[gnome-builder/1074-vala-language-server-add-support-using-gvls: 5/14] GVls: add initial plugin implementation

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 3b8f34e4edf2c619c9200df0dfbfed7f079ee204
Author: Daniel Espinosa Ortiz <esodan gmail com>
Date:   Thu Nov 14 20:13:35 2019 -0600

    GVls: add initial plugin implementation

 meson_options.txt               |   1 +
 src/plugins/gvls/gvls.plugin    |   9 ++
 src/plugins/gvls/gvls_plugin.py | 221 ++++++++++++++++++++++++++++++++++++++++
 src/plugins/gvls/meson.build    |  15 +++
 src/plugins/meson.build         |   1 +
 5 files changed, 247 insertions(+)
---
diff --git a/meson_options.txt b/meson_options.txt
index 15fce38b1..2947519e9 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -45,6 +45,7 @@ option('plugin_gnome_code_assistance', type: 'boolean')
 option('plugin_go_langserv', type: 'boolean')
 option('plugin_gradle', type: 'boolean')
 option('plugin_grep', type: 'boolean')
+option('plugin_gvls', type: 'boolean')
 option('plugin_html_completion', type: 'boolean')
 option('plugin_html_preview', type: 'boolean')
 option('plugin_jedi', type: 'boolean')
diff --git a/src/plugins/gvls/gvls.plugin b/src/plugins/gvls/gvls.plugin
new file mode 100644
index 000000000..dc826e62c
--- /dev/null
+++ b/src/plugins/gvls/gvls.plugin
@@ -0,0 +1,9 @@
+# gvls.plugin
+[Plugin]
+Name=GNOME Vala Language Server for GNOME Builder plugin
+Module=gvls-plugin
+Author=Daniel Espinosa
+Description=GNOME Builder plugin for GVLS, without any LPS protocol support
+Copyright=Copyright © 2019 Daniel Espinosa
+X-Completion-Provider-Languages=vala
+
diff --git a/src/plugins/gvls/gvls_plugin.py b/src/plugins/gvls/gvls_plugin.py
new file mode 100644
index 000000000..b95ded550
--- /dev/null
+++ b/src/plugins/gvls/gvls_plugin.py
@@ -0,0 +1,221 @@
+#!/usr/bin/env python
+
+# gvls_plugin.py
+#
+# Copyright 2016 Christian Hergert <chergert redhat com>
+# Copyright 2019 Daniel Espinosa <esodan gmail com>
+#
+# 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 of the License, 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, see <http://www.gnu.org/licenses/>.
+
+"""
+This plugin provides integration with the Vala Language Server.
+It builds off the generic language service components in libide
+by bridging them to our supervised Vala Language Server.
+"""
+
+import gi
+import os
+
+from gi.repository import GLib
+from gi.repository import Gio
+from gi.repository import GObject
+from gi.repository import Ide
+
+DEV_MODE = False
+
+class GVlsService(Ide.Object):
+    _client = None
+    _has_started = False
+    _supervisor = None
+    _monitor = None
+
+    @classmethod
+    def from_context(klass, context):
+        return context.ensure_child_typed(GVlsService)
+
+    @GObject.Property(type=Ide.LspClient)
+    def client(self):
+        return self._client
+
+    @client.setter
+    def client(self, value):
+        self._client = value
+        self.notify('client')
+
+    def do_parent_set(self, parent):
+        """
+        No useful for VLS
+        """
+        if parent is None:
+            return
+
+        context = self.get_context()
+        workdir = context.ref_workdir()
+        cargo_toml = workdir.get_child('Cargo.toml')
+
+        if cargo_toml.query_exists():
+            try:
+                self._monitor = cargo_toml.monitor(0, None)
+                self._monitor.set_rate_limit(5 * 1000) # 5 Seconds
+                self._monitor.connect('changed', self._monitor_changed_cb)
+            except Exception as ex:
+                Ide.debug('Failed to monitor Cargo.toml for changes:', repr(ex))
+
+    def _monitor_changed_cb(self, monitor, file, other_file, event_type):
+        """
+        This method is called when Cargo.toml has changed. We need to
+        cancel any supervised process and force the language server to
+        restart. Otherwise, we risk it not picking up necessary changes.
+        """
+        if self._supervisor is not None:
+            subprocess = self._supervisor.get_subprocess()
+            if subprocess is not None:
+                subprocess.force_exit()
+
+    def do_stop(self):
+        """
+        Stops the Rust Language Server upon request to shutdown the
+        GVlsService.
+        """
+        if self._monitor is not None:
+            monitor, self._monitor = self._monitor, None
+            if monitor is not None:
+                monitor.cancel()
+
+        if self._supervisor is not None:
+            supervisor, self._supervisor = self._supervisor, None
+            supervisor.stop()
+
+    def _ensure_started(self):
+        """
+        Start the Vala service which provides communication with the
+        Vala Language Server. We supervise our own instance of the
+        language server and restart it as necessary using the
+        Ide.SubprocessSupervisor.
+
+        Various extension points (diagnostics, symbol providers, etc) use
+        the GVlsService to access the rust components they need.
+        """
+        # To avoid starting the `gvls` process unconditionally at startup,
