#
cargo_platform/
cfg.rs

    1use crate::error::{ParseError, ParseErrorKind::*};
    2use std::fmt;
    3use std::hash::{Hash, Hasher};
    4use std::iter;
    5use std::str::{self, FromStr};
    6
    7/// A cfg expression.
    8#[derive(Eq, PartialEq, Hash, Ord, PartialOrd, Clone, Debug)]
    9pub enum CfgExpr {
    10    Not(Box<CfgExpr>),
    11    All(Vec<CfgExpr>),
    12    Any(Vec<CfgExpr>),
    13    Value(Cfg),
    14    True,
    15    False,
    16}
    17
    18/// A cfg value.
    19#[derive(Eq, PartialEq, Hash, Ord, PartialOrd, Clone, Debug)]
    20pub enum Cfg {
    21    /// A named cfg value, like `unix`.
    22    Name(Ident),
    23    /// A key/value cfg pair, like `target_os = "linux"`.
    24    KeyPair(Ident, String),
    25}
    26
    27/// A identifier
    28#[derive(Eq, Ord, PartialOrd, Clone, Debug)]
    29pub struct Ident {
    30    /// The identifier
    31    pub name: String,
    32    /// Is this a raw ident: `r#async`
    33    ///
    34    /// It's mainly used for display and doesn't take
    35    /// part in the hash or equality (`foo` == `r#foo`).
    36    pub raw: bool,
    37}
    38
    39#[derive(PartialEq)]
    40enum Token<'a> {
    41    LeftParen,
    42    RightParen,
    43    Ident(bool, &'a str),
    44    Comma,
    45    Equals,
    46    String(&'a str),
    47}
    48
    49/// The list of keywords.
    50///
    51/// We should consider all the keywords, but some are conditional on
    52/// the edition so for now we just consider true/false.
    53///
    54/// <https://doc.rust-lang.org/reference/keywords.html>
    55pub(crate) const KEYWORDS: &[&str; 2] = &["true", "false"];
    56
    57#[derive(Clone)]
    58struct Tokenizer<'a> {
    59    s: iter::Peekable<str::CharIndices<'a>>,
    60    orig: &'a str,
    61}
    62
    63struct Parser<'a> {
    64    t: Tokenizer<'a>,
    65}
    66
    67impl Ident {
    68    pub fn as_str(&self) -> &str {
    69        &self.name
    70    }
    71}
    72
    73impl Hash for Ident {
    74    fn hash<H: Hasher>(&self, state: &mut H) {
    75        self.name.hash(state);
    76    }
    77}
    78
    79impl PartialEq<str> for Ident {
    80    fn eq(&self, other: &str) -> bool {
    81        self.name == other
    82    }
    83}
    84
    85impl PartialEq<&str> for Ident {
    86    fn eq(&self, other: &&str) -> bool {
    87        self.name == *other
    88    }
    89}
    90
    91impl PartialEq<Ident> for Ident {
    92    fn eq(&self, other: &Ident) -> bool {
    93        self.name == other.name
    94    }
    95}
    96
    97impl fmt::Display for Ident {
    98    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    99        if self.raw {
    100            f.write_str("r#")?;
    101        }
    102        f.write_str(&*self.name)
    103    }
    104}
    105
    106impl FromStr for Cfg {
    107    type Err = ParseError;
    108
    109    fn from_str(s: &str) -> Result<Cfg, Self::Err> {
    110        let mut p = Parser::new(s);
    111        let e = p.cfg()?;
    112        if let Some(rest) = p.rest() {
    113            return Err(ParseError::new(
    114                p.t.orig,
    115                UnterminatedExpression(rest.to_string()),
    116            ));
    117        }
    118        Ok(e)
    119    }
    120}
    121
    122impl fmt::Display for Cfg {
    123    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    124        match *self {
    125            Cfg::Name(ref s) => s.fmt(f),
    126            Cfg::KeyPair(ref k, ref v) => write!(f, "{} = \"{}\"", k, v),
    127        }
    128    }
    129}
    130
    131impl CfgExpr {
    132    /// Utility function to check if the key, "cfg(..)" matches the `target_cfg`
    133    pub fn matches_key(key: &str, target_cfg: &[Cfg]) -> bool {
    134        if key.starts_with("cfg(") && key.ends_with(')') {
    135            let cfg = &key[4..key.len() - 1];
    136
    137            CfgExpr::from_str(cfg)
    138                .ok()
    139                .map(|ce| ce.matches(target_cfg))
    140                .unwrap_or(false)
    141        } else {
    142            false
    143        }
    144    }
    145
    146    pub fn matches(&self, cfg: &[Cfg]) -> bool {
    147        match *self {
    148            CfgExpr::Not(ref e) => !e.matches(cfg),
    149            CfgExpr::All(ref e) => e.iter().all(|e| e.matches(cfg)),
    150            CfgExpr::Any(ref e) => e.iter().any(|e| e.matches(cfg)),
    151            CfgExpr::Value(ref e) => cfg.contains(e),
    152            CfgExpr::True => true,
    153            CfgExpr::False => false,
    154        }
    155    }
    156}
    157
    158impl FromStr for CfgExpr {
    159    type Err = ParseError;
    160
    161    fn from_str(s: &str) -> Result<CfgExpr, Self::Err> {
    162        let mut p = Parser::new(s);
    163        let e = p.expr()?;
    164        if let Some(rest) = p.rest() {
    165            return Err(ParseError::new(
    166                p.t.orig,
    167                UnterminatedExpression(rest.to_string()),
    168            ));
    169        }
    170        Ok(e)
    171    }
    172}
    173
    174impl fmt::Display for CfgExpr {
    175    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    176        match *self {
    177            CfgExpr::Not(ref e) => write!(f, "not({})", e),
    178            CfgExpr::All(ref e) => write!(f, "all({})", CommaSep(e)),
    179            CfgExpr::Any(ref e) => write!(f, "any({})", CommaSep(e)),
    180            CfgExpr::Value(ref e) => write!(f, "{}", e),
    181            CfgExpr::True => write!(f, "true"),
    182            CfgExpr::False => write!(f, "false"),
    183        }
    184    }
    185}
    186
