lib.rs - source
Description: Source of the Rust file `library/proc_macro/src/lib.rs`.

#
proc_macro/
lib.rs

    1//! A support library for macro authors when defining new macros.
    2//!
    3//! This library, provided by the standard distribution, provides the types
    4//! consumed in the interfaces of procedurally defined macro definitions such as
    5//! function-like macros `#[proc_macro]`, macro attributes `#[proc_macro_attribute]` and
    6//! custom derive attributes `#[proc_macro_derive]`.
    7//!
    8//! See [the book] for more.
    9//!
    10//! [the book]: ../book/ch19-06-macros.html#procedural-macros-for-generating-code-from-attributes
    11
    12#![stable(feature = "proc_macro_lib", since = "1.15.0")]
    13#![deny(missing_docs)]
    14#![doc(
    15    html_playground_url = "https://play.rust-lang.org/",
    16    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
    17    test(no_crate_inject, attr(deny(warnings))),
    18    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
    19)]
    20#![doc(rust_logo)]
    21#![feature(rustdoc_internals)]
    22#![feature(staged_api)]
    23#![feature(allow_internal_unstable)]
    24#![feature(decl_macro)]
    25#![feature(negative_impls)]
    26#![feature(panic_can_unwind)]
    27#![feature(restricted_std)]
    28#![feature(rustc_attrs)]
    29#![feature(extend_one)]
    30#![recursion_limit = "256"]
    31#![allow(internal_features)]
    32#![deny(ffi_unwind_calls)]
    33#![allow(rustc::internal)] // Can't use FxHashMap when compiled as part of the standard library
    34#![warn(rustdoc::unescaped_backticks)]
    35#![warn(unreachable_pub)]
    36#![deny(unsafe_op_in_unsafe_fn)]
    37
    38#[unstable(feature = "proc_macro_internals", issue = "27812")]
    39#[doc(hidden)]
    40pub mod bridge;
    41
    42mod diagnostic;
    43mod escape;
    44mod to_tokens;
    45
    46use core::ops::BitOr;
    47use std::ffi::CStr;
    48use std::ops::{Range, RangeBounds};
    49use std::path::PathBuf;
    50use std::str::FromStr;
    51use std::{error, fmt};
    52
    53#[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
    54pub use diagnostic::{Diagnostic, Level, MultiSpan};
    55#[unstable(feature = "proc_macro_value", issue = "136652")]
    56pub use rustc_literal_escaper::EscapeError;
    57use rustc_literal_escaper::{MixedUnit, unescape_byte_str, unescape_c_str, unescape_str};
    58#[unstable(feature = "proc_macro_totokens", issue = "130977")]
    59pub use to_tokens::ToTokens;
    60
    61use crate::escape::{EscapeOptions, escape_bytes};
    62
    63/// Errors returned when trying to retrieve a literal unescaped value.
    64#[unstable(feature = "proc_macro_value", issue = "136652")]
    65#[derive(Debug, PartialEq, Eq)]
    66pub enum ConversionErrorKind {
    67    /// The literal failed to be escaped, take a look at [`EscapeError`] for more information.
    68    FailedToUnescape(EscapeError),
    69    /// Trying to convert a literal with the wrong type.
    70    InvalidLiteralKind,
    71}
    72
    73/// Determines whether proc_macro has been made accessible to the currently
    74/// running program.
    75///
    76/// The proc_macro crate is only intended for use inside the implementation of
    77/// procedural macros. All the functions in this crate panic if invoked from
    78/// outside of a procedural macro, such as from a build script or unit test or
    79/// ordinary Rust binary.
    80///
    81/// With consideration for Rust libraries that are designed to support both
    82/// macro and non-macro use cases, `proc_macro::is_available()` provides a
    83/// non-panicking way to detect whether the infrastructure required to use the
    84/// API of proc_macro is presently available. Returns true if invoked from
    85/// inside of a procedural macro, false if invoked from any other binary.
    86#[stable(feature = "proc_macro_is_available", since = "1.57.0")]
    87pub fn is_available() -> bool {
    88    bridge::client::is_available()
    89}
    90
    91/// The main type provided by this crate, representing an abstract stream of
    92/// tokens, or, more specifically, a sequence of token trees.
    93/// The type provides interfaces for iterating over those token trees and, conversely,
    94/// collecting a number of token trees into one stream.
    95///
    96/// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
    97/// and `#[proc_macro_derive]` definitions.
    98#[cfg_attr(feature = "rustc-dep-of-std", rustc_diagnostic_item = "TokenStream")]
    99#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    100#[derive(Clone)]
    101pub struct TokenStream(Option<bridge::client::TokenStream>);
    102
    103#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    104impl !Send for TokenStream {}
    105#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    106impl !Sync for TokenStream {}
    107
    108/// Error returned from `TokenStream::from_str`.
    109#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    110#[non_exhaustive]
    111#[derive(Debug)]
    112pub struct LexError;
    113
    114#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
    115impl fmt::Display for LexError {
    116    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    117        f.write_str("cannot parse string into token stream")
    118    }
    119}
    120
    121#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
    122impl error::Error for LexError {}
    123
    124#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    125impl !Send for LexError {}
    126#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    127impl !Sync for LexError {}
    128
    129/// Error returned from `TokenStream::expand_expr`.
    130#[unstable(feature = "proc_macro_expand", issue = "90765")]
    131#[non_exhaustive]
    132#[derive(Debug)]
    133pub struct ExpandError;
    134
    135#[unstable(feature = "proc_macro_expand", issue = "90765")]
    136impl fmt::Display for ExpandError {
    137    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    138        f.write_str("macro expansion failed")
    139    }
    140}
    141
    142#[unstable(feature = "proc_macro_expand", issue = "90765")]
    143impl error::Error for ExpandError {}
    144
    145#[unstable(feature = "proc_macro_expand", issue = "90765")]
    146impl !Send for ExpandError {}
    147
    148#[unstable(feature = "proc_macro_expand", issue = "90765")]
    149impl !Sync for ExpandError {}
    150
    151impl TokenStream {
    152    /// Returns an empty `TokenStream` containing no token trees.
    153    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    154    pub fn new() -> TokenStream {
    155        TokenStream(None)
    156    }
    157
    158    /// Checks if this `TokenStream` is empty.
    159    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    160    pub fn is_empty(&self) -> bool {
    161        self.0.as_ref().map(|h| h.is_empty()).unwrap_or(true)
    162    }
    163
    164    /// Parses this `TokenStream` as an expression and attempts to expand any
    165    /// macros within it. Returns the expanded `TokenStream`.
    166    ///
    167    /// Currently only expressions expanding to literals will succeed, although
    168    /// this may be relaxed in the future.
    169    ///
    170    /// NOTE: In error conditions, `expand_expr` may leave macros unexpanded,
    171    /// report an error, failing compilation, and/or return an `Err(..)`. The
    172    /// specific behavior for any error condition, and what conditions are
    173    /// considered errors, is unspecified and may change in the future.
    174    #[unstable(feature = "proc_macro_expand", issue = "90765")]
    175    pub fn expand_expr(&self) -> Result<TokenStream, ExpandError> {
    176        let stream = self.0.as_ref().ok_or(ExpandError)?;
    177        match bridge::client::TokenStream::expand_expr(stream) {
    178            Ok(stream) => Ok(TokenStream(Some(stream))),
    179            Err(_) => Err(ExpandError),
    180        }
    181    }
    182}
    183
    184/// Attempts to break the string into tokens and parse those tokens into a token stream.
    185/// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
    186/// or characters not existing in the language.
    187/// All tokens in the parsed stream get `Span::call_site()` spans.
    188///
    189/// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
    190/// change these errors into `LexError`s later.
