Add matrix TOC with cross-reference columns

Replace the default LaTeX TOC with a table matching the Carmina
Leonis style: song titles with columns for reference books (MO,
PfLB) and the current songbook page number. Uses expl3 iow to
write song data to a .songtoc file during compilation and reads
it back on the second pass. Alternating row colors via rowcolors.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

songbook-style.sty

@@ -14,8 +14,11 @@
 \RequirePackage[hidelinks]{hyperref}
 \RequirePackage{fancyhdr}
 \RequirePackage{xcolor}
+\RequirePackage{longtable}
+\RequirePackage{array}
+\RequirePackage{colortbl}
+\RequirePackage{rotating}
 \RequirePackage[minimal]{leadsheets}
-% Pre-mark musicsymbols as loaded to avoid missing musix11 font error
 \ExplSyntaxOn
 \cs_new:cpn {leadsheets-library-musicsymbols-loaded} {}
 \ExplSyntaxOff
@@ -25,7 +28,11 @@
 \setmainfont{TeX Gyre Heros}
 \newfontfamily\frakfont{UnifrakturMaguntia-Book}[Path=fonts/,Extension=.ttf]
 
-% --- Page style: page numbers at bottom-outer, large ---
+% --- Colors ---
+\definecolor{tocrowgray}{gray}{0.92}
+\definecolor{tocheadgray}{gray}{0.75}
+
+% --- Page style ---
 \pagestyle{fancy}
 \fancyhf{}
 \fancyfoot[LE]{\large\bfseries\thepage}
@@ -47,14 +54,104 @@
   chorus/named = false,
   chorus/numbered = false,
   after-song = \songendsection,
+  disable-measuring,
 }
 
-% --- Chord appearance: regular weight, black (matching reference style) ---
 \setchords{
   format = \small,
 }
 
-% --- Command to render metadata at bottom of song ---
+% ==========================================================================
+% Song TOC matrix
+% ==========================================================================
+
+\newcounter{songnumber}
+\newcounter{tocrowcount}
+
+\ExplSyntaxOn
+\iow_new:N \g__sb_toc_iow
+\tl_new:N \l__sb_title_tl
+\tl_new:N \l__sb_mo_tl
+\tl_new:N \l__sb_pflb_tl
+\tl_new:N \l__sb_num_tl
+\bool_new:N \g__sb_toc_opened_bool
+
+% Lazy-open: only truncate the file when first song writes to it
+% This ensures the TOC reads the PREVIOUS run's data before truncation
+\cs_new_protected:Npn \__sb_ensure_toc_open:
+{
+  \bool_if:NF \g__sb_toc_opened_bool
+  {
+    \iow_open:Nn \g__sb_toc_iow { \c_sys_jobname_str .songtoc }
+    \bool_gset_true:N \g__sb_toc_opened_bool
+  }
+}
+
+\AtEndDocument{
+  \bool_if:NT \g__sb_toc_opened_bool
+  { \iow_close:N \g__sb_toc_iow }
+}
+
+\cs_new_protected:Npn \writesongtoc
+{
+  \__sb_ensure_toc_open:
+  \stepcounter{songnumber}
+  \tl_set:Nx \l__sb_num_tl { \int_use:N \c@songnumber }
+  \label{song:\tl_use:N \l__sb_num_tl}
+  \tl_set:Nx \l__sb_title_tl { \songproperty{title} }
+  \tl_set:Nx \l__sb_mo_tl { \songproperty{mundorgel} }
+  \tl_set:Nx \l__sb_pflb_tl { \songproperty{pfadfinderliederbuch} }
+  \iow_now:Nx \g__sb_toc_iow
+  {
+    \exp_not:N \songtocrow
+      { \l__sb_title_tl }
+      { \l__sb_mo_tl }
+      { \l__sb_pflb_tl }
+      { \exp_not:N \pageref { song: \l__sb_num_tl } }
+  }
+}
+\ExplSyntaxOff
+
+% --- Render one TOC row ---
+\newcommand{\songtocrow}[4]{%
+  #1 & #2 & #3 & \cellcolor{tocheadgray}\textbf{#4} \\
+  \hline
+}
+
+% --- Rotated column header ---
+\newcommand{\rotheader}[1]{%
+  \begin{turn}{70}\footnotesize\textbf{#1}\end{turn}%
+}
+
+% --- Print the song TOC table ---
+\newcommand{\printsongtoc}{%
+  \thispagestyle{fancy}%
+  {\Large\bfseries Inhaltsverzeichnis\par}%
+  \vspace{5mm}%
+  \footnotesize
+  \rowcolors{2}{tocrowgray}{white}%
+  \begin{longtable}{%
+    >{\raggedright\arraybackslash}p{0.52\textwidth}|%
+    >{\centering\arraybackslash}p{0.10\textwidth}|%
+    >{\centering\arraybackslash}p{0.10\textwidth}|%
+    >{\centering\arraybackslash\columncolor{tocheadgray}}p{0.12\textwidth}%
+  }
+  & \rotheader{MO} & \rotheader{PfLB}
+  & \rotheader{\normalsize Lieder-\newline\normalsize buch} \\
+  \hline
+  \endfirsthead
+  & \rotheader{MO} & \rotheader{PfLB}
+  & \rotheader{\normalsize Lieder-\newline\normalsize buch} \\
+  \hline
+  \endhead
+  \InputIfFileExists{\jobname.songtoc}{}{}%
+  \end{longtable}%
+}
+
+% ==========================================================================
+% Song end section
+% ==========================================================================
+
 \newcommand{\songendsection}{%
   \vfill
   \ifsongproperty{note}{%
@@ -74,7 +171,6 @@
       }{}%
     }%
   \endgroup
-  % Reference book footer
   \vspace{3mm}%
   \begingroup\footnotesize
     \noindent
@@ -92,9 +188,12 @@
   \newpage
 }
 
-% --- Song title template: Fraktur title, metadata at bottom ---
+% ==========================================================================
+% Song title template
+% ==========================================================================
+
 \definesongtitletemplate{songbook}{%
   {\LARGE\frakfont\songproperty{title}\par}%
-  \addcontentsline{toc}{section}{\songproperty{title}}%
+  \writesongtoc
   \vspace{4mm}%
 }