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Fix legacy C2S slider segment parsing #6

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Merged
Starrah merged 2 commits into from
Oct 8, 2026
Merged

Fix legacy C2S slider segment parsing #6

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ef62fb4
Fix legacy C2S slider segment parsing
Oct 7, 2026
fc03836
refactor: C2SParser add "VERSION" parsing, and use VERSION to decide …
Starrah Oct 8, 2026
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47 changes: 30 additions & 17 deletions parser/chu/C2sParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,24 +12,23 @@ namespace MuConvert.chu;
* C2S 格式解析器（官方格式，RESOLUTION=384 tick/小节）。
* Tab 分隔文本，识别 HEADER / TIMING / NOTES 区段。
*/
public class C2sParser: BaseChuParser
public class C2sParser : BaseChuParser
{
private int RSL = 384;
private static readonly HashSet<string> HeadTags = new(StringComparer.OrdinalIgnoreCase)
{ "VERSION", "MUSIC", "SEQUENCEID", "DIFFICULT", "LEVEL", "CREATOR", "BPM_DEF", "MET_DEF", "RESOLUTION", "CLK_DEF", "PROGJUDGE_BPM", "PROGJUDGE_AER", "TUTORIAL" };
private static readonly HashSet<string> TimingTags = new(StringComparer.OrdinalIgnoreCase)
{ "BPM", "MET", "SFL", "SLP" };

private bool _used;
private int _version;
// C2S 会原始记录 targetNote 字符串；用于在 FillAllPrevious 推断有多个候选时优先匹配。
private readonly Dictionary<ChuNote, string> _rawTargetNote = new();
private readonly Dictionary<(Rational Time, int Cell, int Width), List<(Rational, int)>> _slaRecords = new();
private readonly Dictionary<SegDictKey, List<ChuNote>> segDict = new();

public override (ChuChart, List<Alert>) Parse(string text)
{
if (_used) throw new Exception(Locale.InstanceMultipleUsage);
_used = true;
if (_version > 0) throw new Exception(Locale.InstanceMultipleUsage);
var chart = new ChuChart();
var alerts = new List<Alert>();
var lines = text.Replace("\r\n", "\n").Split('\n');
Expand Down Expand Up @@ -81,6 +80,10 @@ private void ParseHeader(string[] p, ChuChart chart)
var tag = p[0].ToUpperInvariant();
switch (tag)
{
case "VERSION":
var segs = p[1].Split('.').Select(int.Parse).ToArray();
_version = segs[0] * 100 + segs[1];
break;
case "MUSIC": chart.MusicId = Int(p, 1).ToString(); break;
case "DIFFICULT": chart.Difficulty = Int(p, 1); break;
case "LEVEL": chart.Level = Decimal(p, 1); break;
Expand All @@ -95,7 +98,7 @@ private void ParseTiming(string[] p, ChuChart chart)
switch (tag)
{
case "BPM":
chart.BpmList.Add(new BPM(Int(p, 1) + new Rational(Int(p, 2), RSL),
chart.BpmList.Add(new BPM(Int(p, 1) + new Rational(Int(p, 2), RSL),
decimal.Parse(p[3], CultureInfo.InvariantCulture)));
break;
case "MET":
Expand Down Expand Up @@ -127,11 +130,11 @@ private ChuSegment ParseSegment(ChuNote note, string[] p, string type)
seg.Length = new Rational(Int(p, durationIdx), RSL);
if (note.Type is ChuNoteType.Slide or ChuNoteType.Crush)
{
seg.EndCell = Int(p, durationIdx + 1);
seg.EndWidth = Math.Max(1, Int(p, durationIdx + 2, 1));
seg.EndCell = Int(p, durationIdx + 1);
seg.EndWidth = Math.Max(1, Int(p, durationIdx + 2, note.EndWidth));
if (note.IsAir) seg.EndHeight = Decimal(p, durationIdx + 3, 5);
}

return seg;
}

Expand All @@ -141,7 +144,8 @@ private void ParseNote(string[] p, ChuChart chart, List<Alert> alerts, int lineN
ChuNote? note = new ChuNote
{
Time = Int(p, 1) + new Rational(Int(p, 2), RSL),
Cell = Int(p, 3), Width = Math.Max(1, Int(p, 4, 1)),
Cell = Int(p, 3),
Width = Math.Max(1, Int(p, 4, 1)),
};

if (type == "SLA")
Expand All @@ -151,7 +155,7 @@ private void ParseNote(string[] p, ChuChart chart, List<Alert> alerts, int lineN
_slaRecords.Add((note.Time, note.Cell, note.Width), (length, groupId));
return;
}

var t = type switch
{
"TAP" or "CHR" => (ChuNoteType.Tap, false),
Expand All @@ -167,16 +171,22 @@ private void ParseNote(string[] p, ChuChart chart, List<Alert> alerts, int lineN
};
if (t == null) return;
(note.Type, note.IsAir) = t.Value;