    191#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    192impl FromStr for TokenStream {
    193    type Err = LexError;
    194
    195    fn from_str(src: &str) -> Result<TokenStream, LexError> {
    196        Ok(TokenStream(Some(bridge::client::TokenStream::from_str(src))))
    197    }
    198}
    199
    200/// Prints the token stream as a string that is supposed to be losslessly convertible back
    201/// into the same token stream (modulo spans), except for possibly `TokenTree::Group`s
    202/// with `Delimiter::None` delimiters and negative numeric literals.
    203///
    204/// Note: the exact form of the output is subject to change, e.g. there might
    205/// be changes in the whitespace used between tokens. Therefore, you should
    206/// *not* do any kind of simple substring matching on the output string (as
    207/// produced by `to_string`) to implement a proc macro, because that matching
    208/// might stop working if such changes happen. Instead, you should work at the
    209/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
    210/// `TokenTree::Punct`, or `TokenTree::Literal`.
    211#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    212impl fmt::Display for TokenStream {
    213    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    214        match &self.0 {
    215            Some(ts) => write!(f, "{}", ts.to_string()),
    216            None => Ok(()),
    217        }
    218    }
    219}
    220
    221/// Prints tokens in a form convenient for debugging.
    222#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    223impl fmt::Debug for TokenStream {
    224    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    225        f.write_str("TokenStream ")?;
    226        f.debug_list().entries(self.clone()).finish()
    227    }
    228}
    229
    230#[stable(feature = "proc_macro_token_stream_default", since = "1.45.0")]
    231impl Default for TokenStream {
    232    fn default() -> Self {
    233        TokenStream::new()
    234    }
    235}
    236
    237#[unstable(feature = "proc_macro_quote", issue = "54722")]
    238pub use quote::{HasIterator, RepInterp, ThereIsNoIteratorInRepetition, ext, quote, quote_span};
    239
    240fn tree_to_bridge_tree(
    241    tree: TokenTree,
    242) -> bridge::TokenTree<bridge::client::TokenStream, bridge::client::Span, bridge::client::Symbol> {
    243    match tree {
    244        TokenTree::Group(tt) => bridge::TokenTree::Group(tt.0),
    245        TokenTree::Punct(tt) => bridge::TokenTree::Punct(tt.0),
    246        TokenTree::Ident(tt) => bridge::TokenTree::Ident(tt.0),
    247        TokenTree::Literal(tt) => bridge::TokenTree::Literal(tt.0),
    248    }
    249}
    250
    251/// Creates a token stream containing a single token tree.
    252#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    253impl From<TokenTree> for TokenStream {
    254    fn from(tree: TokenTree) -> TokenStream {
    255        TokenStream(Some(bridge::client::TokenStream::from_token_tree(tree_to_bridge_tree(tree))))
    256    }
    257}
    258
    259/// Non-generic helper for implementing `FromIterator<TokenTree>` and
    260/// `Extend<TokenTree>` with less monomorphization in calling crates.
    261struct ConcatTreesHelper {
    262    trees: Vec<
    263        bridge::TokenTree<
    264            bridge::client::TokenStream,
    265            bridge::client::Span,
    266            bridge::client::Symbol,
    267        >,
    268    >,
    269}
    270
    271impl ConcatTreesHelper {
    272    fn new(capacity: usize) -> Self {
    273        ConcatTreesHelper { trees: Vec::with_capacity(capacity) }
    274    }
    275
    276    fn push(&mut self, tree: TokenTree) {
    277        self.trees.push(tree_to_bridge_tree(tree));
    278    }
    279
    280    fn build(self) -> TokenStream {
    281        if self.trees.is_empty() {
    282            TokenStream(None)
    283        } else {
    284            TokenStream(Some(bridge::client::TokenStream::concat_trees(None, self.trees)))
    285        }
    286    }
    287
    288    fn append_to(self, stream: &mut TokenStream) {
    289        if self.trees.is_empty() {
    290            return;
    291        }
    292        stream.0 = Some(bridge::client::TokenStream::concat_trees(stream.0.take(), self.trees))
    293    }
    294}
    295
    296/// Non-generic helper for implementing `FromIterator<TokenStream>` and
    297/// `Extend<TokenStream>` with less monomorphization in calling crates.
    298struct ConcatStreamsHelper {
    299    streams: Vec<bridge::client::TokenStream>,
    300}
    301
    302impl ConcatStreamsHelper {
    303    fn new(capacity: usize) -> Self {
    304        ConcatStreamsHelper { streams: Vec::with_capacity(capacity) }
    305    }
    306
    307    fn push(&mut self, stream: TokenStream) {
    308        if let Some(stream) = stream.0 {
    309            self.streams.push(stream);
    310        }
    311    }
    312
    313    fn build(mut self) -> TokenStream {
    314        if self.streams.len() <= 1 {
    315            TokenStream(self.streams.pop())
    316        } else {
    317            TokenStream(Some(bridge::client::TokenStream::concat_streams(None, self.streams)))
    318        }
    319    }
    320
    321    fn append_to(mut self, stream: &mut TokenStream) {
    322        if self.streams.is_empty() {
    323            return;
    324        }
    325        let base = stream.0.take();
    326        if base.is_none() && self.streams.len() == 1 {
    327            stream.0 = self.streams.pop();
    328        } else {
    329            stream.0 = Some(bridge::client::TokenStream::concat_streams(base, self.streams));
    330        }
    331    }
    332}
    333
    334/// Collects a number of token trees into a single stream.
    335#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    336impl FromIterator<TokenTree> for TokenStream {
    337    fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
    338        let iter = trees.into_iter();
    339        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
    340        iter.for_each(|tree| builder.push(tree));
    341        builder.build()
    342    }
    343}
    344
    345/// A "flattening" operation on token streams, collects token trees
    346/// from multiple token streams into a single stream.
    347#[stable(feature = "proc_macro_lib", since = "1.15.0")]
    348impl FromIterator<TokenStream> for TokenStream {
    349    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
    350        let iter = streams.into_iter();
    351        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
    352        iter.for_each(|stream| builder.push(stream));
    353        builder.build()
    354    }
    355}
    356
    357#[stable(feature = "token_stream_extend", since = "1.30.0")]
    358impl Extend<TokenTree> for TokenStream {
    359    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
    360        let iter = trees.into_iter();
    361        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
    362        iter.for_each(|tree| builder.push(tree));
    363        builder.append_to(self);
    364    }
    365}
    366
    367#[stable(feature = "token_stream_extend", since = "1.30.0")]
    368impl Extend<TokenStream> for TokenStream {
    369    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
    370        let iter = streams.into_iter();
    371        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
    372        iter.for_each(|stream| builder.push(stream));
    373        builder.append_to(self);
    374    }
    375}
    376
    377macro_rules! extend_items {
    378    ($($item:ident)*) => {
    379        $(
    380            #[stable(feature = "token_stream_extend_tt_items", since = "1.92.0")]
    381            impl Extend<$item> for TokenStream {
    382                fn extend<T: IntoIterator<Item = $item>>(&mut self, iter: T) {
    383                    self.extend(iter.into_iter().map(TokenTree::$item));
    384                }
    385            }
    386        )*
    387    };
    388}
    389
    390extend_items!(Group Literal Punct Ident);
    391
    392/// Public implementation details for the `TokenStream` type, such as iterators.
    393#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    394pub mod token_stream {
    395    use crate::{Group, Ident, Literal, Punct, TokenStream, TokenTree, bridge};
    396
    397    /// An iterator over `TokenStream`'s `TokenTree`s.
    398    /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
    399    /// and returns whole groups as token trees.
