mkvmerge: chapters: support specifying MPLS with --chapters

Fixes/implements #3735

NEWS.md

@@ -7,6 +7,10 @@
 * MKVToolNix GUI: jobs: the status bar now differentiates between numbers of
   warnings/errors that occurred in the current session and those that occurred
   before the current session. Implements #3732.
+* mkvmerge: chapters: added support for specifying MPLS files with
+  `--chapters`, too, not just as regular source files. The documentation
+  stated this was possible already, but that wasn't actually the
+  case. Implements/fixes #3735.
 
 ## Bug fixes
 

src/common/chapters/bluray.cpp

@@ -16,6 +16,8 @@
 #include "common/chapters/chapters.h"
 #include "common/construct.h"
 #include "common/ebml.h"
+#include "common/hacks.h"
+#include "common/mm_file_io.h"
 #include "common/unique_numbers.h"
 
 namespace mtx::chapters {
@@ -66,4 +68,19 @@ convert_mpls_chapters_kax_chapters(mtx::bluray::mpls::chapters_t const &mpls_cha
   return kax_chapters;
 }
 
+std::shared_ptr<libmatroska::KaxChapters>
+maybe_parse_bluray(std::string const &file_name,
+                   mtx::bcp47::language_c const &language) {
+
+  mm_file_io_c in{file_name};
+  auto parser = mtx::bluray::mpls::parser_c{};
+
+  parser.enable_dropping_last_entry_if_at_end(!mtx::hacks::is_engaged(mtx::hacks::KEEP_LAST_CHAPTER_IN_MPLS));
+
+  if (parser.parse(in))
+    return mtx::chapters::convert_mpls_chapters_kax_chapters(parser.get_chapters(), language, g_chapter_generation_name_template.get_translated());
+
+  return {};
+}
+
 }

src/common/chapters/bluray.h

@@ -21,5 +21,6 @@ class KaxChapters;
 namespace mtx::chapters {
 
 std::shared_ptr<libmatroska::KaxChapters> convert_mpls_chapters_kax_chapters(mtx::bluray::mpls::chapters_t const &chapters, mtx::bcp47::language_c const &main_language, std::string const &name_template = {});
+std::shared_ptr<libmatroska::KaxChapters> maybe_parse_bluray(std::string const &file_name, mtx::bcp47::language_c const &language);
 
 }

src/common/chapters/chapters.cpp

@@ -22,6 +22,7 @@
 
 #include "common/bcp47.h"
 #include "common/chapters/chapters.h"
+#include "common/chapters/bluray.h"
 #include "common/chapters/dvd.h"
 #include "common/construct.h"
 #include "common/container.h"
@@ -548,6 +549,16 @@ parse(const std::string &file_name,
     }
 #endif
 
+    auto parsed_bluray_chapters = maybe_parse_bluray(file_name, language);
+    if (parsed_bluray_chapters) {
+      unify_legacy_and_bcp47_languages_and_countries(*parsed_bluray_chapters);
+
+      if (format)
+        *format = format_e::bluray;
+
+      return parsed_bluray_chapters;
+    }
+
     mm_text_io_c in(std::make_shared<mm_file_io_c>(file_name));
     auto parsed_chapters = parse(&in, min_ts, max_ts, offset, language, charset, exception_on_error, format, tags);
 

src/common/chapters/chapters.h

@@ -56,6 +56,7 @@ enum class format_e {
   cue,
   ffmpeg_meta,
   dvd,
+  bluray,
 };
 
 mtx::chapters::kax_cptr