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best_projection.rs
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best_projection.rs
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use std::collections::hash_map::Entry::*;
use std::collections::HashMap;
use std::convert::TryFrom;
use crate::HashedSlice;
use crate::Tokenization;
#[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Clone, Copy, Hash)]
struct Coord {
next_lcs: usize,
next_seq: usize,
}
#[derive(Debug)]
pub struct NormalizationInput<'a> {
pub seq: &'a Tokenization<'a>,
pub lcs: &'a Tokenization<'a>,
}
#[derive(Debug)]
struct Context<'a> {
seq_index: HashMap<HashedSlice<'a>, Vec<usize>>,
}
impl<'a> Context<'a> {
fn new(input: &'a NormalizationInput) -> Self {
let mut seq_index = HashMap::new();
for i in 0..to_isize(input.lcs.nb_tokens()) {
match seq_index.entry(input.lcs.nth_token(i)) {
Occupied(_) => (),
Vacant(e) => {
e.insert(vec![]);
}
}
}
for i in 0..input.seq.nb_tokens() {
match seq_index.entry(input.seq.nth_token(to_isize(i))) {
Occupied(e) => {
e.into_mut().push(i);
}
Vacant(_) => (),
}
}
Context { seq_index }
}
fn get_indexes(&self, tok: &HashedSlice<'a>, min_value: usize) -> &[usize] {
match self.seq_index.get(tok) {
Some(values) => {
let min_idx = match values.binary_search(&min_value) {
Ok(i) | Err(i) => i,
};
&values[min_idx..]
}
None => &[],
}
}
}
#[derive(Debug)]
pub struct NormalizationResult {
pub path: Vec<isize>,
pub starts_with_shared: bool,
}
pub fn normalize_partition(input: &NormalizationInput) -> NormalizationResult {
let context = Context::new(input);
let root = Coord {
next_lcs: 0,
next_seq: 0,
};
let target = Coord {
next_lcs: input.lcs.nb_tokens(),
next_seq: input.seq.nb_tokens(),
};
let mut frontier = vec![root];
let mut prev = HashMap::new();
let mut found_seq = None;
while !frontier.is_empty() && found_seq == None {
let mut new_frontier = vec![];
for coord in frontier {
if coord.next_lcs == target.next_lcs {
found_seq = Some(coord.next_seq);
if coord.next_seq == target.next_seq {
break;
} else {
// TODO do something more clever here
continue;
}
}
let start_lcs = coord.next_lcs;
let lcs_len = input.lcs.nb_tokens() - start_lcs;
let mut last_enqueued_snake_len = 0;
for start_seq in context.get_indexes(
&input.lcs.nth_token(coord.next_lcs as isize),
coord.next_seq,
) {
if start_seq + lcs_len > input.seq.nb_tokens() {
break;
}
let mut snake_len = 1;
let max_smake_len = lcs_len.min(input.seq.nb_tokens() - start_seq);
while snake_len < max_smake_len {
let lcs_tok = input.lcs.nth_token((start_lcs + snake_len) as isize);
let seq_tok = input.seq.nth_token((start_seq + snake_len) as isize);
if lcs_tok != seq_tok {
break;
}
snake_len += 1
}
let next_coord = Coord {
next_lcs: start_lcs + snake_len,
next_seq: start_seq + snake_len,
};
if last_enqueued_snake_len < snake_len || next_coord == target {
if next_coord.next_lcs == target.next_lcs {
if next_coord.next_seq == target.next_seq {
found_seq = Some(next_coord.next_seq);
} else if found_seq == None {
found_seq = Some(next_coord.next_seq);
}
}
match prev.entry(next_coord) {
Occupied(_) => continue,
Vacant(e) => e.insert(coord),
};
new_frontier.push(next_coord);
last_enqueued_snake_len = snake_len;
}
}
}
frontier = new_frontier;
}
let target = found_seq.map(|next_seq| Coord {
next_lcs: input.lcs.nb_tokens(),
next_seq,
});
let mut path = vec![];
let mut starts_with_shared = false;
let mut coord = target.as_ref();
let mut seq = input.seq.nb_tokens();
let mut lcs = input.lcs.nb_tokens();
while let Some(&coord_content) = coord {
let next_seq = coord_content.next_seq;
let next_lcs = coord_content.next_lcs;
let snake_len = lcs - next_lcs;
push_if_not_last(&mut path, to_isize(seq - snake_len));
starts_with_shared = !push_if_not_last(&mut path, to_isize(next_seq));
coord = prev.get(&coord_content);
seq = next_seq;
lcs = next_lcs;
}
path.reverse();
NormalizationResult {
path,
starts_with_shared,
}
}
fn push_if_not_last(v: &mut Vec<isize>, val: isize) -> bool {
let should_push = v.last() != Some(&val);
if should_push {
v.push(val);
}
should_push
}
fn to_isize(input: usize) -> isize {
isize::try_from(input).unwrap()
}
pub struct Parts<'a> {
index: usize,
normalization: &'a Vec<isize>,
tokenization: &'a Tokenization<'a>,
}
impl<'a> Parts<'a> {
pub fn new(normalization: &'a NormalizationResult, tokenization: &'a Tokenization) -> Self {
Parts {
index: if normalization.starts_with_shared {
0
} else {
1
},
normalization: &normalization.path,
tokenization,
}
}
}
impl<'a> Iterator for Parts<'a> {
type Item = (usize, usize);
fn next(&mut self) -> Option<Self::Item> {
if self.index + 1 < self.normalization.len() {
let prev = self.normalization[self.index];
let curr = self.normalization[self.index + 1];
let from = self.tokenization.nth_span(prev).lo;
let to = self.tokenization.nth_span(curr - 1).hi;
self.index += 2;
Some((from, to))
} else {
None
}
}
}