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-rw-r--r--syn/src/lit.rs1382
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diff --git a/syn/src/lit.rs b/syn/src/lit.rs
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+use proc_macro2::{Literal, Span};
+use std::fmt::{self, Display};
+use std::str::{self, FromStr};
+
+#[cfg(feature = "printing")]
+use proc_macro2::Ident;
+
+#[cfg(feature = "parsing")]
+use proc_macro2::TokenStream;
+
+use proc_macro2::TokenTree;
+
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
+
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, Parser};
+use crate::{Error, Result};
+
+ast_enum_of_structs! {
+ /// A Rust literal such as a string or integer or boolean.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or `"full"`
+ /// feature.*
+ ///
+ /// # Syntax tree enum
+ ///
+ /// This type is a [syntax tree enum].
+ ///
+ /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums
+ //
+ // TODO: change syntax-tree-enum link to an intra rustdoc link, currently
+ // blocked on https://github.com/rust-lang/rust/issues/62833
+ pub enum Lit #manual_extra_traits {
+ /// A UTF-8 string literal: `"foo"`.
+ Str(LitStr),
+
+ /// A byte string literal: `b"foo"`.
+ ByteStr(LitByteStr),
+
+ /// 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 infinte 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"`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitStr #manual_extra_traits_debug {
+ repr: Box<LitStrRepr>,
+ }
+}
+
+#[cfg_attr(feature = "clone-impls", derive(Clone))]
+struct LitStrRepr {
+ token: Literal,
+ suffix: Box<str>,
+}
+
+ast_struct! {
+ /// A byte string literal: `b"foo"`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitByteStr #manual_extra_traits_debug {
+ token: Literal,
+ }
+}
+
+ast_struct! {
+ /// A byte literal: `b'f'`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitByte #manual_extra_traits_debug {
+ token: Literal,
+ }
+}
+
+ast_struct! {
+ /// A character literal: `'a'`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitChar #manual_extra_traits_debug {
+ token: Literal,
+ }
+}
+
+ast_struct! {
+ /// An integer literal: `1` or `1u16`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitInt #manual_extra_traits_debug {
+ repr: Box<LitIntRepr>,
+ }
+}
+
+#[cfg_attr(feature = "clone-impls", derive(Clone))]
+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 infinte or NaN.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitFloat #manual_extra_traits_debug {
+ repr: Box<LitFloatRepr>,
+ }
+}
+
+#[cfg_attr(feature = "clone-impls", derive(Clone))]
+struct LitFloatRepr {
+ token: Literal,
+ digits: Box<str>,
+ suffix: Box<str>,
+}
+
+ast_struct! {
+ /// A boolean literal: `true` or `false`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or
+ /// `"full"` feature.*
+ pub struct LitBool #manual_extra_traits_debug {
+ pub value: bool,
+ pub span: Span,
+ }
+}
+
+#[cfg(feature = "extra-traits")]
+impl Eq for Lit {}
+
+#[cfg(feature = "extra-traits")]
+impl PartialEq for Lit {
+ fn eq(&self, other: &Self) -> bool {
+ match (self, other) {
+ (Lit::Str(this), Lit::Str(other)) => this == other,
+ (Lit::ByteStr(this), Lit::ByteStr(other)) => this == other,
+ (Lit::Byte(this), Lit::Byte(other)) => this == other,
+ (Lit::Char(this), Lit::Char(other)) => this == other,
+ (Lit::Int(this), Lit::Int(other)) => this == other,
+ (Lit::Float(this), Lit::Float(other)) => this == other,
+ (Lit::Bool(this), Lit::Bool(other)) => this == other,
+ (Lit::Verbatim(this), Lit::Verbatim(other)) => this.to_string() == other.to_string(),
+ _ => false,
+ }
+ }
+}
+
+#[cfg(feature = "extra-traits")]
+impl Hash for Lit {
+ fn hash<H>(&self, hash: &mut H)
+ where
+ H: Hasher,
+ {
+ match self {
+ Lit::Str(lit) => {
+ hash.write_u8(0);
