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use std::str::{self, FromStr}; use std::iter; use std::fmt; use util::{CargoError, CargoResult, human}; #[derive(Clone, PartialEq, Debug)] pub enum Cfg { Name(String), KeyPair(String, String), } #[derive(Clone, PartialEq, Debug)] pub enum CfgExpr { Not(Box<CfgExpr>), All(Vec<CfgExpr>), Any(Vec<CfgExpr>), Value(Cfg), } #[derive(PartialEq)] enum Token<'a> { LeftParen, RightParen, Ident(&'a str), Comma, Equals, String(&'a str), } struct Tokenizer<'a> { s: iter::Peekable<str::CharIndices<'a>>, orig: &'a str, } struct Parser<'a> { t: iter::Peekable<Tokenizer<'a>>, } impl FromStr for Cfg { type Err = Box<CargoError>; fn from_str(s: &str) -> CargoResult<Cfg> { let mut p = Parser::new(s); let e = p.cfg()?; if p.t.next().is_some() { bail!("malformed cfg value or key/value pair") } Ok(e) } } impl fmt::Display for Cfg { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { Cfg::Name(ref s) => s.fmt(f), Cfg::KeyPair(ref k, ref v) => write!(f, "{} = \"{}\"", k, v), } } } impl CfgExpr { pub fn matches(&self, cfg: &[Cfg]) -> bool { match *self { CfgExpr::Not(ref e) => !e.matches(cfg), CfgExpr::All(ref e) => e.iter().all(|e| e.matches(cfg)), CfgExpr::Any(ref e) => e.iter().any(|e| e.matches(cfg)), CfgExpr::Value(ref e) => cfg.contains(e), } } } impl FromStr for CfgExpr { type Err = Box<CargoError>; fn from_str(s: &str) -> CargoResult<CfgExpr> { let mut p = Parser::new(s); let e = p.expr()?; if p.t.next().is_some() { bail!("can only have one cfg-expression, consider using all() or \ any() explicitly") } Ok(e) } } impl fmt::Display for CfgExpr { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { CfgExpr::Not(ref e) => write!(f, "not({})", e), CfgExpr::All(ref e) => write!(f, "all({})", CommaSep(e)), CfgExpr::Any(ref e) => write!(f, "any({})", CommaSep(e)), CfgExpr::Value(ref e) => write!(f, "{}", e), } } } struct CommaSep<'a, T: 'a>(&'a [T]); impl<'a, T: fmt::Display> fmt::Display for CommaSep<'a, T> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { for (i, v) in self.0.iter().enumerate() { if i > 0 { write!(f, ", ")?; } write!(f, "{}", v)?; } Ok(()) } } impl<'a> Parser<'a> { fn new(s: &'a str) -> Parser<'a> { Parser { t: Tokenizer { s: s.char_indices().peekable(), orig: s, }.peekable(), } } fn expr(&mut self) -> CargoResult<CfgExpr> { match self.t.peek() { Some(&Ok(Token::Ident(op @ "all"))) | Some(&Ok(Token::Ident(op @ "any"))) => { self.t.next(); let mut e = Vec::new(); self.eat(Token::LeftParen)?; while !self.try(Token::RightParen) { e.push(self.expr()?); if !self.try(Token::Comma) { self.eat(Token::RightParen)?; break } } if op == "all" { Ok(CfgExpr::All(e)) } else { Ok(CfgExpr::Any(e)) } } Some(&Ok(Token::Ident("not"))) => { self.t.next(); self.eat(Token::LeftParen)?; let e = self.expr()?; self.eat(Token::RightParen)?; Ok(CfgExpr::Not(Box::new(e))) } Some(&Ok(..)) => self.cfg().map(CfgExpr::Value), Some(&Err(..)) => { Err(self.t.next().unwrap().err().unwrap()) } None => bail!("expected start of a cfg expression, \ found nothing"), } } fn cfg(&mut self) -> CargoResult<Cfg> { match self.t.next() { Some(Ok(Token::Ident(name))) => { let e = if self.try(Token::Equals) { let val = match self.t.next() { Some(Ok(Token::String(s))) => s, Some(Ok(t)) => bail!("expected a string, found {}", t.classify()), Some(Err(e)) => return Err(e), None => bail!("expected a string, found nothing"), }; Cfg::KeyPair(name.to_string(), val.to_string()) } else { Cfg::Name(name.to_string()) }; Ok(e) } Some(Ok(t)) => bail!("expected identifier, found {}", t.classify()), Some(Err(e)) => Err(e), None => bail!("expected identifier, found nothing"), } } fn try(&mut self, token: Token<'a>) -> bool { match self.t.peek() { Some(&Ok(ref t)) if token == *t => {} _ => return false, } self.t.next(); true } fn eat(&mut self, token: Token<'a>) -> CargoResult<()> { match self.t.next() { Some(Ok(ref t)) if token == *t => Ok(()), Some(Ok(t)) => bail!("expected {}, found {}", token.classify(), t.classify()), Some(Err(e)) => Err(e), None => bail!("expected {}, but cfg expr ended", token.classify()), } } } impl<'a> Iterator for Tokenizer<'a> { type Item = CargoResult<Token<'a>>; fn next(&mut self) -> Option<CargoResult<Token<'a>>> { loop { match self.s.next() { Some((_, ' ')) => {} Some((_, '(')) => return Some(Ok(Token::LeftParen)), Some((_, ')')) => return Some(Ok(Token::RightParen)), Some((_, ',')) => return Some(Ok(Token::Comma)), Some((_, '=')) => return Some(Ok(Token::Equals)), Some((start, '"')) => { while let Some((end, ch)) = self.s.next() { if ch == '"' { return Some(Ok(Token::String(&self.orig[start+1..end]))) } } return Some(Err(human("unterminated string in cfg".to_string()))) } Some((start, ch)) if is_ident_start(ch) => { while let Some(&(end, ch)) = self.s.peek() { if !is_ident_rest(ch) { return Some(Ok(Token::Ident(&self.orig[start..end]))) } else { self.s.next(); } } return Some(Ok(Token::Ident(&self.orig[start..]))) } Some((_, ch)) => { return Some(Err(human(format!("unexpected character in \ cfg `{}`, expected parens, \ a comma, an identifier, or \ a string", ch)))) } None => return None } } } } fn is_ident_start(ch: char) -> bool { ch == '_' || ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z') } fn is_ident_rest(ch: char) -> bool { is_ident_start(ch) || ('0' <= ch && ch <= '9') } impl<'a> Token<'a> { fn classify(&self) -> &str { match *self { Token::LeftParen => "`(`", Token::RightParen => "`)`", Token::Ident(..) => "an identifier", Token::Comma => "`,`", Token::Equals => "`=`", Token::String(..) => "a string", } } }