    400    #[derive(Clone)]
    401    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    402    pub struct IntoIter(
    403        std::vec::IntoIter<
    404            bridge::TokenTree<
    405                bridge::client::TokenStream,
    406                bridge::client::Span,
    407                bridge::client::Symbol,
    408            >,
    409        >,
    410    );
    411
    412    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    413    impl Iterator for IntoIter {
    414        type Item = TokenTree;
    415
    416        fn next(&mut self) -> Option<TokenTree> {
    417            self.0.next().map(|tree| match tree {
    418                bridge::TokenTree::Group(tt) => TokenTree::Group(Group(tt)),
    419                bridge::TokenTree::Punct(tt) => TokenTree::Punct(Punct(tt)),
    420                bridge::TokenTree::Ident(tt) => TokenTree::Ident(Ident(tt)),
    421                bridge::TokenTree::Literal(tt) => TokenTree::Literal(Literal(tt)),
    422            })
    423        }
    424
    425        fn size_hint(&self) -> (usize, Option<usize>) {
    426            self.0.size_hint()
    427        }
    428
    429        fn count(self) -> usize {
    430            self.0.count()
    431        }
    432    }
    433
    434    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    435    impl IntoIterator for TokenStream {
    436        type Item = TokenTree;
    437        type IntoIter = IntoIter;
    438
    439        fn into_iter(self) -> IntoIter {
    440            IntoIter(self.0.map(|v| v.into_trees()).unwrap_or_default().into_iter())
    441        }
    442    }
    443}
    444
    445/// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
    446/// For example, `quote!(a + b)` will produce an expression, that, when evaluated, constructs
    447/// the `TokenStream` `[Ident("a"), Punct('+', Alone), Ident("b")]`.
    448///
    449/// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
    450/// To quote `$` itself, use `$$`.
    451#[unstable(feature = "proc_macro_quote", issue = "54722")]
    452#[allow_internal_unstable(proc_macro_def_site, proc_macro_internals, proc_macro_totokens)]
    453#[rustc_builtin_macro]
    454pub macro quote($($t:tt)*) {
    455    /* compiler built-in */
    456}
    457
    458#[unstable(feature = "proc_macro_internals", issue = "27812")]
    459#[doc(hidden)]
    460mod quote;
    461
    462/// A region of source code, along with macro expansion information.
    463#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    464#[derive(Copy, Clone)]
    465pub struct Span(bridge::client::Span);
    466
    467#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    468impl !Send for Span {}
    469#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    470impl !Sync for Span {}
    471
    472macro_rules! diagnostic_method {
    473    ($name:ident, $level:expr) => {
    474        /// Creates a new `Diagnostic` with the given `message` at the span
    475        /// `self`.
    476        #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
    477        pub fn $name<T: Into<String>>(self, message: T) -> Diagnostic {
    478            Diagnostic::spanned(self, $level, message)
    479        }
    480    };
    481}
    482
    483impl Span {
    484    /// A span that resolves at the macro definition site.
    485    #[unstable(feature = "proc_macro_def_site", issue = "54724")]
    486    pub fn def_site() -> Span {
    487        Span(bridge::client::Span::def_site())
    488    }
    489
    490    /// The span of the invocation of the current procedural macro.
    491    /// Identifiers created with this span will be resolved as if they were written
    492    /// directly at the macro call location (call-site hygiene) and other code
    493    /// at the macro call site will be able to refer to them as well.
    494    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    495    pub fn call_site() -> Span {
    496        Span(bridge::client::Span::call_site())
    497    }
    498
    499    /// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
    500    /// definition site (local variables, labels, `$crate`) and sometimes at the macro
    501    /// call site (everything else).
    502    /// The span location is taken from the call-site.
    503    #[stable(feature = "proc_macro_mixed_site", since = "1.45.0")]
    504    pub fn mixed_site() -> Span {
    505        Span(bridge::client::Span::mixed_site())
    506    }
    507
    508    /// The `Span` for the tokens in the previous macro expansion from which
    509    /// `self` was generated from, if any.
    510    #[unstable(feature = "proc_macro_span", issue = "54725")]
    511    pub fn parent(&self) -> Option<Span> {
    512        self.0.parent().map(Span)
    513    }
    514
    515    /// The span for the origin source code that `self` was generated from. If
    516    /// this `Span` wasn't generated from other macro expansions then the return
    517    /// value is the same as `*self`.
    518    #[unstable(feature = "proc_macro_span", issue = "54725")]
    519    pub fn source(&self) -> Span {
    520        Span(self.0.source())
    521    }
    522
    523    /// Returns the span's byte position range in the source file.
    524    #[unstable(feature = "proc_macro_span", issue = "54725")]
    525    pub fn byte_range(&self) -> Range<usize> {
    526        self.0.byte_range()
    527    }
    528
    529    /// Creates an empty span pointing to directly before this span.
    530    #[stable(feature = "proc_macro_span_location", since = "1.88.0")]
    531    pub fn start(&self) -> Span {
    532        Span(self.0.start())
    533    }
    534
    535    /// Creates an empty span pointing to directly after this span.
    536    #[stable(feature = "proc_macro_span_location", since = "1.88.0")]
    537    pub fn end(&self) -> Span {
    538        Span(self.0.end())
    539    }
    540
    541    /// The one-indexed line of the source file where the span starts.
    542    ///
    543    /// To obtain the line of the span's end, use `span.end().line()`.
    544    #[stable(feature = "proc_macro_span_location", since = "1.88.0")]
    545    pub fn line(&self) -> usize {
    546        self.0.line()
    547    }
    548
    549    /// The one-indexed column of the source file where the span starts.
    550    ///
    551    /// To obtain the column of the span's end, use `span.end().column()`.
    552    #[stable(feature = "proc_macro_span_location", since = "1.88.0")]
    553    pub fn column(&self) -> usize {
    554        self.0.column()
    555    }
    556
    557    /// The path to the source file in which this span occurs, for display purposes.
    558    ///
    559    /// This might not correspond to a valid file system path.
    560    /// It might be remapped (e.g. `"/src/lib.rs"`) or an artificial path (e.g. `"<command line>"`).
    561    #[stable(feature = "proc_macro_span_file", since = "1.88.0")]
    562    pub fn file(&self) -> String {
    563        self.0.file()
    564    }
    565
    566    /// The path to the source file in which this span occurs on the local file system.
    567    ///
    568    /// This is the actual path on disk. It is unaffected by path remapping.
    569    ///
    570    /// This path should not be embedded in the output of the macro; prefer `file()` instead.
    571    #[stable(feature = "proc_macro_span_file", since = "1.88.0")]
    572    pub fn local_file(&self) -> Option<PathBuf> {
    573        self.0.local_file().map(PathBuf::from)
    574    }
    575
    576    /// Creates a new span encompassing `self` and `other`.
    577    ///
    578    /// Returns `None` if `self` and `other` are from different files.
    579    #[unstable(feature = "proc_macro_span", issue = "54725")]
    580    pub fn join(&self, other: Span) -> Option<Span> {
    581        self.0.join(other.0).map(Span)
    582    }
    583
    584    /// Creates a new span with the same line/column information as `self` but
    585    /// that resolves symbols as though it were at `other`.
    586    #[stable(feature = "proc_macro_span_resolved_at", since = "1.45.0")]
    587    pub fn resolved_at(&self, other: Span) -> Span {
    588        Span(self.0.resolved_at(other.0))
    589    }
    590
    591    /// Creates a new span with the same name resolution behavior as `self` but
    592    /// with the line/column information of `other`.
    593    #[stable(feature = "proc_macro_span_located_at", since = "1.45.0")]
    594    pub fn located_at(&self, other: Span) -> Span {
    595        other.resolved_at(*self)
    596    }
    597
    598    /// Compares two spans to see if they're equal.
    599    #[unstable(feature = "proc_macro_span", issue = "54725")]
    600    pub fn eq(&self, other: &Span) -> bool {
    601        self.0 == other.0
    602    }
    603
    604    /// Returns the source text behind a span. This preserves the original source
    605    /// code, including spaces and comments. It only returns a result if the span
    606    /// corresponds to real source code.
    607    ///
    608    /// Note: The observable result of a macro should only rely on the tokens and
    609    /// not on this source text. The result of this function is a best effort to
    610    /// be used for diagnostics only.
