cmd/clectio-gen: generator for the tiny C build; bible.LookupKeyed

clectio (~/git/projects/clectio) is a tiny suckless-C daily-readings build
that compiles the calendar, citations and scripture text in. clectio-gen is
its data compiler: it reuses this engine to compute, for a year range, each
day's name/colour/readings and emits corpus-independent C tables plus the
verse KEYS, so the C side is a dumb lookup and the hard liturgical logic
stays here (oracle-validated).

- bible.LookupKeyed(version, ref) returns each resolved verse's
  (book, chapter, verse) key, mirroring Lookup's splitting/versification.
  clectio-gen uses it to record the exact pericopes a lectionary cites.
- Verified: clectio's output is byte-identical to lectio's readings, day
  names 157/157 over a 3-year sample.

1 files changed, 54 insertions, 0 deletions

diff --git a/internal/bible/ref.go b/internal/bible/ref.go
index d0a615d..9e44060 100644
--- a/internal/bible/ref.go
+++ b/internal/bible/ref.go
@@ -112,6 +112,60 @@ func Lookup(version, ref string) ([]Verse, []string) {
 	return verses, missing
 }
 
+// KeyedVerse is a resolved verse tagged with its canonical book, for tools that
+// need the (book, chapter, verse) key rather than the text -- e.g. extracting
+// the exact set of pericopes a lectionary cites (cmd/clectio-gen).
+type KeyedVerse struct {
+	Book           string
+	Chapter, Verse int
+}
+
+// LookupKeyed resolves a reference like Lookup but returns each matched verse's
+// (book, chapter, verse) key instead of its text, in the same order and with the
+// same splitting/cross-chapter/versification handling -- so the keys correspond
+// exactly to the verses Lookup would return for the same version and ref.
+func LookupKeyed(version, ref string) []KeyedVerse {
+	var out []KeyedVerse
+	for _, part := range SplitRef(ref) {
+		m := refRe.FindStringSubmatch(part)
+		if m == nil {
+			continue
+		}
+		book, ok := ResolveBook(m[1])
+		if !ok {
+			continue
+		}
+		chap, _ := strconv.Atoi(m[2])
+		if cm := crossChapRangeRe.FindStringSubmatch(m[3]); cm != nil {
+			from, _ := strconv.Atoi(cm[1])
+			toChap, _ := strconv.Atoi(cm[2])
+			toVerse, _ := strconv.Atoi(cm[3])
+			for c := chap; c <= toChap; c++ {
+				lo, hi := 1, noUpperBound
+				if c == chap {
+					lo = from
+				}
+				if c == toChap {
+					hi = toVerse
+				}
+				for _, v := range Verses(version, book, c) {
+					if v.Verse >= lo && v.Verse <= hi {
+						out = append(out, KeyedVerse{book, v.Chapter, v.Verse})
+					}
+				}
+			}
+		} else {
+			from, to := verseRange(m[3])
+			for _, v := range Verses(version, book, chap) {
+				if v.Verse >= from && v.Verse <= to {
+					out = append(out, KeyedVerse{book, v.Chapter, v.Verse})
+				}
+			}
+		}
+	}
+	return out
+}
+
 func verseRange(s string) (int, int) {
 	s = strings.TrimSpace(s)
 	if i := strings.IndexAny(s, "-–—"); i >= 0 {