slog: TextHandler use dot instead of middle dot to separate group names

Middle dots haven't worked well for Go symbol names.
Don't use them here; ordinary dots are fine.

Change-Id: I527b12c3da64e798d2327dd5a37178235d6fbbe0
Reviewed-on: https://go-review.googlesource.com/c/exp/+/445335
Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>

slog/handler.go

@@ -320,9 +320,7 @@ func (s *handleState) openGroups() {
 }
 
 // Separator for group names and keys.
-// We use the uncommon character middle-dot rather than an ordinary dot
-// to reduce the likelihood of ambiguous group structure.
-const keyComponentSep = "·"
+const keyComponentSep = '.'
 
 // openGroup starts a new group of attributes
 // with the given name.
@@ -333,7 +331,7 @@ func (s *handleState) openGroup(name string) {
 		s.sep = ""
 	} else {
 		s.prefix.WriteString(name)
-		s.prefix.WriteString(keyComponentSep)
+		s.prefix.WriteByte(keyComponentSep)
 	}
 }
 
@@ -342,7 +340,7 @@ func (s *handleState) closeGroup(name string) {
 	if s.h.json {
 		s.buf.WriteByte('}')
 	} else {
-		(*s.prefix) = (*s.prefix)[:len(*s.prefix)-len(name)-len(keyComponentSep)]
+		(*s.prefix) = (*s.prefix)[:len(*s.prefix)-len(name)-1 /* forkeyComponentSep */]
 	}
 	s.sep = s.h.attrSep()
 }