    611    #[stable(feature = "proc_macro_source_text", since = "1.66.0")]
    612    pub fn source_text(&self) -> Option<String> {
    613        self.0.source_text()
    614    }
    615
    616    // Used by the implementation of `Span::quote`
    617    #[doc(hidden)]
    618    #[unstable(feature = "proc_macro_internals", issue = "27812")]
    619    pub fn save_span(&self) -> usize {
    620        self.0.save_span()
    621    }
    622
    623    // Used by the implementation of `Span::quote`
    624    #[doc(hidden)]
    625    #[unstable(feature = "proc_macro_internals", issue = "27812")]
    626    pub fn recover_proc_macro_span(id: usize) -> Span {
    627        Span(bridge::client::Span::recover_proc_macro_span(id))
    628    }
    629
    630    diagnostic_method!(error, Level::Error);
    631    diagnostic_method!(warning, Level::Warning);
    632    diagnostic_method!(note, Level::Note);
    633    diagnostic_method!(help, Level::Help);
    634}
    635
    636/// Prints a span in a form convenient for debugging.
    637#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    638impl fmt::Debug for Span {
    639    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    640        self.0.fmt(f)
    641    }
    642}
    643
    644/// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
    645#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    646#[derive(Clone)]
    647pub enum TokenTree {
    648    /// A token stream surrounded by bracket delimiters.
    649    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    650    Group(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Group),
    651    /// An identifier.
    652    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    653    Ident(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Ident),
    654    /// A single punctuation character (`+`, `,`, `$`, etc.).
    655    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    656    Punct(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Punct),
    657    /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
    658    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    659    Literal(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Literal),
    660}
    661
    662#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    663impl !Send for TokenTree {}
    664#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    665impl !Sync for TokenTree {}
    666
    667impl TokenTree {
    668    /// Returns the span of this tree, delegating to the `span` method of
    669    /// the contained token or a delimited stream.
    670    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    671    pub fn span(&self) -> Span {
    672        match *self {
    673            TokenTree::Group(ref t) => t.span(),
    674            TokenTree::Ident(ref t) => t.span(),
    675            TokenTree::Punct(ref t) => t.span(),
    676            TokenTree::Literal(ref t) => t.span(),
    677        }
    678    }
    679
    680    /// Configures the span for *only this token*.
    681    ///
    682    /// Note that if this token is a `Group` then this method will not configure
    683    /// the span of each of the internal tokens, this will simply delegate to
    684    /// the `set_span` method of each variant.
    685    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    686    pub fn set_span(&mut self, span: Span) {
    687        match *self {
    688            TokenTree::Group(ref mut t) => t.set_span(span),
    689            TokenTree::Ident(ref mut t) => t.set_span(span),
    690            TokenTree::Punct(ref mut t) => t.set_span(span),
    691            TokenTree::Literal(ref mut t) => t.set_span(span),
    692        }
    693    }
    694}
    695
    696/// Prints token tree in a form convenient for debugging.
    697#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    698impl fmt::Debug for TokenTree {
    699    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    700        // Each of these has the name in the struct type in the derived debug,
    701        // so don't bother with an extra layer of indirection
    702        match *self {
    703            TokenTree::Group(ref tt) => tt.fmt(f),
    704            TokenTree::Ident(ref tt) => tt.fmt(f),
    705            TokenTree::Punct(ref tt) => tt.fmt(f),
    706            TokenTree::Literal(ref tt) => tt.fmt(f),
    707        }
    708    }
    709}
    710
    711#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    712impl From<Group> for TokenTree {
    713    fn from(g: Group) -> TokenTree {
    714        TokenTree::Group(g)
    715    }
    716}
    717
    718#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    719impl From<Ident> for TokenTree {
    720    fn from(g: Ident) -> TokenTree {
    721        TokenTree::Ident(g)
    722    }
    723}
    724
    725#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    726impl From<Punct> for TokenTree {
    727    fn from(g: Punct) -> TokenTree {
    728        TokenTree::Punct(g)
    729    }
    730}
    731
    732#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    733impl From<Literal> for TokenTree {
    734    fn from(g: Literal) -> TokenTree {
    735        TokenTree::Literal(g)
    736    }
    737}
    738
    739/// Prints the token tree as a string that is supposed to be losslessly convertible back
    740/// into the same token tree (modulo spans), except for possibly `TokenTree::Group`s
    741/// with `Delimiter::None` delimiters and negative numeric literals.
    742///
    743/// Note: the exact form of the output is subject to change, e.g. there might
    744/// be changes in the whitespace used between tokens. Therefore, you should
    745/// *not* do any kind of simple substring matching on the output string (as
    746/// produced by `to_string`) to implement a proc macro, because that matching
    747/// might stop working if such changes happen. Instead, you should work at the
    748/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
    749/// `TokenTree::Punct`, or `TokenTree::Literal`.
    750#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    751impl fmt::Display for TokenTree {
    752    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    753        match self {
    754            TokenTree::Group(t) => write!(f, "{t}"),
    755            TokenTree::Ident(t) => write!(f, "{t}"),
    756            TokenTree::Punct(t) => write!(f, "{t}"),
    757            TokenTree::Literal(t) => write!(f, "{t}"),
    758        }
    759    }
    760}
    761
    762/// A delimited token stream.
    763///
    764/// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
    765#[derive(Clone)]
    766#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    767pub struct Group(bridge::Group<bridge::client::TokenStream, bridge::client::Span>);
    768
    769#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    770impl !Send for Group {}
    771#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    772impl !Sync for Group {}
    773
    774/// Describes how a sequence of token trees is delimited.
    775#[derive(Copy, Clone, Debug, PartialEq, Eq)]
    776#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    777pub enum Delimiter {
    778    /// `( ... )`
    779    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    780    Parenthesis,
    781    /// `{ ... }`
    782    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    783    Brace,
    784    /// `[ ... ]`
    785    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    786    Bracket,
    787    /// `∅ ... ∅`
    788    /// An invisible delimiter, that may, for example, appear around tokens coming from a
    789    /// "macro variable" `$var`. It is important to preserve operator priorities in cases like
    790    /// `$var * 3` where `$var` is `1 + 2`.
    791    /// Invisible delimiters might not survive roundtrip of a token stream through a string.
    792    ///
    793    /// <div class="warning">
    794    ///
    795    /// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
    796    /// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
    797    /// of a proc_macro macro are preserved, and only in very specific circumstances.
    798    /// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
    799    /// operator priorities as indicated above. The other `Delimiter` variants should be used
    800    /// instead in this context. This is a rustc bug. For details, see
    801    /// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
    802    ///
    803    /// </div>
    804    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    805    None,
    806}
    807
    808impl Group {
    809    /// Creates a new `Group` with the given delimiter and token stream.
    810    ///
    811    /// This constructor will set the span for this group to
    812    /// `Span::call_site()`. To change the span you can use the `set_span`
    813    /// method below.
    814    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    815    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
    816        Group(bridge::Group {
    817            delimiter,
    818            stream: stream.0,
    819            span: bridge::DelimSpan::from_single(Span::call_site().0),
    820        })
    821    }
    822
    823    /// Returns the delimiter of this `Group`
    824    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    825    pub fn delimiter(&self) -> Delimiter {
    826        self.0.delimiter
    827    }
    828
    829    /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
    830    ///
    831    /// Note that the returned token stream does not include the delimiter
    832    /// returned above.
    833    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    834    pub fn stream(&self) -> TokenStream {
    835        TokenStream(self.0.stream.clone())
    836    }
    837
    838    /// Returns the span for the delimiters of this token stream, spanning the
    839    /// entire `Group`.
    840    ///
    841    /// ```text
    842    /// pub fn span(&self) -> Span {
    843    ///            ^^^^^^^
    844    /// ```
    845    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    846    pub fn span(&self) -> Span {
    847        Span(self.0.span.entire)
    848    }
    849
    850    /// Returns the span pointing to the opening delimiter of this group.