+        # we lazily start it when the first provider tries to bind a client
+        # to its :client property.
+        if not self._has_started:
+            self._has_started = True
+
+            # Setup a launcher to spawn the rust language server
+            launcher = self._create_launcher()
+            launcher.set_clear_env(False)
+            sysroot = self._discover_sysroot()
+            if DEV_MODE:
+                launcher.setenv('RUST_LOG', 'debug', True)
+            # Locate the directory of the project and run gvls from there.
+            workdir = self.get_context().ref_workdir()
+            launcher.set_cwd(workdir.get_path())
+
+            # If org.gnome.gvls.stdio.Server is installed by GVls
+            path_to_rls = "org.gnome.gvls.stdio.Server"
+
+            # Setup our Argv. We want to communicate over STDIN/STDOUT,
+            # so it does not require any command line options.
+            launcher.push_argv(path_to_rls)
+
+            # Spawn our peer process and monitor it for
+            # crashes. We may need to restart it occasionally.
+            self._supervisor = Ide.SubprocessSupervisor()
+            self._supervisor.connect('spawned', self._gvls_spawned)
+            self._supervisor.set_launcher(launcher)
+            self._supervisor.start()
+
+    def _gvls_spawned(self, supervisor, subprocess):
+        """
+        This callback is executed when the `org.gnome.gvls.stdio.Server` process is spawned.
+        We can use the stdin/stdout to create a channel for our
+        LspClient.
+        """
+        stdin = subprocess.get_stdin_pipe()
+        stdout = subprocess.get_stdout_pipe()
+        io_stream = Gio.SimpleIOStream.new(stdout, stdin)
+
+        if self._client:
+            self._client.stop()
+            self._client.destroy()
+
+        self._client = Ide.LspClient.new(io_stream)
+        self.append(self._client)
+        self._client.add_language('vala')
+        self._client.start()
+        self.notify('client')
+
+    def _create_launcher(self):
+        """
+        Creates a launcher to be used by the vala service.
+
+        In the future, we might be able to rely on the runtime for
+        the tooling. Maybe even the program if flatpak-builder has
+        prebuilt our dependencies.
+        """
+        flags = Gio.SubprocessFlags.STDIN_PIPE | Gio.SubprocessFlags.STDOUT_PIPE
+        if not DEV_MODE:
+            flags |= Gio.SubprocessFlags.STDERR_SILENCE
+        launcher = Ide.SubprocessLauncher()
+        launcher.set_flags(flags)
+        launcher.set_cwd(GLib.get_home_dir())
+        launcher.set_run_on_host(True)
+        return launcher
+
+    @classmethod
+    def bind_client(klass, provider):
+        """
+        This helper tracks changes to our client as it might happen when
+        our `org.gnome.gvls.Server` process has crashed.
+        """
+        context = provider.get_context()
+        self = GVlsService.from_context(context)
+        self._ensure_started()
+        self.bind_property('client', provider, 'client', GObject.BindingFlags.SYNC_CREATE)
+
+class GVlsDiagnosticProvider(Ide.LspDiagnosticProvider):
+    def do_load(self):
+        GVlsService.bind_client(self)
+
+class GVlsCompletionProvider(Ide.LspCompletionProvider):
+    def do_load(self, context):
+        GVlsService.bind_client(self)
+
+    def do_get_priority(self, context):
+        # This provider only activates when it is very likely that we
+        # want the results. So use high priority (negative is better).
+        return -1000
+
+class GVlsRenameProvider(Ide.LspRenameProvider):
+    def do_load(self):
+        GVlsService.bind_client(self)
+
+class GVlsSymbolResolver(Ide.LspSymbolResolver):
+    def do_load(self):
+        GVlsService.bind_client(self)
+
+class GVlsHighlighter(Ide.LspHighlighter):
+    def do_load(self):
+        GVlsService.bind_client(self)
+
+class GVlsFormatter(Ide.LspFormatter):
+    def do_load(self):
+        GVlsService.bind_client(self)
+
+class GVlsHoverProvider(Ide.LspHoverProvider):
+    def do_prepare(self):
+        self.props.category = 'Vala'
+        self.props.priority = 200
+        GVlsService.bind_client(self)
diff --git a/src/plugins/gvls/meson.build b/src/plugins/gvls/meson.build
new file mode 100644
index 000000000..248c8a39c
--- /dev/null
+++ b/src/plugins/gvls/meson.build
@@ -0,0 +1,15 @@
+if get_option('plugin_gvls')
+
+#dependency('gvls-0.12')
+
+install_data('gvls_plugin.py', install_dir: plugindir)
+
+configure_file(
+          input: 'gvls.plugin',
+         output: 'gvls.plugin',
+  configuration: config_h,
+        install: true,
+    install_dir: plugindir,
+)
+
+endif
diff --git a/src/plugins/meson.build b/src/plugins/meson.build
index 9cf9c9120..2c185658e 100644
--- a/src/plugins/meson.build
+++ b/src/plugins/meson.build
@@ -125,6 +125,7 @@ subdir('vim')
 subdir('waf')
 subdir('words')
 subdir('xml-pack')
+subdir('gvls')
 
 plugins = static_library('plugins', plugins_sources,
          dependencies: plugins_deps,