+ lit.hash(hash);
+ }
+ Lit::ByteStr(lit) => {
+ hash.write_u8(1);
+ lit.hash(hash);
+ }
+ Lit::Byte(lit) => {
+ hash.write_u8(2);
+ lit.hash(hash);
+ }
+ Lit::Char(lit) => {
+ hash.write_u8(3);
+ lit.hash(hash);
+ }
+ Lit::Int(lit) => {
+ hash.write_u8(4);
+ lit.hash(hash);
+ }
+ Lit::Float(lit) => {
+ hash.write_u8(5);
+ lit.hash(hash);
+ }
+ Lit::Bool(lit) => {
+ hash.write_u8(6);
+ lit.hash(hash);
+ }
+ Lit::Verbatim(lit) => {
+ hash.write_u8(7);
+ lit.to_string().hash(hash);
+ }
+ }
+ }
+}
+
+impl LitStr {
+ pub fn new(value: &str, span: Span) -> Self {
+ let mut lit = Literal::string(value);
+ lit.set_span(span);
+ LitStr {
+ repr: Box::new(LitStrRepr {
+ token: lit,
+ suffix: Box::<str>::default(),
+ }),
+ }
+ }
+
+ pub fn value(&self) -> String {
+ let (value, _) = value::parse_lit_str(&self.repr.token.to_string());
+ 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 proc_macro2::Span;
+ /// use syn::{Attribute, Error, Ident, Lit, Meta, MetaNameValue, 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);
+ /// }
+ ///
+ /// match attr.parse_meta()? {
+ /// Meta::NameValue(MetaNameValue { lit: Lit::Str(lit_str), .. }) => {
+ /// lit_str.parse().map(Some)
+ /// }
+ /// _ => {
+ /// let message = "expected #[path = \"...\"]";
+ /// Err(Error::new_spanned(attr, message))
+ /// }
+ /// }
+ /// }
+ /// ```
+ #[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")]
+ 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 mut tokens = crate::parse_str(&self.value())?;
+ tokens = respan_token_stream(tokens, self.span());
+
+ parser.parse2(tokens)
+ }
+
+ 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
+ }
+}
+
+impl LitByteStr {
+ pub fn new(value: &[u8], span: Span) -> Self {
+ let mut token = Literal::byte_string(value);
+ token.set_span(span);
+ LitByteStr { token }
+ }
+
+ pub fn value(&self) -> Vec<u8> {
+ value::parse_lit_byte_str(&self.token.to_string())
+ }
+
+ pub fn span(&self) -> Span {
+ self.token.span()
+ }
+
+ pub fn set_span(&mut self, span: Span) {
+ self.token.set_span(span)
+ }
+}
+
+impl LitByte {
+ pub fn new(value: u8, span: Span) -> Self {
+ let mut token = Literal::u8_suffixed(value);
+ token.set_span(span);
+ LitByte { token }
+ }
+
+ pub fn value(&self) -> u8 {
+ value::parse_lit_byte(&self.token.to_string())
+ }
+
+ pub fn span(&self) -> Span {
+ self.token.span()
+ }
+
+ pub fn set_span(&mut self, span: Span) {
+ self.token.set_span(span)
+ }
+}
+
+impl LitChar {
+ pub fn new(value: char, span: Span) -> Self {
+ let mut token = Literal::character(value);
+ token.set_span(span);
+ LitChar { token }
+ }
+
+ pub fn value(&self) -> char {
+ value::parse_lit_char(&self.token.to_string())
+ }
+
+ pub fn span(&self) -> Span {
+ self.token.span()
+ }
+
+ pub fn set_span(&mut self, span: Span) {
+ self.token.set_span(span)
+ }
+}
+
+impl LitInt {
+ pub fn new(repr: &str, span: Span) -> Self {
+ if let Some((digits, suffix)) = value::parse_lit_int(repr) {
+ let mut token = value::to_literal(repr);
+ token.set_span(span);
+ LitInt {
+ repr: Box::new(LitIntRepr {
+ token,
+ digits,
+ suffix,
+ }),
+ }
+ } else {
+ panic!("Not an integer literal: `{}`", repr);
+ }
+ }
+
+ 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)
+ }
+}
+
+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 {
+ if let Some((digits, suffix)) = value::parse_lit_float(repr) {
+ let mut token = value::to_literal(repr);
+ token.set_span(span);
+ LitFloat {
+ repr: Box::new(LitFloatRepr {
+ token,
+ digits,
+ suffix,
+ }),
+ }
+ } else {
+ panic!("Not a float literal: `{}`", repr);
+ }
+ }
+
+ 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)
+ }
+}
+
+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)
+ }
+}
+
+#[cfg(feature = "extra-traits")]
+mod debug_impls {
