Add support for job control

This commit adds support for job control (running processes
asynchronously from plugins) with the JobStart, JobSend, and JobStop
functions (copying neovim's job control).

This commit also makes the linter plugin work asynchronously, so the
editor won't be frozen while the linter checks your code for errors.

cmd/micro/job.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"bytes"
+	"io"
+	"os/exec"
+	"strings"
+)
+
+type JobFunction struct {
+	function func(string, ...string)
+	output   string
+	args     []string
+}
+
+type CallbackFile struct {
+	io.Writer
+
+	callback func(string, ...string)
+	args     []string
+}
+
+func (f *CallbackFile) Write(data []byte) (int, error) {
+	jobFunc := JobFunction{f.callback, string(data), f.args}
+	jobs <- jobFunc
+	return f.Writer.Write(data)
+}
+
+func JobStart(cmd string, onStdout, onStderr, onExit string, userargs ...string) *exec.Cmd {
+	split := strings.Split(cmd, " ")
+	args := split[1:]
+	cmdName := split[0]
+
+	proc := exec.Command(cmdName, args...)
+	var outbuf bytes.Buffer
+	if onStdout != "" {
+		proc.Stdout = &CallbackFile{&outbuf, LuaFunctionJob(onStdout), userargs}
+	} else {
+		proc.Stdout = &outbuf
+	}
+	if onStderr != "" {
+		proc.Stderr = &CallbackFile{&outbuf, LuaFunctionJob(onStderr), userargs}
+	} else {
+		proc.Stderr = &outbuf
+	}
+
+	go func() {
+		proc.Run()
+		jobFunc := JobFunction{LuaFunctionJob(onExit), string(outbuf.Bytes()), userargs}
+		jobs <- jobFunc
+	}()
+
+	return proc
+}
+
+func JobStop(cmd *exec.Cmd) {
+	cmd.Process.Kill()
+}
+
+func JobSend(cmd *exec.Cmd, data string) {
+	stdin, err := cmd.StdinPipe()
+	if err != nil {
+		return
+	}
+
+	stdin.Write([]byte(data))
+}

cmd/micro/messenger.go

@@ -106,7 +106,7 @@ func (m *Messenger) YesNoPrompt(prompt string) (bool, bool) {
 		m.Display()
 		screen.ShowCursor(Count(m.message), h-1)
 		screen.Show()
-		event := screen.PollEvent()
+		event := <-events
 
 		switch e := event.(type) {
 		case *tcell.EventKey:
@@ -149,7 +149,7 @@ func (m *Messenger) Prompt(prompt, historyType string, completionType Completion
 		m.Clear()
 		m.Display()
 
-		event := screen.PollEvent()
+		event := <-events
 
 		switch e := event.(type) {
 		case *tcell.EventKey:

cmd/micro/micro.go

@@ -52,6 +52,9 @@ var (
 	// This is the currently open tab
 	// It's just an index to the tab in the tabs array
 	curTab int
+
+	jobs   chan JobFunction
+	events chan tcell.Event
 )
 
 // LoadInput loads the file input for the editor
@@ -245,14 +248,33 @@ func main() {
 	L.SetGlobal("MakeCommand", luar.New(L, MakeCommand))
 	L.SetGlobal("CurView", luar.New(L, CurView))
 
+	L.SetGlobal("JobStart", luar.New(L, JobStart))
+	L.SetGlobal("JobSend", luar.New(L, JobSend))
+	L.SetGlobal("JobStop", luar.New(L, JobStop))
+
 	LoadPlugins()
 
+	jobs = make(chan JobFunction, 100)
+	events = make(chan tcell.Event)
+
+	go func() {
+		for {
+			events <- screen.PollEvent()
+		}
+	}()
+
 	for {
 		// Display everything
 		RedrawAll()
 
-		// Wait for the user's action
-		event := screen.PollEvent()
+		var event tcell.Event
+		select {
+		case f := <-jobs:
+			f.function(f.output, f.args...)
+			continue
+		case event = <-events:
+		}
+
 		if TabbarHandleMouseEvent(event) {
 			continue
 		}

cmd/micro/plugin.go

@@ -23,12 +23,15 @@ func Call(function string, args []string) error {
 	if luaFunc.String() == "nil" {
 		return errors.New("function does not exist: " + function)
 	}
-	luaArgs := luar.New(L, args)
+	var luaArgs []lua.LValue
+	for _, v := range args {
+		luaArgs = append(luaArgs, luar.New(L, v))
+	}
 	err := L.CallByParam(lua.P{
 		Fn:      luaFunc,
 		NRet:    0,
 		Protect: true,
-	}, luaArgs)
+	}, luaArgs...)
 	return err
 }
 
@@ -57,6 +60,15 @@ func LuaFunctionCommand(function string) func([]string) {
 	}
 }
 
+func LuaFunctionJob(function string) func(string, ...string) {
+	return func(output string, args ...string) {
+		err := Call(function, append([]string{output}, args...))
+		if err != nil {
+			TermMessage(err)
+		}
+	}
+}
+
 // LoadPlugins loads the pre-installed plugins and the plugins located in ~/.config/micro/plugins
 func LoadPlugins() {
 	files, _ := ioutil.ReadDir(configDir + "/plugins")

runtime/plugins/linter/linter.lua

@@ -34,9 +34,11 @@ end
 function linter_lint(linter, cmd, errorformat)
     CurView():ClearGutterMessages(linter)
 
-    local handle = io.popen("(" .. cmd .. ")" .. " 2>&1")
-    local lines = linter_split(handle:read("*a"), "\n")
-    handle:close()
+    JobStart(cmd, "", "", "linter_onExit", linter, errorformat)
+end
+
+function linter_onExit(output, linter, errorformat)
+    local lines = linter_split(output, "\n")
 
     local regex = errorformat:gsub("%%f", "(.+)"):gsub("%%l", "(%d+)"):gsub("%%m", "(.+)")
     for _,line in ipairs(lines) do