Files
orchid/orchid-std/src/macros/rule/vec_match.rs

95 lines
3.0 KiB
Rust

use std::cmp::Ordering;
use itertools::Itertools;
use orchid_base::name::Sym;
use super::scal_match::scalv_match;
use super::shared::VecMatcher;
use super::state::{MatchState, StateEntry};
use crate::macros::MacTree;
#[must_use]
pub fn vec_match<'a>(
matcher: &VecMatcher,
seq: &'a [MacTree],
save_loc: &impl Fn(Sym) -> bool,
) -> Option<MatchState<'a>> {
match matcher {
VecMatcher::Placeh { key, nonzero } => {
if *nonzero && seq.is_empty() {
return None;
}
Some(MatchState::from_ph(key.clone(), StateEntry::Vec(seq)))
},
VecMatcher::Scan { left, sep, right, direction } => {
if seq.len() < sep.len() {
return None;
}
for lpos in direction.walk(0..=seq.len() - sep.len()) {
let rpos = lpos + sep.len();
let state = vec_match(left, &seq[..lpos], save_loc)
.and_then(|s| Some(s.combine(scalv_match(sep, &seq[lpos..rpos], save_loc)?)))
.and_then(|s| Some(s.combine(vec_match(right, &seq[rpos..], save_loc)?)));
if let Some(s) = state {
return Some(s);
}
}
None
},
VecMatcher::Middle { left, left_sep, mid, right_sep, right, key_order } => {
if seq.len() < left_sep.len() + right_sep.len() {
return None;
}
// Valid locations for the left separator
let lposv = seq[..seq.len() - right_sep.len()]
.windows(left_sep.len())
.enumerate()
.filter_map(|(i, window)| scalv_match(left_sep, window, save_loc).map(|s| (i, s)))
.collect::<Vec<_>>();
// Valid locations for the right separator
let rposv = seq[left_sep.len()..]
.windows(right_sep.len())
.enumerate()
.filter_map(|(i, window)| scalv_match(right_sep, window, save_loc).map(|s| (i, s)))
.collect::<Vec<_>>();
// Valid combinations of locations for the separators
let mut pos_pairs = lposv
.into_iter()
.cartesian_product(rposv)
.filter(|((lpos, _), (rpos, _))| lpos + left_sep.len() <= *rpos)
.map(|((lpos, lstate), (rpos, rstate))| (lpos, rpos, lstate.combine(rstate)))
.collect::<Vec<_>>();
// In descending order of size
pos_pairs.sort_by_key(|(l, r, _)| -((r - l) as i64));
let eql_clusters = pos_pairs.into_iter().chunk_by(|(al, ar, _)| ar - al);
for (_gap_size, cluster) in eql_clusters.into_iter() {
let best_candidate = cluster
.into_iter()
.filter_map(|(lpos, rpos, state)| {
Some(
state
.combine(vec_match(left, &seq[..lpos], save_loc)?)
.combine(vec_match(mid, &seq[lpos + left_sep.len()..rpos], save_loc)?)
.combine(vec_match(right, &seq[rpos + right_sep.len()..], save_loc)?),
)
})
.max_by(|a, b| {
for key in key_order {
let alen = a.ph_len(key).expect("key_order references scalar or missing");
let blen = b.ph_len(key).expect("key_order references scalar or missing");
match alen.cmp(&blen) {
Ordering::Equal => (),
any => return any,
}
}
Ordering::Equal
});
if let Some(state) = best_candidate {
return Some(state);
}
}
None
},
}
}