slog/handler_test.go

@@ -49,13 +49,13 @@ func TestDefaultHandle(t *testing.T) {
 					Int("d", 4)),
 				Int("e", 5),
 			},
-			want: "INFO message a=1 g·b=2 g·h·c=3 g·d=4 e=5",
+			want: "INFO message a=1 g.b=2 g.h.c=3 g.d=4 e=5",
 		},
 		{
 			name:  "group",
 			with:  func(h Handler) Handler { return h.WithAttrs(preAttrs).WithGroup("s") },
 			attrs: attrs,
-			want:  "INFO message pre=0 s·a=1 s·b=two",
+			want:  "INFO message pre=0 s.a=1 s.b=two",
 		},
 		{
 			name: "preformatted groups",
@@ -66,7 +66,7 @@ func TestDefaultHandle(t *testing.T) {
 					WithGroup("s2")
 			},
 			attrs: attrs,
-			want:  "INFO message p1=1 s1·p2=2 s1·s2·a=1 s1·s2·b=two",
+			want:  "INFO message p1=1 s1.p2=2 s1.s2.a=1 s1.s2.b=two",
 		},
 		{
 			name: "two with-groups",
@@ -76,7 +76,7 @@ func TestDefaultHandle(t *testing.T) {
 					WithGroup("s2")
 			},
 			attrs: attrs,
-			want:  "INFO message p1=1 s1·s2·a=1 s1·s2·b=two",
+			want:  "INFO message p1=1 s1.s2.a=1 s1.s2.b=two",
 		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
@@ -204,14 +204,14 @@ func TestJSONAndTextHandlers(t *testing.T) {
 					Int("d", 4)),
 				Int("e", 5),
 			},
-			wantText: "msg=message a=1 g·b=2 g·h·c=3 g·d=4 e=5",
+			wantText: "msg=message a=1 g.b=2 g.h.c=3 g.d=4 e=5",
 			wantJSON: `{"msg":"message","a":1,"g":{"b":2,"h":{"c":3},"d":4},"e":5}`,
 		},
 		{
 			name:     "empty group",
 			replace:  removeKeys(TimeKey, LevelKey),
 			attrs:    []Attr{Group("g"), Group("h", Int("a", 1))},
-			wantText: "msg=message h·a=1",
+			wantText: "msg=message h.a=1",
 			wantJSON: `{"msg":"message","g":{},"h":{"a":1}}`,
 		},
 		{
@@ -221,10 +221,10 @@ func TestJSONAndTextHandlers(t *testing.T) {
 				String("a b", "x\t\n\000y"),
 				Group(" b.c=\"\\x2E\t",
 					String("d=e", "f.g\""),
-					Int("m·d", 1)), // middle dot is not escaped
+					Int("m.d", 1)), // dot is not escaped
 			},
-			wantText: `msg=message "a b"="x\t\n\x00y" " b.c=\"\\x2E\t·d=e"="f.g\"" " b.c=\"\\x2E\t·m·d"=1`,
-			wantJSON: `{"msg":"message","a b":"x\t\n\u0000y"," b.c=\"\\x2E\t":{"d=e":"f.g\"","m·d":1}}`,
+			wantText: `msg=message "a b"="x\t\n\x00y" " b.c=\"\\x2E\t.d=e"="f.g\"" " b.c=\"\\x2E\t.m.d"=1`,
+			wantJSON: `{"msg":"message","a b":"x\t\n\u0000y"," b.c=\"\\x2E\t":{"d=e":"f.g\"","m.d":1}}`,
 		},
 		{
 			name:    "LogValuer",
@@ -234,7 +234,7 @@ func TestJSONAndTextHandlers(t *testing.T) {
 				Any("name", logValueName{"Ren", "Hoek"}),
 				Int("b", 2),
 			},
-			wantText: "msg=message a=1 name·first=Ren name·last=Hoek b=2",
+			wantText: "msg=message a=1 name.first=Ren name.last=Hoek b=2",
 			wantJSON: `{"msg":"message","a":1,"name":{"first":"Ren","last":"Hoek"},"b":2}`,
 		},
 		{
@@ -242,7 +242,7 @@ func TestJSONAndTextHandlers(t *testing.T) {
 			replace:  removeKeys(TimeKey, LevelKey),
 			with:     func(h Handler) Handler { return h.WithAttrs(preAttrs).WithGroup("s") },
 			attrs:    attrs,
-			wantText: "msg=message pre=3 x=y s·a=one s·b=2",
+			wantText: "msg=message pre=3 x=y s.a=one s.b=2",
 			wantJSON: `{"msg":"message","pre":3,"x":"y","s":{"a":"one","b":2}}`,
 		},
 		{
@@ -255,7 +255,7 @@ func TestJSONAndTextHandlers(t *testing.T) {
 					WithGroup("s2")
 			},
 			attrs:    attrs,
-			wantText: "msg=message p1=1 s1·p2=2 s1·s2·a=one s1·s2·b=2",
+			wantText: "msg=message p1=1 s1.p2=2 s1.s2.a=one s1.s2.b=2",
 			wantJSON: `{"msg":"message","p1":1,"s1":{"p2":2,"s2":{"a":"one","b":2}}}`,
 		},
 		{
@@ -267,7 +267,7 @@ func TestJSONAndTextHandlers(t *testing.T) {
 					WithGroup("s2")
 			},
 			attrs:    attrs,
-			wantText: "msg=message p1=1 s1·s2·a=one s1·s2·b=2",
+			wantText: "msg=message p1=1 s1.s2.a=one s1.s2.b=2",
 			wantJSON: `{"msg":"message","p1":1,"s1":{"s2":{"a":"one","b":2}}}`,
 		},
 	} {

slog/text_handler.go

@@ -76,10 +76,9 @@ func (h *TextHandler) WithGroup(name string) Handler {
 // Keys and values are quoted with [strconv.Quote] if they contain Unicode space
 // characters, non-printing characters, '"' or '='.
 //
-// Keys inside groups consist of components (keys or group names)
-// separated by the Unicode middle dot character, '·'. No further escaping is
-// performed. If it is necessary to reconstruct the group structure of a key
-// even in the presence of middle dots inside components, use
+// Keys inside groups consist of components (keys or group names) separated by
+// dots. No further escaping is performed. If it is necessary to reconstruct the
+// group structure of a key even in the presence of dots inside components, use
 // [HandlerOptions.ReplaceAttr] to escape the keys.
 //
 // Each call to Handle results in a single serialized call to