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#[cfg(feature = "parsing")]
use crate::lookahead;
#[cfg(feature = "parsing")]
use crate::parse::{Parse, Parser};
use crate::{Error, Result};
use proc_macro2::{Ident, Literal, Span};
#[cfg(feature = "parsing")]
use proc_macro2::{TokenStream, TokenTree};
use std::ffi::{CStr, CString};
use std::fmt::{self, Display};
#[cfg(feature = "extra-traits")]
use std::hash::{Hash, Hasher};
use std::str::{self, FromStr};
ast_enum_of_structs! {
/// A Rust literal such as a string or integer or boolean.
///
/// # Syntax tree enum
///
/// This type is a [syntax tree enum].
///
/// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
#[non_exhaustive]
pub enum Lit {
/// A UTF-8 string literal: `"foo"`.
Str(LitStr),
/// A byte string literal: `b"foo"`.
ByteStr(LitByteStr),
/// A nul-terminated C-string literal: `c"foo"`.
CStr(LitCStr),
/// A byte literal: `b'f'`.
Byte(LitByte),
/// A character literal: `'a'`.
Char(LitChar),
/// An integer literal: `1` or `1u16`.
Int(LitInt),
/// A floating point literal: `1f64` or `1.0e10f64`.
///
/// Must be finite. May not be infinite or NaN.
Float(LitFloat),
/// A boolean literal: `true` or `false`.
Bool(LitBool),
/// A raw token literal not interpreted by Syn.
Verbatim(Literal),
}
}
ast_struct! {
/// A UTF-8 string literal: `"foo"`.
pub struct LitStr {
repr: Box<LitRepr>,
}
}
ast_struct! {
/// A byte string literal: `b"foo"`.
pub struct LitByteStr {
repr: Box<LitRepr>,
}
}
ast_struct! {
/// A nul-terminated C-string literal: `c"foo"`.
pub struct LitCStr {
repr: Box<LitRepr>,
}
}
ast_struct! {
/// A byte literal: `b'f'`.
pub struct LitByte {
repr: Box<LitRepr>,
}
}
ast_struct! {
/// A character literal: `'a'`.
pub struct LitChar {
repr: Box<LitRepr>,
}
}
struct LitRepr {
token: Literal,
suffix: Box<str>,
}
ast_struct! {
/// An integer literal: `1` or `1u16`.
pub struct LitInt {
repr: Box<LitIntRepr>,
}
}
struct LitIntRepr {
token: Literal,
digits: Box<str>,
suffix: Box<str>,
}
ast_struct! {
/// A floating point literal: `1f64` or `1.0e10f64`.
///
/// Must be finite. May not be infinite or NaN.
pub struct LitFloat {
repr: Box<LitFloatRepr>,
}
}
struct LitFloatRepr {
token: Literal,
digits: Box<str>,
suffix: Box<str>,
}
ast_struct! {
/// A boolean literal: `true` or `false`.
pub struct LitBool {
pub value: bool,
pub span: Span,
}
}
impl LitStr {
pub fn new(value: &str, span: Span) -> Self {
let mut token = Literal::string(value);
token.set_span(span);
LitStr {
repr: Box::new(LitRepr {
token,
suffix: Box::<str>::default(),
}),
}
}
pub fn value(&self) -> String {
let repr = self.repr.token.to_string();
let (value, _suffix) = value::parse_lit_str(&repr);
String::from(value)
}
/// Parse a syntax tree node from the content of this string literal.
///
/// All spans in the syntax tree will point to the span of this `LitStr`.
///
/// # Example
///
/// ```
/// use syn::{Attribute, Error, Expr, Lit, Meta, Path, Result};
///
/// // Parses the path from an attribute that looks like:
/// //
/// // #[path = "a::b::c"]
/// //
/// // or returns `None` if the input is some other attribute.
/// fn get_path(attr: &Attribute) -> Result<Option<Path>> {
/// if !attr.path().is_ident("path") {
/// return Ok(None);
/// }
///
/// if let Meta::NameValue(meta) = &attr.meta {
/// if let Expr::Lit(expr) = &meta.value {
/// if let Lit::Str(lit_str) = &expr.lit {
/// return lit_str.parse().map(Some);
/// }
/// }
/// }
///
/// let message = "expected #[path = \"...\"]";
/// Err(Error::new_spanned(attr, message))
/// }
/// ```
#[cfg(feature = "parsing")]
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn parse<T: Parse>(&self) -> Result<T> {
self.parse_with(T::parse)
}
/// Invoke parser on the content of this string literal.
///
/// All spans in the syntax tree will point to the span of this `LitStr`.
///
/// # Example
///
/// ```
/// # use proc_macro2::Span;
/// # use syn::{LitStr, Result};
/// #
/// # fn main() -> Result<()> {
/// # let lit_str = LitStr::new("a::b::c", Span::call_site());
/// #
/// # const IGNORE: &str = stringify! {
/// let lit_str: LitStr = /* ... */;
/// # };
///
/// // Parse a string literal like "a::b::c" into a Path, not allowing
/// // generic arguments on any of the path segments.
