bridge-solver

A fast double-dummy solver for bridge, with par-contract scoring, cardplay analysis, PBN file processing, and a WebAssembly build for the browser.

Attribution and License

The double-dummy solver core is a Rust reimplementation of macroxue/bridge-solver by Hanhong Xue, which is licensed MIT OR Apache-2.0. This project follows suit and is licensed under either of:

• Apache License, Version 2.0
• MIT license

at your option. Both files retain Hanhong Xue's copyright notice alongside the Rust implementation's, as those licences require.

The search engine corresponds to upstream commit 75b4619, which predates upstream's relicensing in dc2d4df (2026-08-14, GPL-2.0 to MIT OR Apache-2.0).

Not derived from upstream

The following are original work with no upstream counterpart:

• src/par.rs — par contract and optimum score calculation
• src/analyse_play.rs — double-dummy cardplay analysis
• wasm/ — WebAssembly bindings and LIN parsing
• web/ — the browser application
• PBN input/output, and the bin/bridge-solver PBN-processing binary

Annotating PBN files

The bridge-solver binary (build with --features cli) fills in double-dummy and par analysis on PBN files, writing Bridge Composer compatible tags: DoubleDummyTricks, OptimumResultTable, and — when the board states its vulnerability — OptimumScore and ParContract.

bridge-solver -i deals.pbn                 # analyze one file to stdout
bridge-solver -i deals.pbn -o out.pbn      # ...or to another file
bridge-solver -w -i Curated/               # annotate a tree in place

Directories are searched recursively for *.pbn, so a build can annotate a whole collection in one command with no scripting around it. The pass is designed to be safe to run over source material:

• Only what is missing. A board that already has a DoubleDummyTricks tag is passed through byte-for-byte. Use --recalculate to redo those too.
• Nothing else is touched. Files are edited line by line rather than reparsed and rewritten, so % directives (Bridge Composer's fonts, page setup and colours), ; comments, and hand-authored {...} commentary all survive exactly as written. Annotating a collection only ever adds lines.
• Incomplete deals are skipped. Auction-only teaching boards, written as [Deal "N:... ... ... ..."], parse into empty hands; they are left alone rather than stamped with a fabricated all-zero table.
• --mark-verified sets bit 0x00080000 ("double-dummy data has been verified") in each annotated board's [BCFlags], adding the tag if absent and preserving every bit already there. This records provenance only, and is not needed to make the analysis appear (see below).
• Re-runs are no-ops. Unchanged files are not rewritten, so mtimes do not churn. In-place writes go through a temporary file and a rename.

Bridge Composer displays double-dummy analysis whenever the tags are present. There is no per-board flag to enable it: which parts appear is its report-level DDA format setting (Makeable contracts, Grid (2 rows), Grid (4 rows), Grid (4 rows, no par), Grid (4 rows, in diagram)). Par is included in every format except the last two, and "Makeable contracts" and "Grid (4 rows)" show the par contract as well — which is why OptimumScore and ParContract are written alongside the table rather than the table alone.