[gnome-builder/wip/albfan/java-langserver] java-langserv: LSP integration for Java

[Alberto Fanjul <albfan src gnome org>]

commit b9490346d6051860d488d6ff3eaf9c6faff4cfa7
Author: Alberto Fanjul <albertofanjul gmail com>
Date:   Fri Apr 12 12:03:03 2019 +0200

    java-langserv: LSP integration for Java
    
    Basic integration with ls running from host

 meson_options.txt                                  |   1 +
 src/plugins/java-langserv/README.md                |  37 +++++
 src/plugins/java-langserv/java-langserv.plugin     |  10 ++
 .../java-langserv/java_langserver_plugin.py        | 164 +++++++++++++++++++++
 src/plugins/java-langserv/meson.build              |  13 ++
 src/plugins/meson.build                            |   2 +
 6 files changed, 227 insertions(+)
---
diff --git a/meson_options.txt b/meson_options.txt
index 57fe9301c..74be15e41 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -46,6 +46,7 @@ option('plugin_gradle', type: 'boolean')
 option('plugin_grep', type: 'boolean')
 option('plugin_html_completion', type: 'boolean')
 option('plugin_html_preview', type: 'boolean')
+option('plugin_java_langserv', type: 'boolean')
 option('plugin_jedi', type: 'boolean')
 option('plugin_jhbuild', type: 'boolean')
 option('plugin_make', type: 'boolean')
diff --git a/src/plugins/java-langserv/README.md b/src/plugins/java-langserv/README.md
new file mode 100644
index 000000000..5c2d23670
--- /dev/null
+++ b/src/plugins/java-langserv/README.md
@@ -0,0 +1,37 @@
+# language server client for java
+
+Wrap [java-language-server](https://github.com/georgewfraser/java-language-server).
+
+## Installing and testing
+
+1. Install `java-language-server`
+
+```
+git clone https://github.com/georgewfraser/java-language-server
+cd java-language-server
+JAVA_HOME=/path/to/jdk11 scripts/link_mac.sh
+```
+
+2. Set up your environment
+
+Create a launcher in /usr/bin
+
+```
+$ cat > /usr/bin/javals <<EOF
+#!/bin/bash
+
+/path/to/java-language-server/dist/mac/bin/launcher $@
+```
+
+Alternatively create a script in a custom path with `JAVALS_CMD` env:
+
+```
+export JAVALS_CMD="/custom/path/to/javals-script"
+```
+
+3. Launch Builder, open a java project
+4. Right click on a method and click 'go to definition'
+
+## Bugs:
+
+Please report on IRC or gitlab
diff --git a/src/plugins/java-langserv/java-langserv.plugin b/src/plugins/java-langserv/java-langserv.plugin
new file mode 100644
index 000000000..df79d76cf
--- /dev/null
+++ b/src/plugins/java-langserv/java-langserv.plugin
@@ -0,0 +1,10 @@
+[Plugin]
+Builtin=true
+Copyright=Copyright © 2019 Alberto Fanjul
+Description=Provides LSP integration for java
+Hidden=true
+Loader=python3
+Module=java_langserver_plugin
+Name=Java Language Server Plugin
+X-Builder-ABI=@PACKAGE_ABI@
+X-Symbol-Resolver-Languages=java
diff --git a/src/plugins/java-langserv/java_langserver_plugin.py 
b/src/plugins/java-langserv/java_langserver_plugin.py
new file mode 100755
index 000000000..83883501a
--- /dev/null
+++ b/src/plugins/java-langserv/java_langserver_plugin.py
@@ -0,0 +1,164 @@
+#!/usr/bin/env python3
+
+# java_langserv_plugin.py
+#
+# Copyright 2019 Alberto Fanjul <albertofanjul 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 Java Language Server.
+It builds off the generic language service components in libide
+by bridging them to our supervised Java Language Server.
+"""
+
+import os
+import gi
+
+from gi.repository import GLib
+from gi.repository import Gio
+from gi.repository import GObject
+from gi.repository import Ide
+
+DEV_MODE = os.getenv('DEV_MODE') and True or False
+
+class JavaService(Ide.Object):
+    _client = None
+    _has_started = False
+    _supervisor = None
+
+    @classmethod
+    def from_context(klass, context):
+        return context.ensure_child_typed(JavaService)
+
+    @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_stop(self):
+        if self._supervisor:
+            supervisor, self._supervisor = self._supervisor, None
+            supervisor.stop()
+
+    def _which_java_lanserver(self):
+        path = os.getenv('JAVALS_CMD')
+        if path and os.path.exists(os.path.expanduser(path)):