    187struct CommaSep<'a, T>(&'a [T]);
    188
    189impl<'a, T: fmt::Display> fmt::Display for CommaSep<'a, T> {
    190    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
    191        for (i, v) in self.0.iter().enumerate() {
    192            if i > 0 {
    193                write!(f, ", ")?;
    194            }
    195            write!(f, "{}", v)?;
    196        }
    197        Ok(())
    198    }
    199}
    200
    201impl<'a> Parser<'a> {
    202    fn new(s: &'a str) -> Parser<'a> {
    203        Parser {
    204            t: Tokenizer {
    205                s: s.char_indices().peekable(),
    206                orig: s,
    207            },
    208        }
    209    }
    210
    211    fn expr(&mut self) -> Result<CfgExpr, ParseError> {
    212        match self.peek() {
    213            Some(Ok(Token::Ident(false, op @ "all")))
    214            | Some(Ok(Token::Ident(false, op @ "any"))) => {
    215                self.t.next();
    216                let mut e = Vec::new();
    217                self.eat(&Token::LeftParen)?;
    218                while !self.r#try(&Token::RightParen) {
    219                    e.push(self.expr()?);
    220                    if !self.r#try(&Token::Comma) {
    221                        self.eat(&Token::RightParen)?;
    222                        break;
    223                    }
    224                }
    225                if op == "all" {
    226                    Ok(CfgExpr::All(e))
    227                } else {
    228                    Ok(CfgExpr::Any(e))
    229                }
    230            }
    231            Some(Ok(Token::Ident(false, "not"))) => {
    232                self.t.next();
    233                self.eat(&Token::LeftParen)?;
    234                let e = self.expr()?;
    235                self.eat(&Token::RightParen)?;
    236                Ok(CfgExpr::Not(Box::new(e)))
    237            }
    238            Some(Ok(..)) => self.cfg().map(|v| match v {
    239                Cfg::Name(n) if n == "true" => CfgExpr::True,
    240                Cfg::Name(n) if n == "false" => CfgExpr::False,
    241                v => CfgExpr::Value(v),
    242            }),
    243            Some(Err(..)) => Err(self.t.next().unwrap().err().unwrap()),
    244            None => Err(ParseError::new(
    245                self.t.orig,
    246                IncompleteExpr("start of a cfg expression"),
    247            )),
    248        }
    249    }
    250
    251    fn cfg(&mut self) -> Result<Cfg, ParseError> {
    252        match self.t.next() {
    253            Some(Ok(Token::Ident(raw, name))) => {
    254                let e = if self.r#try(&Token::Equals) {
    255                    let val = match self.t.next() {
    256                        Some(Ok(Token::String(s))) => s,
    257                        Some(Ok(t)) => {
    258                            return Err(ParseError::new(
    259                                self.t.orig,
    260                                UnexpectedToken {
    261                                    expected: "a string",
    262                                    found: t.classify(),
    263                                },
    264                            ));
    265                        }
    266                        Some(Err(e)) => return Err(e),
    267                        None => {
    268                            return Err(ParseError::new(self.t.orig, IncompleteExpr("a string")));
    269                        }
    270                    };
    271                    Cfg::KeyPair(
    272                        Ident {
    273                            name: name.to_string(),
    274                            raw,
    275                        },
    276                        val.to_string(),
    277                    )
    278                } else {
    279                    Cfg::Name(Ident {
    280                        name: name.to_string(),
    281                        raw,
    282                    })
    283                };
    284                Ok(e)
    285            }
    286            Some(Ok(t)) => Err(ParseError::new(
    287                self.t.orig,
    288                UnexpectedToken {
    289                    expected: "identifier",
    290                    found: t.classify(),
    291                },
    292            )),
    293            Some(Err(e)) => Err(e),
    294            None => Err(ParseError::new(self.t.orig, IncompleteExpr("identifier"))),
    295        }
    296    }
    297
    298    fn peek(&mut self) -> Option<Result<Token<'a>, ParseError>> {
    299        self.t.clone().next()
    300    }
    301
    302    fn r#try(&mut self, token: &Token<'a>) -> bool {
    303        match self.peek() {
    304            Some(Ok(ref t)) if token == t => {}
    305            _ => return false,
    306        }
    307        self.t.next();
    308        true
    309    }
    310
    311    fn eat(&mut self, token: &Token<'a>) -> Result<(), ParseError> {
    312        match self.t.next() {
    313            Some(Ok(ref t)) if token == t => Ok(()),
    314            Some(Ok(t)) => Err(ParseError::new(
    315                self.t.orig,
    316                UnexpectedToken {
    317                    expected: token.classify(),
    318                    found: t.classify(),
    319                },
    320            )),
    321            Some(Err(e)) => Err(e),
    322            None => Err(ParseError::new(
    323                self.t.orig,
    324                IncompleteExpr(token.classify()),
    325            )),
    326        }
    327    }
    328
    329    /// Returns the rest of the input from the current location.
