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@ -1,15 +1,13 @@
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//! Implements Dijkstra's algorithm for shortest path, to find an
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//! optimal and readable diff between two ASTs.
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use std::{
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cmp::{Ordering, Reverse},
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collections::BinaryHeap,
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};
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use std::cmp::{Ordering, Reverse};
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use crate::{
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graph::{mark_route, neighbours, Edge, Vertex},
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syntax::Syntax,
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};
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use radix_heap::RadixHeapMap;
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use rustc_hash::FxHashMap;
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/// A vertex with a distance.
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@ -55,12 +53,9 @@ fn shortest_path(start: Vertex) -> Vec<(Edge, Vertex)> {
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// We want to visit nodes with the shortest distance first, but
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// BinaryHeap is a max-heap. Ensure nodes are wrapped with Reverse
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// to flip comparisons.
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let mut heap: BinaryHeap<Reverse<_>> = BinaryHeap::new();
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let mut heap: RadixHeapMap<Reverse<_>, Vertex> = RadixHeapMap::new();
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heap.push(Reverse(OrdVertex {
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distance: 0,
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current: start,
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}));
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heap.push(Reverse(0), start);
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// TODO: this grows very big. Consider using IDA* to reduce memory
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// usage.
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@ -69,7 +64,7 @@ fn shortest_path(start: Vertex) -> Vec<(Edge, Vertex)> {
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let end;
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loop {
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match heap.pop() {
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Some(Reverse(OrdVertex { distance, current })) => {
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Some((Reverse(distance), current)) => {
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if current.is_end() {
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end = current;
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break;
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@ -86,10 +81,7 @@ fn shortest_path(start: Vertex) -> Vec<(Edge, Vertex)> {
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predecessors
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.insert(next.clone(), (distance_to_next, current.clone(), edge));
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heap.push(Reverse(OrdVertex {
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distance: distance_to_next,
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current: next,
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}));
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heap.push(Reverse(distance_to_next), next);
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}
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}
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}
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Wilfred Hughes