mu-server: restore readline-support

Restore readline support for `mu server' (but _only_ when readline is
found and when in tty mode)

NEWS.org

@@ -3,6 +3,9 @@
 
 * 1.5.x (unreleased, development version)
 
+*** mu
+    - Optionally provide readline support for the mu server (when in tty-mode)
+
 *** mu4e
 
     - Honor ~truncate-string-ellipsis~ so you can now use 'fancy' ellipses for

lib/utils/Makefile.am

@@ -53,6 +53,8 @@ libmu_utils_la_SOURCES=						\
 	mu-log.h						\
 	mu-command-parser.cc					\
 	mu-command-parser.hh					\
+	mu-readline.cc						\
+	mu-readline.hh						\
 	mu-sexp-parser.cc					\
 	mu-sexp-parser.hh					\
 	mu-str.c						\

lib/utils/mu-readline.cc

@@ -0,0 +1,131 @@
+/*
+** Copyright (C) 2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+** This program is free software; you can redistribute it and/or modify it
+** under the terms of the GNU General Public License as published by the
+** Free Software Foundation; either version 3, or (at your option) any
+** later version.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software Foundation,
+** Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+**
+*/
+
+#include "mu-readline.hh"
+#include "config.h"
+
+#include <iostream>
+#include <unistd.h>
+#include <string>
+#include <glib.h>
+#include <glib/gprintf.h>
+
+#ifdef HAVE_LIBREADLINE
+#  if defined(HAVE_READLINE_READLINE_H)
+#    include <readline/readline.h>
+#  elif defined(HAVE_READLINE_H)
+#    include <readline.h>
+#  else /* !defined(HAVE_READLINE_H) */
+extern char *readline ();
+#  endif /* !defined(HAVE_READLINE_H) */
+char *cmdline = NULL;
+#else /* !defined(HAVE_READLINE_READLINE_H) */
+/* no readline */
+#endif /* HAVE_LIBREADLINE */
+
+#ifdef HAVE_READLINE_HISTORY
+#  if defined(HAVE_READLINE_HISTORY_H)
+#    include <readline/history.h>
+#  elif defined(HAVE_HISTORY_H)
+#    include <history.h>
+#  else /* !defined(HAVE_HISTORY_H) */
+extern void add_history ();
+extern int write_history ();
+extern int read_history ();
+#  endif /* defined(HAVE_READLINE_HISTORY_H) */
+/* no history */
+#endif /* HAVE_READLINE_HISTORY */
+
+
+#if defined(HAVE_LIBREADLINE) && defined(HAVE_READLINE_HISTORY)
+#define HAVE_READLINE (1)
+#else
+#define HAVE_READLINE (0)
+#endif
+
+using namespace Mu;
+
+static bool        is_a_tty{};
+static std::string hist_path;
+static size_t      max_lines{};
+
+void
+Mu::setup_readline (const std::string& histpath, size_t maxlines)
+{
+        is_a_tty  = !!::isatty(::fileno(stdout));
+        hist_path = histpath;
+        max_lines = maxlines;
+
+#if HAVE_READLINE
+        rl_bind_key('\t', rl_insert); // default (filenames) is not useful
+        using_history();
+        read_history(hist_path.c_str());
+
+        if (max_lines > 0)
+                stifle_history(max_lines);
+#endif /*HAVE_READLINE*/
+}
+
+
+void
+Mu::shutdown_readline ()
+{
+#if HAVE_READLINE
+        if (!is_a_tty)
+                return;
+
+        write_history(hist_path.c_str());
+        if (max_lines > 0)
+                history_truncate_file (hist_path.c_str(), max_lines);
+#endif /*HAVE_READLINE*/
+}
+
+
+std::string
+Mu::read_line(bool& do_quit)
+{
+#if HAVE_READLINE
+        if (is_a_tty) {
+                auto buf = readline(";; mu% ");
+                if (!buf) {
+                        do_quit = true;
+                        return {};
+                }
+                std::string line{buf};
+                ::free(buf);
+                return line;
+        }
+#endif /*HAVE_READLINE*/
+
+        std::string line;
+        std::cout << ";; mu> ";
+        if (!std::getline(std::cin, line))
+                do_quit = true;
+
+        return line;
+}
+
+
+void
+Mu::save_line(const std::string& line) {
+#if HAVE_READLINE
+        if (is_a_tty)
+                add_history(line.c_str());
+#endif /*HAVE_READLINE*/
+}

lib/utils/mu-readline.hh

@@ -0,0 +1,54 @@
+/*
+** Copyright (C) 2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+** This program is free software; you can redistribute it and/or modify it
+** under the terms of the GNU General Public License as published by the
+** Free Software Foundation; either version 3, or (at your option) any
+** later version.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software Foundation,
+** Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+**
+*/
+#include <string>
+
+namespace Mu {
+
+/**
+ * Setup readline when available & on tty.
+ *
+ * @param histpath path to the history file
+ * @param max_lines maximum number of history to save
+ */
+void setup_readline(const std::string &histpath, size_t max_lines);
+
+/**
+ * Shutdown readline
+*
+ */
+void shutdown_readline();
+
+
+/**
+ * Read a command line
+ *
+ * @param do_quit recceives whether we should quit.
+ *
+ * @return the string read or empty
+ */
+std::string read_line(bool &do_quit);
+
+/**
+ * Save a line to history (or do nothing when readline is not active)
+ *
+ * @param line a line.
+ */
+void save_line(const std::string &line);
+
+} // namespace Mu

mu/mu-cmd-server.cc

@@ -40,6 +40,7 @@
 #include "utils/mu-str.h"
 #include "utils/mu-utils.hh"
 #include "utils/mu-command-parser.hh"
+#include "utils/mu-readline.hh"
 
 using namespace Mu;
 using namespace Command;
@@ -1270,17 +1271,6 @@ make_command_map (Context& context)
       return cmap;
 }
 
-
-static std::string
-read_line(bool& do_quit)
-{
-        std::string line;
-        std::cout << ";; mu> ";
-        if (!std::getline(std::cin, line))
-                do_quit = true;
-        return line;
-}
-
 MuError
 mu_cmd_server (MuConfig *opts, GError **err) try
 {
@@ -1300,6 +1290,10 @@ mu_cmd_server (MuConfig *opts, GError **err) try
                 return MU_OK;
         }
 
+
+        const auto histpath{std::string{mu_runtime_path(MU_RUNTIME_PATH_CACHE)} + "/history"};
+        setup_readline(histpath, 50);
+
         install_sig_handler();
         std::cout << ";; Welcome to the "  << PACKAGE_STRING << " command-server\n"
                   << ";; Use (help) to get a list of commands, (quit) to quit.\n";
@@ -1322,6 +1316,7 @@ mu_cmd_server (MuConfig *opts, GError **err) try
                                      er.what(), line.c_str());
                 }
         }
+        shutdown_readline();
 
         return MU_OK;