    851    ///
    852    /// ```text
    853    /// pub fn span_open(&self) -> Span {
    854    ///                 ^
    855    /// ```
    856    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
    857    pub fn span_open(&self) -> Span {
    858        Span(self.0.span.open)
    859    }
    860
    861    /// Returns the span pointing to the closing delimiter of this group.
    862    ///
    863    /// ```text
    864    /// pub fn span_close(&self) -> Span {
    865    ///                        ^
    866    /// ```
    867    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
    868    pub fn span_close(&self) -> Span {
    869        Span(self.0.span.close)
    870    }
    871
    872    /// Configures the span for this `Group`'s delimiters, but not its internal
    873    /// tokens.
    874    ///
    875    /// This method will **not** set the span of all the internal tokens spanned
    876    /// by this group, but rather it will only set the span of the delimiter
    877    /// tokens at the level of the `Group`.
    878    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    879    pub fn set_span(&mut self, span: Span) {
    880        self.0.span = bridge::DelimSpan::from_single(span.0);
    881    }
    882}
    883
    884/// Prints the group as a string that should be losslessly convertible back
    885/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
    886/// with `Delimiter::None` delimiters.
    887#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    888impl fmt::Display for Group {
    889    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    890        write!(f, "{}", TokenStream::from(TokenTree::from(self.clone())))
    891    }
    892}
    893
    894#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    895impl fmt::Debug for Group {
    896    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    897        f.debug_struct("Group")
    898            .field("delimiter", &self.delimiter())
    899            .field("stream", &self.stream())
    900            .field("span", &self.span())
    901            .finish()
    902    }
    903}
    904
    905/// A `Punct` is a single punctuation character such as `+`, `-` or `#`.
    906///
    907/// Multi-character operators like `+=` are represented as two instances of `Punct` with different
    908/// forms of `Spacing` returned.
    909#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    910#[derive(Clone)]
    911pub struct Punct(bridge::Punct<bridge::client::Span>);
    912
    913#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    914impl !Send for Punct {}
    915#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    916impl !Sync for Punct {}
    917
    918/// Indicates whether a `Punct` token can join with the following token
    919/// to form a multi-character operator.
    920#[derive(Copy, Clone, Debug, PartialEq, Eq)]
    921#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    922pub enum Spacing {
    923    /// A `Punct` token can join with the following token to form a multi-character operator.
    924    ///
    925    /// In token streams constructed using proc macro interfaces, `Joint` punctuation tokens can be
    926    /// followed by any other tokens. However, in token streams parsed from source code, the
    927    /// compiler will only set spacing to `Joint` in the following cases.
    928    /// - When a `Punct` is immediately followed by another `Punct` without a whitespace. E.g. `+`
    929    ///   is `Joint` in `+=` and `++`.
    930    /// - When a single quote `'` is immediately followed by an identifier without a whitespace.
    931    ///   E.g. `'` is `Joint` in `'lifetime`.
    932    ///
    933    /// This list may be extended in the future to enable more token combinations.
    934    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    935    Joint,
    936    /// A `Punct` token cannot join with the following token to form a multi-character operator.
    937    ///
    938    /// `Alone` punctuation tokens can be followed by any other tokens. In token streams parsed
    939    /// from source code, the compiler will set spacing to `Alone` in all cases not covered by the
    940    /// conditions for `Joint` above. E.g. `+` is `Alone` in `+ =`, `+ident` and `+()`. In
    941    /// particular, tokens not followed by anything will be marked as `Alone`.
    942    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    943    Alone,
    944}
    945
    946impl Punct {
    947    /// Creates a new `Punct` from the given character and spacing.
    948    /// The `ch` argument must be a valid punctuation character permitted by the language,
    949    /// otherwise the function will panic.
    950    ///
    951    /// The returned `Punct` will have the default span of `Span::call_site()`
    952    /// which can be further configured with the `set_span` method below.
    953    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    954    pub fn new(ch: char, spacing: Spacing) -> Punct {
    955        const LEGAL_CHARS: &[char] = &[
    956            '=', '<', '>', '!', '~', '+', '-', '*', '/', '%', '^', '&', '|', '@', '.', ',', ';',
    957            ':', '#', '$', '?', '\'',
    958        ];
    959        if !LEGAL_CHARS.contains(&ch) {
    960            panic!("unsupported character `{:?}`", ch);
    961        }
    962        Punct(bridge::Punct {
    963            ch: ch as u8,
    964            joint: spacing == Spacing::Joint,
    965            span: Span::call_site().0,
    966        })
    967    }
    968
    969    /// Returns the value of this punctuation character as `char`.
    970    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    971    pub fn as_char(&self) -> char {
    972        self.0.ch as char
    973    }
    974
    975    /// Returns the spacing of this punctuation character, indicating whether it can be potentially
    976    /// combined into a multi-character operator with the following token (`Joint`), or whether the
    977    /// operator has definitely ended (`Alone`).
    978    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    979    pub fn spacing(&self) -> Spacing {
    980        if self.0.joint { Spacing::Joint } else { Spacing::Alone }
    981    }
    982
    983    /// Returns the span for this punctuation character.
    984    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    985    pub fn span(&self) -> Span {
    986        Span(self.0.span)
    987    }
    988
    989    /// Configure the span for this punctuation character.
    990    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    991    pub fn set_span(&mut self, span: Span) {
    992        self.0.span = span.0;
    993    }
    994}
    995
    996/// Prints the punctuation character as a string that should be losslessly convertible
    997/// back into the same character.
    998#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    999impl fmt::Display for Punct {
    1000    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1001        write!(f, "{}", self.as_char())
    1002    }
    1003}
    1004
    1005#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1006impl fmt::Debug for Punct {
    1007    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1008        f.debug_struct("Punct")
    1009            .field("ch", &self.as_char())
    1010            .field("spacing", &self.spacing())
    1011            .field("span", &self.span())
    1012            .finish()
    1013    }
    1014}
    1015
    1016#[stable(feature = "proc_macro_punct_eq", since = "1.50.0")]
    1017impl PartialEq<char> for Punct {
    1018    fn eq(&self, rhs: &char) -> bool {
    1019        self.as_char() == *rhs
    1020    }
    1021}
    1022
    1023#[stable(feature = "proc_macro_punct_eq_flipped", since = "1.52.0")]
    1024impl PartialEq<Punct> for char {
    1025    fn eq(&self, rhs: &Punct) -> bool {
    1026        *self == rhs.as_char()
    1027    }
    1028}
    1029
    1030/// An identifier (`ident`).
    1031#[derive(Clone)]
    1032#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1033pub struct Ident(bridge::Ident<bridge::client::Span, bridge::client::Symbol>);
    1034
    1035impl Ident {
    1036    /// Creates a new `Ident` with the given `string` as well as the specified
    1037    /// `span`.
    1038    /// The `string` argument must be a valid identifier permitted by the
    1039    /// language (including keywords, e.g. `self` or `fn`). Otherwise, the function will panic.
    1040    ///
    1041    /// The constructed identifier will be NFC-normalized. See the [Reference] for more info.
    1042    ///
    1043    /// Note that `span`, currently in rustc, configures the hygiene information
    1044    /// for this identifier.
    1045    ///
    1046    /// As of this time `Span::call_site()` explicitly opts-in to "call-site" hygiene
    1047    /// meaning that identifiers created with this span will be resolved as if they were written
    1048    /// directly at the location of the macro call, and other code at the macro call site will be
    1049    /// able to refer to them as well.
    1050    ///
    1051    /// Later spans like `Span::def_site()` will allow to opt-in to "definition-site" hygiene
    1052    /// meaning that identifiers created with this span will be resolved at the location of the
    1053    /// macro definition and other code at the macro call site will not be able to refer to them.
    1054    ///
    1055    /// Due to the current importance of hygiene this constructor, unlike other
    1056    /// tokens, requires a `Span` to be specified at construction.
