Add []byte fields support

Add efficient []byte field support with no string conversion.

context.go

@@ -26,6 +26,12 @@ func (c Context) Str(key, val string) Context {
 	return c
 }
 
+// Bytes adds the field key with val as a []byte to the logger context.
+func (c Context) Bytes(key string, val []byte) Context {
+	c.l.context = appendBytes(c.l.context, key, val)
+	return c
+}
+
 // AnErr adds the field key with err as a string to the logger context.
 func (c Context) AnErr(key string, err error) Context {
 	c.l.context = appendErrorKey(c.l.context, key, err)

event.go

@@ -121,6 +121,15 @@ func (e *Event) Str(key, val string) *Event {
 	return e
 }
 
+// Bytes adds the field key with val as a []byte to the *Event context.
+func (e *Event) Bytes(key string, val []byte) *Event {
+	if !e.enabled {
+		return e
+	}
+	e.buf = appendBytes(e.buf, key, val)
+	return e
+}
+
 // AnErr adds the field key with err as a string to the *Event context.
 // If err is nil, no field is added.
 func (e *Event) AnErr(key string, err error) *Event {

field.go

@@ -19,6 +19,10 @@ func appendString(dst []byte, key, val string) []byte {
 	return appendJSONString(appendKey(dst, key), val)
 }
 
+func appendBytes(dst []byte, key string, val []byte) []byte {
+	return appendJSONBytes(appendKey(dst, key), val)
+}
+
 func appendErrorKey(dst []byte, key string, err error) []byte {
 	if err == nil {
 		return dst

json.go

@@ -94,3 +94,72 @@ func appendJSONStringComplex(dst []byte, s string, i int) []byte {
 	}
 	return dst
 }
+
+// appendJSONBytes is a mirror of appendJSONString with []byte arg
+func appendJSONBytes(dst, s []byte) []byte {
+	dst = append(dst, '"')
+	for i := 0; i < len(s); i++ {
+		if s[i] < 0x20 || s[i] > 0x7e || s[i] == '\\' || s[i] == '"' {
+			dst = appendJSONBytesComplex(dst, s, i)
+			return append(dst, '"')
+		}
+	}
+	dst = append(dst, s...)
+	return append(dst, '"')
+}
+
+// appendJSONBytesComplex is a mirror of the appendJSONStringComplex
+// with []byte arg
+func appendJSONBytesComplex(dst, s []byte, i int) []byte {
+	start := 0
+	for i < len(s) {
+		b := s[i]
+		if b >= utf8.RuneSelf {
+			r, size := utf8.DecodeRune(s[i:])
+			if r == utf8.RuneError && size == 1 {
+				if start < i {
+					dst = append(dst, s[start:i]...)
+				}
+				dst = append(dst, `\ufffd`...)
+				i += size
+				start = i
+				continue
+			}
+			i += size
+			continue
+		}
+		if b >= 0x20 && b <= 0x7e && b != '\\' && b != '"' {
+			i++
+			continue
+		}
+		// We encountered a character that needs to be encoded.
+		// Let's append the previous simple characters to the byte slice
+		// and switch our operation to read and encode the remainder
+		// characters byte-by-byte.
+		if start < i {
+			dst = append(dst, s[start:i]...)
+		}
+		switch b {
+		case '"', '\\':
+			dst = append(dst, '\\', b)
+		case '\b':
+			dst = append(dst, '\\', 'b')
+		case '\f':
+			dst = append(dst, '\\', 'f')
+		case '\n':
+			dst = append(dst, '\\', 'n')
+		case '\r':
+			dst = append(dst, '\\', 'r')
+		case '\t':
+			dst = append(dst, '\\', 't')
+		default:
+			dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
+		}
+		i++
+		start = i
+	}
+	if start < len(s) {
+		dst = append(dst, s[start:]...)
+	}
+	return dst
+}

json_test.go

@@ -2,13 +2,13 @@ package zerolog
 
 import (
 	"testing"
+	"unicode"
 )
 
-func TestAppendJSONString(t *testing.T) {
-	encodeStringTests := []struct {
+var encodeStringTests = []struct {
 	in  string
 	out string
-	}{
+}{
 	{"", `""`},
 	{"\\", `"\\"`},
 	{"\x00", `"\u0000"`},
@@ -51,8 +51,9 @@ func TestAppendJSONString(t *testing.T) {
 	{"foo\"bar\"baz", `"foo\"bar\"baz"`},
 	{"\x1ffoo\x1fbar\x1fbaz", `"\u001ffoo\u001fbar\u001fbaz"`},
 	{"emoji \u2764\ufe0f!", `"emoji ❤️!"`},
-	}
+}
 
+func TestAppendJSONString(t *testing.T) {
 	for _, tt := range encodeStringTests {
 		b := appendJSONString([]byte{}, tt.in)
 		if got, want := string(b), tt.out; got != want {
@@ -61,6 +62,52 @@ func TestAppendJSONString(t *testing.T) {
 	}
 }
 
+func TestAppendJSONBytes(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		b := appendJSONBytes([]byte{}, []byte(tt.in))
+		if got, want := string(b), tt.out; got != want {
+			t.Errorf("appendJSONBytes(%q) = %#q, want %#q", tt.in, got, want)
+		}
+	}
+}
+
+func TestStringBytes(t *testing.T) {
+	t.Parallel()
+	// Test that encodeState.stringBytes and encodeState.string use the same encoding.
+	var r []rune
+	for i := '\u0000'; i <= unicode.MaxRune; i++ {
+		r = append(r, i)
+	}
+	s := string(r) + "\xff\xff\xffhello" // some invalid UTF-8 too
+
+	enc := string(appendJSONString([]byte{}, s))
+	encBytes := string(appendJSONBytes([]byte{}, []byte(s)))
+
+	if enc != encBytes {
+		i := 0
+		for i < len(enc) && i < len(encBytes) && enc[i] == encBytes[i] {
+			i++
+		}
+		enc = enc[i:]
+		encBytes = encBytes[i:]
+		i = 0
+		for i < len(enc) && i < len(encBytes) && enc[len(enc)-i-1] == encBytes[len(encBytes)-i-1] {
+			i++
+		}
+		enc = enc[:len(enc)-i]
+		encBytes = encBytes[:len(encBytes)-i]
+
+		if len(enc) > 20 {
+			enc = enc[:20] + "..."
+		}
+		if len(encBytes) > 20 {
+			encBytes = encBytes[:20] + "..."
+		}
+
+		t.Errorf("encodings differ at %#q vs %#q", enc, encBytes)
+	}
+}
+
 func BenchmarkAppendJSONString(b *testing.B) {
 	tests := map[string]string{
 		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
@@ -80,3 +127,24 @@ func BenchmarkAppendJSONString(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkAppendJSONBytes(b *testing.B) {
+	tests := map[string]string{
+		"NoEncoding":       `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingFirst":    `"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingMiddle":   `aaaaaaaaaaaaaaaaaaaaaaaaa"aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"EncodingLast":     `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"`,
+		"MultiBytesFirst":  `❤️aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesMiddle": `aaaaaaaaaaaaaaaaaaaaaaaaa❤️aaaaaaaaaaaaaaaaaaaaaaaa`,
+		"MultiBytesLast":   `aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa❤️`,
+	}
+	for name, str := range tests {
+		byt := []byte(str)
+		b.Run(name, func(b *testing.B) {
+			buf := make([]byte, 0, 100)
+			for i := 0; i < b.N; i++ {
+				_ = appendJSONBytes(buf, byt)
+			}
+		})
+	}
+}