &Ident) -> bool {
self.inner == other.inner
}
}
impl<T> PartialEq<T> for Ident
where
T: ?Sized + AsRef<str>,
{
fn eq(&self, other: &T) -> bool {
self.inner == other
}
}
impl Eq for Ident {}
impl PartialOrd for Ident {
fn partial_cmp(&self, other: &Ident) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for Ident {
fn cmp(&self, other: &Ident) -> Ordering {
self.to_string().cmp(&other.to_string())
}
}
impl Hash for Ident {
fn hash<H: Hasher>(&self, hasher: &mut H) {
self.to_string().hash(hasher);
}
}
/// Prints the identifier as a string that should be losslessly convertible back
/// into the same identifier.
impl Display for Ident {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.inner, f)
}
}
impl Debug for Ident {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
/// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
/// byte character (`b'a'`), an integer or floating point number with or without
/// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
///
/// Boolean literals like `true` and `false` do not belong here, they are
/// `Ident`s.
#[derive(Clone)]
pub struct Literal {
inner: imp::Literal,
_marker: ProcMacroAutoTraits,
}
macro_rules! suffixed_int_literals {
($($name:ident => $kind:ident,)*) => ($(
/// Creates a new suffixed integer literal with the specified value.
///
/// This function will create an integer like `1u32` where the integer
/// value specified is the first part of the token and the integral is
/// also suffixed at the end. Literals created from negative numbers may
/// not survive roundtrips through `TokenStream` or strings and may be
/// broken into two tokens (`-` and positive literal).
///
/// Literals created through this method have the `Span::call_site()`
/// span by default, which can be configured with the `set_span` method
/// below.
pub fn $name(n: $kind) -> Literal {
Literal::_new(imp::Literal::$name(n))
}
)*)
}
macro_rules! unsuffixed_int_literals {
($($name:ident => $kind:ident,)*) => ($(
/// Creates a new unsuffixed integer literal with the specified value.
///
/// This function will create an integer like `1` where the integer
/// value specified is the first part of the token. No suffix is
/// specified on this token, meaning that invocations like
/// `Literal::i8_unsuffixed(1)` are equivalent to
/// `Literal::u32_unsuffixed(1)`. Literals created from negative numbers
/// may not survive roundtrips through `TokenStream` or strings and may
/// be broken into two tokens (`-` and positive literal).
///
/// Literals created through this method have the `Span::call_site()`
/// span by default, which can be configured with the `set_span` method
/// below.
pub fn $name(n: $kind) -> Literal {
Literal::_new(imp::Literal::$name(n))
}
)*)
}
impl Literal {
fn _new(inner: imp::Literal) -> Self {
Literal {
inner,
_marker: MARKER,
}
}
fn _new_fallback(inner: fallback::Literal) -> Self {
Literal {
inner: inner.into(),
_marker: MARKER,
}
}
suffixed_int_literals! {
u8_suffixed => u8,
u16_suffixed => u16,
u32_suffixed => u32,
u64_suffixed => u64,
u128_suffixed => u128,
usize_suffixed => usize,
i8_suffixed => i8,
i16_suffixed => i16,
i32_suffixed => i32,
i64_suffixed => i64,
i128_suffixed => i128,
isize_suffixed => isize,
}
unsuffixed_int_literals! {
u8_unsuffixed => u8,
u16_unsuffixed => u16,
u32_unsuffixed => u32,
u64_unsuffixed => u64,
u128_unsuffixed => u128,
usize_unsuffixed => usize,
i8_unsuffixed => i8,
i16_unsuffixed => i16,
i32_unsuffixed => i32,
i64_unsuffixed => i64,
i128_unsuffixed => i128,
isize_unsuffixed => isize,
}
/// Creates a new unsuffixed floating-point literal.
///
/// This constructor is similar to those like `Literal::i8_unsuffixed` where
/// the float's value is emitted directly into the token but no suffix is
/// used, so it may be inferred to be a `f64` later in the compiler.
/// Literals created from negative numbers may not survive round-trips
/// through `TokenStream` or strings and may be broken into two tokens (`-`
/// and positive literal).
///
/// # Panics
///
/// This function requires that the specified float is finite, for example
/// if it is infinity or NaN this function will panic.
pub fn f64_unsuffixed(f: f64) -> Literal {
assert!(f.is_finite());
Literal::_new(imp::Literal::f64_unsuffixed(f))
}
/// Creates a new suffixed floating-point literal.
///
/// This constructor will create a literal like `1.0f64` where the value
/// specified is the preceding part of the token and `f64` is the suffix of
/// the token. This token will always be inferred to be an `f64` in the
/// compiler. Literals created from negative numbers may not survive
/// round-trips through `TokenStream` or strings and may be broken into two
/// tokens (`-` and positive literal).
