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use crate::{common::*, perm_trait::Permutation, size::PermSize};
#[cfg(feature = "std")]
pub use with_std::*;
pub use without_std::*;
#[derive(Clone, Debug, Eq, Hash)]
pub struct Perm<S>
where
S: PermSize,
{
pub(super) indices: S::Container,
}
impl<SL, SR> PartialEq<Perm<SR>> for Perm<SL>
where
SL: PermSize,
SR: PermSize,
{
fn eq(&self, other: &Perm<SR>) -> bool {
self.indices.as_ref() == other.indices.as_ref()
}
}
mod without_std {
use super::*;
use crate::size::Static;
pub type PermS<const SIZE: usize> = Perm<Static<{ SIZE }>>;
pub type Perm0 = PermS<0>;
pub type Perm1 = PermS<1>;
pub type Perm2 = PermS<2>;
pub type Perm4 = PermS<4>;
pub type Perm5 = PermS<5>;
pub type Perm6 = PermS<6>;
pub type Perm7 = PermS<7>;
pub type Perm8 = PermS<8>;
pub type Perm9 = PermS<9>;
pub type Perm10 = PermS<10>;
pub type Perm11 = PermS<11>;
pub type Perm12 = PermS<12>;
pub type Perm13 = PermS<13>;
pub type Perm14 = PermS<14>;
pub type Perm15 = PermS<15>;
pub type Perm16 = PermS<16>;
pub type Perm17 = PermS<17>;
pub type Perm18 = PermS<18>;
pub type Perm19 = PermS<19>;
pub type Perm20 = PermS<20>;
pub type Perm21 = PermS<21>;
pub type Perm22 = PermS<22>;
pub type Perm23 = PermS<23>;
pub type Perm24 = PermS<24>;
pub type Perm25 = PermS<25>;
pub type Perm26 = PermS<26>;
pub type Perm27 = PermS<27>;
pub type Perm28 = PermS<28>;
pub type Perm29 = PermS<29>;
pub type Perm30 = PermS<30>;
pub type Perm31 = PermS<31>;
pub type Perm32 = PermS<32>;
impl<const SIZE: usize> PermS<SIZE> {
pub fn identity() -> Self {
let mut indices = [0; SIZE];
(0..SIZE).for_each(|index| indices[index] = index);
Self { indices }
}
pub fn swap(first: usize, second: usize) -> Option<Self> {
if first >= SIZE || second >= SIZE || first == second {
return None;
}
let min = first.min(second);
let max = first.max(second);
let mut indices = [0; SIZE];
indices[min] = max;
indices[max] = min;
(0..min).for_each(|index| {
indices[index] = index;
});
((min + 1)..max).for_each(|index| {
indices[index] = index;
});
((max + 1)..SIZE).for_each(|index| {
indices[index] = index;
});
Some(Self { indices })
}
pub fn cycle() -> Self {
let mut indices = [0; SIZE];
iter::once(SIZE - 1)
.chain(0..(SIZE - 1))
.enumerate()
.for_each(|(dst, src)| {
indices[dst] = src;
});
Self { indices }
}
pub fn reverse_cycle() -> Self {
let mut indices = [0; SIZE];
(1..SIZE)
.chain(iter::once(0))
.enumerate()
.for_each(|(dst, src)| {
indices[dst] = src;
});
Self { indices }
}
pub fn permute_indices(&self, perm: &PermS<SIZE>) -> Self {
self.conjugate_with(perm)
}
pub fn conjugate_with(&self, other: &PermS<SIZE>) -> Self {
&(&other.inverse() * self) * other
}
pub fn to_size<const NEW_SIZE: usize>(&self) -> Option<PermS<NEW_SIZE>> {
if SIZE > NEW_SIZE {
for dst in NEW_SIZE..SIZE {
let src = self.indices[dst];
if src != dst {
return None;
}
}
let mut new_indices = [0; NEW_SIZE];
new_indices.copy_from_slice(&self.indices[..NEW_SIZE]);
Some(PermS {
indices: new_indices,
})
} else {
let mut new_indices = [0; NEW_SIZE];
new_indices[..SIZE].copy_from_slice(&self.indices[..SIZE]);
(SIZE..NEW_SIZE).for_each(|index| {
new_indices[index] = index;
});
Some(PermS {
indices: new_indices,
})
}
}
}
impl Perm0 {
pub fn empty() -> Self {
Self { indices: [] }
}
}
impl Perm1 {
pub fn unit() -> Self {
Self { indices: [0] }
}
}
impl Perm2 {
pub fn swap2() -> Self {
Self { indices: [1, 0] }
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{apply::PermApply, from_indices::PermFromIndices};
use rand::prelude::*;
#[test]
fn static_identity() {
const SIZE: usize = 2014;
