Extract shared natural-HOPO helpers into natural-hopo.ts - #105
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…art (state-derived) The three derived boolean flags on ParsedChart (hasLyrics, hasVocals, hasForcedNotes) were parse-time snapshots that went stale whenever consumers mutated chart data post-parse. Remove them from ParsedChart entirely; scanChart derives all three at scan time from the current chart state, piggybacking on its existing single note-walk (no extra iterations). - hasLyrics / hasVocals: computed from parsedChart.vocalTracks.parts — constant-time existence check. - hasForcedNotes: inverts resolveFretModifiers. A note is 'forced' iff its resolved flag disagrees with the natural HOPO state the parser would pick without any force events, or it carries the tap flag (tap can only come from explicit forceTap). Inlined helpers for isNaturalHopo, isFretChord, isSameFretNote, isInFretNote, computeHopoThresholdTicks in chart-scanner.ts (duplicated from notes-parser.ts; a follow-up can extract to a shared helper). Semantic change to note: under the new definition, redundantly-applied force events (e.g. explicit forceHopo on a naturally-HOPO note) no longer contribute to hasForcedNotes — the chart plays identically with or without them, so state-derived detection correctly says false. This eliminates the need for any 'hasForcedNotes backstop' in writers since the flag round-trips naturally: the writer emits force events exactly when a flag disagrees with natural state, and the scanner detects those same disagreements on re-parse. ScannedChart.notesData's shape is unchanged (hasLyrics / hasVocals / hasForcedNotes still present); only the population source changes. Consumers that previously read parsedChart.hasLyrics / parsedChart.hasVocals / parsedChart.hasForcedNotes must switch to scanChart output.
The chart scanner, chart writer, and MIDI writer each had their own
near-identical copies of isFretChord / isSameFretNote / isInFretNote /
isNaturalHopo over NoteEvent[], and the parser had the same three
helpers again over TrackEvent[]. This consolidates all five callsites
into src/chart/natural-hopo.ts.
The helpers are generic (<T, E extends { type: T }> + an isFret
predicate); thin wrappers are exported for each concrete group type:
- NoteEvent-based (scanner + writers): isFretChord / isSameFretNote /
isInFretNote, plus the combined isNaturalHopo.
- TrackEvent-based (parser's resolveFretModifiers):
isFretChordRawEvents / isSameFretNoteRawEvents /
isInFretNoteRawEvents. The parser still builds its natural-HOPO
check inline — it compares effectiveNotes to lastNotes while
passing the raw pre-coalesced events to isSameFretNoteRawEvents,
a subtlety no NoteEvent callsite has.
The isFretNoteType / isFretEventType predicates are also exported,
so the parser's two standalone isFretNote(...) callsites (filtering
event lists outside the group helpers) share the same definition too.
The parser's four local helpers (isFretNote, isSameFretNote, isFretChord,
isInFretNote) are deleted.
Net: ~70 LOC of duplication removed across scanner, parser, and (in
the writer branches further up the stack) the two writers. One file
owns every natural-HOPO rule.
This commit updates the scanner + parser; the writers move to the
shared helpers in the two branches further up the stack that own them.
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Summary
The chart scanner, chart writer, and MIDI writer each had their own near-identical copies of
isFretChord/isSameFretNote/isInFretNote/isNaturalHopooverNoteEvent[], and the parser had the same three helpers again overTrackEvent[]. This PR consolidates all five callsites intosrc/chart/natural-hopo.ts.The helpers are generic (
<T, E extends { type: T }>+ anisFret: (t: T) => booleanpredicate); thin wrappers are exported for each concrete group type:isFretChord,isSameFretNote,isInFretNote, plus the combinedisNaturalHopo.resolveFretModifiers):isFretChordRawEvents,isSameFretNoteRawEvents,isInFretNoteRawEvents. (The parser still builds its own natural-HOPO check inline because it compareseffectiveNotestolastNoteswhile passing the raw pre-coalescedeventstoisSameFretNoteRawEvents— a subtlety no NoteEvent callsite has.)The
isFretNoteType/isFretEventTypepredicates are also exported, so the parser's two otherisFretNote(...)callsites (filtering event lists) share the same definition too. The parser's four local helpers (isFretNote,isSameFretNote,isFretChord,isInFretNote) are deleted.Net: ~70 LOC of duplication removed across the scanner, parser, and (in the later writer PRs) two writers. One file owns every natural-HOPO rule; changes to the rules happen in one place.
Stack (bottom → top)
Test plan
yarn testgreen at this branch (290 tests) and at the tip of the stack (442 tests).