Merge pull request #128 from mikeb26/fromPosition

Scanner: fix parsing of PGNs w/ starting position

fixtures/pgns/0014.pgn

@@ -0,0 +1,55 @@
+[Event "Fantasy Caro-Kann: Starting Position"]
+[Result "*"]
+[UTCDate "2023.05.29"]
+[UTCTime "16:05:07"]
+[Variant "Standard"]
+[ECO "B12"]
+[Opening "Caro-Kann Defense: Maróczy Variation"]
+
+1. e4 c6 2. d4 d5 3. f3 *
+
+
+[Event "Fantasy Caro-Kann: 3. ... dxe4"]
+[Result "*"]
+[UTCDate "2023.05.29"]
+[UTCTime "16:05:48"]
+[Variant "Standard"]
+[FEN "rnbqkbnr/pp2pppp/2p5/3p4/3PP3/5P2/PPP3PP/RNBQKBNR b KQkq - 0 3"]
+[SetUp "1"]
+
+3... dxe4 4. fxe4 e5 5. Nf3 Bg4 (5... exd4 6. Bc4) 6. Bc4 Nd7 7. O-O Ngf6 8. c3 *
+
+
+[Event "Fantasy Caro-Kann: 3. ... e6"]
+[Result "*"]
+[UTCDate "2023.05.29"]
+[UTCTime "16:06:13"]
+[Variant "Standard"]
+[FEN "rnbqkbnr/pp2pppp/2p5/3p4/3PP3/5P2/PPP3PP/RNBQKBNR b KQkq - 0 3"]
+[SetUp "1"]
+
+3... e6 4. Nc3 Bb4 (4... Nf6 5. e5) 5. Bd2 Ne7 6. Bd3 *
+
+
+[Event "Fantasy Caro-Kann: 3. ... g6"]
+[Result "*"]
+[UTCDate "2023.05.29"]
+[UTCTime "16:06:42"]
+[Variant "Standard"]
+[FEN "rnbqkbnr/pp2pppp/2p5/3p4/3PP3/5P2/PPP3PP/RNBQKBNR b KQkq - 0 3"]
+[SetUp "1"]
+
+3... g6 4. Nc3 Bg7 5. Be3 *
+
+
+[Event "Fantasy Caro-Kann: 3. ... Qb6"]
+[Result "*"]
+[UTCDate "2023.05.29"]
+[UTCTime "16:07:08"]
+[Variant "Standard"]
+[FEN "rnbqkbnr/pp2pppp/2p5/3p4/3PP3/5P2/PPP3PP/RNBQKBNR b KQkq - 0 3"]
+[SetUp "1"]
+
+3... Qb6 4. Nc3 dxe4 5. fxe4 e5 6. Nf3 exd4 7. Nxd4 *
+
+

pgn.go

@@ -37,6 +37,8 @@ const (
 // a game or EOF was reached.  Running scan populates
 // data for Next() and Err().
 func (s *Scanner) Scan() bool {
+	moveListRe := regexp.MustCompile(`^\d+\.`)
+
 	if s.err == io.EOF {
 		return false
 	}
@@ -64,7 +66,7 @@ func (s *Scanner) Scan() bool {
 		}
 		line := strings.TrimSpace(s.scanr.Text())
 		isTagPair := strings.HasPrefix(line, "[")
-		isMoveSeq := strings.HasPrefix(line, "1. ")
+		isMoveSeq := moveListRe.MatchString(line)
 		switch state {
 		case notInPGN:
 			if !isTagPair {

pgn_test.go

@@ -154,6 +154,41 @@ func TestScanner(t *testing.T) {
 	}
 }
 
+func TestScannerWithFromPosFENs(t *testing.T) {
+	finalPositions := []string{
+		"rnbqkbnr/pp2pppp/2p5/3p4/3PP3/5P2/PPP3PP/RNBQKBNR b KQkq - 0 3",
+		"r2qkb1r/pp1n1ppp/2p2n2/4p3/2BPP1b1/2P2N2/PP4PP/RNBQ1RK1 b kq - 0 8",
+		"rnbqk2r/pp2nppp/2p1p3/3p4/1b1PP3/2NB1P2/PPPB2PP/R2QK1NR b KQkq - 5 6",
+		"rnbqk1nr/pp2ppbp/2p3p1/3p4/3PP3/2N1BP2/PPP3PP/R2QKBNR b KQkq - 3 5",
+		"rnb1kbnr/pp3ppp/1qp5/8/3NP3/2N5/PPP3PP/R1BQKB1R b KQkq - 0 7",
+	}
+	fname := "fixtures/pgns/0014.pgn"
+	f, err := os.Open(fname)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+	scanner := NewScanner(f)
+	games := []*Game{}
+	for idx := 0; scanner.Scan(); {
+		game := scanner.Next()
+		if len(game.moves) == 0 {
+			continue
+		}
+		finalPos := game.Position().String()
+		if finalPos != finalPositions[idx] {
+			t.Fatalf(fname+" game %v expected final pos %v but got %v", idx,
+				finalPositions[idx], finalPos)
+		}
+		games = append(games, game)
+		idx++
+	}
+	if len(games) != len(finalPositions) {
+		t.Fatalf(fname+" expected %v games but got %v", len(finalPositions),
+			len(games))
+	}
+}
+
 func BenchmarkPGN(b *testing.B) {
 	pgn := mustParsePGN("fixtures/pgns/0001.pgn")
 	b.ResetTimer()