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// Copyright (C) 2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package internal
import (
"io"
"unicode/utf8"
)
// interfaces /////////////////////////////////////////////////////////////////
type RuneWriter interface {
WriteRune(rune) (int, error)
}
// An AllWriter is the union of several common writer interfaces.
type AllWriter interface {
io.Writer
io.ByteWriter
RuneWriter
io.StringWriter
}
// implementations ////////////////////////////////////////////////////////////
func WriteByte(w io.Writer, b byte) error {
var buf [1]byte
buf[0] = b
_, err := w.Write(buf[:])
return err
}
func WriteRune(w io.Writer, r rune) (int, error) {
var buf [utf8.UTFMax]byte
n := utf8.EncodeRune(buf[:], r)
return w.Write(buf[:n])
}
func WriteString(w io.Writer, s string) (int, error) {
return w.Write([]byte(s))
}
// wrappers ///////////////////////////////////////////////////////////////////
// NNN
type (
writerNNN interface{ io.Writer }
writerNNNWrapper struct{ writerNNN }
)
func (w writerNNNWrapper) WriteByte(b byte) error { return WriteByte(w, b) }
func (w writerNNNWrapper) WriteRune(r rune) (int, error) { return WriteRune(w, r) }
func (w writerNNNWrapper) WriteString(s string) (int, error) { return WriteString(w, s) }
// NNY
type (
writerNNY interface {
io.Writer
io.StringWriter
}
writerNNYWrapper struct{ writerNNY }
)
func (w writerNNYWrapper) WriteByte(b byte) error { return WriteByte(w, b) }
func (w writerNNYWrapper) WriteRune(r rune) (int, error) { return WriteRune(w, r) }
// NYN
type (
writerNYN interface {
io.Writer
RuneWriter
}
writerNYNWrapper struct{ writerNYN }
)
func (w writerNYNWrapper) WriteByte(b byte) error { return WriteByte(w, b) }
func (w writerNYNWrapper) WriteString(s string) (int, error) { return WriteString(w, s) }
// NYY
type (
writerNYY interface {
io.Writer
RuneWriter
io.StringWriter
}
writerNYYWrapper struct{ writerNYY }
)
func (w writerNYYWrapper) WriteByte(b byte) error { return WriteByte(w, b) }
// YNN
type (
writerYNN interface {
io.Writer
io.ByteWriter
}
writerYNNWrapper struct{ writerYNN }
)
func (w writerYNNWrapper) WriteRune(r rune) (int, error) { return WriteRune(w, r) }
func (w writerYNNWrapper) WriteString(s string) (int, error) { return WriteString(w, s) }
// YNY
type (
writerYNY interface {
io.Writer
io.ByteWriter
io.StringWriter
}
writerYNYWrapper struct{ writerYNY }
)
func (w writerYNYWrapper) WriteRune(r rune) (int, error) { return WriteRune(w, r) }
// YYN
type (
writerYYN interface {
io.Writer
io.ByteWriter
RuneWriter
}
writerYYNWrapper struct{ writerYYN }
)
func (w writerYYNWrapper) WriteString(s string) (int, error) { return WriteString(w, s) }
// NewAllWriter wraps an io.Writer turning it in to an AllWriter. If
// the io.Writer already has any of the other write methods, then its
// native version of those methods are used.
func NewAllWriter(inner io.Writer) AllWriter {
switch inner := inner.(type) {
// 3 Y bits
case AllWriter: // YYY:
return inner
// 2 Y bits
case writerNYY:
return writerNYYWrapper{writerNYY: inner}
case writerYNY:
return writerYNYWrapper{writerYNY: inner}
case writerYYN:
return writerYYNWrapper{writerYYN: inner}
// 1 Y bit
case writerNNY:
return writerNNYWrapper{writerNNY: inner}
case writerNYN:
return writerNYNWrapper{writerNYN: inner}
case writerYNN:
return writerYNNWrapper{writerYNN: inner}
// 0 Y bits
default: // NNN:
return writerNNNWrapper{writerNNN: inner}
}
}
// discard /////////////////////////////////////////////////////////////////////
// Discard is like io.Discard, but implements AllWriter.
var Discard = discard{}
type discard struct{}
func (discard) Write(p []byte) (int, error) { return len(p), nil }
func (discard) WriteByte(b byte) error { return nil }
func (discard) WriteRune(r rune) (int, error) { return 0, nil }
func (discard) WriteString(s string) (int, error) { return len(s), nil }
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