utils: Implement sexp command parser

Implement a sexp parser, and on top of that a command parser (for mu4e
commands). Add tests, too.

lib/utils/test-sexp-parser.cc

@@ -0,0 +1,75 @@
+/*
+** Copyright (C) 2020 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+**  This library is free software; you can redistribute it and/or
+**  modify it under the terms of the GNU Lesser General Public License
+**  as published by the Free Software Foundation; either version 2.1
+**  of the License, or (at your option) any later version.
+**
+**  This library 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
+**  Lesser General Public License for more details.
+**
+**  You should have received a copy of the GNU Lesser General Public
+**  License along with this library; if not, write to the Free
+**  Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+**  02110-1301, USA.
+*/
+
+#include <vector>
+#include <glib.h>
+
+#include <iostream>
+#include <sstream>
+
+#include "mu-command-parser.hh"
+#include "mu-utils.hh"
+
+using namespace Mu;
+
+static bool
+check_parse (const std::string& expr, const std::string& expected)
+{
+        try {
+                const auto parsed{to_string(Sexp::parse(expr))};
+                g_assert_cmpstr(parsed.c_str(), ==, expected.c_str());
+                return true;
+
+        } catch (const Error& err) {
+                g_warning ("caught exception parsing '%s': %s", expr.c_str(), err.what());
+                return false;
+        }
+}
+
+static void
+test_parser()
+{
+        check_parse(R"(:foo-123)", "<symbol>{:foo-123}");
+        check_parse(R"("foo")",    "<string>{foo}");
+        check_parse(R"(12345)",    "<integer>{12345}");
+        check_parse(R"((123 bar "cuux"))",    "<list>(<integer>{123}<symbol>{bar}<string>{cuux})");
+
+        check_parse(R"("\"")", "<string>{\"}");
+        check_parse(R"("\\")", "<string>{\\}");
+}
+
+int
+main (int argc, char *argv[]) try
+{
+        g_test_init (&argc, &argv, NULL);
+
+        if (argc == 2) {
+                std::cout << Sexp::parse(argv[1]) << '\n';
+                return 0;
+        }
+
+        g_test_add_func ("/utils/command-parser/parse", test_parser);
+
+	return g_test_run ();
+
+
+} catch (const std::runtime_error& re) {
+        std::cerr << re.what() << "\n";
+        return 1;
+}