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use crate::error::{ParseError, ParseErrorKind::*};
use std::fmt;
use std::iter;
use std::str::{self, FromStr};
/// A cfg expression.
#[derive(Eq, PartialEq, Hash, Ord, PartialOrd, Clone, Debug)]
pub enum CfgExpr {
Not(Box<CfgExpr>),
All(Vec<CfgExpr>),
Any(Vec<CfgExpr>),
Value(Cfg),
}
/// A cfg value.
#[derive(Eq, PartialEq, Hash, Ord, PartialOrd, Clone, Debug)]
pub enum Cfg {
/// A named cfg value, like `unix`.
Name(String),
/// A key/value cfg pair, like `target_os = "linux"`.
KeyPair(String, String),
}
#[derive(PartialEq)]
enum Token<'a> {
LeftParen,
RightParen,
Ident(&'a str),
Comma,
Equals,
String(&'a str),
}
#[derive(Clone)]
struct Tokenizer<'a> {
s: iter::Peekable<str::CharIndices<'a>>,
orig: &'a str,
}
struct Parser<'a> {
t: Tokenizer<'a>,
}
impl FromStr for Cfg {
type Err = ParseError;
fn from_str(s: &str) -> Result<Cfg, Self::Err> {
let mut p = Parser::new(s);
let e = p.cfg()?;
if let Some(rest) = p.rest() {
return Err(ParseError::new(
p.t.orig,
UnterminatedExpression(rest.to_string()),
));
}
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 {
/// Utility function to check if the key, "cfg(..)" matches the `target_cfg`
pub fn matches_key(key: &str, target_cfg: &[Cfg]) -> bool {
if key.starts_with("cfg(") && key.ends_with(')') {
let cfg = &key[4..key.len() - 1];
CfgExpr::from_str(cfg)
.ok()
.map(|ce| ce.matches(target_cfg))
.unwrap_or(false)
} else {
false
}
}
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 = ParseError;
fn from_str(s: &str) -> Result<CfgExpr, Self::Err> {
let mut p = Parser::new(s);
let e = p.expr()?;
if let Some(rest) = p.rest() {
return Err(ParseError::new(
p.t.orig,
UnterminatedExpression(rest.to_string()),
));
}
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 [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,
},
}
}
fn expr(&mut self) -> Result<CfgExpr, ParseError> {
match self.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.r#try(&Token::RightParen) {
e.push(self.expr()?);
if !self.r#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 => Err(ParseError::new(
self.t.orig,
IncompleteExpr("start of a cfg expression"),
)),
}
}
fn cfg(&mut self) -> Result<Cfg, ParseError> {
match self.t.next() {
Some(Ok(Token::Ident(name))) => {
let e = if self.r#try(&Token::Equals) {
let val = match self.t.next() {
Some(Ok(Token::String(s))) => s,
Some(Ok(t)) => {
return Err(ParseError::new(
self.t.orig,
UnexpectedToken {
expected: "a string",
found: t.classify(),
},
))
}
Some(Err(e)) => return Err(e),
None => {
return Err(ParseError::new(self.t.orig, IncompleteExpr("a string")))
}
};
Cfg::KeyPair(name.to_string(), val.to_string())
} else {
Cfg::Name(name.to_string())
};
Ok(e)
}
Some(Ok(t)) => Err(ParseError::new(
self.t.orig,
UnexpectedToken {
expected: "identifier",
found: t.classify(),
},
)),
Some(Err(e)) => Err(e),
None => Err(ParseError::new(self.t.orig, IncompleteExpr("identifier"))),
}
}
fn peek(&mut self) -> Option<Result<Token<'a>, ParseError>> {
self.t.clone().next()
}
fn r#try(&mut self, token: &Token<'a>) -> bool {
match self.peek() {
Some(Ok(ref t)) if token == t => {}
_ => return false,
}
self.t.next();
true
}
fn eat(&mut self, token: &Token<'a>) -> Result<(), ParseError> {
match self.t.next() {
Some(Ok(ref t)) if token == t => Ok(()),
Some(Ok(t)) => Err(ParseError::new(
self.t.orig,
UnexpectedToken {
expected: token.classify(),
found: t.classify(),
},
)),
Some(Err(e)) => Err(e),
None => Err(ParseError::new(
self.t.orig,
IncompleteExpr(token.classify()),
)),
}
}
/// Returns the rest of the input from the current location.
fn rest(&self) -> Option<&str> {
let mut s = self.t.s.clone();
loop {
match s.next() {
Some((_, ' ')) => {}
Some((start, _ch)) => return Some(&self.t.orig[start..]),
None => return None,
}
}
}
}
impl<'a> Iterator for Tokenizer<'a> {
type Item = Result<Token<'a>, ParseError>;
fn next(&mut self) -> Option<Result<Token<'a>, ParseError>> {
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(ParseError::new(self.orig, UnterminatedString)));
}
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(ParseError::new(self.orig, UnexpectedChar(ch))));
}
None => return None,
}
}
}
}
fn is_ident_start(ch: char) -> bool {
ch == '_' || ch.is_ascii_alphabetic()
}
fn is_ident_rest(ch: char) -> bool {
is_ident_start(ch) || ch.is_ascii_digit()
}
impl<'a> Token<'a> {
fn classify(&self) -> &'static str {
match *self {
Token::LeftParen => "`(`",
Token::RightParen => "`)`",
Token::Ident(..) => "an identifier",
Token::Comma => "`,`",
Token::Equals => "`=`",
Token::String(..) => "a string",
}
}
}