Implemented control over automatic linebreaks between unison notes.

Fixes gregorio-project#1504

.gitignore

@@ -127,3 +127,4 @@ ctan
 *.pyg
 .agignore
 *.orig
+compile_commands.json

CHANGELOG.md

@@ -4,6 +4,7 @@ As of v3.0.0 this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased][develop]
 
+- Added a configurable setting `\gresetunisonbreakbehavior` to control automatic line breaks between unison notes above a syllable.  Defaults to `breakable` for backwards compatibility, but may be set to `unbreakable` if that behavior is desired.  See [#1504](https://github.com/gregorio-project/gregorio/issues/1504).
 
 ## [Unreleased][CTAN]
 

doc/Command_Index_User.tex

@@ -1178,6 +1178,19 @@ \subsubsection{End of Line Behavior}
                   lines.  Defaults to \getgrecount{unbreakablefinalnotes}.\\
 \end{argtable}
 
+\macroname{\textbackslash gresetunisonbreakbehavior}{\{\#1\}}{gregoriotex-main.tex}
+Macro to determine whether an automatic linebreak may occur between unison notes
+over a syllable.  This behavior governs how the system works when no explicit
+space is put between the notes.  In other words, any explicit space between the
+notes take precedence over this setting.
+
+\begin{argtable}
+  \#1 & \texttt{breakable}   & Allow automatic linebreaks between unison notes
+                               (default)\\
+      & \texttt{unbreakable} & Disallow automatic linebreaks between unison
+                               notes\\
+\end{argtable}
+
 
 \subsubsection{Bar spacing}
 

doc/Command_Index_gregorio.tex

@@ -402,6 +402,7 @@ \section{Gregorio Controls}
   & \texttt{4} & Ad-hoc space.\\
   \#2 & \texttt{0} & Space is breakable.\\
   & \texttt{1} & Space is unbreakable.\\
+  & \texttt{2} & Space is breakable according to the \verb=\setunisonbreakbehavior= setting.\\
   \#3 & integer & The number of notes in the syllable prior to this macro.\\
 \end{argtable}
 
@@ -444,11 +445,12 @@ \section{Gregorio Controls}
   & \texttt{20} & Space between a punctum inclinatum and a ``no-bar'' glyph two pitches above. \\
   & \texttt{21} & Space between a punctum inclinatum and a ``no-bar'' glyph three or four pitches above \\
   & \texttt{22} & Half-space. \\
+  & \texttt{23} & Space between unison puncta inclinata. \\
 \end{argtable}
 
 \macroname{\textbackslash GreFinalCustos}{\#1\#2}{gregoriotex-signs.tex}
 Typesets a custos after the final bar in a score.
-
+um
 \begin{argtable}
   \#1 & integer & Height number of custos.\\
   \#2 & \texttt{Flat} & The custos should have a flat.\\

doc/Command_Index_internal.tex

@@ -1961,6 +1961,10 @@ \subsection{Flags}
 \macroname{\textbackslash ifgre@unbreakableendofelement}{}{gregoriotex-main.tex}
 Boolean used by \verb=\GreEndOfElement= to store whether the line may be broken at that point.
 
+\macroname{\textbackslash gre@unbreakableendofelement@unison}{}{gregoriotex-main.tex}
+Alias that sets \verb=\ifgre@unbreakableendofelement= according to the
+\verb=\setunisonbreakbehavior= preference.
+
 \macroname{\textbackslash gre@count@syllablenotes}{}{gregoriotex-syllable.tex}
 Count containing the number of notes in the syllable.
 

src/gregoriotex/gregoriotex-write.c

@@ -3847,6 +3847,75 @@ static bool is_before_linebreak(const gregorio_syllable *syllable,
     return false;
 }
 