+ use super::*;
+ use std::fmt::{self, Debug};
+
+ impl Debug for LitStr {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitStr")
+ .field("token", &format_args!("{}", self.repr.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitByteStr {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitByteStr")
+ .field("token", &format_args!("{}", self.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitByte {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitByte")
+ .field("token", &format_args!("{}", self.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitChar {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitChar")
+ .field("token", &format_args!("{}", self.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitInt {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitInt")
+ .field("token", &format_args!("{}", self.repr.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitFloat {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitFloat")
+ .field("token", &format_args!("{}", self.repr.token))
+ .finish()
+ }
+ }
+
+ impl Debug for LitBool {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ formatter
+ .debug_struct("LitBool")
+ .field("value", &self.value)
+ .finish()
+ }
+ }
+}
+
+macro_rules! lit_extra_traits {
+ ($ty:ident, $($field:ident).+) => {
+ #[cfg(feature = "extra-traits")]
+ impl Eq for $ty {}
+
+ #[cfg(feature = "extra-traits")]
+ impl PartialEq for $ty {
+ fn eq(&self, other: &Self) -> bool {
+ self.$($field).+.to_string() == other.$($field).+.to_string()
+ }
+ }
+
+ #[cfg(feature = "extra-traits")]
+ impl Hash for $ty {
+ fn hash<H>(&self, state: &mut H)
+ where
+ H: Hasher,
+ {
+ self.$($field).+.to_string().hash(state);
+ }
+ }
+
+ #[cfg(feature = "parsing")]
+ #[doc(hidden)]
+ #[allow(non_snake_case)]
+ pub fn $ty(marker: lookahead::TokenMarker) -> $ty {
+ match marker {}
+ }
+ };
+}
+
+lit_extra_traits!(LitStr, repr.token);
+lit_extra_traits!(LitByteStr, token);
+lit_extra_traits!(LitByte, token);
+lit_extra_traits!(LitChar, token);
+lit_extra_traits!(LitInt, repr.token);
+lit_extra_traits!(LitFloat, repr.token);
+lit_extra_traits!(LitBool, value);
+
+ast_enum! {
+ /// The style of a string literal, either plain quoted or a raw string like
+ /// `r##"data"##`.
+ ///
+ /// *This type is available if Syn is built with the `"derive"` or `"full"`
+ /// feature.*
+ pub enum StrStyle #no_visit {
+ /// 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")]
+#[doc(hidden)]
+#[allow(non_snake_case)]
+pub fn Lit(marker: lookahead::TokenMarker) -> Lit {
+ match marker {}
+}
+
+#[cfg(feature = "parsing")]
+pub mod parsing {
+ use super::*;
+ use crate::parse::{Parse, ParseStream, Result};
+
+ 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));
+ }
+ while let Some((ident, rest)) = cursor.ident() {
+ let value = if ident == "true" {
+ true
+ } else if ident == "false" {
+ false
+ } else {
+ break;
+ };
+ let lit_bool = LitBool {
+ value,
+ span: ident.span(),
+ };
+ return Ok((Lit::Bool(lit_bool), rest));
+ }
+ Err(cursor.error("expected literal"))
+ })
+ }
+ }
+
+ impl Parse for LitStr {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Str(lit) => Ok(lit),
+ _ => Err(head.error("expected string literal")),
+ }
+ }
+ }
+
+ impl Parse for LitByteStr {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::ByteStr(lit) => Ok(lit),
+ _ => Err(head.error("expected byte string literal")),
+ }
+ }
+ }
+
+ impl Parse for LitByte {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Byte(lit) => Ok(lit),
+ _ => Err(head.error("expected byte literal")),
+ }
+ }
+ }
+
+ impl Parse for LitChar {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Char(lit) => Ok(lit),
+ _ => Err(head.error("expected character literal")),
+ }
+ }
+ }
+
