source: code/trunk/vendor/github.com/sirupsen/logrus/writer.go@ 67

package logrus

import (
        "bufio"
        "io"
        "runtime"
)

// Writer at INFO level. See WriterLevel for details.
func (logger *Logger) Writer() *io.PipeWriter {
        return logger.WriterLevel(InfoLevel)
}

// WriterLevel returns an io.Writer that can be used to write arbitrary text to
// the logger at the given log level. Each line written to the writer will be
// printed in the usual way using formatters and hooks. The writer is part of an
// io.Pipe and it is the callers responsibility to close the writer when done.
// This can be used to override the standard library logger easily.
func (logger *Logger) WriterLevel(level Level) *io.PipeWriter {
        return NewEntry(logger).WriterLevel(level)
}

func (entry *Entry) Writer() *io.PipeWriter {
        return entry.WriterLevel(InfoLevel)
}

func (entry *Entry) WriterLevel(level Level) *io.PipeWriter {
        reader, writer := io.Pipe()

        var printFunc func(args ...interface{})

        switch level {
        case TraceLevel:
                printFunc = entry.Trace
        case DebugLevel:
                printFunc = entry.Debug
        case InfoLevel:
                printFunc = entry.Info
        case WarnLevel:
                printFunc = entry.Warn
        case ErrorLevel:
                printFunc = entry.Error
        case FatalLevel:
                printFunc = entry.Fatal
        case PanicLevel:
                printFunc = entry.Panic
        default:
                printFunc = entry.Print
        }

        go entry.writerScanner(reader, printFunc)
        runtime.SetFinalizer(writer, writerFinalizer)

        return writer
}

func (entry *Entry) writerScanner(reader *io.PipeReader, printFunc func(args ...interface{})) {
        scanner := bufio.NewScanner(reader)
        for scanner.Scan() {
                printFunc(scanner.Text())
        }
        if err := scanner.Err(); err != nil {
                entry.Errorf("Error while reading from Writer: %s", err)
        }
        reader.Close()
}

func writerFinalizer(writer *io.PipeWriter) {
        writer.Close()
}