colog/std_formatter.go

package colog

import (
	"fmt"
	"log"
	"path/filepath"
	"time"
)

var colorLabels = LevelMap{
	LDebug: []byte("[\x1b[0;36mDBG\x1b[0m] "),
	LInfo:  []byte("[\x1b[0;32mINF\x1b[0m] "),
	LWarn:  []byte("\x1b[0;35m[WARN]\x1b[0m "),
	LError: []byte("\x1b[0;31m[ERR]\x1b[0m "),
}

var plainLabels = LevelMap{
	LDebug: []byte("[DBG] "),
	LInfo:  []byte("[INF] "),
	LWarn:  []byte("[WARN] "),
	LError: []byte("[ERR] "),
}

// StdFormatter supports plain and color level headers
// and bold/padded fields
type StdFormatter struct {
	Flag           int
	Colors         bool // Force enable colors
	NoColors       bool // Force disable colors (has preference)
	colorSupported bool
}

// Format takes and entry and returns the formatted output in bytes
func (sf *StdFormatter) Format(e *Entry) ([]byte, error) {

	// Normal headers.  time, file, etc
	var header, message []byte
	sf.stdHeader(&header, e.Time, e.File, e.Line)

	// Level headers
	headers := sf.levelHeaders()
	message = append(headers[e.Level], append(header, e.Message...)...)

	return append(message, '\n'), nil
}

// levelHeaders returns plain or color level headers
// depending on user preference and output support
func (sf *StdFormatter) levelHeaders() LevelMap {
	switch {
	case sf.NoColors:
		return plainLabels
	case sf.Colors:
		return colorLabels
	case sf.colorSupported:
		return colorLabels
	}
	return plainLabels
}

// Flags returns the output flags for the formatter.
func (sf *StdFormatter) Flags() int {
	return sf.Flag
}

// SetFlags sets the output flags for the formatter.
func (sf *StdFormatter) SetFlags(flags int) {
	sf.Flag = flags
}

// ColorSupported enables or disables the colors, this will be called on every
func (sf *StdFormatter) ColorSupported(supp bool) {
	sf.Colors = supp
}

// Adapted replica of log.Logger.formatHeader
func (sf *StdFormatter) stdHeader(buf *[]byte, t time.Time, file string, line int) {
	if sf.Flag&(log.Ldate|log.Ltime|log.Lmicroseconds) != 0 {
		if sf.Flag&log.Ldate != 0 {
			year, month, day := t.Date()
			itoa(buf, year, 4)
			*buf = append(*buf, '/')
			itoa(buf, int(month), 2)
			*buf = append(*buf, '/')
			itoa(buf, day, 2)
			*buf = append(*buf, ' ')
		}
		if sf.Flag&(log.Ltime|log.Lmicroseconds) != 0 {
			hour, min, sec := t.Clock()
			itoa(buf, hour, 2)
			*buf = append(*buf, ':')
			itoa(buf, min, 2)
			*buf = append(*buf, ':')
			itoa(buf, sec, 2)
			if sf.Flag&log.Lmicroseconds != 0 {
				*buf = append(*buf, '.')
				itoa(buf, t.Nanosecond()/1e3, 6)
			}
			*buf = append(*buf, ' ')
		}
	}
	if sf.Flag&(log.Lshortfile|log.Llongfile) != 0 {
		if sf.Flag&log.Lshortfile != 0 {
			short := file
			for i := len(file) - 1; i > 0; i-- {
				if file[i] == '/' {
					short = file[i+1:]
					break
				}
			}
			file = short
		} else {
			file = filepath.Base(filepath.Dir(file)) + "/" + filepath.Base(file)
		}

		if sf.Colors {
			file = fmt.Sprintf("\x1b[1;30m%s:%d:\x1b[0m ", file, line)
		} else {
			file = fmt.Sprintf("%s:%d: ", file, line)
		}

		*buf = append(*buf, file...)
	}
}

// Replica of log.Logger.itoa
func itoa(buf *[]byte, i int, wid int) {
	var u = uint(i)
	if u == 0 && wid <= 1 {
		*buf = append(*buf, '0')
		return
	}

	// Assemble decimal in reverse order.
	var b [32]byte
	bp := len(b)
	for ; u > 0 || wid > 0; u /= 10 {
		bp--
		wid--
		b[bp] = byte(u%10) + '0'
	}
	*buf = append(*buf, b[bp:]...)
}