| //! Code related to parsing literals. |
| |
| use crate::ast::{self, Lit, LitKind}; |
| use crate::symbol::{kw, sym, Symbol}; |
| use crate::token::{self, Token}; |
| use crate::tokenstream::TokenTree; |
| |
| use log::debug; |
| use rustc_data_structures::sync::Lrc; |
| use syntax_pos::Span; |
| use rustc_lexer::unescape::{unescape_char, unescape_byte}; |
| use rustc_lexer::unescape::{unescape_str, unescape_byte_str}; |
| use rustc_lexer::unescape::{unescape_raw_str, unescape_raw_byte_str}; |
| |
| use std::ascii; |
| |
| pub enum LitError { |
| NotLiteral, |
| LexerError, |
| InvalidSuffix, |
| InvalidIntSuffix, |
| InvalidFloatSuffix, |
| NonDecimalFloat(u32), |
| IntTooLarge, |
| } |
| |
| impl LitKind { |
| /// Converts literal token into a semantic literal. |
| fn from_lit_token(lit: token::Lit) -> Result<LitKind, LitError> { |
| let token::Lit { kind, symbol, suffix } = lit; |
| if suffix.is_some() && !kind.may_have_suffix() { |
| return Err(LitError::InvalidSuffix); |
| } |
| |
| Ok(match kind { |
| token::Bool => { |
| assert!(symbol.is_bool_lit()); |
| LitKind::Bool(symbol == kw::True) |
| } |
| token::Byte => return unescape_byte(&symbol.as_str()) |
| .map(LitKind::Byte).map_err(|_| LitError::LexerError), |
| token::Char => return unescape_char(&symbol.as_str()) |
| .map(LitKind::Char).map_err(|_| LitError::LexerError), |
| |
| // There are some valid suffixes for integer and float literals, |
| // so all the handling is done internally. |
| token::Integer => return integer_lit(symbol, suffix), |
| token::Float => return float_lit(symbol, suffix), |
| |
| token::Str => { |
| // If there are no characters requiring special treatment we can |
| // reuse the symbol from the token. Otherwise, we must generate a |
| // new symbol because the string in the LitKind is different to the |
| // string in the token. |
| let s = symbol.as_str(); |
| let symbol = if s.contains(&['\\', '\r'][..]) { |
| let mut buf = String::with_capacity(s.len()); |
| let mut error = Ok(()); |
| unescape_str(&s, &mut |_, unescaped_char| { |
| match unescaped_char { |
| Ok(c) => buf.push(c), |
| Err(_) => error = Err(LitError::LexerError), |
| } |
| }); |
| error?; |
| Symbol::intern(&buf) |
| } else { |
| symbol |
| }; |
| LitKind::Str(symbol, ast::StrStyle::Cooked) |
| } |
| token::StrRaw(n) => { |
| // Ditto. |
| let s = symbol.as_str(); |
| let symbol = if s.contains('\r') { |
| let mut buf = String::with_capacity(s.len()); |
| let mut error = Ok(()); |
| unescape_raw_str(&s, &mut |_, unescaped_char| { |
| match unescaped_char { |
| Ok(c) => buf.push(c), |
| Err(_) => error = Err(LitError::LexerError), |
| } |
| }); |
| error?; |
| buf.shrink_to_fit(); |
| Symbol::intern(&buf) |
| } else { |
| symbol |
| }; |
| LitKind::Str(symbol, ast::StrStyle::Raw(n)) |
| } |
| token::ByteStr => { |
| let s = symbol.as_str(); |
| let mut buf = Vec::with_capacity(s.len()); |
| let mut error = Ok(()); |
| unescape_byte_str(&s, &mut |_, unescaped_byte| { |
| match unescaped_byte { |
| Ok(c) => buf.push(c), |
| Err(_) => error = Err(LitError::LexerError), |
| } |
| }); |
| error?; |
| buf.shrink_to_fit(); |
| LitKind::ByteStr(Lrc::new(buf)) |
| } |
| token::ByteStrRaw(_) => { |
| let s = symbol.as_str(); |
| let bytes = if s.contains('\r') { |
| let mut buf = Vec::with_capacity(s.len()); |
| let mut error = Ok(()); |
| unescape_raw_byte_str(&s, &mut |_, unescaped_byte| { |
| match unescaped_byte { |
| Ok(c) => buf.push(c), |