    330    fn rest(&self) -> Option<&str> {
    331        let mut s = self.t.s.clone();
    332        loop {
    333            match s.next() {
    334                Some((_, ' ')) => {}
    335                Some((start, _ch)) => return Some(&self.t.orig[start..]),
    336                None => return None,
    337            }
    338        }
    339    }
    340}
    341
    342impl<'a> Iterator for Tokenizer<'a> {
    343    type Item = Result<Token<'a>, ParseError>;
    344
    345    fn next(&mut self) -> Option<Result<Token<'a>, ParseError>> {
    346        loop {
    347            match self.s.next() {
    348                Some((_, ' ')) => {}
    349                Some((_, '(')) => return Some(Ok(Token::LeftParen)),
    350                Some((_, ')')) => return Some(Ok(Token::RightParen)),
    351                Some((_, ',')) => return Some(Ok(Token::Comma)),
    352                Some((_, '=')) => return Some(Ok(Token::Equals)),
    353                Some((start, '"')) => {
    354                    while let Some((end, ch)) = self.s.next() {
    355                        if ch == '"' {
    356                            return Some(Ok(Token::String(&self.orig[start + 1..end])));
    357                        }
    358                    }
    359                    return Some(Err(ParseError::new(self.orig, UnterminatedString)));
    360                }
    361                Some((start, ch)) if is_ident_start(ch) => {
    362                    let (start, raw) = if ch == 'r' {
    363                        if let Some(&(_pos, '#')) = self.s.peek() {
    364                            // starts with `r#` is a raw ident
    365                            self.s.next();
    366                            if let Some((start, ch)) = self.s.next() {
    367                                if is_ident_start(ch) {
    368                                    (start, true)
    369                                } else {
    370                                    // not a starting ident character
    371                                    return Some(Err(ParseError::new(
    372                                        self.orig,
    373                                        UnexpectedChar(ch),
    374                                    )));
    375                                }
    376                            } else {
    377                                // not followed by a ident, error out
    378                                return Some(Err(ParseError::new(
    379                                    self.orig,
    380                                    IncompleteExpr("identifier"),
    381                                )));
    382                            }
    383                        } else {
    384                            // starts with `r` but not does continue with `#`
    385                            // cannot be a raw ident
    386                            (start, false)
    387                        }
    388                    } else {
    389                        // do not start with `r`, cannot be a raw ident
    390                        (start, false)
    391                    };
    392                    while let Some(&(end, ch)) = self.s.peek() {
    393                        if !is_ident_rest(ch) {
    394                            return Some(Ok(Token::Ident(raw, &self.orig[start..end])));
    395                        } else {
    396                            self.s.next();
    397                        }
    398                    }
    399                    return Some(Ok(Token::Ident(raw, &self.orig[start..])));
    400                }
    401                Some((_, ch)) => {
    402                    return Some(Err(ParseError::new(self.orig, UnexpectedChar(ch))));
    403                }
    404                None => return None,
    405            }
    406        }
    407    }
    408}
    409
    410fn is_ident_start(ch: char) -> bool {
    411    ch == '_' || ch.is_ascii_alphabetic()
    412}
    413
    414fn is_ident_rest(ch: char) -> bool {
    415    is_ident_start(ch) || ch.is_ascii_digit()
    416}
    417
    418impl<'a> Token<'a> {
    419    fn classify(&self) -> &'static str {
    420        match *self {
    421            Token::LeftParen => "`(`",
    422            Token::RightParen => "`)`",
    423            Token::Ident(..) => "an identifier",
    424            Token::Comma => "`,`",
    425            Token::Equals => "`=`",
    426            Token::String(..) => "a string",
    427        }
    428    }
    429}