    1057    ///
    1058    /// [Reference]: https://doc.rust-lang.org/nightly/reference/identifiers.html#r-ident.normalization
    1059    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1060    pub fn new(string: &str, span: Span) -> Ident {
    1061        Ident(bridge::Ident {
    1062            sym: bridge::client::Symbol::new_ident(string, false),
    1063            is_raw: false,
    1064            span: span.0,
    1065        })
    1066    }
    1067
    1068    /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
    1069    /// The `string` argument be a valid identifier permitted by the language
    1070    /// (including keywords, e.g. `fn`). Keywords which are usable in path segments
    1071    /// (e.g. `self`, `super`) are not supported, and will cause a panic.
    1072    #[stable(feature = "proc_macro_raw_ident", since = "1.47.0")]
    1073    pub fn new_raw(string: &str, span: Span) -> Ident {
    1074        Ident(bridge::Ident {
    1075            sym: bridge::client::Symbol::new_ident(string, true),
    1076            is_raw: true,
    1077            span: span.0,
    1078        })
    1079    }
    1080
    1081    /// Returns the span of this `Ident`, encompassing the entire string returned
    1082    /// by [`to_string`](ToString::to_string).
    1083    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1084    pub fn span(&self) -> Span {
    1085        Span(self.0.span)
    1086    }
    1087
    1088    /// Configures the span of this `Ident`, possibly changing its hygiene context.
    1089    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1090    pub fn set_span(&mut self, span: Span) {
    1091        self.0.span = span.0;
    1092    }
    1093}
    1094
    1095/// Prints the identifier as a string that should be losslessly convertible back
    1096/// into the same identifier.
    1097#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1098impl fmt::Display for Ident {
    1099    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1100        if self.0.is_raw {
    1101            f.write_str("r#")?;
    1102        }
    1103        fmt::Display::fmt(&self.0.sym, f)
    1104    }
    1105}
    1106
    1107#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1108impl fmt::Debug for Ident {
    1109    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1110        f.debug_struct("Ident")
    1111            .field("ident", &self.to_string())
    1112            .field("span", &self.span())
    1113            .finish()
    1114    }
    1115}
    1116
    1117/// A literal string (`"hello"`), byte string (`b"hello"`), C string (`c"hello"`),
    1118/// character (`'a'`), byte character (`b'a'`), an integer or floating point number
    1119/// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
    1120/// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.
    1121#[derive(Clone)]
    1122#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1123pub struct Literal(bridge::Literal<bridge::client::Span, bridge::client::Symbol>);
    1124
    1125macro_rules! suffixed_int_literals {
    1126    ($($name:ident => $kind:ident,)*) => ($(
    1127        /// Creates a new suffixed integer literal with the specified value.
    1128        ///
    1129        /// This function will create an integer like `1u32` where the integer
    1130        /// value specified is the first part of the token and the integral is
    1131        /// also suffixed at the end.
    1132        /// Literals created from negative numbers might not survive round-trips through
    1133        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1134        ///
    1135        /// Literals created through this method have the `Span::call_site()`
    1136        /// span by default, which can be configured with the `set_span` method
    1137        /// below.
    1138        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1139        pub fn $name(n: $kind) -> Literal {
    1140            Literal(bridge::Literal {
    1141                kind: bridge::LitKind::Integer,
    1142                symbol: bridge::client::Symbol::new(&n.to_string()),
    1143                suffix: Some(bridge::client::Symbol::new(stringify!($kind))),
    1144                span: Span::call_site().0,
    1145            })
    1146        }
    1147    )*)
    1148}
    1149
    1150macro_rules! unsuffixed_int_literals {
    1151    ($($name:ident => $kind:ident,)*) => ($(
    1152        /// Creates a new unsuffixed integer literal with the specified value.
    1153        ///
    1154        /// This function will create an integer like `1` where the integer
    1155        /// value specified is the first part of the token. No suffix is
    1156        /// specified on this token, meaning that invocations like
    1157        /// `Literal::i8_unsuffixed(1)` are equivalent to
    1158        /// `Literal::u32_unsuffixed(1)`.
    1159        /// Literals created from negative numbers might not survive rountrips through
    1160        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1161        ///
    1162        /// Literals created through this method have the `Span::call_site()`
    1163        /// span by default, which can be configured with the `set_span` method
    1164        /// below.
    1165        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1166        pub fn $name(n: $kind) -> Literal {
    1167            Literal(bridge::Literal {
    1168                kind: bridge::LitKind::Integer,
    1169                symbol: bridge::client::Symbol::new(&n.to_string()),
    1170                suffix: None,
    1171                span: Span::call_site().0,
    1172            })
    1173        }
    1174    )*)
    1175}
    1176
    1177impl Literal {
    1178    fn new(kind: bridge::LitKind, value: &str, suffix: Option<&str>) -> Self {
    1179        Literal(bridge::Literal {
    1180            kind,
    1181            symbol: bridge::client::Symbol::new(value),
    1182            suffix: suffix.map(bridge::client::Symbol::new),
    1183            span: Span::call_site().0,
    1184        })
    1185    }
    1186
    1187    suffixed_int_literals! {
    1188        u8_suffixed => u8,
    1189        u16_suffixed => u16,
    1190        u32_suffixed => u32,
    1191        u64_suffixed => u64,
    1192        u128_suffixed => u128,
    1193        usize_suffixed => usize,
    1194        i8_suffixed => i8,
    1195        i16_suffixed => i16,
    1196        i32_suffixed => i32,
    1197        i64_suffixed => i64,
    1198        i128_suffixed => i128,
    1199        isize_suffixed => isize,
    1200    }
    1201
    1202    unsuffixed_int_literals! {
    1203        u8_unsuffixed => u8,
    1204        u16_unsuffixed => u16,
    1205        u32_unsuffixed => u32,
    1206        u64_unsuffixed => u64,
    1207        u128_unsuffixed => u128,
    1208        usize_unsuffixed => usize,
    1209        i8_unsuffixed => i8,
    1210        i16_unsuffixed => i16,
    1211        i32_unsuffixed => i32,
    1212        i64_unsuffixed => i64,
    1213        i128_unsuffixed => i128,
    1214        isize_unsuffixed => isize,
    1215    }
    1216
    1217    /// Creates a new unsuffixed floating-point literal.
    1218    ///
    1219    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
    1220    /// the float's value is emitted directly into the token but no suffix is
    1221    /// used, so it may be inferred to be a `f64` later in the compiler.
    1222    /// Literals created from negative numbers might not survive rountrips through
    1223    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1224    ///
    1225    /// # Panics
    1226    ///
    1227    /// This function requires that the specified float is finite, for
    1228    /// example if it is infinity or NaN this function will panic.
    1229    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1230    pub fn f32_unsuffixed(n: f32) -> Literal {
    1231        if !n.is_finite() {
    1232            panic!("Invalid float literal {n}");
    1233        }
    1234        let mut repr = n.to_string();
    1235        if !repr.contains('.') {
    1236            repr.push_str(".0");
    1237        }
    1238        Literal::new(bridge::LitKind::Float, &repr, None)
    1239    }
    1240
    1241    /// Creates a new suffixed floating-point literal.
    1242    ///
    1243    /// This constructor will create a literal like `1.0f32` where the value
    1244    /// specified is the preceding part of the token and `f32` is the suffix of
    1245    /// the token. This token will always be inferred to be an `f32` in the
    1246    /// compiler.
    1247    /// Literals created from negative numbers might not survive rountrips through
    1248    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1249    ///
    1250    /// # Panics
    1251    ///
    1252    /// This function requires that the specified float is finite, for
    1253    /// example if it is infinity or NaN this function will panic.
    1254    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1255    pub fn f32_suffixed(n: f32) -> Literal {
    1256        if !n.is_finite() {
    1257            panic!("Invalid float literal {n}");
    1258        }
    1259        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f32"))
    1260    }
    1261
    1262    /// Creates a new unsuffixed floating-point literal.