+            return path
+        return "javals"
+
+    def _ensure_started(self):
+        # To avoid starting the process unconditionally at startup, 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
+
+            launcher = self._create_launcher()
+            launcher.set_clear_env(False)
+
+            # Locate the directory of the project and run java-langserver from there
+            workdir = self.get_context().ref_workdir()
+            launcher.set_cwd(workdir.get_path())
+
+
+            # Bash will load the host $PATH for us.
+            # This does mean there will be a possible .bashrc vs .bash_profile
+            # discrepancy. Possibly there is a better native way to make sure that
+            # builder running in flatpak can run processes in the host context with
+            # the host's $PATH.
+            launcher.push_argv("/bin/bash")
+            launcher.push_argv("--login")
+            launcher.push_argv("-c")
+            launcher.push_argv('exec %s %s' % (self._which_java_lanserver(),
+                "--quiet" if not DEV_MODE else ""))
+
+            # 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._ls_spawned)
+            self._supervisor.set_launcher(launcher)
+            self._supervisor.start()
+
+    def _ls_spawned(self, supervisor, subprocess):
+        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('java')
+        self._client.start()
+        self.notify('client')
+
+    def _create_launcher(self):
+        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):
+        context = provider.get_context()
+        self = JavaService.from_context(context)
+        self._ensure_started()
+        self.bind_property('client', provider, 'client', GObject.BindingFlags.SYNC_CREATE)
+
+class JavaDiagnosticProvider(Ide.LspDiagnosticProvider):
+    def do_load(self):
+        JavaService.bind_client(self)
+
+class JavaRenameProvider(Ide.LspRenameProvider):
+    def do_load(self):
+        JavaService.bind_client(self)
+
+class JavaSymbolResolver(Ide.LspSymbolResolver, Ide.SymbolResolver):
+    def do_load(self):
+        JavaService.bind_client(self)
+
+class JavaHighlighter(Ide.LspHighlighter):
+    def do_load(self):
+        JavaService.bind_client(self)
+
+class JavaCompletionProvider(Ide.LspCompletionProvider, Ide.CompletionProvider):
+    def do_load(self, context):
+        JavaService.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 JavaFormatter(Ide.LspFormatter, Ide.Formatter):
+    def do_load(self):
+        JavaService.bind_client(self)
+
+class JavaHoverProvider(Ide.LspHoverProvider):
+    def do_prepare(self):
+        self.props.category = 'Java'
+        self.props.priority = 200
+        JavaService.bind_client(self)
+
diff --git a/src/plugins/java-langserv/meson.build b/src/plugins/java-langserv/meson.build
new file mode 100644
index 000000000..00213c6fa
--- /dev/null
+++ b/src/plugins/java-langserv/meson.build
@@ -0,0 +1,13 @@
+if get_option('plugin_java_langserv')
+
+install_data('java_langserver_plugin.py', install_dir: plugindir)
+
+configure_file(
+          input: 'java-langserv.plugin',
+         output: 'java-langserv.plugin',
+  configuration: config_h,
+        install: true,
+    install_dir: plugindir,
+)
+
+endif
diff --git a/src/plugins/meson.build b/src/plugins/meson.build
index 0c5fd6aa4..1adeae1a9 100644
--- a/src/plugins/meson.build
+++ b/src/plugins/meson.build
@@ -77,6 +77,7 @@ subdir('grep')
 subdir('history')
 subdir('html-completion')
 subdir('html-preview')
+subdir('java-langserv')
 subdir('jedi')
 subdir('jhbuild')
 subdir('line-spacing')
@@ -158,6 +159,7 @@ status += [
   'Grep .................. : @0@'.format(get_option('plugin_grep')),
   'HTML Completion ....... : @0@'.format(get_option('plugin_html_completion')),
   'HTML Preview .......... : @0@'.format(get_option('plugin_html_preview')),
+  'Java Language Server... : @0@'.format(get_option('plugin_java_langserv')),
   'Jedi .................. : @0@'.format(get_option('plugin_jedi')),
   'JHBuild ............... : @0@'.format(get_option('plugin_jhbuild')),
   'Make .................. : @0@'.format(get_option('plugin_make')),