From 76b81a99688031a25bec9a92717d12d68e77d38a Mon Sep 17 00:00:00 2001
From: Christoph Wagner <tux@goldenerreiter.org>
Date: Mon, 24 Nov 2025 09:51:33 +0100
Subject: [PATCH] no breaks in toc after section title

---
 private_includes/book/toc_include.ily | 45 ++++++++++++++++-----------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/private_includes/book/toc_include.ily b/private_includes/book/toc_include.ily
index b872527..ce8d882 100644
--- a/private_includes/book/toc_include.ily
+++ b/private_includes/book/toc_include.ily
@@ -90,7 +90,7 @@
      (for-each (lambda (category)
             (let* ((catsym (string->symbol category))
                    (catlist (hashq-ref category-index-hash catsym
-                              (list (list label 'indexCategoryMarkup `(((rawtext . ,category))))))))
+                              (list (list label 'indexCategoryMarkup `(((combine-with-next . #t) (rawtext . ,category))))))))
               (if (assq catsym category-names)
                 (hashq-set! category-index-hash catsym
                   (cons (list label markup-symbol textoptions) catlist))
@@ -114,7 +114,7 @@
      (for-each (lambda (authorID)
             (let* ((authorsym (string->symbol authorID))
                    (authorlist (hashq-ref author-index-hash authorsym
-                              (list (list label 'indexAuthorMarkup `(((rawtext . ,authorID))))))))
+                              (list (list label 'indexAuthorMarkup `(((combine-with-next . #t) (rawtext . ,authorID))))))))
                 (hashq-set! author-index-hash authorsym
                   (cons (list label markup-symbol textoptions) authorlist))
                 ))
@@ -218,20 +218,29 @@
 }
 
 #(define (prepare-item-markup items layout)
-   (map (lambda (index-item)
-         (let* ((label (car index-item))
-                (index-markup (cadr index-item))
-                (textoptions (caddr index-item))
-                (text (chain-assoc-get 'rawtext textoptions))
-                (alternative (chain-assoc-get 'alternative textoptions))
-                (songnumber (chain-assoc-get 'songnumber textoptions)))
-           (markup #:override (cons 'index:label label)
-             #:override (cons 'index:page (markup #:custom-page-number label -1))
-             #:override (cons 'index:text text)
-             #:override (cons 'index:alternative alternative)
-             #:override (cons 'index:songnumber songnumber)
-             (ly:output-def-lookup layout index-markup))))
-       (items)))
+  (define (single-item-markup index-item)
+    (let* ((label (car index-item))
+           (index-markup (cadr index-item))
+           (textoptions (caddr index-item))
+           (text (chain-assoc-get 'rawtext textoptions))
+           (alternative (chain-assoc-get 'alternative textoptions))
+           (songnumber (chain-assoc-get 'songnumber textoptions)))
+      (markup #:override (cons 'index:label label)
+        #:override (cons 'index:page (markup #:custom-page-number label -1))
+        #:override (cons 'index:text text)
+        #:override (cons 'index:alternative alternative)
+        #:override (cons 'index:songnumber songnumber)
+        (ly:output-def-lookup layout index-markup))))
+  (if (null? items)
+      items
+      (let* ((index-item (car items))
+             (combine-with-next (chain-assoc-get 'combine-with-next (caddr index-item) #f))
+             (restitems (cdr items))
+             (item-markup (single-item-markup index-item)))
+        (if (and combine-with-next (not (null? restitems)))
+            (cons (make-column-markup (list item-markup (single-item-markup (car restitems)))) (prepare-item-markup (cdr restitems) layout))
+            (cons item-markup (prepare-item-markup restitems layout))))
+      ))
 
 #(define-markup-list-command (index-in-columns-with-title layout props index-type title-markup) (symbol? markup?)
   ( _i "Outputs index alphabetical sorted or in categories" )
@@ -245,7 +254,7 @@
         (make-columnlayout-markup-list songTocColumns 2
           (let ((h (- (ly:output-def-lookup layout 'paper-height) 12)))
             (cons (- h (interval-length (ly:stencil-extent title Y))) h))
-          (prepare-item-markup items layout))))))
+          (prepare-item-markup (items) layout))))))
 
 indexItem =
 #(define-music-function (parser location sorttext text) (string? markup?)
@@ -255,7 +264,7 @@ indexItem =
 indexSection =
 #(define-music-function (parser location sorttext text) (string? markup?)
    "Add a section line to the alphabetical index, using @code{indexSectionMarkup} paper variable markup. This can be used to divide the alphabetical index into different sections, for example one section for each first letter."
-   (add-index-item! 'indexSectionMarkup (prepend-alist-chain 'rawtext text '()) sorttext))
+   (add-index-item! 'indexSectionMarkup (prepend-alist-chain 'combine-with-next #t (prepend-alist-chain 'rawtext text '())) sorttext))
 
 #(define (extract-and-check-vars-from-header bookheader varlist)
   (let* ((headervars (hash-map->list cons (struct-ref (ly:book-header bookheader) 0)))