| Err(_) => error = Err(LitError::LexerError), |
| } |
| }); |
| error?; |
| buf.shrink_to_fit(); |
| buf |
| } else { |
| symbol.to_string().into_bytes() |
| }; |
| |
| LitKind::ByteStr(Lrc::new(bytes)) |
| }, |
| token::Err => LitKind::Err(symbol), |
| }) |
| } |
| |
| /// Attempts to recover a token from semantic literal. |
| /// This function is used when the original token doesn't exist (e.g. the literal is created |
| /// by an AST-based macro) or unavailable (e.g. from HIR pretty-printing). |
| pub fn to_lit_token(&self) -> token::Lit { |
| let (kind, symbol, suffix) = match *self { |
| LitKind::Str(symbol, ast::StrStyle::Cooked) => { |
| // Don't re-intern unless the escaped string is different. |
| let s = symbol.as_str(); |
| let escaped = s.escape_default().to_string(); |
| let symbol = if s == escaped { symbol } else { Symbol::intern(&escaped) }; |
| (token::Str, symbol, None) |
| } |
| LitKind::Str(symbol, ast::StrStyle::Raw(n)) => { |
| (token::StrRaw(n), symbol, None) |
| } |
| LitKind::ByteStr(ref bytes) => { |
| let string = bytes.iter().cloned().flat_map(ascii::escape_default) |
| .map(Into::<char>::into).collect::<String>(); |
| (token::ByteStr, Symbol::intern(&string), None) |
| } |
| LitKind::Byte(byte) => { |
| let string: String = ascii::escape_default(byte).map(Into::<char>::into).collect(); |
| (token::Byte, Symbol::intern(&string), None) |
| } |
| LitKind::Char(ch) => { |
| let string: String = ch.escape_default().map(Into::<char>::into).collect(); |
| (token::Char, Symbol::intern(&string), None) |
| } |
| LitKind::Int(n, ty) => { |
| let suffix = match ty { |
| ast::LitIntType::Unsigned(ty) => Some(ty.name()), |
| ast::LitIntType::Signed(ty) => Some(ty.name()), |
| ast::LitIntType::Unsuffixed => None, |
| }; |
| (token::Integer, sym::integer(n), suffix) |
| } |
| LitKind::Float(symbol, ty) => { |
| let suffix = match ty { |
| ast::LitFloatType::Suffixed(ty) => Some(ty.name()), |
| ast::LitFloatType::Unsuffixed => None, |
| }; |
| (token::Float, symbol, suffix) |
| } |
| LitKind::Bool(value) => { |
| let symbol = if value { kw::True } else { kw::False }; |
| (token::Bool, symbol, None) |
| } |
| LitKind::Err(symbol) => { |
| (token::Err, symbol, None) |
| } |
| }; |
| |
| token::Lit::new(kind, symbol, suffix) |
| } |
| } |
| |
| impl Lit { |
| /// Converts literal token into an AST literal. |
| pub fn from_lit_token(token: token::Lit, span: Span) -> Result<Lit, LitError> { |
| Ok(Lit { token, kind: LitKind::from_lit_token(token)?, span }) |
| } |
| |
| /// Converts arbitrary token into an AST literal. |
| pub fn from_token(token: &Token) -> Result<Lit, LitError> { |
| let lit = match token.kind { |
| token::Ident(name, false) if name.is_bool_lit() => |
| token::Lit::new(token::Bool, name, None), |
| token::Literal(lit) => |
| lit, |
| token::Interpolated(ref nt) => { |
| if let token::NtExpr(expr) | token::NtLiteral(expr) = &**nt { |
| if let ast::ExprKind::Lit(lit) = &expr.kind { |
| return Ok(lit.clone()); |
| } |
| } |
| return Err(LitError::NotLiteral); |
| } |
| _ => return Err(LitError::NotLiteral) |
| }; |
| |
| Lit::from_lit_token(lit, token.span) |
| } |
| |
| /// Attempts to recover an AST literal from semantic literal. |
| /// This function is used when the original token doesn't exist (e.g. the literal is created |
| /// by an AST-based macro) or unavailable (e.g. from HIR pretty-printing). |
| pub fn from_lit_kind(kind: LitKind, span: Span) -> Lit { |