let perm = PermS::<SIZE>::identity();
let mut rng = rand::thread_rng();
let mut orig = [0usize; SIZE];
rng.fill(orig.as_mut());
let mut new = orig.clone();
perm.apply(&mut new);
assert_eq!(orig, new);
}
#[test]
fn static_swap() {
let perm = PermS::<6>::swap(5, 3).unwrap();
assert_eq!(perm.indices(), &[0, 1, 2, 5, 4, 3]);
}
#[test]
fn static_permute_indices() {
let index_map = PermS::from_indices([3, 5, 0, 1, 2, 4]).unwrap();
let orig = PermS::<6>::swap(5, 3).unwrap();
let new = orig.permute_indices(&index_map);
assert_eq!(new, PermS::<6>::swap(0, 1).unwrap());
}
}
}
#[cfg(feature = "std")]
mod with_std {
use super::*;
use crate::{product::PermProduct, size::Dynamic};
pub type PermD = Perm<Dynamic>;
impl PermD {
pub fn empty() -> Self {
Self { indices: vec![] }
}
pub fn unit() -> Self {
Self { indices: vec![0] }
}
pub fn swap(size: usize, first: usize, second: usize) -> Option<Self> {
if first >= size || second >= size || first == second {
return None;
}
let min = first.min(second);
let max = first.max(second);
let indices: Vec<_> = (0..min)
.chain(iter::once(max))
.chain((min + 1)..max)
.chain(iter::once(min))
.chain((max + 1)..size)
.collect();
Some(Self { indices })
}
pub fn identity(size: usize) -> Self {
let mut indices = vec![0; size];
(0..size).for_each(|index| indices[index] = index);
Self { indices }
}
pub fn cycle(size: usize) -> Self {
let mut indices = vec![0; size];
iter::once(size - 1)
.chain(0..(size - 1))
.enumerate()
.for_each(|(dst, src)| {
indices[dst] = src;
});
Self { indices }
}
pub fn reverse_cycle(size: usize) -> Self {
let mut indices = vec![0; size];
(1..size)
.chain(iter::once(0))
.enumerate()
.for_each(|(dst, src)| {
indices[dst] = src;
});
Self { indices }
}
pub fn permute_indices(&self, perm: &PermD) -> Option<Self> {
self.conjugate_with(perm)
}
pub fn conjugate_with(&self, other: &PermD) -> Option<Self> {
other.inverse().perm_product(self)?.perm_product(other)
}
pub fn to_size(&self, new_size: usize) -> Option<PermD> {
let orig_size = self.indices.len();
if orig_size > new_size {
for dst in new_size..orig_size {
let src = self.indices[dst];
if src != dst {
return None;
}
}
let mut new_indices = vec![0; new_size];
new_indices.copy_from_slice(&self.indices[..new_size]);
Some(PermD {
indices: new_indices,
})
} else {
let mut new_indices = vec![0; new_size];
new_indices[..orig_size].copy_from_slice(&self.indices[..orig_size]);
(orig_size..new_size).for_each(|index| {
new_indices[index] = index;
});
Some(PermD {
indices: new_indices,
})
}
}
pub fn into_static<const SIZE: usize>(self) -> Option<PermS<SIZE>> {
let Self { indices } = self;
let indices = <[usize; SIZE]>::try_from(indices).ok()?;
Some(PermS { indices })
}
}
impl<const SIZE: usize> PermS<SIZE> {
pub fn into_dynamic(self) -> PermD {
let Self { indices } = self;
PermD {
indices: Vec::from(indices),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{apply::PermApply, from_indices::PermFromIndices};
use rand::prelude::*;
#[test]
fn dynamic_identity() {
const SIZE: usize = 2014;
let perm = PermD::identity(SIZE);
let mut rng = rand::thread_rng();
let mut orig = [0usize; SIZE];
rng.fill(orig.as_mut());
let mut new = orig.clone();
perm.apply(&mut new).unwrap();
assert_eq!(orig, new);
}
#[test]
fn dynamic_swap() {
let perm = PermD::swap(6, 5, 3).unwrap();
assert_eq!(perm.indices(), &[0, 1, 2, 5, 4, 3]);
}
#[test]
fn dynamic_permute_indices() {
let index_map = PermD::from_indices([3, 5, 0, 1, 2, 4]).unwrap();
let orig = PermD::swap(6, 5, 3).unwrap();
let new = orig.permute_indices(&index_map).unwrap();
assert_eq!(new, PermD::swap(6, 0, 1).unwrap());
}
}
}