Formatter (#12)

* WIP: add template formatter

* partial compatibility with prev version

* handle braces, add docs about templating

* more explicit levels brace replacement

* add TRACE level

* handle valid template with invalid var in

README.md

@@ -33,19 +33,41 @@ _Without `lgr.Caller*` it will drop `{caller}` part_
 `lgr.New` call accepts functional options:
 
 - `lgr.Debug` - turn debug mode on to allow messages with "DEBUG" level (filtered overwise)
+- `lgr.Out(io.Writer)` - sets the output writer, default `os.Stdout`
+- `lgr.Err(io.Writer)` - sets the error writer, default `os.Stderr`
 - `lgr.CallerFile` - adds the caller file info
 - `lgr.CallerFunc` - adds the caller function info
 - `lgr.CallerPkg` - adds the caller package
 - `lgr.LevelBraces` - wraps levels with "[" and "]"
 - `lgr.Msec` - adds milliseconds to timestamp
-- `lgr.Out(io.Writer)` - sets the output writer, default `os.Stdout`
-- `lgr.Err(io.Writer)` - sets the error writer, default `os.Stderr`
+- `lgr.Format` - sets custom template, overwrite all other formatting modifiers.
+
+#### formatting templates:
+
+Several predefined templates provided and can be passed directly to `lgr.Format`, i.e. `lgr.Format(lgr.WithMsec)`
 
+```
+	Short      = `{{.DT.Format "2006/01/02 15:04:05"}} {{.Level}} {{.Message}}`
+	WithMsec   = `{{.DT.Format "2006/01/02 15:04:05.000"}} {{.Level}} {{.Message}}`
+	WithPkg    = `{{.DT.Format "2006/01/02 15:04:05.000"}} {{.Level}} ({{.CallerPkg}}) {{.Message}}`
+	ShortDebug = `{{.DT.Format "2006/01/02 15:04:05.000"}} {{.Level}} ({{.CallerFile}}:{{.CallerLine}}) {{.Message}}`
+	FuncDebug  = `{{.DT.Format "2006/01/02 15:04:05.000"}} {{.Level}} ({{.CallerFunc}}) {{.Message}}`
+	FullDebug  = `{{.DT.Format "2006/01/02 15:04:05.000"}} {{.Level}} ({{.CallerFile}}:{{.CallerLine}} {{.CallerFunc}}) {{.Message}}`
+```
+
+User can make a custom template and pass it directly to `lgr.Format`. For example:
+
+```go    
+    lgr.Format(`{{.Level}} - {{.DT.Format "2006-01-02T15:04:05Z07:00") - {{.CallerPkg}} - {{.Message}}`)
+```
+)
+
 ### levels
 
-`lgr.Logf` recognizes prefixes like "INFO" or "[INFO]" as levels. The full list of supported levels - "DEBUG", "INFO", "WARN", "ERROR", "PANIC" and "FATAL"
+`lgr.Logf` recognizes prefixes like "INFO" or "[INFO]" as levels. The full list of supported levels - "TRACE", "DEBUG", "INFO", "WARN", "ERROR", "PANIC" and "FATAL"
 
-- `DEBUG` will be filtered unless `lgr.Debug` option defined
+- `TRACE` will be filtered unless `lgr.Trace` option defined
+- `DEBUG` will be filtered unless `lgr.Debug` or `lgr.Trace` options defined
 - `INFO` and `WARN` don't have any special behavior attached
 - `ERROR` sends messages to both out and err writers
 - `PANIC` and `FATAL` send messages to both out and err writers. In addition sends dump of callers and runtime info to err only, and calls `os.Exit(1)`.