string? targetNote = null;
if (note.Type is ChuNoteType.Tap or ChuNoteType.Mine or ChuNoteType.Flick)
{
if (type == "CHR") ParseEnum<ExDirection>(Str(p, 5), x=>note.Ex = x);
if (type == "CHR")
{
note.Ex = ExDirection.UP; // default value when CHR direction parsing failed
var direction = Str(p, 5);
if (!(string.IsNullOrEmpty(direction) && _version < 108))
ParseEnum<ExDirection>(direction, x => note.Ex = x);
}
else if (note is { Type: ChuNoteType.Tap, IsAir: true })
{
ParseEnum<AirDirection>(type, x=>note.AirDirection = x);
ParseEnum<AirDirection>(type, x => note.AirDirection = x);
targetNote = Str(p, 5);
if (p.Length >= 7) ParseEnum<NoteColor>(Str(p, 6), x=>note.Color = x);
if (p.Length >= 7) ParseEnum<NoteColor>(Str(p, 6), x => note.Color = x);
}
}
else
Expand All @@ -186,10 +196,13 @@ private void ParseNote(string[] p, ChuChart chart, List<Alert> alerts, int lineN
if (ChuUtils.ShouldHaveHeight(note)) note.Height = Decimal(p, 6, 5);
if (note.Type == ChuNoteType.Crush) note.CrushInterval = CrushInterval(p, 5);
if (note.IsAir) // 解析颜色
ParseEnum<NoteColor>(Str(p, note.Type == ChuNoteType.Hold ? 7 : 11), x=>note.Color = x);
{
var color = Str(p, note.Type == ChuNoteType.Hold ? 7 : 11);
if (!string.IsNullOrEmpty(color)) ParseEnum<NoteColor>(color, x => note.Color = x);
}
if (type is "HXD" or "SXD" or "SXC") // 解析Ex
ParseEnum<ExDirection>(Str(p, type == "HXD" ? 6 : 9), x=>note.Ex = x);
ParseEnum<ExDirection>(Str(p, type == "HXD" ? 6 : 9), x => note.Ex = x);

// 首先，对Air Hold/Air Slide，需要读取TargetNote，确定它是否是接续段；其他类型的音符，则默认允许是接续段
bool canConnect = true, isConnect = false;
if (note is { IsAir: true, Type: ChuNoteType.Hold or ChuNoteType.Slide })
Expand Down
46 changes: 43 additions & 3 deletions tests/chu/ChuTests.cs
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Expand Up @@ -39,6 +39,46 @@ public void C2sRoundTrip(string c2sPath)
AssertNotesEqual(chart.Notes, reparsed.Notes);
}

[Fact]
public void C2sMissingOptionalAttributesPreservesAirNoteParents()
{
var c2s = string.Join('\n',
"BPM\t0\t0\t120",
"CHR\t0\t0\t0\t4",
"AHD\t0\t0\t0\t4\tCHR\t96",
"SLD\t0\t0\t0\t4\t96\t6\t4\tSLD",
"AHD\t0\t96\t6\t4\tSLD\t96");

var (chart, alerts) = new C2sParser().Parse(c2s);

Assert.Empty(alerts);
var chr = Assert.Single(chart.Notes, n => n.Type == ChuNoteType.Tap);
Assert.Equal(ExDirection.UP, chr.Ex);

var slide = Assert.Single(chart.Notes, n => n.Type == ChuNoteType.Slide);
var airHolds = chart.Notes.Where(n => n is { Type: ChuNoteType.Hold, IsAir: true }).ToList();
Assert.Equal(2, airHolds.Count);
Assert.Same(chr, airHolds.Single(n => n.TargetNote?.Type == ChuNoteType.Tap).TargetNote);
Assert.Same(slide, airHolds.Single(n => n.TargetNote?.Type == ChuNoteType.Slide).TargetNote);
Assert.All(airHolds, note => Assert.Equal(NoteColor.DEF, note.Color));
}

[Fact]
public void C2sSlideMissingEndWidthContinuesAtStartWidth()
{
var c2s = string.Join('\n',
"BPM\t0\t0\t120",
"SLC\t0\t0\t6\t4\t24\t6",
"SLC\t0\t24\t6\t4\t52\t5");

var (chart, alerts) = new C2sParser().Parse(c2s);

Assert.Empty(alerts);
var slide = Assert.Single(chart.Notes);
Assert.Equal(2, slide.Segments.Count);
Assert.Equal(4, slide.Segments[0].EndWidth);
}

/// <summary>
/// 绝对坐标下的一段 Slide/Hold/Crush 路径，用于跨 note 的 segment 错配回收。
/// </summary>
Expand Down Expand Up @@ -690,15 +730,15 @@ public void C2sToUgcViaGenerator(string c2sPath)
{
var (c2s, _) = new C2sParser().Parse(File.ReadAllText(c2sPath));
Assert.NotEmpty(c2s.Notes);

var (ugcText, _) = new UgcGenerator().Generate(c2s);
Assert.Contains("@VER", ugcText);
Assert.Contains("#5'0", ugcText);

// Sheriruth Expert/Master 存在同位置 CHR+HLD/SLD 叠放（非 ExLong）；默认会把 CHR 消费进长条，
// 导致与官谱 IR 不对齐，故仅对这两张开启 NoExLong。
var noExLong = c2sPath.Contains("2351_02") || c2sPath.Contains("2351_03");

// 再把转出来的ugc，parse回去，比较是否和一开始的c2s等价
var (ugcReparsed, _) = new UgcParser(noExLong: noExLong).Parse(ugcText);
Assert.NotEmpty(ugcReparsed.Notes);
Expand Down
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