/// let basic_path = lit_str.parse_with(syn::Path::parse_mod_style)?;
/// #
/// # Ok(())
/// # }
/// ```
#[cfg(feature = "parsing")]
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
pub fn parse_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
use proc_macro2::Group;
// Token stream with every span replaced by the given one.
fn respan_token_stream(stream: TokenStream, span: Span) -> TokenStream {
stream
.into_iter()
.map(|token| respan_token_tree(token, span))
.collect()
}
// Token tree with every span replaced by the given one.
fn respan_token_tree(mut token: TokenTree, span: Span) -> TokenTree {
match &mut token {
TokenTree::Group(g) => {
let stream = respan_token_stream(g.stream(), span);
*g = Group::new(g.delimiter(), stream);
g.set_span(span);
}
other => other.set_span(span),
}
token
}
// Parse string literal into a token stream with every span equal to the
// original literal's span.
let span = self.span();
let mut tokens = TokenStream::from_str(&self.value())?;
tokens = respan_token_stream(tokens, span);
let result = crate::parse::parse_scoped(parser, span, tokens)?;
let suffix = self.suffix();
if !suffix.is_empty() {
return Err(Error::new(
self.span(),
format!("unexpected suffix `{}` on string literal", suffix),
));
}
Ok(result)
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl LitByteStr {
pub fn new(value: &[u8], span: Span) -> Self {
let mut token = Literal::byte_string(value);
token.set_span(span);
LitByteStr {
repr: Box::new(LitRepr {
token,
suffix: Box::<str>::default(),
}),
}
}
pub fn value(&self) -> Vec<u8> {
let repr = self.repr.token.to_string();
let (value, _suffix) = value::parse_lit_byte_str(&repr);
value
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl LitCStr {
pub fn new(value: &CStr, span: Span) -> Self {
let mut token = Literal::c_string(value);
token.set_span(span);
LitCStr {
repr: Box::new(LitRepr {
token,
suffix: Box::<str>::default(),
}),
}
}
pub fn value(&self) -> CString {
let repr = self.repr.token.to_string();
let (value, _suffix) = value::parse_lit_c_str(&repr);
value
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl LitByte {
pub fn new(value: u8, span: Span) -> Self {
let mut token = Literal::u8_suffixed(value);
token.set_span(span);
LitByte {
repr: Box::new(LitRepr {
token,
suffix: Box::<str>::default(),
}),
}
}
pub fn value(&self) -> u8 {
let repr = self.repr.token.to_string();
let (value, _suffix) = value::parse_lit_byte(&repr);
value
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl LitChar {
pub fn new(value: char, span: Span) -> Self {
let mut token = Literal::character(value);
token.set_span(span);
LitChar {
repr: Box::new(LitRepr {
token,
suffix: Box::<str>::default(),
}),
}
}
pub fn value(&self) -> char {
let repr = self.repr.token.to_string();
let (value, _suffix) = value::parse_lit_char(&repr);
value
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl LitInt {
pub fn new(repr: &str, span: Span) -> Self {
let (digits, suffix) = match value::parse_lit_int(repr) {
Some(parse) => parse,
None => panic!("not an integer literal: `{}`", repr),
};
let mut token: Literal = repr.parse().unwrap();
token.set_span(span);
LitInt {
repr: Box::new(LitIntRepr {
token,
digits,
suffix,
}),
}
}
pub fn base10_digits(&self) -> &str {
&self.repr.digits
}
/// Parses the literal into a selected number type.
///
/// This is equivalent to `lit.base10_digits().parse()` except that the
/// resulting errors will be correctly spanned to point to the literal token
/// in the macro input.
