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|
//! Iterating over set flag values.
use crate::{Flags, Flag};
/// An iterator over a set of flags.
///
/// Any bits that don't correspond to a valid flag will be yielded
/// as a final item from the iterator.
pub struct Iter<B: 'static> {
inner: IterNames<B>,
done: bool,
}
impl<B: Flags> Iter<B> {
/// Create a new iterator over the given set of flags.
pub(crate) fn new(flags: &B) -> Self {
Iter {
inner: IterNames::new(flags),
done: false,
}
}
}
impl<B: 'static> Iter<B> {
#[doc(hidden)]
pub const fn __private_const_new(flags: &'static [Flag<B>], source: B, state: B) -> Self {
Iter {
inner: IterNames::__private_const_new(flags, source, state),
done: false,
}
}
}
impl<B: Flags> Iterator for Iter<B> {
type Item = B;
fn next(&mut self) -> Option<Self::Item> {
match self.inner.next() {
Some((_, flag)) => Some(flag),
None if !self.done => {
self.done = true;
// After iterating through valid names, if there are any bits left over
// then return one final value that includes them. This makes `into_iter`
// and `from_iter` roundtrip
if !self.inner.remaining().is_empty() {
Some(B::from_bits_retain(self.inner.state.bits()))
} else {
None
}
}
None => None,
}
}
}
/// An iterator over a set of flags and their names.
///
/// Any bits that don't correspond to a valid flag will be ignored.
pub struct IterNames<B: 'static> {
flags: &'static [Flag<B>],
idx: usize,
source: B,
state: B,
}
impl<B: Flags> IterNames<B> {
/// Create a new iterator over the given set of flags.
pub(crate) fn new(flags: &B) -> Self {
IterNames {
flags: B::FLAGS,
idx: 0,
state: B::from_bits_retain(flags.bits()),
source: B::from_bits_retain(flags.bits()),
}
}
}
impl<B: 'static> IterNames<B> {
#[doc(hidden)]
pub const fn __private_const_new(flags: &'static [Flag<B>], source: B, state: B) -> Self {
IterNames {
flags,
idx: 0,
state,
source,
}
}
/// Get the remaining (unyielded) flags.
///
/// Once the iterator has finished, this method can be used to
/// check whether or not there are any bits that didn't correspond
/// to a valid flag remaining.
pub fn remaining(&self) -> &B {
&self.state
}
}
impl<B: Flags> Iterator for IterNames<B> {
type Item = (&'static str, B);
fn next(&mut self) -> Option<Self::Item> {
while let Some(flag) = self.flags.get(self.idx) {
// Short-circuit if our state is empty
if self.state.is_empty() {
return None;
}
self.idx += 1;
let bits = flag.value().bits();
// NOTE: We check whether the flag exists in self, but remove it from
// a different value. This ensure that overlapping flags are handled
// properly. Take the following example:
//
// const A: 0b00000001;
// const B: 0b00000101;
//
// Given the bits 0b00000101, both A and B are set. But if we removed A
// as we encountered it we'd be left with 0b00000100, which doesn't
// correspond to a valid flag on its own.
if self.source.contains(B::from_bits_retain(bits)) {
self.state.remove(B::from_bits_retain(bits));
return Some((flag.name(), B::from_bits_retain(bits)));
}
}
None
}
}
|