+ impl Parse for LitInt {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Int(lit) => Ok(lit),
+ _ => Err(head.error("expected integer literal")),
+ }
+ }
+ }
+
+ impl Parse for LitFloat {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Float(lit) => Ok(lit),
+ _ => Err(head.error("expected floating point literal")),
+ }
+ }
+ }
+
+ impl Parse for LitBool {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let head = input.fork();
+ match input.parse()? {
+ Lit::Bool(lit) => Ok(lit),
+ _ => Err(head.error("expected boolean literal")),
+ }
+ }
+ }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+ use super::*;
+ use proc_macro2::TokenStream;
+ use quote::{ToTokens, TokenStreamExt};
+
+ impl ToTokens for LitStr {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.repr.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitByteStr {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitByte {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitChar {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitInt {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.repr.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitFloat {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ self.repr.token.to_tokens(tokens);
+ }
+ }
+
+ impl ToTokens for LitBool {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ let s = if self.value { "true" } else { "false" };
+ tokens.append(Ident::new(s, self.span));
+ }
+ }
+}
+
+mod value {
+ use super::*;
+ use crate::bigint::BigInt;
+ use proc_macro2::TokenStream;
+ use std::char;
+ 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) {
+ b'"' | b'r' => {
+ let (_, suffix) = parse_lit_str(&repr);
+ return Lit::Str(LitStr {
+ repr: Box::new(LitStrRepr { token, suffix }),
+ });
+ }
+ b'b' => match byte(&repr, 1) {
+ b'"' | b'r' => {
+ return Lit::ByteStr(LitByteStr { token });
+ }
+ b'\'' => {
+ return Lit::Byte(LitByte { token });
+ }
+ _ => {}
+ },
+ b'\'' => {
+ return Lit::Char(LitChar { token });
+ }
+ b'0'..=b'9' | b'-' => {
+ if !(repr.ends_with("f32") || repr.ends_with("f64")) {
+ if let Some((digits, suffix)) = parse_lit_int(&repr) {
+ return Lit::Int(LitInt {
+ repr: Box::new(LitIntRepr {
+ token,
+ digits,
+ suffix,
+ }),
+ });
+ }
+ }
+ if let Some((digits, suffix)) = parse_lit_float(&repr) {
+ return Lit::Float(LitFloat {
+ repr: Box::new(LitFloatRepr {
+ token,
+ digits,
+ suffix,
+ }),
+ });
+ }
+ }
+ b't' | b'f' => {
+ if repr == "true" || repr == "false" {
+ return Lit::Bool(LitBool {
+ value: repr == "true",
+ span: token.span(),
+ });
+ }
+ }
+ _ => {}
+ }
+
+ panic!("Unrecognized literal: `{}`", repr);
+ }
+ }
+
+ /// Get the byte at offset idx, or a default of `b'\0'` if we're looking
+ /// past the end of the input buffer.
+ pub 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 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
+ // https://github.com/rust-lang-nursery/rust-clippy/issues/2329
+ #[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 <= 0x80, "Invalid \\x byte in string literal");
+ char::from_u32(u32::from(byte)).unwrap()
+ }
+ b'u' => {
+ let (chr, rest) = backslash_u(s);
+ s = rest;
+ chr
+ }
+ b'n' => '\n',
+ b'r' => '\r',
+ b't' => '\t',
+ b'\\' => '\\',
+ b'0' => '\0',
+ b'\'' => '\'',
+ b'"' => '"',
+ b'\r' | b'\n' => loop {
+ let ch = next_chr(s);
+ if ch.is_whitespace() {
+ s = &s[ch.len_utf8()..];
+ } else {
+ continue 'outer;
+ }
+ },
+ b => panic!("unexpected byte {:?} after \\ character in byte literal", 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'"');
+ assert_eq!(byte(s, s.len() - pounds - 1), b'"');
+ for end in s[s.len() - pounds..].bytes() {
+ assert_eq!(end, b'#');
+ }
+
+ let content = s[pounds + 1..s.len() - pounds - 1]
+ .to_owned()
+ .into_boxed_str();
+ let suffix = Box::<str>::default(); // todo