///
/// ```
/// use syn::LitInt;
/// use syn::parse::{Parse, ParseStream, Result};
///
/// struct Port {
/// value: u16,
/// }
///
/// impl Parse for Port {
/// fn parse(input: ParseStream) -> Result<Self> {
/// let lit: LitInt = input.parse()?;
/// let value = lit.base10_parse::<u16>()?;
/// Ok(Port { value })
/// }
/// }
/// ```
pub fn base10_parse<N>(&self) -> Result<N>
where
N: FromStr,
N::Err: Display,
{
self.base10_digits()
.parse()
.map_err(|err| Error::new(self.span(), err))
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl From<Literal> for LitInt {
fn from(token: Literal) -> Self {
let repr = token.to_string();
if let Some((digits, suffix)) = value::parse_lit_int(&repr) {
LitInt {
repr: Box::new(LitIntRepr {
token,
digits,
suffix,
}),
}
} else {
panic!("not an integer literal: `{}`", repr);
}
}
}
impl Display for LitInt {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.repr.token.fmt(formatter)
}
}
impl LitFloat {
pub fn new(repr: &str, span: Span) -> Self {
let (digits, suffix) = match value::parse_lit_float(repr) {
Some(parse) => parse,
None => panic!("not a float literal: `{}`", repr),
};
let mut token: Literal = repr.parse().unwrap();
token.set_span(span);
LitFloat {
repr: Box::new(LitFloatRepr {
token,
digits,
suffix,
}),
}
}
pub fn base10_digits(&self) -> &str {
&self.repr.digits
}
pub fn base10_parse<N>(&self) -> Result<N>
where
N: FromStr,
N::Err: Display,
{
self.base10_digits()
.parse()
.map_err(|err| Error::new(self.span(), err))
}
pub fn suffix(&self) -> &str {
&self.repr.suffix
}
pub fn span(&self) -> Span {
self.repr.token.span()
}
pub fn set_span(&mut self, span: Span) {
self.repr.token.set_span(span);
}
pub fn token(&self) -> Literal {
self.repr.token.clone()
}
}
impl From<Literal> for LitFloat {
fn from(token: Literal) -> Self {
let repr = token.to_string();
if let Some((digits, suffix)) = value::parse_lit_float(&repr) {
LitFloat {
repr: Box::new(LitFloatRepr {
token,
digits,
suffix,
}),
}
} else {
panic!("not a float literal: `{}`", repr);
}
}
}
impl Display for LitFloat {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.repr.token.fmt(formatter)
}
}
impl LitBool {
pub fn new(value: bool, span: Span) -> Self {
LitBool { value, span }
}
pub fn value(&self) -> bool {
self.value
}
pub fn span(&self) -> Span {
self.span
}
pub fn set_span(&mut self, span: Span) {
self.span = span;
}
pub fn token(&self) -> Ident {
let s = if self.value { "true" } else { "false" };
Ident::new(s, self.span)
}
}
#[cfg(feature = "extra-traits")]
mod debug_impls {
use crate::lit::{LitBool, LitByte, LitByteStr, LitCStr, LitChar, LitFloat, LitInt, LitStr};
use std::fmt::{self, Debug};
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitStr {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitStr")
}
}
impl LitStr {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitByteStr {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitByteStr")
}
}
impl LitByteStr {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitCStr {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitCStr")
}
}
impl LitCStr {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitByte {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitByte")
}
}
impl LitByte {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitChar {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitChar")
}
}
impl LitChar {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitInt {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitInt")
}
}
impl LitInt {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitFloat {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitFloat")
}
}
impl LitFloat {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("token", &format_args!("{}", self.repr.token))
.finish()
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Debug for LitBool {
fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
self.debug(formatter, "LitBool")
}
}
impl LitBool {
pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
formatter
.debug_struct(name)
.field("value", &self.value)
.finish()
}
}
}
#[cfg(feature = "clone-impls")]
#[cfg_attr(docsrs, doc(cfg(feature = "clone-impls")))]
impl Clone for LitRepr {
fn clone(&self) -> Self {
LitRepr {
token: self.token.clone(),
suffix: self.suffix.clone(),
}
}
}
#[cfg(feature = "clone-impls")]
#[cfg_attr(docsrs, doc(cfg(feature = "clone-impls")))]
impl Clone for LitIntRepr {
fn clone(&self) -> Self {
LitIntRepr {
token: self.token.clone(),
digits: self.digits.clone(),
suffix: self.suffix.clone(),
}
}
}
#[cfg(feature = "clone-impls")]
#[cfg_attr(docsrs, doc(cfg(feature = "clone-impls")))]
impl Clone for LitFloatRepr {
fn clone(&self) -> Self {
LitFloatRepr {
token: self.token.clone(),
digits: self.digits.clone(),
suffix: self.suffix.clone(),
}
}
}
macro_rules! lit_extra_traits {
($ty:ident) => {
#[cfg(feature = "clone-impls")]
#[cfg_attr(docsrs, doc(cfg(feature = "clone-impls")))]
impl Clone for $ty {
fn clone(&self) -> Self {
$ty {
repr: self.repr.clone(),
}
}
}
#[cfg(feature = "extra-traits")]
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl PartialEq for $ty {
fn eq(&self, other: &Self) -> bool {
self.repr.token.to_string() == other.repr.token.to_string()
}
}
#[cfg(feature = "extra-traits")]
#[cfg_attr(docsrs, doc(cfg(feature = "extra-traits")))]
impl Hash for $ty {
fn hash<H>(&self, state: &mut H)
where
H: Hasher,
{
self.repr.token.to_string().hash(state);
}
}
#[cfg(feature = "parsing")]
pub_if_not_doc! {
#[doc(hidden)]
#[allow(non_snake_case)]
pub fn $ty(marker: lookahead::TokenMarker) -> $ty {
match marker {}
}
}
};
}
lit_extra_traits!(LitStr);
lit_extra_traits!(LitByteStr);
lit_extra_traits!(LitCStr);
lit_extra_traits!(LitByte);
lit_extra_traits!(LitChar);
lit_extra_traits!(LitInt);
lit_extra_traits!(LitFloat);
#[cfg(feature = "parsing")]
pub_if_not_doc! {
#[doc(hidden)]
#[allow(non_snake_case)]
pub fn LitBool(marker: lookahead::TokenMarker) -> LitBool {
match marker {}
}
}
/// The style of a string literal, either plain quoted or a raw string like
/// `r##"data"##`.
pub enum StrStyle {
/// An ordinary string like `"data"`.
