Re-order --help messages.

Divided them into 3 categories:
  - general
  - search
  - output

Closes: #12

man/epubgrep.1.adoc

@@ -52,6 +52,9 @@ Display a short help message and exit.
 *V*, *--version*::
 Show version, copyright and license.
 
+*--debug*::
+Write debug output to the terminal and log file.
+
 *-G*, *--basic-regexp*::
 _PATTERN_ is a POSIX basic regular expression. This is the default.
 
@@ -69,13 +72,22 @@ _PATTERN_ is a Perl regular expression.
 *-i*, *--ignore-case*::
 Ignore case distinctions in pattern and data.
 
-*-e* _PATTERN_, *--regexp* _PATTERN_::
-Use additional _PATTERN_ for matching. Can be used more than once.
-
 *-a*, *--raw*::
 Do not clean up text before searching. No HTML stripping, no newline removal,
 all files will be read (not just the text documents listed in the spine).
 
+*-r*, *--recursive*::
+Read all files under each directory, recursively, following symbolic links only
+if they are on the command line. Silently skips directories that are not
+readable by the user.
+
+*-R*, *--dereference-recursive*::
+Read all files under each directory, recursively. Follow all symbolic
+links. Silently skips directories that are not readable by the user.
+
+*-e* _PATTERN_, *--regexp* _PATTERN_::
+Use additional _PATTERN_ for matching. Can be used more than once.
+
 *-C* _NUMBER_, *context* _NUMBER_::
 Print _NUMBER_ words of context around matches.
 
@@ -88,23 +100,11 @@ Suppress the mentioning of file names on output. _WHICH_ is ‘filesystem’ for
 file names on your file systems, ‘in-epub’ for the file names inside the EPUB or
 ‘all’. Chapters and page numbers will still be output.
 
-*-r*, *--recursive*::
-Read all files under each directory, recursively, following symbolic links only
-if they are on the command line. Silently skips directories that are not
-readable by the user.
-
-*-R*, *--dereference-recursive*::
-Read all files under each directory, recursively. Follow all symbolic
-links. Silently skips directories that are not readable by the user.
-
 *--ignore-archive-errors*::
 Ignore errors about wrong file formats. When you search directories recursively,
 it is likely that there are files which are not EPUB files. This setting
 suppresses errors related to them.
 
-*--debug*::
-Write debug output to the terminal and log file.
-
 *--json*::
 Output JSON instead of plain text. JSON will only be output at the end of the
 program. There will be an object named `generator` with the property
@@ -116,7 +116,8 @@ Output HTML instead of plain text. HTML will only be output at the end of the
 program.
 
 *--status*::
-Output status message every *--status-interval* seconds to standard error.
+Output status message every *--status-interval* seconds to standard
+error. Default is 30.
 
 *--status-interval* _NUMBER_::
 Set status message interval to _NUMBER_ seconds.

src/options.cpp

@@ -49,13 +49,19 @@ using std::cout;
 
 options parse_options(int argc, char *argv[])
 {
-    po::options_description options_visible(translate("Available options"));
     // clang-format off
-    options_visible.add_options()
+    po::options_description options_general(translate("General options"));
+    options_general.add_options()
         ("help,h",
          translate("Display this help and exit.").str().data())
         ("version,V",
          translate("Display version information and exit.").str().data())
+        ("debug",
+         translate("Enable debug output.").str().data())
+    ;
+
+    po::options_description options_search(translate("Search options"));
+    options_search.add_options()
         ("basic-regexp,G",
          translate("PATTERN is a basic regular expression (default).")
          .str().data())
@@ -66,14 +72,25 @@ options parse_options(int argc, char *argv[])
          .str().data())
         ("perl-regexp,P",
          translate("PATTERN is a Perl regular expression.").str().data())
+
         ("ignore-case,i",
          translate("Ignore case distinctions in pattern and data.")
          .str().data())
+        ("raw,a",
+         translate("Do not clean up text before searching.").str().data())
+        ("recursive,r",
+         translate("Read all files under each directory, recursively.")
+         .str().data())
+        ("dereference-recursive,R",
+         translate("Read all files under each directory, recursively, "
+                   "following symlinks.").str().data())
         ("regexp,e", po::value<std::vector<std::string>>()
          ->value_name(translate("PATTERN"))->composing()->required(),
          translate("Use additional PATTERN for matching.").str().data())
-        ("raw,a",
-         translate("Do not clean up text before searching.").str().data())
+    ;
+
+    po::options_description options_output(translate("Output options"));
+    options_output.add_options()
         ("context,C", po::value<std::uint64_t>()
          ->value_name(translate("NUMBER"))->default_value(0),
          translate("Print NUMBER words of context around matches.")
@@ -83,16 +100,8 @@ options parse_options(int argc, char *argv[])
         ("no-filename",po::value<std::string>()->value_name(translate("WHICH")),
          translate("Suppress the mentioning of file names on output. "
                    "WHICH is ‘filesystem’, ‘in-epub’ or ‘all’.").str().data())
-        ("recursive,r",
-         translate("Read all files under each directory, recursively.")
-         .str().data())
-        ("dereference-recursive,R",
-         translate("Read all files under each directory, recursively, "
-                   "following symlinks.").str().data())
         ("ignore-archive-errors",
          translate("Ignore errors about wrong file formats.").str().data())
-        ("debug",
-         translate("Enable debug output.").str().data())
         ("json",
          translate("Output JSON instead of plain text.").str().data())
         ("html",
@@ -112,6 +121,12 @@ options parse_options(int argc, char *argv[])
          ->value_name("FILE"), "Input file to search.")
         ;
     // clang-format on
+
+    po::options_description options_visible;
+    options_visible.add(options_general)
+        .add(options_search)
+        .add(options_output);
+
     po::options_description options_all("Allowed options");
     options_all.add(options_visible).add(options_hidden);