adaptor_test.go

@@ -11,14 +11,14 @@ import (
 
 func TestAdaptor_ToWriter(t *testing.T) {
 	rout, rerr := bytes.NewBuffer([]byte{}), bytes.NewBuffer([]byte{})
-	l := New(Out(rout), Err(rerr), Msec, LevelBraces)
+	l := New(Out(rout), Err(rerr), Format(WithMsec))
 	l.now = func() time.Time { return time.Date(2018, 1, 7, 13, 2, 34, 0, time.Local) }
 
 	wr := ToWriter(l, "WARN")
 	sz, err := wr.Write([]byte("something blah 123"))
 	require.NoError(t, err)
 	assert.Equal(t, 18, sz)
-	assert.Equal(t, "2018/01/07 13:02:34.000 [WARN]  something blah 123\n", rout.String())
+	assert.Equal(t, "2018/01/07 13:02:34.000 WARN  something blah 123\n", rout.String())
 }
 
 func TestAdaptor_ToWriterNoLevel(t *testing.T) {
@@ -41,15 +41,15 @@ func TestAdaptor_ToWriterNoLevel(t *testing.T) {
 
 func TestAdaptor_ToStdLogger(t *testing.T) {
 	rout, rerr := bytes.NewBuffer([]byte{}), bytes.NewBuffer([]byte{})
-	l := New(Out(rout), Err(rerr), Msec, LevelBraces)
+	l := New(Out(rout), Err(rerr), Format(WithMsec))
 	l.now = func() time.Time { return time.Date(2018, 1, 7, 13, 2, 34, 0, time.Local) }
 
 	wr := ToStdLogger(l, "WARN")
 	wr.Print("something")
-	assert.Equal(t, "2018/01/07 13:02:34.000 [WARN]  something\n", rout.String())
+	assert.Equal(t, "2018/01/07 13:02:34.000 WARN  something\n", rout.String())
 
 	rout.Reset()
 	rerr.Reset()
 	wr.Printf("xxx %s", "yyy")
-	assert.Equal(t, "2018/01/07 13:02:34.000 [WARN]  xxx yyy\n", rout.String())
+	assert.Equal(t, "2018/01/07 13:02:34.000 WARN  xxx yyy\n", rout.String())
 }

interface_test.go

@@ -67,16 +67,18 @@ func TestDefault(t *testing.T) {
 
 func TestDefaultWithSetup(t *testing.T) {
 	buff := bytes.NewBuffer([]byte{})
-	Setup(Out(buff), Debug, CallerFile, CallerFunc, Msec, LevelBraces)
+	Setup(Out(buff), Debug, Format(FullDebug))
 	def.now = func() time.Time { return time.Date(2018, 1, 7, 13, 2, 34, 0, time.Local) }
-	Printf("[INFO] something 123 %s", "xyz")
-	assert.Equal(t, "2018/01/07 13:02:34.000 [INFO]  {lgr/interface_test.go:72 lgr.TestDefaultWithSetup} something 123 xyz\n", buff.String())
+	Printf("[DEBUG] something 123 %s", "xyz")
+	assert.Equal(t, "2018/01/07 13:02:34.000 DEBUG (lgr/interface_test.go:72 lgr.TestDefaultWithSetup) something 123 xyz\n",
+		buff.String())
 }
 
 func TestDefaultFuncWithSetup(t *testing.T) {
 	buff := bytes.NewBuffer([]byte{})
-	Setup(Out(buff), Debug, CallerFile, CallerFunc, Msec, LevelBraces)
+	Setup(Out(buff), Debug, Format(FullDebug))
 	def.now = func() time.Time { return time.Date(2018, 1, 7, 13, 2, 34, 0, time.Local) }
 	Default().Logf("[INFO] something 123 %s", "xyz")
-	assert.Equal(t, "2018/01/07 13:02:34.000 [INFO]  {lgr/interface_test.go:80 lgr.TestDefaultFuncWithSetup} something 123 xyz\n", buff.String())
+	assert.Equal(t, "2018/01/07 13:02:34.000 INFO  (lgr/interface_test.go:81 lgr."+
+		"TestDefaultFuncWithSetup) something 123 xyz\n", buff.String())
 }