alexkappa/mustache

package mustache

import (
    "bufio"
    "bytes"
    "io"
)

type writer struct {
    hasText bool
    hasTag  bool
    w       io.Writer
    b       *bufio.Writer
}

func newWriter(w io.Writer) *writer {
    return &writer{
        hasText: false,
        hasTag:  false,
        w:       w,
        b:       bufio.NewWriter(w),
    }
}

func (w *writer) text() {
    w.hasText = true
}

func (w *writer) tag() {
    w.hasTag = true
}

func (w *writer) reset() {
    w.hasTag = false
    w.hasText = false
}

func (w *writer) flush() error {
    defer w.reset()
    if w.hasTag && !w.hasText {
        w.b.Reset(w.w)
        return nil
    }
    return w.b.Flush()
}

func (w *writer) write(r rune) error {
    _, err := w.b.WriteRune(r)
    if err != nil {
        return err
    }
    if r == '\n' {
        return w.flush()
    }
    return nil
}

func (w *writer) Write(b []byte) (int, error) {
    for i, r := range bytes.Runes(b) {
        err := w.write(r)
        if err != nil {
            return i, err
        }
    }
    return len(b), nil
}