add --version flag (#210)

This helps with Brew packaging.

Closes #210

config.vala.in

@@ -1,4 +1,5 @@
 namespace Config {
-    const string libvala_version = "@LIBVALA_VERSION@";
-    const string version = "@VLS_VERSION@";
+    const string LIBVALA_VERSION = "@LIBVALA_VERSION@";
+    const string PROJECT_BUGSITE = "@PROJECT_BUGSITE@";
+    const string PROJECT_NAME = "@PROJECT_NAME@";
 }

meson.build

@@ -42,12 +42,17 @@ endif
 
 conf = configuration_data()
 conf.set('LIBVALA_VERSION', libvala.version())
-conf.set('VLS_VERSION', meson.project_version())
+conf.set('PROJECT_BUGSITE', 'https://github.com/Prince781/vala-language-server/issues')
+conf.set('PROJECT_NAME', meson.project_name())
 
 conf_file = configure_file(input: 'config.vala.in',
                            output: 'config.vala',
                            configuration: conf)
 
+version_file = vcs_tag(input: 'version.vala.in',
+                       output: 'version.vala',
+                       command: ['git', 'describe', '--tags', '--dirty'])
+
 add_project_arguments(['--enable-gobject-tracing', '--fatal-warnings'], language: 'vala')
 
 extra_vala_sources = files([

src/meson.build

@@ -35,6 +35,6 @@ endif
 
 executable('vala-language-server',
   dependencies: deps,
-  sources: [vls_src, conf_file, extra_vala_sources],
+  sources: [vls_src, conf_file, version_file, extra_vala_sources],
   c_args: ['-DG_LOG_DOMAIN="vls"'],
   install: true)

src/server.vala

@@ -253,7 +253,7 @@ class Vls.Server : Object {
                 ),
                 serverInfo: buildDict (
                     name: new Variant.string ("Vala Language Server"),
-                    version: new Variant.string (Config.version)
+                    version: new Variant.string (Config.PROJECT_VERSION)
                 )
             ), cancellable);
         } catch (Error e) {
@@ -1968,9 +1968,38 @@ class Vls.Server : Object {
     }
 }
 
-void main () {
+/**
+ * `--version`
+ */
+bool opt_version;
+
+const OptionEntry[] entries = {
+    { "version", 'V', OptionFlags.NONE, OptionArg.NONE, ref opt_version, "Print the version and commit info", null },
+    {}
+};
+
+int main (string[] args) {
     Environment.set_prgname ("vala-language-server");
+    var ocontext = new OptionContext ("- vala-language-server");
+    ocontext.add_main_entries (entries, null);
+    ocontext.set_summary ("A language server for Vala");
+    ocontext.set_description (@"Report bugs to $(Config.PROJECT_BUGSITE)");
+    try {
+        ocontext.parse (ref args);
+    } catch (Error e) {
+        stderr.printf ("%s\n", e.message);
+        stderr.printf ("Run '%s --version' to print version, or no arguments to run the language server.\n", args[0]);
+        return 1;
+    }
+
+    if (opt_version) {
+        stdout.printf ("%s %s\n", Config.PROJECT_NAME, Config.PROJECT_VERSION);
+        return 1;
+    }
+
+    // otherwise
     var loop = new MainLoop ();
     new Vls.Server (loop);
     loop.run ();
+    return 0;
 }

version.vala.in

@@ -0,0 +1,3 @@
+namespace Config {
+    const string PROJECT_VERSION = "@VCS_TAG@";
+}