Simon Gardling
204ba85202
This made the code so fast, that the `board` benchmark became completely useless. So that benchmark was removed. Overall, we're looking at a futher 20% performance increase in `future_moves`
67 lines
2.6 KiB
Rust
67 lines
2.6 KiB
Rust
use super::{
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misc::{diag_raw, split_from},
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Board, CoordPair,
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};
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use arrayvec::ArrayVec;
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use std::collections::HashSet;
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/// A chain of positions across the board
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type Chain = ArrayVec<CoordPair, { (Board::BOARD_SIZE - 1) as usize }>;
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/// A collection of chains (up vert, down vert, left horiz, right horiz, diagonals....)
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pub type ChainCollection = ArrayVec<Chain, 8>;
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/// Creates a lookup map for adjacencies and chains from each position on the board
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pub fn gen_adj_lookup() -> PosMap<ChainCollection> {
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PosMap(
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Board::all_positions()
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.map(|coord| {
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let (i, j) = coord.into();
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let (i_chain, j_chain) = (
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split_from(0..=Board::BOARD_SIZE - 1, i),
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split_from(0..=Board::BOARD_SIZE - 1, j),
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);
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let chains: ChainCollection = ArrayVec::from_iter(
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i_chain
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.clone()
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.into_iter()
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.map(|range| range.map(move |i| (i, j)))
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.map(Iterator::collect)
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.chain(
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j_chain
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.clone()
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.into_iter()
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.map(|range| range.map(move |j| (i, j)))
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.map(Iterator::collect),
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)
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.chain(diag_raw(i_chain, j_chain).map(Iterator::collect))
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.filter(|x: &Vec<(u8, u8)>| !x.is_empty()) // PERF! filter out empty chains +~5% perf boost (in [`Board::place`])
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.map(|x: Vec<(u8, u8)>| x.into_iter().map(|x| x.into()).collect()),
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);
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// make sure all chains are in the proper range so we can ignore bounds checking later
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assert!(
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chains
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.iter()
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.flatten()
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.map(|&x| x.into())
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.flat_map(|(i, j)| [i, j]) // flatten to just numbers
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.all(|x| (0..Board::BOARD_SIZE).contains(&x)),
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"chains go out-of-bounds"
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);
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// SAFETY! ensure all nodes in all chains are unique across chains, ensures beavior in
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// [`Board::propegate_from`]
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let mut uniq = HashSet::new();
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assert!(
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chains.iter().flatten().all(move |x| uniq.insert(x)),
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"there are duplicate nodes in chain"
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);
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chains
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})
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.collect(),
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)
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}
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