Ilia Denisov
256999b42c
- Rename module to gitea.iliadenisov.ru/developer/scrabble-solver so it can be consumed as a versioned dependency (no go.work replace / CI clone). - De-internalize wordlist and dictdawg as public packages. - Remove cmd/builddict, dictprep/, the dictionaries submodule and the dawg Makefile: the word-list parsing and DAWG build now live in the separate scrabble-dictionary repository, which publishes the DAWG set as a release artifact. - internal/dict loads the committed dawg/en_sowpods.dawg fixture for cmd/stress. - Update README/CLAUDE docs accordingly.
109 lines
3.0 KiB
Go
109 lines
3.0 KiB
Go
package scrabble
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import (
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dawg "github.com/iliadenisov/dafsa"
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"gitea.iliadenisov.ru/developer/scrabble-solver/board"
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"gitea.iliadenisov.ru/developer/scrabble-solver/internal/encoding"
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)
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// letterSet is a bit set over alphabet letter indexes (alphabets are at most 63
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// letters, so a uint64 suffices). It encodes a square's cross-set: the letters that,
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// placed on the square, form a legal perpendicular word.
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type letterSet uint64
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func (s letterSet) has(l byte) bool { return s&(letterSet(1)<<l) != 0 }
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// fullSet is the cross-set of a square with no perpendicular neighbours: every letter
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// is allowed.
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func fullSet(size int) letterSet { return letterSet(uint64(1)<<uint(size)) - 1 }
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// columnContext returns the contiguous run of filled cells immediately above and below
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// the empty square (r, c), each read top to bottom, as alphabet letter indexes. These
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// are the tiles a perpendicular (vertical) word through (r, c) would include.
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func columnContext(b *board.Board, r, c int) (above, below []byte) {
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start := r
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for start-1 >= 0 && b.Filled(start-1, c) {
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start--
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}
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for rr := start; rr < r; rr++ {
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above = append(above, encoding.Letter(b.At(rr, c)))
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}
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end := r
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for end+1 < b.Rows() && b.Filled(end+1, c) {
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end++
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}
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for rr := r + 1; rr <= end; rr++ {
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below = append(below, encoding.Letter(b.At(rr, c)))
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}
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return above, below
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}
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// completers returns the letters X (< size) that complete a word when followed from
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// state: those whose arc leads directly to an accepting node. It is a single arc
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// enumeration — the deterministic cross-set primitive.
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func completers(cur *dawg.Cursor, state dawg.Node, size int) letterSet {
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var set letterSet
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lim := byte(size)
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cur.Arcs(state, func(a dawg.Arc) bool {
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if a.Final && a.Label < lim {
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set |= letterSet(1) << a.Label
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}
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return true
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})
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return set
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}
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// walk follows word left to right from the cursor's root.
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func walk(cur *dawg.Cursor, word []byte) (dawg.Node, bool) {
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n := cur.Root()
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for _, l := range word {
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var ok bool
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if n, _, ok = cur.Next(n, l); !ok {
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return n, false
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}
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}
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return n, true
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}
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// dawgCrossSet returns the letters X for which above·X·below is a stored word. A right
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// extension (no tiles below) is deterministic — X just completes the prefix above. A
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// left extension (tiles below) is non-deterministic and must probe each X.
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func dawgCrossSet(cur *dawg.Cursor, above, below []byte, size int) letterSet {
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switch {
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case len(above) == 0 && len(below) == 0:
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return fullSet(size)
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case len(below) == 0:
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node, ok := walk(cur, above)
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if !ok {
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return 0
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}
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return completers(cur, node, size)
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default:
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node := cur.Root()
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if len(above) > 0 {
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var ok bool
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if node, ok = walk(cur, above); !ok {
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return 0
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}
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}
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var set letterSet
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for x := range size {
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m, final, ok := cur.Next(node, byte(x))
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if !ok {
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continue
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}
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for _, l := range below {
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if m, final, ok = cur.Next(m, l); !ok {
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break
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}
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}
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if ok && final {
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set |= letterSet(1) << uint(x)
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}
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}
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return set
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}
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}
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