summaryrefslogtreecommitdiffstats
path: root/compiler/rustc_ast/src/util/literal.rs
blob: 9c18f55c03b4d28c091bf6cc411f215e7fc05c91 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
//! Code related to parsing literals.

use crate::ast::{self, Lit, LitKind};
use crate::token::{self, Token};

use rustc_lexer::unescape::{unescape_byte, unescape_char};
use rustc_lexer::unescape::{unescape_byte_literal, unescape_literal, Mode};
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::Span;

use std::ascii;
use tracing::debug;

pub enum LitError {
    NotLiteral,
    LexerError,
    InvalidSuffix,
    InvalidIntSuffix,
    InvalidFloatSuffix,
    NonDecimalFloat(u32),
    IntTooLarge,
}

impl LitKind {
    /// Converts literal token into a semantic literal.
    pub 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(());
                    // Force-inlining here is aggressive but the closure is
                    // called on every char in the string, so it can be
                    // hot in programs with many long strings.
                    unescape_literal(
                        &s,
                        Mode::Str,
                        &mut #[inline(always)]
                        |_, unescaped_char| match unescaped_char {
                            Ok(c) => buf.push(c),
                            Err(err) => {
                                if err.is_fatal() {
                                    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_literal(&s, Mode::RawStr, &mut |_, unescaped_char| {
                            match unescaped_char {
                                Ok(c) => buf.push(c),
                                Err(err) => {
                                    if err.is_fatal() {
                                        error = Err(LitError::LexerError);
                                    }
                                }
                            }
                        });
                        error?;
                        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_literal(&s, Mode::ByteStr, &mut |_, unescaped_byte| {
                    match unescaped_byte {
                        Ok(c) => buf.push(c),
                        Err(err) => {
                            if err.is_fatal() {
                                error = Err(LitError::LexerError);
                            }
                        }
                    }
                });
                error?;
                LitKind::ByteStr(buf.into())
            }
            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_byte_literal(&s, Mode::RawByteStr, &mut |_, unescaped_byte| {
                        match unescaped_byte {
                            Ok(c) => buf.push(c),
                            Err(err) => {
                                if err.is_fatal() {
                                    error = Err(LitError::LexerError);
                                }
                            }
                        }
                    });
                    error?;
                    buf
                } else {
                    symbol.to_string().into_bytes()
                };

                LitKind::ByteStr(bytes.into())
            }
            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.
    ///
    /// Keep this in sync with `Token::can_begin_literal_or_bool` excluding unary negation.
    pub fn from_token(token: &Token) -> Result<Lit, LitError> {
        let lit = match token.uninterpolate().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
                    && 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.
    pub fn to_token(&self) -> Token {
        let kind = match self.token.kind {
            token::Bool => token::Ident(self.token.symbol, false),
            _ => token::Literal(self.token),
        };
        Token::new(kind, 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 }
    })
}