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use serde::de::{Deserializer, SeqAccess, Visitor};
use serde::ser::{SerializeSeq, Serializer};
use serde::{Deserialize, Serialize};
use std::collections::BTreeMap;
use std::fmt;
use std::marker::PhantomData;
use std::num::{NonZeroU16, NonZeroU32};
#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
pub struct IntegerId(#[doc(hidden)] pub NonZeroU16);
#[derive(Debug, Default)]
pub struct IntegerInterner {
map: BTreeMap<u64, IntegerId>,
values: Vec<u64>,
}
impl IntegerInterner {
#[inline]
pub fn new() -> Self {
Self::default()
}
#[inline]
pub fn intern(&mut self, value: impl Into<u64>) -> IntegerId {
debug_assert_eq!(self.map.len(), self.values.len());
let value = value.into();
if let Some(id) = self.map.get(&value) {
return *id;
}
assert!((self.values.len() as u64) < (std::u16::MAX as u64));
let id = IntegerId(unsafe { NonZeroU16::new_unchecked(self.values.len() as u16 + 1) });
self.values.push(value);
self.map.insert(value, id);
debug_assert_eq!(self.map.len(), self.values.len());
id
}
pub fn already_interned(&self, value: impl Into<u64>) -> Option<IntegerId> {
let value = value.into();
self.map.get(&value).copied()
}
#[inline]
pub fn lookup(&self, id: IntegerId) -> u64 {
let index = id.0.get() as usize - 1;
self.values[index]
}
}
impl From<IntegerId> for NonZeroU32 {
#[inline]
fn from(id: IntegerId) -> NonZeroU32 {
id.0.into()
}
}
impl Serialize for IntegerInterner {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let mut seq = serializer.serialize_seq(Some(self.values.len()))?;
for p in &self.values {
seq.serialize_element(&p)?;
}
seq.end()
}
}
impl<'de> Deserialize<'de> for IntegerInterner {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
deserializer.deserialize_seq(IntegerInternerVisitor {
marker: PhantomData,
})
}
}
struct IntegerInternerVisitor {
marker: PhantomData<fn() -> IntegerInterner>,
}
impl<'de> Visitor<'de> for IntegerInternerVisitor {
type Value = IntegerInterner;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
write!(
formatter,
"a `peepmatic_runtime::integer_interner::IntegerInterner`"
)
}
fn visit_seq<M>(self, mut access: M) -> Result<Self::Value, M::Error>
where
M: SeqAccess<'de>,
{
const DEFAULT_CAPACITY: usize = 16;
let capacity = access.size_hint().unwrap_or(DEFAULT_CAPACITY);
let mut interner = IntegerInterner {
map: BTreeMap::new(),
values: Vec::with_capacity(capacity),
};
while let Some(path) = access.next_element::<u64>()? {
interner.intern(path);
}
Ok(interner)
}
}
#[cfg(test)]
mod tests {
use super::*;
use serde_test::{assert_tokens, Token};
use std::iter::successors;
#[derive(Debug, Serialize, Deserialize)]
#[serde(transparent)]
pub struct OrderedIntegerInterner(IntegerInterner);
impl PartialEq for OrderedIntegerInterner {
fn eq(&self, other: &OrderedIntegerInterner) -> bool {
self.0.values.iter().eq(other.0.values.iter())
}
}
fn intern_fib(interner: &mut IntegerInterner, skip: usize, take: usize) {
successors(Some((0, 1)), |(a, b): &(u64, u64)| {
a.checked_add(*b).map(|c| (*b, c))
})
.skip(skip)
.take(take)
.for_each(|(i, _)| {
interner.intern(i);
})
}
#[test]
fn test_ser_de_empty_interner() {
let interner = IntegerInterner::new();
assert_tokens(
&OrderedIntegerInterner(interner),
&[Token::Seq { len: Some(0) }, Token::SeqEnd],
);
}
#[test]
fn test_ser_de_fibonacci_interner() {
let mut interner = IntegerInterner::new();
intern_fib(&mut interner, 10, 5);
assert_tokens(
&OrderedIntegerInterner(interner),
&[
Token::Seq { len: Some(5) },
Token::U64(55),
Token::U64(89),
Token::U64(144),
Token::U64(233),
Token::U64(377),
Token::SeqEnd,
],
);
}
}