Cooked,
/// A raw string like `r##"data"##`.
///
/// The unsigned integer is the number of `#` symbols used.
Raw(usize),
}
#[cfg(feature = "parsing")]
pub_if_not_doc! {
#[doc(hidden)]
#[allow(non_snake_case)]
pub fn Lit(marker: lookahead::TokenMarker) -> Lit {
match marker {}
}
}
#[cfg(feature = "parsing")]
pub(crate) mod parsing {
use crate::buffer::Cursor;
use crate::error::Result;
use crate::lit::{
value, Lit, LitBool, LitByte, LitByteStr, LitCStr, LitChar, LitFloat, LitFloatRepr, LitInt,
LitIntRepr, LitStr,
};
use crate::parse::{Parse, ParseStream, Unexpected};
use crate::token::{self, Token};
use proc_macro2::{Literal, Punct, Span};
use std::cell::Cell;
use std::rc::Rc;
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for Lit {
fn parse(input: ParseStream) -> Result<Self> {
input.step(|cursor| {
if let Some((lit, rest)) = cursor.literal() {
return Ok((Lit::new(lit), rest));
}
if let Some((ident, rest)) = cursor.ident() {
let value = ident == "true";
if value || ident == "false" {
let lit_bool = LitBool {
value,
span: ident.span(),
};
return Ok((Lit::Bool(lit_bool), rest));
}
}
if let Some((punct, rest)) = cursor.punct() {
if punct.as_char() == '-' {
if let Some((lit, rest)) = parse_negative_lit(punct, rest) {
return Ok((lit, rest));
}
}
}
Err(cursor.error("expected literal"))
})
}
}
fn parse_negative_lit(neg: Punct, cursor: Cursor) -> Option<(Lit, Cursor)> {
let (lit, rest) = cursor.literal()?;
let mut span = neg.span();
span = span.join(lit.span()).unwrap_or(span);
let mut repr = lit.to_string();
repr.insert(0, '-');
if let Some((digits, suffix)) = value::parse_lit_int(&repr) {
let mut token: Literal = repr.parse().unwrap();
token.set_span(span);
return Some((
Lit::Int(LitInt {
repr: Box::new(LitIntRepr {
token,
digits,
suffix,
}),
}),
rest,
));
}
let (digits, suffix) = value::parse_lit_float(&repr)?;
let mut token: Literal = repr.parse().unwrap();
token.set_span(span);
Some((
Lit::Float(LitFloat {
repr: Box::new(LitFloatRepr {
token,
digits,
suffix,
}),
}),
rest,
))
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitStr {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Str(lit)) => Ok(lit),
_ => Err(head.error("expected string literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitByteStr {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::ByteStr(lit)) => Ok(lit),
_ => Err(head.error("expected byte string literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitCStr {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::CStr(lit)) => Ok(lit),
_ => Err(head.error("expected C string literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitByte {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Byte(lit)) => Ok(lit),
_ => Err(head.error("expected byte literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitChar {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Char(lit)) => Ok(lit),
_ => Err(head.error("expected character literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitInt {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Int(lit)) => Ok(lit),
_ => Err(head.error("expected integer literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitFloat {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Float(lit)) => Ok(lit),
_ => Err(head.error("expected floating point literal")),
}
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
impl Parse for LitBool {
fn parse(input: ParseStream) -> Result<Self> {
let head = input.fork();
match input.parse() {
Ok(Lit::Bool(lit)) => Ok(lit),
_ => Err(head.error("expected boolean literal")),
}
}
}
fn peek_impl(cursor: Cursor, peek: fn(ParseStream) -> bool) -> bool {
let scope = Span::call_site();
let unexpected = Rc::new(Cell::new(Unexpected::None));
let buffer = crate::parse::new_parse_buffer(scope, cursor, unexpected);
peek(&buffer)
}
macro_rules! impl_token {
($display:literal $name:ty) => {
impl Token for $name {
fn peek(cursor: Cursor) -> bool {
fn peek(input: ParseStream) -> bool {
<$name as Parse>::parse(input).is_ok()
}
peek_impl(cursor, peek)
}
fn display() -> &'static str {
$display
}
}
impl token::private::Sealed for $name {}
};
}
impl_token!("literal" Lit);
impl_token!("string literal" LitStr);
impl_token!("byte string literal" LitByteStr);
impl_token!("C-string literal" LitCStr);
impl_token!("byte literal" LitByte);
impl_token!("character literal" LitChar);
impl_token!("integer literal" LitInt);
impl_token!("floating point literal" LitFloat);
impl_token!("boolean literal" LitBool);
}
#[cfg(feature = "printing")]
mod printing {
use crate::lit::{LitBool, LitByte, LitByteStr, LitCStr, LitChar, LitFloat, LitInt, LitStr};
use proc_macro2::TokenStream;
use quote::{ToTokens, TokenStreamExt};
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitStr {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitByteStr {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitCStr {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitByte {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitChar {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitInt {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitFloat {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.repr.token.to_tokens(tokens);
}
}
#[cfg_attr(docsrs, doc(cfg(feature = "printing")))]
impl ToTokens for LitBool {
fn to_tokens(&self, tokens: &mut TokenStream) {
tokens.append(self.token());
}
}
}
mod value {
use crate::bigint::BigInt;
use crate::lit::{
Lit, LitBool, LitByte, LitByteStr, LitCStr, LitChar, LitFloat, LitFloatRepr, LitInt,
LitIntRepr, LitRepr, LitStr,
};
use proc_macro2::{Literal, Span};
use std::ascii;
use std::char;
use std::ffi::CString;
use std::ops::{Index, RangeFrom};
impl Lit {
/// Interpret a Syn literal from a proc-macro2 literal.