    1263    ///
    1264    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
    1265    /// the float's value is emitted directly into the token but no suffix is
    1266    /// used, so it may be inferred to be a `f64` later in the compiler.
    1267    /// Literals created from negative numbers might not survive rountrips through
    1268    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1269    ///
    1270    /// # Panics
    1271    ///
    1272    /// This function requires that the specified float is finite, for
    1273    /// example if it is infinity or NaN this function will panic.
    1274    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1275    pub fn f64_unsuffixed(n: f64) -> Literal {
    1276        if !n.is_finite() {
    1277            panic!("Invalid float literal {n}");
    1278        }
    1279        let mut repr = n.to_string();
    1280        if !repr.contains('.') {
    1281            repr.push_str(".0");
    1282        }
    1283        Literal::new(bridge::LitKind::Float, &repr, None)
    1284    }
    1285
    1286    /// Creates a new suffixed floating-point literal.
    1287    ///
    1288    /// This constructor will create a literal like `1.0f64` where the value
    1289    /// specified is the preceding part of the token and `f64` is the suffix of
    1290    /// the token. This token will always be inferred to be an `f64` in the
    1291    /// compiler.
    1292    /// Literals created from negative numbers might not survive rountrips through
    1293    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
    1294    ///
    1295    /// # Panics
    1296    ///
    1297    /// This function requires that the specified float is finite, for
    1298    /// example if it is infinity or NaN this function will panic.
    1299    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1300    pub fn f64_suffixed(n: f64) -> Literal {
    1301        if !n.is_finite() {
    1302            panic!("Invalid float literal {n}");
    1303        }
    1304        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f64"))
    1305    }
    1306
    1307    /// String literal.
    1308    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1309    pub fn string(string: &str) -> Literal {
    1310        let escape = EscapeOptions {
    1311            escape_single_quote: false,
    1312            escape_double_quote: true,
    1313            escape_nonascii: false,
    1314        };
    1315        let repr = escape_bytes(string.as_bytes(), escape);
    1316        Literal::new(bridge::LitKind::Str, &repr, None)
    1317    }
    1318
    1319    /// Character literal.
    1320    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1321    pub fn character(ch: char) -> Literal {
    1322        let escape = EscapeOptions {
    1323            escape_single_quote: true,
    1324            escape_double_quote: false,
    1325            escape_nonascii: false,
    1326        };
    1327        let repr = escape_bytes(ch.encode_utf8(&mut [0u8; 4]).as_bytes(), escape);
    1328        Literal::new(bridge::LitKind::Char, &repr, None)
    1329    }
    1330
    1331    /// Byte character literal.
    1332    #[stable(feature = "proc_macro_byte_character", since = "1.79.0")]
    1333    pub fn byte_character(byte: u8) -> Literal {
    1334        let escape = EscapeOptions {
    1335            escape_single_quote: true,
    1336            escape_double_quote: false,
    1337            escape_nonascii: true,
    1338        };
    1339        let repr = escape_bytes(&[byte], escape);
    1340        Literal::new(bridge::LitKind::Byte, &repr, None)
    1341    }
    1342
    1343    /// Byte string literal.
    1344    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1345    pub fn byte_string(bytes: &[u8]) -> Literal {
    1346        let escape = EscapeOptions {
    1347            escape_single_quote: false,
    1348            escape_double_quote: true,
    1349            escape_nonascii: true,
    1350        };
    1351        let repr = escape_bytes(bytes, escape);
    1352        Literal::new(bridge::LitKind::ByteStr, &repr, None)
    1353    }
    1354
    1355    /// C string literal.
    1356    #[stable(feature = "proc_macro_c_str_literals", since = "1.79.0")]
    1357    pub fn c_string(string: &CStr) -> Literal {
    1358        let escape = EscapeOptions {
    1359            escape_single_quote: false,
    1360            escape_double_quote: true,
    1361            escape_nonascii: false,
    1362        };
    1363        let repr = escape_bytes(string.to_bytes(), escape);
    1364        Literal::new(bridge::LitKind::CStr, &repr, None)
    1365    }
    1366
    1367    /// Returns the span encompassing this literal.
    1368    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1369    pub fn span(&self) -> Span {
    1370        Span(self.0.span)
    1371    }
    1372
    1373    /// Configures the span associated for this literal.
    1374    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1375    pub fn set_span(&mut self, span: Span) {
    1376        self.0.span = span.0;
    1377    }
    1378
    1379    /// Returns a `Span` that is a subset of `self.span()` containing only the
    1380    /// source bytes in range `range`. Returns `None` if the would-be trimmed
    1381    /// span is outside the bounds of `self`.
    1382    // FIXME(SergioBenitez): check that the byte range starts and ends at a
    1383    // UTF-8 boundary of the source. otherwise, it's likely that a panic will
    1384    // occur elsewhere when the source text is printed.
    1385    // FIXME(SergioBenitez): there is no way for the user to know what
    1386    // `self.span()` actually maps to, so this method can currently only be
    1387    // called blindly. For example, `to_string()` for the character 'c' returns
    1388    // "'\u{63}'"; there is no way for the user to know whether the source text
    1389    // was 'c' or whether it was '\u{63}'.
    1390    #[unstable(feature = "proc_macro_span", issue = "54725")]
    1391    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
    1392        self.0.span.subspan(range.start_bound().cloned(), range.end_bound().cloned()).map(Span)
    1393    }
    1394
    1395    fn with_symbol_and_suffix<R>(&self, f: impl FnOnce(&str, &str) -> R) -> R {
    1396        self.0.symbol.with(|symbol| match self.0.suffix {
    1397            Some(suffix) => suffix.with(|suffix| f(symbol, suffix)),
    1398            None => f(symbol, ""),
    1399        })
    1400    }
    1401
    1402    /// Invokes the callback with a `&[&str]` consisting of each part of the
    1403    /// literal's representation. This is done to allow the `ToString` and
    1404    /// `Display` implementations to borrow references to symbol values, and
    1405    /// both be optimized to reduce overhead.
    1406    fn with_stringify_parts<R>(&self, f: impl FnOnce(&[&str]) -> R) -> R {
    1407        /// Returns a string containing exactly `num` '#' characters.
    1408        /// Uses a 256-character source string literal which is always safe to
    1409        /// index with a `u8` index.
    1410        fn get_hashes_str(num: u8) -> &'static str {
    1411            const HASHES: &str = "\
    1412            ################################################################\
    1413            ################################################################\
    1414            ################################################################\
    1415            ################################################################\
    1416            ";
    1417            const _: () = assert!(HASHES.len() == 256);
    1418            &HASHES[..num as usize]
    1419        }
    1420
    1421        self.with_symbol_and_suffix(|symbol, suffix| match self.0.kind {
    1422            bridge::LitKind::Byte => f(&["b'", symbol, "'", suffix]),
    1423            bridge::LitKind::Char => f(&["'", symbol, "'", suffix]),
    1424            bridge::LitKind::Str => f(&["\"", symbol, "\"", suffix]),
    1425            bridge::LitKind::StrRaw(n) => {
    1426                let hashes = get_hashes_str(n);
    1427                f(&["r", hashes, "\"", symbol, "\"", hashes, suffix])
    1428            }
    1429            bridge::LitKind::ByteStr => f(&["b\"", symbol, "\"", suffix]),
    1430            bridge::LitKind::ByteStrRaw(n) => {
    1431                let hashes = get_hashes_str(n);
    1432                f(&["br", hashes, "\"", symbol, "\"", hashes, suffix])
    1433            }
    1434            bridge::LitKind::CStr => f(&["c\"", symbol, "\"", suffix]),
    1435            bridge::LitKind::CStrRaw(n) => {
    1436                let hashes = get_hashes_str(n);
    1437                f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
    1438            }
    1439
    1440            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
    1441                f(&[symbol, suffix])
    1442            }
    1443        })
    1444    }
    1445
    1446    /// Returns the unescaped string value if the current literal is a string or a string literal.
