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[position, perft] Move Perft into the position crate

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Move the Perft trait into the position crate, and let the perft binary call into
that.

Amend Position::make_move to return a bool in the Ok case that indicates whether
the position has been seen before. Use this to decide whether to continue
recursing during the Perft run. I haven't seen that this makes a difference in
the counts returned by Perft yet.
This commit is contained in:
Eryn Wells 2025-06-16 09:01:58 -07:00
parent f0b6cb5f08
commit 7744dd06f0
4 changed files with 82 additions and 39 deletions
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33
perft/src/main.rs
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@ -1,4 +1,4 @@
use chessfriend_position::{fen::FromFenStr, GeneratedMove, Position, ValidateMove};
use chessfriend_position::{fen::FromFenStr, perft::Perft, Position};
use clap::Parser;
#[derive(Parser, Debug)]
@ -10,38 +10,11 @@ struct Arguments {
fen: Option<String>,
}
trait Perft {
fn perft(&mut self, depth: usize) -> u64;
}
impl Perft for Position {
fn perft(&mut self, depth: usize) -> u64 {
if depth == 0 {
return 1;
}
let mut nodes_counted: u64 = 0;
let legal_moves: Vec<GeneratedMove> = self.all_legal_moves(None).collect();
for generated_ply in legal_moves {
self.make_move(generated_ply.into(), ValidateMove::No)
.expect("unable to make generated move");
nodes_counted += self.perft(depth - 1);
self.unmake_last_move().expect("unable to unmake last move");
}
nodes_counted
}
}
fn main() -> anyhow::Result<()> {
let args = Arguments::parse();
let depth = args.depth;
println!("Searching to depth {depth}");
println!("depth={depth}");
let mut position = if let Some(fen) = args.fen {
Position::from_fen_str(&fen)?
@ -51,7 +24,7 @@ fn main() -> anyhow::Result<()> {
let nodes_searched = position.perft(depth);
println!("Nodes searched: {nodes_searched}");
println!("nodes={nodes_searched}");
Ok(())
}