pub fn new(token: Literal) -> Self {
let repr = token.to_string();
match byte(&repr, 0) {
// "...", r"...", r#"..."#
b'"' | b'r' => {
let (_, suffix) = parse_lit_str(&repr);
return Lit::Str(LitStr {
repr: Box::new(LitRepr { token, suffix }),
});
}
b'b' => match byte(&repr, 1) {
// b"...", br"...", br#"...#"
b'"' | b'r' => {
let (_, suffix) = parse_lit_byte_str(&repr);
return Lit::ByteStr(LitByteStr {
repr: Box::new(LitRepr { token, suffix }),
});
}
// b'...'
b'\'' => {
let (_, suffix) = parse_lit_byte(&repr);
return Lit::Byte(LitByte {
repr: Box::new(LitRepr { token, suffix }),
});
}
_ => {}
},
// c"...", cr"...", cr#"..."#
b'c' => {
let (_, suffix) = parse_lit_c_str(&repr);
return Lit::CStr(LitCStr {
repr: Box::new(LitRepr { token, suffix }),
});
}
// '...'
b'\'' => {
let (_, suffix) = parse_lit_char(&repr);
return Lit::Char(LitChar {
repr: Box::new(LitRepr { token, suffix }),
});
}
b'0'..=b'9' | b'-' => {
// 0, 123, 0xFF, 0o77, 0b11
if let Some((digits, suffix)) = parse_lit_int(&repr) {
return Lit::Int(LitInt {
repr: Box::new(LitIntRepr {
token,
digits,
suffix,
}),
});
}
// 1.0, 1e-1, 1e+1
if let Some((digits, suffix)) = parse_lit_float(&repr) {
return Lit::Float(LitFloat {
repr: Box::new(LitFloatRepr {
token,
digits,
suffix,
}),
});
}
}
// true, false
b't' | b'f' => {
if repr == "true" || repr == "false" {
return Lit::Bool(LitBool {
value: repr == "true",
span: token.span(),
});
}
}
b'(' if repr == "(/*ERROR*/)" => return Lit::Verbatim(token),
_ => {}
}
panic!("unrecognized literal: `{}`", repr);
}
pub fn suffix(&self) -> &str {
match self {
Lit::Str(lit) => lit.suffix(),
Lit::ByteStr(lit) => lit.suffix(),
Lit::CStr(lit) => lit.suffix(),
Lit::Byte(lit) => lit.suffix(),
Lit::Char(lit) => lit.suffix(),
Lit::Int(lit) => lit.suffix(),
Lit::Float(lit) => lit.suffix(),
Lit::Bool(_) | Lit::Verbatim(_) => "",
}
}
pub fn span(&self) -> Span {
match self {
Lit::Str(lit) => lit.span(),
Lit::ByteStr(lit) => lit.span(),
Lit::CStr(lit) => lit.span(),
Lit::Byte(lit) => lit.span(),
Lit::Char(lit) => lit.span(),
Lit::Int(lit) => lit.span(),
Lit::Float(lit) => lit.span(),
Lit::Bool(lit) => lit.span,
Lit::Verbatim(lit) => lit.span(),
}
}
pub fn set_span(&mut self, span: Span) {
match self {
Lit::Str(lit) => lit.set_span(span),
Lit::ByteStr(lit) => lit.set_span(span),
Lit::CStr(lit) => lit.set_span(span),
Lit::Byte(lit) => lit.set_span(span),
Lit::Char(lit) => lit.set_span(span),
Lit::Int(lit) => lit.set_span(span),
Lit::Float(lit) => lit.set_span(span),
Lit::Bool(lit) => lit.span = span,
Lit::Verbatim(lit) => lit.set_span(span),
}
}
}
/// Get the byte at offset idx, or a default of `b'\0'` if we're looking
/// past the end of the input buffer.
pub(crate) fn byte<S: AsRef<[u8]> + ?Sized>(s: &S, idx: usize) -> u8 {
let s = s.as_ref();
if idx < s.len() {
s[idx]
} else {
0
}
}
fn next_chr(s: &str) -> char {
s.chars().next().unwrap_or('\0')
}
// Returns (content, suffix).
