[patch] add glg.RawString function for Custom Writer (#27)

Add RawString function

Usage is below

```go
type obj struct{}

func (n obj) Write(b []byte) (int, error) {
	glg.Infof("RawString is %s", glg.RawString(b)) // RawString is debug
	return len(b), nil
}
```
```go
glg.Get().AddLevelWriter(glg.DEBG, obj{})

glg.Debug("debug")
```

Signed-off-by: kpango <[email protected]>

Author: Yusuke Kato

example/main.go

@@ -14,6 +14,7 @@ func (n NetWorkLogger) Write(b []byte) (int, error) {
 	// http.Post("localhost:8080/log", "", bytes.NewReader(b))
 	http.Get("http://127.0.0.1:8080/log")
 	glg.Success("Requested")
+	glg.Infof("RawString is %s", glg.RawString(b))
 	return 1, nil
 }
 

glg.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -86,6 +87,13 @@ const (
 	dfl = len(df) / 3
 
 	timeFormat = "2006-01-02 15:04:05"
+
+	// return code
+	rc  = "\n"
+	rcl = len(rc)
+
+	sep  = "]:\t"
+	sepl = len(sep)
 )
 
 var (
@@ -472,6 +480,17 @@ func (g *Glg) DisableLevelColor(lv LEVEL) *Glg {
 	return g
 }
 
+// RawString returns raw log string exclude time & tags
+func (g *Glg) RawString(data []byte) string {
+	str := *(*string)(unsafe.Pointer(&data))
+	return str[strings.Index(str, sep)+sepl : len(str)-rcl]
+}
+
+// RawString returns raw log string exclude time & tags
+func RawString(data []byte) string {
+	return glg.RawString(data)
+}
+
 // TagStringToLevel converts level string to Glg.LEVEL
 func (g *Glg) TagStringToLevel(tag string) LEVEL {
 	l, ok := g.levelMap.Load(tag)
@@ -626,28 +645,28 @@ func (g *Glg) out(level LEVEL, format string, val ...interface{}) error {
 	b.Write(g.ft.FormattedNow())
 	b.WriteString("\t[")
 	b.WriteString(log.tag)
-	b.WriteString("]:\t")
+	b.WriteString(sep)
 	b.WriteString(format)
 
 	switch log.writeMode {
 	case writeColorStd:
 		buf = b.Bytes()
-		_, err = fmt.Fprintf(log.std, log.color(*(*string)(unsafe.Pointer(&buf)))+"\n", val...)
+		_, err = fmt.Fprintf(log.std, log.color(*(*string)(unsafe.Pointer(&buf)))+rc, val...)
 	case writeStd:
-		b.WriteString("\n")
+		b.WriteString(rc)
 		buf = b.Bytes()
 		_, err = fmt.Fprintf(log.std, *(*string)(unsafe.Pointer(&buf)), val...)
 	case writeWriter:
-		b.WriteString("\n")
+		b.WriteString(rc)
 		buf = b.Bytes()
 		_, err = fmt.Fprintf(log.writer, *(*string)(unsafe.Pointer(&buf)), val...)
 	case writeColorBoth:
 		buf = b.Bytes()
 		var str = *(*string)(unsafe.Pointer(&buf))
-		_, err = fmt.Fprintf(log.std, log.color(str)+"\n", val...)
-		_, err = fmt.Fprintf(log.writer, str+"\n", val...)
+		_, err = fmt.Fprintf(log.std, log.color(str)+rc, val...)
+		_, err = fmt.Fprintf(log.writer, str+rc, val...)
 	case writeBoth:
-		b.WriteString("\n")
+		b.WriteString(rc)
 		buf = b.Bytes()
 		_, err = fmt.Fprintf(io.MultiWriter(log.std, log.writer), *(*string)(unsafe.Pointer(&buf)), val...)
 	}

glg_test.go

@@ -11,6 +11,7 @@ import (
 	"reflect"
 	"strings"
 	"testing"
+	"time"
 )
 
 type ExitError int
@@ -3003,3 +3004,56 @@ func Test_blankFormat(t *testing.T) {
 		})
 	}
 }
+
+func TestGlg_RawString(t *testing.T) {
+	tests := []struct {
+		name string
+		args []byte
+		want string
+	}{
+		{
+			name: "trim",
+			args: []byte(time.Now().Format(timeFormat) + "\t[" + INFO.String() + "]:\tHello Glg" + rc),
+			want: "Hello Glg",
+		},
+		{
+			name: "trim hard",
+			args: []byte(time.Now().Format(timeFormat) + "\t[" + INFO.String() + "]:\tHello Glg]:\tHello" + rc),
+			want: "Hello Glg]:\tHello",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := New()
+			if got := g.RawString(tt.args); got != tt.want {
+				t.Errorf("Glg.RawString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestRawString(t *testing.T) {
+	tests := []struct {
+		name string
+		args []byte
+		want string
+	}{
+		{
+			name: "trim",
+			args: []byte(time.Now().Format(timeFormat) + "\t[" + INFO.String() + "]:\tHello Glg" + rc),
+			want: "Hello Glg",
+		},
+		{
+			name: "trim hard",
+			args: []byte(time.Now().Format(timeFormat) + "\t[" + INFO.String() + "]:\tHello Glg]:\tHello" + rc),
+			want: "Hello Glg]:\tHello",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := RawString(tt.args); got != tt.want {
+				t.Errorf("Glg.RawString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}