Added parallel computing

Readme.md

@@ -21,10 +21,11 @@ import "os/exec"
 
 func main() {
 	err := shelly.Exec(`
-	ls -larth
-	pwd
+	ls -larth &
+	pwd &
 	whoami
 	date`, &shelly.Opts{
+		Await: false,
 		SetupProc: func(cmd *exec.Cmd) {
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
@@ -36,5 +37,8 @@ func main(){
 }
 ```
 
-Please note: Commands may be connected by `;` and `\n`. In any case they will be executed sequentially. 
-`&` will come later (pending implementation), and will allow processes to run in parallel.
+Please note: Commands may be connected by `;` and `\n`. In any case they will be executed sequentially. Lines terminated
+by `&` will be executed in parallel.
+
+In case the Await property is true, shelly will wait for all lines to be executed (including parallel ones), otherwise
+it will return as soon as serial tasks are finished (if any)

lib.go

@@ -6,14 +6,11 @@ import (
 	"log"
 	"os/exec"
 	"strings"
+	"sync"
 )
 
 type Mode int
 
-type Opts struct {
-	SetupProc func(cmd *exec.Cmd)
-}
-
 func (m Mode) String() string {
 	switch m {
 	case MODE_NORMAL:
@@ -36,6 +33,29 @@ const (
 	MODE_ESCAPE_STR
 )
 
+type LineType int
+
+const (
+	LINETYPE_SERIAL LineType = iota
+	LINETYPE_PARALLEL
+	LINETYPE_COMMENT
+)
+
+// Opts tells Exec how to behave
+// Opts.Await will inform whether its call should wait for all parallel started jobs to finish
+// Opts.SetupProc will customize the processes before execution - Eg.: setting out and err
+type Opts struct {
+	Await     bool
+	SetupProc func(cmd *exec.Cmd)
+}
+
+// Line represents a line to be executed by the shell.
+// Can be separated by \n our ; - in case of serial execution. & will be used to identify parallel execution
+type Line struct {
+	Tokens []string
+	LType  LineType
+}
+
 // Tokens will break the string into tokens - It can be later organized in command lines and alikes
 func Tokens(str string) ([]string, error) {
 	params := make([]string, 0)
@@ -127,25 +147,47 @@ func Tokens(str string) ([]string, error) {
 }
 
 // Lines will call Tokens first, and reorg them in executable lines
-func Lines(str string) ([][]string, error) {
-	ret := make([][]string, 0)
+func Lines(str string) ([]Line, error) {
+	ret := make([]Line, 0)
 	tokens, err := Tokens(str)
 	if err != nil {
 		return nil, err
 	}
-	line := make([]string, 0)
+	line := Line{
+		Tokens: make([]string, 0),
+		LType:  LINETYPE_SERIAL,
+	}
 	for _, tk := range tokens {
 		switch tk {
-		case "\n", "&&", ";":
-			if len(line) > 0 {
+		case "\n", ";":
+			if len(line.Tokens) > 0 {
+				if strings.HasPrefix(line.Tokens[0], "#") {
+					line.LType = LINETYPE_COMMENT
+				} else {
+					line.LType = LINETYPE_SERIAL
+				}
 				ret = append(ret, line)
 			}
-			line = make([]string, 0)
+			line = Line{
+				Tokens: make([]string, 0),
+			}
+		case "&":
+			if len(line.Tokens) > 0 {
+				if strings.HasPrefix(line.Tokens[0], "#") {
+					line.LType = LINETYPE_COMMENT
+				} else {
+					line.LType = LINETYPE_PARALLEL
+				}
+				ret = append(ret, line)
+			}
+			line = Line{
+				Tokens: make([]string, 0),
+			}
 		default:
-			line = append(line, tk)
+			line.Tokens = append(line.Tokens, tk)
 		}
 	}
-	if len(line) > 0 {
+	if len(line.Tokens) > 0 {
 		ret = append(ret, line)
 	}
 	return ret, nil
@@ -153,27 +195,56 @@ func Lines(str string) ([][]string, error) {
 
 // Exec will call Lines and execute one by one
 func Exec(str string, opts ...*Opts) error {
+
+	var opt *Opts
+	if opts != nil && len(opts) > 0 {
+		opt = opts[0]
+	}
+
+	if opt.SetupProc == nil {
+		opt.SetupProc = func(cmd *exec.Cmd) {
+
+		}
+	}
+
+	prepCmd := func(l Line) *exec.Cmd {
+		cmd := exec.Command(l.Tokens[0], l.Tokens[1:]...)
+		cmd.Stdout = log.Writer()
+		cmd.Stderr = log.Writer()
+		opt.SetupProc(cmd)
+		return cmd
+	}
+
+	wg := sync.WaitGroup{}
 	lines, err := Lines(str)
+
 	if err != nil {
 		return err
 	}
 	for _, l := range lines {
-		if len(l) < 1 {
+
+		switch l.LType {
+		case LINETYPE_COMMENT:
 			continue
-		}
-		if strings.HasPrefix(l[0], "#") {
-			continue
-		}
-		cmd := exec.Command(l[0], l[1:]...)
-		if opts != nil && len(opts) > 0 {
-			opts[0].SetupProc(cmd)
-		}
-		cmd.Stdout = log.Writer()
-		cmd.Stderr = log.Writer()
+		case LINETYPE_SERIAL:
+			cmd := prepCmd(l)
 			err = cmd.Run()
 			if err != nil {
 				return err
 			}
+		case LINETYPE_PARALLEL:
+			go func(l Line) {
+				cmd := prepCmd(l)
+				wg.Add(1)
+				err = cmd.Run()
+				wg.Done()
+			}(l)
+		}
+
+	}
+
+	if opt.Await {
+		wg.Wait()
 	}
 
 	return nil

lib_test.go

@@ -28,10 +28,11 @@ func TestLines(t *testing.T) {
 
 func TestExec(t *testing.T) {
 	err := Exec(`
-	ls -larth
-	pwd
-	whoami
+	ls -larth &
+	pwd &
+	whoami &
 	date`, &Opts{
+		Await: false,
 		SetupProc: func(cmd *exec.Cmd) {
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
@@ -41,4 +42,6 @@ func TestExec(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	log.Printf("DONE")
+
 }