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// Copyright 2016 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package ansiterm
import (
"io"
"os"
"github.com/mattn/go-colorable"
"github.com/mattn/go-isatty"
)
// colorEnabledWriter returns a writer that can handle the ansi color codes
// and true if the writer passed in is a terminal capable of color. If the
// TERM environment variable is set to "dumb", the terminal is not considered
// color capable.
func colorEnabledWriter(w io.Writer) (io.Writer, bool) {
f, ok := w.(*os.File)
if !ok {
return w, false
}
// NO_COLOR is a relatively new standard for preventing color enabled
// writers rather than using the TERM env.
//
// "...should check for the presence of a NO_COLOR environment variable
// that, when present (regardless of its value), prevents the addition of
// ANSI color."
// See: https://no-color.org/
if _, ok := os.LookupEnv("NO_COLOR"); ok {
return w, false
}
// Check the TERM environment variable specifically
// to check for "dumb" terminals.
if os.Getenv("TERM") == "dumb" {
return w, false
}
if !isatty.IsTerminal(f.Fd()) {
return w, false
}
return colorable.NewColorable(f), true
}
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