    1447    #[unstable(feature = "proc_macro_value", issue = "136652")]
    1448    pub fn str_value(&self) -> Result<String, ConversionErrorKind> {
    1449        self.0.symbol.with(|symbol| match self.0.kind {
    1450            bridge::LitKind::Str => {
    1451                if symbol.contains('\\') {
    1452                    let mut buf = String::with_capacity(symbol.len());
    1453                    let mut error = None;
    1454                    // Force-inlining here is aggressive but the closure is
    1455                    // called on every char in the string, so it can be hot in
    1456                    // programs with many long strings containing escapes.
    1457                    unescape_str(
    1458                        symbol,
    1459                        #[inline(always)]
    1460                        |_, c| match c {
    1461                            Ok(c) => buf.push(c),
    1462                            Err(err) => {
    1463                                if err.is_fatal() {
    1464                                    error = Some(ConversionErrorKind::FailedToUnescape(err));
    1465                                }
    1466                            }
    1467                        },
    1468                    );
    1469                    if let Some(error) = error { Err(error) } else { Ok(buf) }
    1470                } else {
    1471                    Ok(symbol.to_string())
    1472                }
    1473            }
    1474            bridge::LitKind::StrRaw(_) => Ok(symbol.to_string()),
    1475            _ => Err(ConversionErrorKind::InvalidLiteralKind),
    1476        })
    1477    }
    1478
    1479    /// Returns the unescaped string value if the current literal is a c-string or a c-string
    1480    /// literal.
    1481    #[unstable(feature = "proc_macro_value", issue = "136652")]
    1482    pub fn cstr_value(&self) -> Result<Vec<u8>, ConversionErrorKind> {
    1483        self.0.symbol.with(|symbol| match self.0.kind {
    1484            bridge::LitKind::CStr => {
    1485                let mut error = None;
    1486                let mut buf = Vec::with_capacity(symbol.len());
    1487
    1488                unescape_c_str(symbol, |_span, res| match res {
    1489                    Ok(MixedUnit::Char(c)) => {
    1490                        buf.extend_from_slice(c.get().encode_utf8(&mut [0; 4]).as_bytes())
    1491                    }
    1492                    Ok(MixedUnit::HighByte(b)) => buf.push(b.get()),
    1493                    Err(err) => {
    1494                        if err.is_fatal() {
    1495                            error = Some(ConversionErrorKind::FailedToUnescape(err));
    1496                        }
    1497                    }
    1498                });
    1499                if let Some(error) = error {
    1500                    Err(error)
    1501                } else {
    1502                    buf.push(0);
    1503                    Ok(buf)
    1504                }
    1505            }
    1506            bridge::LitKind::CStrRaw(_) => {
    1507                // Raw strings have no escapes so we can convert the symbol
    1508                // directly to a `Lrc<u8>` after appending the terminating NUL
    1509                // char.
    1510                let mut buf = symbol.to_owned().into_bytes();
    1511                buf.push(0);
    1512                Ok(buf)
    1513            }
    1514            _ => Err(ConversionErrorKind::InvalidLiteralKind),
    1515        })
    1516    }
    1517
    1518    /// Returns the unescaped string value if the current literal is a byte string or a byte string
    1519    /// literal.
    1520    #[unstable(feature = "proc_macro_value", issue = "136652")]
    1521    pub fn byte_str_value(&self) -> Result<Vec<u8>, ConversionErrorKind> {
    1522        self.0.symbol.with(|symbol| match self.0.kind {
    1523            bridge::LitKind::ByteStr => {
    1524                let mut buf = Vec::with_capacity(symbol.len());
    1525                let mut error = None;
    1526
    1527                unescape_byte_str(symbol, |_, res| match res {
    1528                    Ok(b) => buf.push(b),
    1529                    Err(err) => {
    1530                        if err.is_fatal() {
    1531                            error = Some(ConversionErrorKind::FailedToUnescape(err));
    1532                        }
    1533                    }
    1534                });
    1535                if let Some(error) = error { Err(error) } else { Ok(buf) }
    1536            }
    1537            bridge::LitKind::ByteStrRaw(_) => {
    1538                // Raw strings have no escapes so we can convert the symbol
    1539                // directly to a `Lrc<u8>`.
    1540                Ok(symbol.to_owned().into_bytes())
    1541            }
    1542            _ => Err(ConversionErrorKind::InvalidLiteralKind),
    1543        })
    1544    }
    1545}
    1546
    1547/// Parse a single literal from its stringified representation.
    1548///
    1549/// In order to parse successfully, the input string must not contain anything
    1550/// but the literal token. Specifically, it must not contain whitespace or
    1551/// comments in addition to the literal.
    1552///
    1553/// The resulting literal token will have a `Span::call_site()` span.
    1554///
    1555/// NOTE: some errors may cause panics instead of returning `LexError`. We
    1556/// reserve the right to change these errors into `LexError`s later.
    1557#[stable(feature = "proc_macro_literal_parse", since = "1.54.0")]
    1558impl FromStr for Literal {
    1559    type Err = LexError;
    1560
    1561    fn from_str(src: &str) -> Result<Self, LexError> {
    1562        match bridge::client::FreeFunctions::literal_from_str(src) {
    1563            Ok(literal) => Ok(Literal(literal)),
    1564            Err(()) => Err(LexError),
    1565        }
    1566    }
    1567}
    1568
    1569/// Prints the literal as a string that should be losslessly convertible
    1570/// back into the same literal (except for possible rounding for floating point literals).
    1571#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1572impl fmt::Display for Literal {
    1573    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1574        self.with_stringify_parts(|parts| {
    1575            for part in parts {
    1576                fmt::Display::fmt(part, f)?;
    1577            }
    1578            Ok(())
    1579        })
    1580    }
    1581}
    1582
    1583#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
    1584impl fmt::Debug for Literal {
    1585    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    1586        f.debug_struct("Literal")
    1587            // format the kind on one line even in {:#?} mode
    1588            .field("kind", &format_args!("{:?}", self.0.kind))
    1589            .field("symbol", &self.0.symbol)
    1590            // format `Some("...")` on one line even in {:#?} mode
    1591            .field("suffix", &format_args!("{:?}", self.0.suffix))
    1592            .field("span", &self.0.span)
    1593            .finish()
    1594    }
    1595}
    1596
    1597#[unstable(
    1598    feature = "proc_macro_tracked_path",
    1599    issue = "99515",
    1600    implied_by = "proc_macro_tracked_env"
    1601)]
    1602/// Functionality for adding environment state to the build dependency info.
    1603pub mod tracked {
    1604
    1605    use std::env::{self, VarError};
    1606    use std::ffi::OsStr;
    1607    use std::path::Path;
    1608
    1609    /// Retrieve an environment variable and add it to build dependency info.
    1610    /// The build system executing the compiler will know that the variable was accessed during
    1611    /// compilation, and will be able to rerun the build when the value of that variable changes.
    1612    /// Besides the dependency tracking this function should be equivalent to `env::var` from the
    1613    /// standard library, except that the argument must be UTF-8.
    1614    #[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
    1615    pub fn env_var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
    1616        let key: &str = key.as_ref();
    1617        let value = crate::bridge::client::FreeFunctions::injected_env_var(key)
    1618            .map_or_else(|| env::var(key), Ok);
    1619        crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());
    1620        value
    1621    }
    1622
    1623    /// Track a file or directory explicitly.
    1624    ///
    1625    /// Commonly used for tracking asset preprocessing.
    1626    #[unstable(feature = "proc_macro_tracked_path", issue = "99515")]
    1627    pub fn path<P: AsRef<Path>>(path: P) {
    1628        let path: &str = path.as_ref().to_str().unwrap();
    1629        crate::bridge::client::FreeFunctions::track_path(path);
    1630    }
    1631}