+ (content, suffix)
+ }
+
+ pub fn parse_lit_byte_str(s: &str) -> Vec<u8> {
+ 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
+ // https://github.com/rust-lang-nursery/rust-clippy/issues/2329
+ #[allow(clippy::needless_continue)]
+ fn parse_lit_byte_str_cooked(mut s: &str) -> Vec<u8> {
+ 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 s = s.as_bytes();
+
+ let mut out = Vec::new();
+ 'outer: loop {
+ let byte = match byte(s, 0) {
+ b'"' => break,
+ b'\\' => {
+ let b = byte(s, 1);
+ s = &s[2..];
+ match b {
+ b'x' => {
+ let (b, rest) = backslash_x(s);
+ s = 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(s, 0);
+ let ch = char::from_u32(u32::from(byte)).unwrap();
+ if ch.is_whitespace() {
+ s = &s[1..];
+ } else {
+ continue 'outer;
+ }
+ },
+ b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+ }
+ }
+ b'\r' => {
+ assert_eq!(byte(s, 1), b'\n', "Bare CR not allowed in string");
+ s = &s[2..];
+ b'\n'
+ }
+ b => {
+ s = &s[1..];
+ b
+ }
+ };
+ out.push(byte);
+ }
+
+ assert_eq!(s, b"\"");
+ out
+ }
+
+ fn parse_lit_byte_str_raw(s: &str) -> Vec<u8> {
+ assert_eq!(byte(s, 0), b'b');
+ String::from(parse_lit_str_raw(&s[1..]).0).into_bytes()
+ }
+
+ pub fn parse_lit_byte(s: &str) -> u8 {
+ 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 s = s[2..].as_bytes();
+
+ let b = match byte(s, 0) {
+ b'\\' => {
+ let b = byte(s, 1);
+ s = &s[2..];
+ match b {
+ b'x' => {
+ let (b, rest) = backslash_x(s);
+ s = 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", b),
+ }
+ }
+ b => {
+ s = &s[1..];
+ b
+ }
+ };
+
+ assert_eq!(byte(s, 0), b'\'');
+ b
+ }
+
+ pub fn parse_lit_char(mut s: &str) -> char {
+ 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 <= 0x80, "Invalid \\x byte in string literal");
+ char::from_u32(u32::from(byte)).unwrap()
+ }
+ b'u' => {
+ let (chr, rest) = backslash_u(s);
+ s = rest;
+ chr
+ }
+ b'n' => '\n',
+ b'r' => '\r',
+ b't' => '\t',
+ b'\\' => '\\',
+ b'0' => '\0',
+ b'\'' => '\'',
+ b'"' => '"',
+ b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+ }
+ }
+ _ => {
+ let ch = next_chr(s);
+ s = &s[ch.len_utf8()..];
+ ch
+ }
+ };
+ assert_eq!(s, "\'", "Expected end of char literal");
+ ch
+ }
+
+ 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(mut s: &str) -> (char, &str) {
+ if byte(s, 0) != b'{' {
+ panic!("expected {{ after \\u");
+ }
+ s = &s[1..];
+
+ let mut ch = 0;
+ for _ in 0..6 {
+ let b = byte(s, 0);
+ match b {
+ b'0'..=b'9' => {
+ ch *= 0x10;
+ ch += u32::from(b - b'0');
+ s = &s[1..];
+ }
+ b'a'..=b'f' => {
+ ch *= 0x10;
+ ch += u32::from(10 + b - b'a');
+ s = &s[1..];
+ }
+ b'A'..=b'F' => {
+ ch *= 0x10;
+ ch += u32::from(10 + b - b'A');
+ s = &s[1..];
+ }
+ b'}' => break,
+ _ => panic!("unexpected non-hex character after \\u"),
+ }
+ }
+ 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 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();
+ 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;
+ }
+ // NOTE: Looking at a floating point literal, we don't want to
+ // consider these integers.
+ b'.' if base == 10 => return None,
+ b'e' | b'E' if base == 10 => return None,
+ _ => break,
+ };
+
+ if digit >= base {
+ return None;
+ }
+
+ value *= base;
+ value += digit;
+ s = &s[1..];
+ }
+
+ 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 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.get(0)? == 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' => {
+ if has_e {
+ 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
+ }
+ }
+
+ pub fn to_literal(s: &str) -> Literal {
+ let stream = s.parse::<TokenStream>().unwrap();
+ match stream.into_iter().next().unwrap() {
+ TokenTree::Literal(l) => l,
+ _ => unreachable!(),
+ }
+ }
+}
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