pub(crate) fn parse_lit_str(s: &str) -> (Box<str>, Box<str>) {
match byte(s, 0) {
b'"' => parse_lit_str_cooked(s),
b'r' => parse_lit_str_raw(s),
_ => unreachable!(),
}
}
// Clippy false positive
#[allow(clippy::needless_continue)]
fn parse_lit_str_cooked(mut s: &str) -> (Box<str>, Box<str>) {
assert_eq!(byte(s, 0), b'"');
s = &s[1..];
let mut content = String::new();
'outer: loop {
let ch = match byte(s, 0) {
b'"' => break,
b'\\' => {
let b = byte(s, 1);
s = &s[2..];
match b {
b'x' => {
let (byte, rest) = backslash_x(s);
s = rest;
assert!(byte <= 0x7F, "invalid \\x byte in string literal");
char::from_u32(u32::from(byte)).unwrap()
}
b'u' => {
let (ch, rest) = backslash_u(s);
s = rest;
ch
}
b'n' => '\n',
b'r' => '\r',
b't' => '\t',
b'\\' => '\\',
b'0' => '\0',
b'\'' => '\'',
b'"' => '"',
b'\r' | b'\n' => loop {
let b = byte(s, 0);
match b {
b' ' | b'\t' | b'\n' | b'\r' => s = &s[1..],
_ => continue 'outer,
}
},
b => panic!(
"unexpected byte '{}' after \\ character in string literal",
ascii::escape_default(b),
),
}
}
b'\r' => {
assert_eq!(byte(s, 1), b'\n', "bare CR not allowed in string");
s = &s[2..];
'\n'
}
_ => {
let ch = next_chr(s);
s = &s[ch.len_utf8()..];
ch
}
};
content.push(ch);
}
assert!(s.starts_with('"'));
let content = content.into_boxed_str();
let suffix = s[1..].to_owned().into_boxed_str();
(content, suffix)
}
fn parse_lit_str_raw(mut s: &str) -> (Box<str>, Box<str>) {
assert_eq!(byte(s, 0), b'r');
s = &s[1..];
let mut pounds = 0;
while byte(s, pounds) == b'#' {
pounds += 1;
}
assert_eq!(byte(s, pounds), b'"');
let close = s.rfind('"').unwrap();
for end in s[close + 1..close + 1 + pounds].bytes() {
assert_eq!(end, b'#');
}
let content = s[pounds + 1..close].to_owned().into_boxed_str();
let suffix = s[close + 1 + pounds..].to_owned().into_boxed_str();
(content, suffix)
}
// Returns (content, suffix).
pub(crate) fn parse_lit_byte_str(s: &str) -> (Vec<u8>, Box<str>) {
assert_eq!(byte(s, 0), b'b');
match byte(s, 1) {
b'"' => parse_lit_byte_str_cooked(s),
b'r' => parse_lit_byte_str_raw(s),
_ => unreachable!(),
}
}
// Clippy false positive
#[allow(clippy::needless_continue)]
fn parse_lit_byte_str_cooked(mut s: &str) -> (Vec<u8>, Box<str>) {
assert_eq!(byte(s, 0), b'b');
assert_eq!(byte(s, 1), b'"');
s = &s[2..];
// We're going to want to have slices which don't respect codepoint boundaries.
let mut v = s.as_bytes();
let mut out = Vec::new();
'outer: loop {
let byte = match byte(v, 0) {
b'"' => break,
b'\\' => {
let b = byte(v, 1);
v = &v[2..];
match b {
b'x' => {
let (b, rest) = backslash_x(v);
v = rest;
b
}
b'n' => b'\n',
b'r' => b'\r',
b't' => b'\t',
b'\\' => b'\\',
b'0' => b'\0',
b'\'' => b'\'',
b'"' => b'"',
b'\r' | b'\n' => loop {
let byte = byte(v, 0);
if matches!(byte, b' ' | b'\t' | b'\n' | b'\r') {
v = &v[1..];
} else {
continue 'outer;
}
},
b => panic!(
"unexpected byte '{}' after \\ character in byte-string literal",
ascii::escape_default(b),
),
}
}
b'\r' => {
assert_eq!(byte(v, 1), b'\n', "bare CR not allowed in string");
v = &v[2..];
b'\n'
}
b => {
v = &v[1..];
b
}
};
out.push(byte);
}
assert_eq!(byte(v, 0), b'"');
let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
(out, suffix)
}
fn parse_lit_byte_str_raw(s: &str) -> (Vec<u8>, Box<str>) {
assert_eq!(byte(s, 0), b'b');
let (value, suffix) = parse_lit_str_raw(&s[1..]);
(String::from(value).into_bytes(), suffix)
}
// Returns (content, suffix).
pub(crate) fn parse_lit_c_str(s: &str) -> (CString, Box<str>) {
assert_eq!(byte(s, 0), b'c');
match byte(s, 1) {
b'"' => parse_lit_c_str_cooked(s),
b'r' => parse_lit_c_str_raw(s),
_ => unreachable!(),
}
}
// Clippy false positive
#[allow(clippy::needless_continue)]
fn parse_lit_c_str_cooked(mut s: &str) -> (CString, Box<str>) {
assert_eq!(byte(s, 0), b'c');
assert_eq!(byte(s, 1), b'"');
s = &s[2..];
// We're going to want to have slices which don't respect codepoint boundaries.
