fmt: allow # and x together for strings
Silly and small but easy to be consistent.
To make it worthwhile, I eliminated an allocation when using
%x on a byte slice.
Fixes #4149.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6574046
diff --git a/src/pkg/fmt/format.go b/src/pkg/fmt/format.go
index 3c9cd0d..ce80116 100644
--- a/src/pkg/fmt/format.go
+++ b/src/pkg/fmt/format.go
@@ -285,18 +285,41 @@
f.padString(s)
}
+// fmt_sbx formats a string or byte slice as a hexadecimal encoding of its bytes.
+func (f *fmt) fmt_sbx(s string, b []byte, digits string) {
+ n := len(b)
+ if b == nil {
+ n = len(s)
+ }
+ x := digits[10] - 'a' + 'x'
+ // TODO: Avoid buffer by pre-padding.
+ var buf []byte
+ for i := 0; i < n; i++ {
+ if i > 0 && f.space {
+ buf = append(buf, ' ')
+ }
+ if f.sharp {
+ buf = append(buf, '0', x)
+ }
+ var c byte
+ if b == nil {
+ c = s[i]
+ } else {
+ c = b[i]
+ }
+ buf = append(buf, digits[c>>4], digits[c&0xF])
+ }
+ f.pad(buf)
+}
+
// fmt_sx formats a string as a hexadecimal encoding of its bytes.
func (f *fmt) fmt_sx(s, digits string) {
- // TODO: Avoid buffer by pre-padding.
- var b []byte
- for i := 0; i < len(s); i++ {
- if i > 0 && f.space {
- b = append(b, ' ')
- }
- v := s[i]
- b = append(b, digits[v>>4], digits[v&0xF])
- }
- f.pad(b)
+ f.fmt_sbx(s, nil, digits)
+}
+
+// fmt_bx formats a byte slice as a hexadecimal encoding of its bytes.
+func (f *fmt) fmt_bx(b []byte, digits string) {
+ f.fmt_sbx("", b, digits)
}
// fmt_q formats a string as a double-quoted, escaped Go string constant.