| Lit { token: kind.to_lit_token(), kind, span } |
| } |
| |
| /// Losslessly convert an AST literal into a token stream. |
| pub fn token_tree(&self) -> TokenTree { |
| let token = match self.token.kind { |
| token::Bool => token::Ident(self.token.symbol, false), |
| _ => token::Literal(self.token), |
| }; |
| TokenTree::token(token, self.span) |
| } |
| } |
| |
| fn strip_underscores(symbol: Symbol) -> Symbol { |
| // Do not allocate a new string unless necessary. |
| let s = symbol.as_str(); |
| if s.contains('_') { |
| let mut s = s.to_string(); |
| s.retain(|c| c != '_'); |
| return Symbol::intern(&s); |
| } |
| symbol |
| } |
| |
| fn filtered_float_lit(symbol: Symbol, suffix: Option<Symbol>, base: u32) |
| -> Result<LitKind, LitError> { |
| debug!("filtered_float_lit: {:?}, {:?}, {:?}", symbol, suffix, base); |
| if base != 10 { |
| return Err(LitError::NonDecimalFloat(base)); |
| } |
| Ok(match suffix { |
| Some(suf) => LitKind::Float(symbol, ast::LitFloatType::Suffixed(match suf { |
| sym::f32 => ast::FloatTy::F32, |
| sym::f64 => ast::FloatTy::F64, |
| _ => return Err(LitError::InvalidFloatSuffix), |
| })), |
| None => LitKind::Float(symbol, ast::LitFloatType::Unsuffixed) |
| }) |
| } |
| |
| fn float_lit(symbol: Symbol, suffix: Option<Symbol>) -> Result<LitKind, LitError> { |
| debug!("float_lit: {:?}, {:?}", symbol, suffix); |
| filtered_float_lit(strip_underscores(symbol), suffix, 10) |
| } |
| |
| fn integer_lit(symbol: Symbol, suffix: Option<Symbol>) -> Result<LitKind, LitError> { |
| debug!("integer_lit: {:?}, {:?}", symbol, suffix); |
| let symbol = strip_underscores(symbol); |
| let s = symbol.as_str(); |
| |
| let base = match s.as_bytes() { |
| [b'0', b'x', ..] => 16, |
| [b'0', b'o', ..] => 8, |
| [b'0', b'b', ..] => 2, |
| _ => 10, |
| }; |
| |
| let ty = match suffix { |
| Some(suf) => match suf { |
| sym::isize => ast::LitIntType::Signed(ast::IntTy::Isize), |
| sym::i8 => ast::LitIntType::Signed(ast::IntTy::I8), |
| sym::i16 => ast::LitIntType::Signed(ast::IntTy::I16), |
| sym::i32 => ast::LitIntType::Signed(ast::IntTy::I32), |
| sym::i64 => ast::LitIntType::Signed(ast::IntTy::I64), |
| sym::i128 => ast::LitIntType::Signed(ast::IntTy::I128), |
| sym::usize => ast::LitIntType::Unsigned(ast::UintTy::Usize), |
| sym::u8 => ast::LitIntType::Unsigned(ast::UintTy::U8), |
| sym::u16 => ast::LitIntType::Unsigned(ast::UintTy::U16), |
| sym::u32 => ast::LitIntType::Unsigned(ast::UintTy::U32), |
| sym::u64 => ast::LitIntType::Unsigned(ast::UintTy::U64), |
| sym::u128 => ast::LitIntType::Unsigned(ast::UintTy::U128), |
| // `1f64` and `2f32` etc. are valid float literals, and |
| // `fxxx` looks more like an invalid float literal than invalid integer literal. |
| _ if suf.as_str().starts_with('f') => return filtered_float_lit(symbol, suffix, base), |
| _ => return Err(LitError::InvalidIntSuffix), |
| } |
| _ => ast::LitIntType::Unsuffixed |
| }; |
| |
| let s = &s[if base != 10 { 2 } else { 0 } ..]; |
| u128::from_str_radix(s, base).map(|i| LitKind::Int(i, ty)).map_err(|_| { |
| // Small bases are lexed as if they were base 10, e.g, the string |
| // might be `0b10201`. This will cause the conversion above to fail, |
| // but these kinds of errors are already reported by the lexer. |
| let from_lexer = |
| base < 10 && s.chars().any(|c| c.to_digit(10).map_or(false, |d| d >= base)); |
| if from_lexer { LitError::LexerError } else { LitError::IntTooLarge } |
| }) |
| } |