+static void write_default_end_of_element(FILE *f,
+        const gregorio_element *const element,
+        const unsigned int note_unit_count) {
+    const gregorio_element *next_element;
+    const gregorio_glyph *last_glyph;
+    const gregorio_note *last_note, *next_note;
+    signed char last_pitch = NO_PITCH;
+    int break_flag = 0;
+
+    /* This is only used in write_syllable, so element is assumed to be:
+     * 1. not NULL
+     * 2. of type GRE_ELEMENT
+     */
+    if (element->next) {
+        next_element = element->next;
+        if (next_element->type == GRE_ALT) {
+            next_element = next_element->next;
+        }
+        if (next_element && next_element->type == GRE_ELEMENT) {
+            for (last_glyph = element->u.first_glyph; last_glyph->next;
+                    last_glyph = last_glyph->next) {
+                /* iterate to find the last glyph */
+            }
+            if (last_glyph->type == GRE_GLYPH) {
+                last_note = gregorio_glyph_last_note(last_glyph);
+                assert(last_note != NULL);
+                if (last_note->type == GRE_NOTE)
+                    switch(last_note->u.note.shape) {
+                    case S_FLAT:
+                    case S_FLAT_PAREN:
+                    case S_SHARP:
+                    case S_SHARP_PAREN:
+                    case S_NATURAL:
+                    case S_NATURAL_PAREN:
+                        break;
+                    default:
+                        last_pitch = last_note->u.note.pitch;
+                        break;
+                }
+            }
+            if (last_pitch != NO_PITCH && next_element->u.first_glyph
+                    && next_element->u.first_glyph->type == GRE_GLYPH) {
+                next_note = next_element->u.first_glyph->u.notes.first_note;
+                if (next_note->type == GRE_NOTE) {
+                    switch(next_note->u.note.shape) {
+                    case S_FLAT:
+                    case S_FLAT_PAREN:
+                    case S_SHARP:
+                    case S_SHARP_PAREN:
+                    case S_NATURAL:
+                    case S_NATURAL_PAREN:
+                        break;
+                    default:
+                        if (next_note->u.note.pitch != NO_PITCH &&
+                                next_note->u.note.pitch - last_pitch == 0) {
+                            /* at a unison */
+                            break_flag = 2;
+                        }
+                        break;
+                    }
+                }
+            }
+
+            fprintf(f, "\\GreEndOfElement{0}{%d}{%u}%%\n", break_flag,
+                    note_unit_count);
+        }
+    }
+}
+
 /*
  * Arguments are relatively obvious. The most obscure is certainly first_of_disc
  * which is 0 all the time, except in the case of a "clef change syllable". In
@@ -4204,19 +4273,12 @@ static void write_syllable(FILE *f, gregorio_syllable *syllable,
                 break;
 
             default:
-                /* here current_element->type is GRE_ELEMENT */
+                /* here element->type is GRE_ELEMENT */
                 assert(element->type == GRE_ELEMENT);
                 handle_last_of_voice(f, syllable, element, *last_of_voice);
                 note_unit_count += write_element(f, syllable, element, status,
                         score);
-                if (element->next && (element->next->type == GRE_ELEMENT
-                                || (element->next->next
-                                        && element->next->type == GRE_ALT
-                                        && element->next->next->type ==
-                                        GRE_ELEMENT))) {
-                    fprintf(f, "\\GreEndOfElement{0}{0}{%u}%%\n",
-                            note_unit_count);
-                }
+                write_default_end_of_element(f, element, note_unit_count);
                 break;
             }
         }

tex/gregoriotex-main.tex

@@ -1506,13 +1506,28 @@
 }%
 
 \newif\ifgre@unbreakableendofelement %
+\def\gresetunisonbreakbehavior#1{%
+  \IfStrEqCase{#1}{%
+    {breakable}%
+      {\global\let\gre@unbreakableendofelement@unison\gre@unbreakableendofelementfalse\relax}%
+    {unbreakable}%
+      {\global\let\gre@unbreakableendofelement@unison\gre@unbreakableendofelementtrue\relax}%
+    }[% all other cases
+      \gre@error{Unrecognized option "#1" for \protect\gresetunisonbreakbehavior\MessageBreak Possible options are: 'breakable' and 'unbreakable'}%
+    ]%
+}%
+\gresetunisonbreakbehavior{breakable}
+
 % macro to end elements, #1 is the type of space, it can be :
 %% 0: default space
 %% 1: larger space
 %% 2: glyph space
 %% 3: zero-width space
 %% 4: custom space
-% #2 is if the space is unbreakable (1) or not (0)
+% #2 is whether the space is breakable :
+%% 0: breakable
+%% 1: unbreakable
+%% 2: unison (breakable according to the unisonbreakbehavior setting)
 % #3 is the number of notes emitted in this syllable before this macro
 \def\GreEndOfElement#1#2#3{%
   \ifnum\gre@count@syllablenotes<\gre@count@unbreakabletotalnotes\relax %
@@ -1525,10 +1540,14 @@
           \gre@count@unbreakablefinalnotes\relax %
         \gre@unbreakableendofelementtrue %
       \else %
-        \ifnum#2=1\relax %
+        \ifcase#2\relax %
+          \gre@unbreakableendofelementfalse %
+        \or% case 1
           \gre@unbreakableendofelementtrue %
+        \or% case 2
+          \gre@unbreakableendofelement@unison %
         \else %
-          \gre@unbreakableendofelementfalse %
+          \gre@error{Unrecognized breakable argument #2}%
         \fi %
       \fi %
     \fi %
@@ -1538,7 +1557,7 @@
   \else %
     \gre@penalty{\the\gre@space@count@endofelementpenalty}%
   \fi %
-  \ifcase#1%
+  \ifcase#1\relax%
     \gre@skip@temp@four = \gre@space@skip@interelementspace\relax%
     \gre@hskip\gre@skip@temp@four %
   \or% case 1
@@ -1552,6 +1571,8 @@
     \gre@hskip\gre@skip@temp@four %
   \or% case 4
     \gre@hskip\gre@skip@temp@four %
+  \else%
+    \gre@error{Unrecognized space type #1}%
   \fi%
   \ifgre@unbreakableendofelement %
     \GreNoBreak %