let mut v = s.as_bytes();
let mut out = Vec::new();
'outer: loop {
let byte = match byte(v, 0) {
b'"' => break,
b'\\' => {
let b = byte(v, 1);
v = &v[2..];
match b {
b'x' => {
let (b, rest) = backslash_x(v);
assert!(b != 0, "\\x00 is not allowed in C-string literal");
v = rest;
b
}
b'u' => {
let (ch, rest) = backslash_u(v);
assert!(ch != '\0', "\\u{{0}} is not allowed in C-string literal");
v = rest;
out.extend_from_slice(ch.encode_utf8(&mut [0u8; 4]).as_bytes());
continue 'outer;
}
b'n' => b'\n',
b'r' => b'\r',
b't' => b'\t',
b'\\' => b'\\',
b'\'' => b'\'',
b'"' => b'"',
b'\r' | b'\n' => loop {
let byte = byte(v, 0);
if matches!(byte, b' ' | b'\t' | b'\n' | b'\r') {
v = &v[1..];
} else {
continue 'outer;
}
},
b => panic!(
"unexpected byte '{}' after \\ character in byte literal",
ascii::escape_default(b),
),
}
}
b'\r' => {
assert_eq!(byte(v, 1), b'\n', "bare CR not allowed in string");
v = &v[2..];
b'\n'
}
b => {
v = &v[1..];
b
}
};
out.push(byte);
}
assert_eq!(byte(v, 0), b'"');
let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
(CString::new(out).unwrap(), suffix)
}
fn parse_lit_c_str_raw(s: &str) -> (CString, Box<str>) {
assert_eq!(byte(s, 0), b'c');
let (value, suffix) = parse_lit_str_raw(&s[1..]);
(CString::new(String::from(value)).unwrap(), suffix)
}
// Returns (value, suffix).
pub(crate) fn parse_lit_byte(s: &str) -> (u8, Box<str>) {
assert_eq!(byte(s, 0), b'b');
assert_eq!(byte(s, 1), b'\'');
// We're going to want to have slices which don't respect codepoint boundaries.
let mut v = s[2..].as_bytes();
let b = match byte(v, 0) {
b'\\' => {
let b = byte(v, 1);
v = &v[2..];
match b {
b'x' => {
let (b, rest) = backslash_x(v);
v = rest;
b
}
b'n' => b'\n',
b'r' => b'\r',
b't' => b'\t',
b'\\' => b'\\',
b'0' => b'\0',
b'\'' => b'\'',
b'"' => b'"',
b => panic!(
"unexpected byte '{}' after \\ character in byte literal",
ascii::escape_default(b),
),
}
}
b => {
v = &v[1..];
b
}
};
assert_eq!(byte(v, 0), b'\'');
let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
(b, suffix)
}
// Returns (value, suffix).
pub(crate) fn parse_lit_char(mut s: &str) -> (char, Box<str>) {
assert_eq!(byte(s, 0), b'\'');
s = &s[1..];
let ch = match byte(s, 0) {
b'\\' => {
let b = byte(s, 1);
s = &s[2..];
match b {
b'x' => {
let (byte, rest) = backslash_x(s);
s = rest;
assert!(byte <= 0x7F, "invalid \\x byte in character literal");
char::from_u32(u32::from(byte)).unwrap()
}
b'u' => {
let (ch, rest) = backslash_u(s);
s = rest;
ch
}
b'n' => '\n',
b'r' => '\r',
b't' => '\t',
b'\\' => '\\',
b'0' => '\0',
b'\'' => '\'',
b'"' => '"',
b => panic!(
"unexpected byte '{}' after \\ character in character literal",
ascii::escape_default(b),
),
}
}
_ => {
let ch = next_chr(s);
s = &s[ch.len_utf8()..];
ch
}
};
assert_eq!(byte(s, 0), b'\'');
let suffix = s[1..].to_owned().into_boxed_str();
(ch, suffix)
}
fn backslash_x<S>(s: &S) -> (u8, &S)
where
S: Index<RangeFrom<usize>, Output = S> + AsRef<[u8]> + ?Sized,
{
let mut ch = 0;
let b0 = byte(s, 0);
let b1 = byte(s, 1);
ch += 0x10
* match b0 {
b'0'..=b'9' => b0 - b'0',
b'a'..=b'f' => 10 + (b0 - b'a'),
b'A'..=b'F' => 10 + (b0 - b'A'),
_ => panic!("unexpected non-hex character after \\x"),
};
ch += match b1 {
b'0'..=b'9' => b1 - b'0',
b'a'..=b'f' => 10 + (b1 - b'a'),
b'A'..=b'F' => 10 + (b1 - b'A'),
_ => panic!("unexpected non-hex character after \\x"),
};
(ch, &s[2..])
