Add neovim-qt compatible layer (#5)

Add shim to rtp, add gtk gui flag

Makefile

@@ -10,6 +10,8 @@ install: install-resources
 	cargo install --root $(PREFIX)
 
 install-resources:
+	mkdir -p $(PREFIX)/share/nvim-gtk/
+	cp -r runtime $(PREFIX)/share/nvim-gtk/ 
 	mkdir -p $(PREFIX)/share/applications/
 	cp desktop/nvim-gtk.desktop $(PREFIX)/share/applications/
 	mkdir -p $(PREFIX)/share/icons/hicolor/128x128/apps/

runtime/plugin/nvim_gui_shim.vim

@@ -0,0 +1,45 @@
+" A Neovim plugin that implements GUI helper commands
+if !has('nvim') || exists('g:GuiLoaded')
+  finish
+endif
+let g:GuiLoaded = 1
+
+" Set GUI font
+function! GuiFont(fname, ...) abort
+	call rpcnotify(1, 'Gui', 'Font', s:NvimQtToPangoFont(a:fname))
+endfunction
+
+" Some subset of parse command from neovim-qt
+" to support interoperability
+function s:NvimQtToPangoFont(fname)
+	let l:attrs = split(a:fname, ':')
+	let l:size = -1
+	for part in l:attrs
+		if len(part) >= 2 && part[0] == 'h'
+			let l:size = strpart(part, 1)
+		endif
+	endfor
+
+	if l:size > 0
+		return l:attrs[0] . ' ' . l:size
+	endif
+
+	return l:attrs[0]
+endf
+
+
+" The GuiFont command. For compatibility there is also Guifont
+function s:GuiFontCommand(fname, bang) abort
+	if a:fname ==# ''
+		if exists('g:GuiFont')
+			echo g:GuiFont
+		else
+			echo 'No GuiFont is set'
+		endif
+	else
+		call GuiFont(a:fname, a:bang ==# '!')
+	endif
+endfunction
+command! -nargs=? -bang Guifont call s:GuiFontCommand("<args>", "<bang>")
+command! -nargs=? -bang GuiFont call s:GuiFontCommand("<args>", "<bang>")
+

src/nvim.rs

@@ -1,4 +1,5 @@
 use std::io::{Result, Error, ErrorKind};
+use std::env;
 use std::process::{Stdio, Command};
 use std::result;
 use std::sync::Arc;
@@ -82,8 +83,21 @@ pub fn initialize(shell: Arc<UiMutex<shell::State>>,
         .arg("--headless")
         .arg("--cmd")
         .arg("set termguicolors")
+        .arg("--cmd")
+        .arg("let g:GtkGuiLoaded = 1")
         .stderr(Stdio::inherit());
 
+    if let Ok(runtime_path) = env::var("NVIM_GTK_RUNTIME_PATH") {
+        cmd.arg("--cmd")
+            .arg(format!("let &rtp.=',{}'", runtime_path));
+    }
+    else if let Some(prefix) = option_env!("PREFIX") {
+        cmd.arg("--cmd")
+            .arg(format!("let &rtp.=',{}/share/nvim-gtk/runtime'", prefix));
+    } else {
+        cmd.arg("--cmd").arg("let &rtp.=',runtime'");
+    }
+
     let session = Session::new_child_cmd(&mut cmd);
 
     let session = match session {