Merge pull request #86 from sumnerevans/decode-pgn-fixes

decodePGN: convert to a more resillient parser

fixtures/pgns/0008.pgn

@@ -0,0 +1 @@
+1.e4 e6 2.d4 d5

fixtures/pgns/0009.pgn

@@ -0,0 +1 @@
+1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 {This opening is called the Ruy Lopez.}

fixtures/pgns/0010.pgn

@@ -0,0 +1 @@
+1. e4 e5 2. Nf3 Nc6 3. Bb5 a6{This opening is called the Ruy Lopez.}

pgn.go

@@ -151,7 +151,6 @@ func (a multiDecoder) Decode(pos *Position, s string) (*Move, error) {
 func decodePGN(pgn string) (*Game, error) {
 	tagPairs := getTagPairs(pgn)
 	moveComments, outcome := moveListWithComments(pgn)
-	// moveStrs, outcome := moveList(pgn)
 	gameFuncs := []func(*Game){}
 	for _, tp := range tagPairs {
 		if strings.ToLower(tp.Key) == "fen" {
@@ -229,74 +228,33 @@ type moveWithComment struct {
 	Comments []string
 }
 
+var moveListTokenRe = regexp.MustCompile(`(?:\d+\.)|(O-O(?:-O)?|\w*[abcdefgh][12345678]\w*(?:=Q)?)|(?:\{([^}]*)\})|(?:\([^)]*\))|(\*|0-1|1-0|1\/2-1\/2)`)
+
 func moveListWithComments(pgn string) ([]moveWithComment, Outcome) {
-	text := stripTagPairs(pgn)
-	// remove variations
-	text = removeSection(`\(`, `\)`, text)
-	text = strings.Replace(text, "\n", " ", -1)
-	text = strings.TrimSpace(text)
-	tokens := strings.Split(text, " ")
+	pgn = stripTagPairs(pgn)
 	var outcome Outcome
 	moves := []moveWithComment{}
-	inComment := false
-	commentTokens := []string{}
-tokenLoop:
-	for _, token := range tokens {
-		token = strings.TrimSpace(token)
-		switch token {
-		case "{":
-			inComment = true
-			commentTokens = []string{}
-		case "}":
-			inComment = false
-			if len(moves) > 0 {
-				moves[len(moves)-1].Comments = append(moves[len(moves)-1].Comments, strings.Join(commentTokens, " "))
-			}
-		case "":
-		case string(NoOutcome), string(WhiteWon), string(BlackWon), string(Draw):
-			outcome = Outcome(token)
-			break tokenLoop
-		default:
-			if inComment {
-				commentTokens = append(commentTokens, token)
-				break
-			}
-			if strings.HasSuffix(token, ".") {
-				break
-			}
-			moves = append(moves, moveWithComment{MoveStr: token})
+
+	for _, match := range moveListTokenRe.FindAllStringSubmatch(pgn, -1) {
+		move, commentText, outcomeText := match[1], match[2], match[3]
+		if len(move+commentText+outcomeText) == 0 {
+			continue
 		}
-	}
-	return moves, outcome
-}
 
-func moveList(pgn string) ([]string, Outcome) {
-	// remove comments
-	text := removeSection("{", "}", pgn)
-	// remove variations
-	text = removeSection(`\(`, `\)`, text)
-	// remove tag pairs
-	text = removeSection(`\[`, `\]`, text)
-	// remove line breaks
-	text = strings.Replace(text, "\n", " ", -1)
+		if outcomeText != "" {
+			outcome = Outcome(outcomeText)
+			break
+		}
 
-	list := strings.Split(text, " ")
-	filtered := []string{}
-	var outcome Outcome
-	for _, move := range list {
-		move = strings.TrimSpace(move)
-		switch move {
-		case string(NoOutcome), string(WhiteWon), string(BlackWon), string(Draw):
-			outcome = Outcome(move)
-		case "":
-		default:
-			results := moveNumRegex.FindStringSubmatch(move)
-			if len(results) == 2 && results[1] != "" {
-				filtered = append(filtered, results[1])
-			}
+		if commentText != "" {
+			moves[len(moves)-1].Comments = append(moves[len(moves)-1].Comments, strings.TrimSpace(commentText))
+		}
+
+		if move != "" {
+			moves = append(moves, moveWithComment{MoveStr: move})
 		}
 	}
-	return filtered, outcome
+	return moves, outcome
 }
 
 func removeSection(leftChar, rightChar, s string) string {

pgn_test.go

@@ -30,6 +30,18 @@ var (
 			PostPos: unsafeFEN("r3kb1r/2qp1pp1/b1n1p2p/pp2P3/5n1B/1PPQ1N2/P1BN1PPP/R3K2R w KQkq - 1 14"),
 			PGN:     mustParsePGN("fixtures/pgns/0004.pgn"),
 		},
+		{
+			PostPos: unsafeFEN("rnbqkbnr/ppp2ppp/4p3/3p4/3PP3/8/PPP2PPP/RNBQKBNR w KQkq d6 0 3"),
+			PGN:     mustParsePGN("fixtures/pgns/0008.pgn"),
+		},
+		{
+			PostPos: unsafeFEN("r1bqkbnr/1ppp1ppp/p1n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 0 4"),
+			PGN:     mustParsePGN("fixtures/pgns/0009.pgn"),
+		},
+		{
+			PostPos: unsafeFEN("r1bqkbnr/1ppp1ppp/p1n5/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 0 4"),
+			PGN:     mustParsePGN("fixtures/pgns/0010.pgn"),
+		},
 	}
 )
 
@@ -47,16 +59,42 @@ func TestValidPGNs(t *testing.T) {
 	}
 }
 
-func TestCommentsDetection(t *testing.T) {
-	pgn := mustParsePGN("fixtures/pgns/0005.pgn")
-	game, err := decodePGN(pgn)
-	if err != nil {
-		t.Fatal(err)
+type commentTest struct {
+	PGN         string
+	MoveNumber  int
+	CommentText string
+}
+
+var (
+	commentTests = []commentTest{
+		{
+			PGN:         mustParsePGN("fixtures/pgns/0005.pgn"),
+			MoveNumber:  7,
+			CommentText: `(-0.25 → 0.39) Inaccuracy. cxd4 was best. [%eval 0.39] [%clk 0:05:05]`,
+		},
+		{
+			PGN:         mustParsePGN("fixtures/pgns/0009.pgn"),
+			MoveNumber:  5,
+			CommentText: `This opening is called the Ruy Lopez.`,
+		},
+		{
+			PGN:         mustParsePGN("fixtures/pgns/0010.pgn"),
+			MoveNumber:  5,
+			CommentText: `This opening is called the Ruy Lopez.`,
+		},
 	}
-	comment := strings.Join(game.Comments()[7], " ")
-	expected := `Inaccuracy. cxd4 was best. [%eval 0.39] [%clk 0:05:05]`
-	if comment != expected {
-		t.Fatalf("expected pgn comment to be %s but got %s", expected, comment)
+)
+
+func TestCommentsDetection(t *testing.T) {
+	for _, test := range commentTests {
+		game, err := decodePGN(test.PGN)
+		if err != nil {
+			t.Fatal(err)
+		}
+		comment := strings.Join(game.Comments()[test.MoveNumber], " ")
+		if comment != test.CommentText {
+			t.Fatalf("expected pgn comment to be %s but got %s", test.CommentText, comment)
+		}
 	}
 }