rust/crates/cfg/src/lib.rs
2021-05-07 23:50:24 +03:00

150 lines
4.2 KiB
Rust

//! cfg defines conditional compiling options, `cfg` attibute parser and evaluator
mod cfg_expr;
mod dnf;
#[cfg(test)]
mod tests;
use std::fmt;
use rustc_hash::FxHashSet;
use tt::SmolStr;
pub use cfg_expr::{CfgAtom, CfgExpr};
pub use dnf::DnfExpr;
/// Configuration options used for conditional compilation on items with `cfg` attributes.
/// We have two kind of options in different namespaces: atomic options like `unix`, and
/// key-value options like `target_arch="x86"`.
///
/// Note that for key-value options, one key can have multiple values (but not none).
/// `feature` is an example. We have both `feature="foo"` and `feature="bar"` if features
/// `foo` and `bar` are both enabled. And here, we store key-value options as a set of tuple
/// of key and value in `key_values`.
///
/// See: https://doc.rust-lang.org/reference/conditional-compilation.html#set-configuration-options
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct CfgOptions {
enabled: FxHashSet<CfgAtom>,
}
impl CfgOptions {
pub fn check(&self, cfg: &CfgExpr) -> Option<bool> {
cfg.fold(&|atom| self.enabled.contains(atom))
}
pub fn insert_atom(&mut self, key: SmolStr) {
self.enabled.insert(CfgAtom::Flag(key));
}
pub fn insert_key_value(&mut self, key: SmolStr, value: SmolStr) {
self.enabled.insert(CfgAtom::KeyValue { key, value });
}
pub fn apply_diff(&mut self, diff: CfgDiff) {
for atom in diff.enable {
self.enabled.insert(atom);
}
for atom in diff.disable {
self.enabled.remove(&atom);
}
}
}
pub struct CfgDiff {
// Invariants: No duplicates, no atom that's both in `enable` and `disable`.
enable: Vec<CfgAtom>,
disable: Vec<CfgAtom>,
}
impl CfgDiff {
/// Returns the total number of atoms changed by this diff.
pub fn len(&self) -> usize {
self.enable.len() + self.disable.len()
}
}
impl fmt::Display for CfgDiff {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if !self.enable.is_empty() {
f.write_str("enable ")?;
for (i, atom) in self.enable.iter().enumerate() {
let sep = match i {
0 => "",
_ if i == self.enable.len() - 1 => " and ",
_ => ", ",
};
f.write_str(sep)?;
write!(f, "{}", atom)?;
}
if !self.disable.is_empty() {
f.write_str("; ")?;
}
}
if !self.disable.is_empty() {
f.write_str("disable ")?;
for (i, atom) in self.disable.iter().enumerate() {
let sep = match i {
0 => "",
_ if i == self.enable.len() - 1 => " and ",
_ => ", ",
};
f.write_str(sep)?;
write!(f, "{}", atom)?;
}
}
Ok(())
}
}
pub struct InactiveReason {
enabled: Vec<CfgAtom>,
disabled: Vec<CfgAtom>,
}
impl fmt::Display for InactiveReason {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if !self.enabled.is_empty() {
for (i, atom) in self.enabled.iter().enumerate() {
let sep = match i {
0 => "",
_ if i == self.enabled.len() - 1 => " and ",
_ => ", ",
};
f.write_str(sep)?;
write!(f, "{}", atom)?;
}
let is_are = if self.enabled.len() == 1 { "is" } else { "are" };
write!(f, " {} enabled", is_are)?;
if !self.disabled.is_empty() {
f.write_str(" and ")?;
}
}
if !self.disabled.is_empty() {
for (i, atom) in self.disabled.iter().enumerate() {
let sep = match i {
0 => "",
_ if i == self.disabled.len() - 1 => " and ",
_ => ", ",
};
f.write_str(sep)?;
write!(f, "{}", atom)?;
}
let is_are = if self.disabled.len() == 1 { "is" } else { "are" };
write!(f, " {} disabled", is_are)?;
}
Ok(())
}
}