}
fn backslash_u<S>(mut s: &S) -> (char, &S)
where
S: Index<RangeFrom<usize>, Output = S> + AsRef<[u8]> + ?Sized,
{
if byte(s, 0) != b'{' {
panic!("{}", "expected { after \\u");
}
s = &s[1..];
let mut ch = 0;
let mut digits = 0;
loop {
let b = byte(s, 0);
let digit = match b {
b'0'..=b'9' => b - b'0',
b'a'..=b'f' => 10 + b - b'a',
b'A'..=b'F' => 10 + b - b'A',
b'_' if digits > 0 => {
s = &s[1..];
continue;
}
b'}' if digits == 0 => panic!("invalid empty unicode escape"),
b'}' => break,
_ => panic!("unexpected non-hex character after \\u"),
};
if digits == 6 {
panic!("overlong unicode escape (must have at most 6 hex digits)");
}
ch *= 0x10;
ch += u32::from(digit);
digits += 1;
s = &s[1..];
}
assert!(byte(s, 0) == b'}');
s = &s[1..];
if let Some(ch) = char::from_u32(ch) {
(ch, s)
} else {
panic!("character code {:x} is not a valid unicode character", ch);
}
}
// Returns base 10 digits and suffix.
pub(crate) fn parse_lit_int(mut s: &str) -> Option<(Box<str>, Box<str>)> {
let negative = byte(s, 0) == b'-';
if negative {
s = &s[1..];
}
let base = match (byte(s, 0), byte(s, 1)) {
(b'0', b'x') => {
s = &s[2..];
16
}
(b'0', b'o') => {
s = &s[2..];
8
}
(b'0', b'b') => {
s = &s[2..];
2
}
(b'0'..=b'9', _) => 10,
_ => return None,
};
let mut value = BigInt::new();
let mut has_digit = false;
'outer: loop {
let b = byte(s, 0);
let digit = match b {
b'0'..=b'9' => b - b'0',
b'a'..=b'f' if base > 10 => b - b'a' + 10,
b'A'..=b'F' if base > 10 => b - b'A' + 10,
b'_' => {
s = &s[1..];
continue;
}
// If looking at a floating point literal, we don't want to
// consider it an integer.
b'.' if base == 10 => return None,
b'e' | b'E' if base == 10 => {
let mut has_exp = false;
for (i, b) in s[1..].bytes().enumerate() {
match b {
b'_' => {}
b'-' | b'+' => return None,
b'0'..=b'9' => has_exp = true,
_ => {
let suffix = &s[1 + i..];
if has_exp && crate::ident::xid_ok(suffix) {
return None;
} else {
break 'outer;
}
}
}
}
if has_exp {
return None;
} else {
break;
}
}
_ => break,
};
if digit >= base {
return None;
}
has_digit = true;
value *= base;
value += digit;
s = &s[1..];
}
if !has_digit {
return None;
}
let suffix = s;
if suffix.is_empty() || crate::ident::xid_ok(suffix) {
let mut repr = value.to_string();
if negative {
repr.insert(0, '-');
}
Some((repr.into_boxed_str(), suffix.to_owned().into_boxed_str()))
} else {
None
}
}
// Returns base 10 digits and suffix.
pub(crate) fn parse_lit_float(input: &str) -> Option<(Box<str>, Box<str>)> {
// Rust's floating point literals are very similar to the ones parsed by
// the standard library, except that rust's literals can contain
// ignorable underscores. Let's remove those underscores.
let mut bytes = input.to_owned().into_bytes();
let start = (*bytes.first()? == b'-') as usize;
match bytes.get(start)? {
b'0'..=b'9' => {}
_ => return None,
}
let mut read = start;
let mut write = start;
let mut has_dot = false;
let mut has_e = false;
let mut has_sign = false;
let mut has_exponent = false;
while read < bytes.len() {
match bytes[read] {
b'_' => {
// Don't increase write
read += 1;
continue;
}
b'0'..=b'9' => {
if has_e {
has_exponent = true;
}
bytes[write] = bytes[read];
}
b'.' => {
if has_e || has_dot {
return None;
}
has_dot = true;
bytes[write] = b'.';
}
b'e' | b'E' => {
match bytes[read + 1..]
.iter()
.find(|b| **b != b'_')
.unwrap_or(&b'\0')
{
b'-' | b'+' | b'0'..=b'9' => {}
_ => break,
}
if has_e {
if has_exponent {
break;
} else {
return None;
}
}
has_e = true;
bytes[write] = b'e';
}
b'-' | b'+' => {
if has_sign || has_exponent || !has_e {
return None;
}
has_sign = true;
if bytes[read] == b'-' {
bytes[write] = bytes[read];
} else {
// Omit '+'
read += 1;
continue;
}
}
_ => break,
}
read += 1;
write += 1;
}
if has_e && !has_exponent {
return None;
}
let mut digits = String::from_utf8(bytes).unwrap();
let suffix = digits.split_off(read);
digits.truncate(write);
if suffix.is_empty() || crate::ident::xid_ok(&suffix) {
Some((digits.into_boxed_str(), suffix.into_boxed_str()))
} else {
None
}
}
}