///
/// # Panics
///
/// This function requires that the specified float is finite, for example
/// if it is infinity or NaN this function will panic.
pub fn f64_suffixed(f: f64) -> Literal {
assert!(f.is_finite());
Literal::_new(imp::Literal::f64_suffixed(f))
}
/// Creates a new unsuffixed floating-point literal.
///
/// This constructor is similar to those like `Literal::i8_unsuffixed` where
/// the float's value is emitted directly into the token but no suffix is
/// used, so it may be inferred to be a `f64` later in the compiler.
/// Literals created from negative numbers may not survive round-trips
/// through `TokenStream` or strings and may be broken into two tokens (`-`
/// and positive literal).
///
/// # Panics
///
/// This function requires that the specified float is finite, for example
/// if it is infinity or NaN this function will panic.
pub fn f32_unsuffixed(f: f32) -> Literal {
assert!(f.is_finite());
Literal::_new(imp::Literal::f32_unsuffixed(f))
}
/// Creates a new suffixed floating-point literal.
///
/// This constructor will create a literal like `1.0f32` where the value
/// specified is the preceding part of the token and `f32` is the suffix of
/// the token. This token will always be inferred to be an `f32` in the
/// compiler. Literals created from negative numbers may not survive
/// round-trips through `TokenStream` or strings and may be broken into two
/// tokens (`-` and positive literal).
///
/// # Panics
///
/// This function requires that the specified float is finite, for example
/// if it is infinity or NaN this function will panic.
pub fn f32_suffixed(f: f32) -> Literal {
assert!(f.is_finite());
Literal::_new(imp::Literal::f32_suffixed(f))
}
/// String literal.
pub fn string(string: &str) -> Literal {
Literal::_new(imp::Literal::string(string))
}
/// Character literal.
pub fn character(ch: char) -> Literal {
Literal::_new(imp::Literal::character(ch))
}
/// Byte character literal.
pub fn byte_character(byte: u8) -> Literal {
Literal::_new(imp::Literal::byte_character(byte))
}
/// Byte string literal.
pub fn byte_string(bytes: &[u8]) -> Literal {
Literal::_new(imp::Literal::byte_string(bytes))
}
/// C string literal.
pub fn c_string(string: &CStr) -> Literal {
Literal::_new(imp::Literal::c_string(string))
}
/// Returns the span encompassing this literal.
pub fn span(&self) -> Span {
Span::_new(self.inner.span())
}
/// Configures the span associated for this literal.
pub fn set_span(&mut self, span: Span) {
self.inner.set_span(span.inner);
}
/// Returns a `Span` that is a subset of `self.span()` containing only
/// the source bytes in range `range`. Returns `None` if the would-be
/// trimmed span is outside the bounds of `self`.
///
/// Warning: the underlying [`proc_macro::Literal::subspan`] method is
/// nightly-only. When called from within a procedural macro not using a
/// nightly compiler, this method will always return `None`.
///
pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
self.inner.subspan(range).map(Span::_new)
}
// Intended for the `quote!` macro to use when constructing a proc-macro2
// token out of a macro_rules $:literal token, which is already known to be
// a valid literal. This avoids reparsing/validating the literal's string
// representation. This is not public API other than for quote.
#[doc(hidden)]
pub unsafe fn from_str_unchecked(repr: &str) -> Self {
Literal::_new(unsafe { imp::Literal::from_str_unchecked(repr) })
}
}
impl FromStr for Literal {
type Err = LexError;
fn from_str(repr: &str) -> Result<Self, LexError> {
repr.parse().map(Literal::_new).map_err(|inner| LexError {
inner,
_marker: MARKER,
})
}
}
impl Debug for Literal {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Debug::fmt(&self.inner, f)
}
}
impl Display for Literal {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
Display::fmt(&self.inner, f)
}
}
/// Public implementation details for the `TokenStream` type, such as iterators.
pub mod token_stream {
use crate::marker::{ProcMacroAutoTraits, MARKER};
use crate::{imp, TokenTree};
use core::fmt::{self, Debug};
pub use crate::TokenStream;
/// An iterator over `TokenStream`'s `TokenTree`s.
///
/// The iteration is "shallow", e.g. the iterator doesn't recurse into
/// delimited groups, and returns whole groups as token trees.
#[derive(Clone)]
pub struct IntoIter {
inner: imp::TokenTreeIter,
_marker: ProcMacroAutoTraits,
}
impl Iterator for IntoIter {
type Item = TokenTree;
fn next(&mut self) -> Option<TokenTree> {
self.inner.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
impl Debug for IntoIter {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str("TokenStream ")?;
f.debug_list().entries(self.clone()).finish()
}
}
impl IntoIterator for TokenStream {
type Item = TokenTree;
type IntoIter = IntoIter;
fn into_iter(self) -> IntoIter {
IntoIter {
inner: self.inner.into_iter(),
_marker: MARKER,
}
}
}
}