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Don't escape ANSI colors in log values (#87)
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* allow to test with color

* added tests

* updated test

* updated needsQuoting

* fixed quoting

---------

Co-authored-by: lmittmann <[email protected]>
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@lmittmann
lmittmann and lmittmann authored Jan 28, 2025
1 parent bd5634c commit cdb3c00
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Showing 2 changed files with 235 additions and 25 deletions.
196 changes: 176 additions & 20 deletions handler.go
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Original file line number Diff line number Diff line change
Expand Up @@ -79,20 +79,24 @@ import (
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"time"
"unicode"
"unicode/utf8"
)

// ANSI modes
const (
ansiReset = "\033[0m"
ansiFaint = "\033[2m"
ansiResetFaint = "\033[22m"
ansiBrightRed = "\033[91m"
ansiBrightGreen = "\033[92m"
ansiBrightYellow = "\033[93m"
ansiBrightRedFaint = "\033[91;2m"
ansiReset = "\u001b[0m"
ansiFaint = "\u001b[2m"
ansiResetFaint = "\u001b[22m"
ansiBrightRed = "\u001b[91m"
ansiBrightGreen = "\u001b[92m"
ansiBrightYellow = "\u001b[93m"
ansiBrightRedFaint = "\u001b[91;2m"

ansiEsc = '\u001b'
)

const errKey = "err"
Expand Down Expand Up @@ -378,15 +382,15 @@ func (h *handler) appendAttr(buf *buffer, attr slog.Attr, groupsPrefix string, g

func (h *handler) appendKey(buf *buffer, key, groups string) {
buf.WriteStringIf(!h.noColor, ansiFaint)
appendString(buf, groups+key, true)
appendString(buf, groups+key, true, !h.noColor)
buf.WriteByte('=')
buf.WriteStringIf(!h.noColor, ansiReset)
}

func (h *handler) appendValue(buf *buffer, v slog.Value, quote bool) {
switch v.Kind() {
case slog.KindString:
appendString(buf, v.String(), quote)
appendString(buf, v.String(), quote, !h.noColor)
case slog.KindInt64:
*buf = strconv.AppendInt(*buf, v.Int64(), 10)
case slog.KindUint64:
Expand All @@ -396,9 +400,9 @@ func (h *handler) appendValue(buf *buffer, v slog.Value, quote bool) {
case slog.KindBool:
*buf = strconv.AppendBool(*buf, v.Bool())
case slog.KindDuration:
appendString(buf, v.Duration().String(), quote)
appendString(buf, v.Duration().String(), quote, !h.noColor)
case slog.KindTime:
appendString(buf, v.Time().String(), quote)
appendString(buf, v.Time().String(), quote, !h.noColor)
case slog.KindAny:
switch cv := v.Any().(type) {
case slog.Level:
Expand All @@ -408,44 +412,196 @@ func (h *handler) appendValue(buf *buffer, v slog.Value, quote bool) {
if err != nil {
break
}
appendString(buf, string(data), quote)
appendString(buf, string(data), quote, !h.noColor)
case *slog.Source:
h.appendSource(buf, cv)
default:
appendString(buf, fmt.Sprintf("%+v", v.Any()), quote)
appendString(buf, fmt.Sprintf("%+v", v.Any()), quote, !h.noColor)
}
}
}

func (h *handler) appendTintError(buf *buffer, err tintError, attrKey, groupsPrefix string) {
buf.WriteStringIf(!h.noColor, ansiBrightRedFaint)
appendString(buf, groupsPrefix+attrKey, true)
appendString(buf, groupsPrefix+attrKey, true, !h.noColor)
buf.WriteByte('=')
buf.WriteStringIf(!h.noColor, ansiResetFaint)
appendString(buf, err.Error(), true)
appendString(buf, err.Error(), true, !h.noColor)
buf.WriteStringIf(!h.noColor, ansiReset)
}

func appendString(buf *buffer, s string, quote bool) {
if quote && needsQuoting(s) {
func appendString(buf *buffer, s string, quote, color bool) {
if quote && !color {
// trim ANSI escape sequences
var inEscape bool
s = cut(s, func(r rune) bool {
if r == ansiEsc {
inEscape = true
} else if inEscape && unicode.IsLetter(r) {
inEscape = false
return true
}

return inEscape
})
}

quote = quote && needsQuoting(s)
switch {
case color && quote:
s = strconv.Quote(s)
s = strings.ReplaceAll(s, `\x1b`, string(ansiEsc))
buf.WriteString(s)
case !color && quote:
*buf = strconv.AppendQuote(*buf, s)
} else {
default:
buf.WriteString(s)
}
}

func cut(s string, f func(r rune) bool) string {
var res []rune
for i := 0; i < len(s); {
r, size := utf8.DecodeRuneInString(s[i:])
if r == utf8.RuneError {
break
}
if !f(r) {
res = append(res, r)
}
i += size
}
return string(res)
}

// Copied from log/slog/text_handler.go.
func needsQuoting(s string) bool {
if len(s) == 0 {
return true
}
for _, r := range s {
if unicode.IsSpace(r) || r == '"' || r == '=' || !unicode.IsPrint(r) {
for i := 0; i < len(s); {
b := s[i]
if b < utf8.RuneSelf {
// Quote anything except a backslash that would need quoting in a
// JSON string, as well as space and '='
if b != '\\' && (b == ' ' || b == '=' || !safeSet[b]) {
return true
}
i++
continue
}
r, size := utf8.DecodeRuneInString(s[i:])
if r == utf8.RuneError || unicode.IsSpace(r) || !unicode.IsPrint(r) {
return true
}
i += size
}
return false
}

// Copied from log/slog/json_handler.go.
//
// safeSet is extended by the ANSI escape code "\u001b".
var safeSet = [utf8.RuneSelf]bool{
' ': true,
'!': true,
'"': false,
'#': true,
'$': true,
'%': true,
'&': true,
'\'': true,
'(': true,
')': true,
'*': true,
'+': true,
',': true,
'-': true,
'.': true,
'/': true,
'0': true,
'1': true,
'2': true,
'3': true,
'4': true,
'5': true,
'6': true,
'7': true,
'8': true,
'9': true,
':': true,
';': true,
'<': true,
'=': true,
'>': true,
'?': true,
'@': true,
'A': true,
'B': true,
'C': true,
'D': true,
'E': true,
'F': true,
'G': true,
'H': true,
'I': true,
'J': true,
'K': true,
'L': true,
'M': true,
'N': true,
'O': true,
'P': true,
'Q': true,
'R': true,
'S': true,
'T': true,
'U': true,
'V': true,
'W': true,
'X': true,
'Y': true,
'Z': true,
'[': true,
'\\': false,
']': true,
'^': true,
'_': true,
'`': true,
'a': true,
'b': true,
'c': true,
'd': true,
'e': true,
'f': true,
'g': true,
'h': true,
'i': true,
'j': true,
'k': true,
'l': true,
'm': true,
'n': true,
'o': true,
'p': true,
'q': true,
'r': true,
's': true,
't': true,
'u': true,
'v': true,
'w': true,
'x': true,
'y': true,
'z': true,
'{': true,
'|': true,
'}': true,
'~': true,
'\u007f': true,
'\u001b': true,
}

type tintError struct{ error }

// Err returns a tinted (colorized) [slog.Attr] that will be written in red color
Expand Down
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