colour: treat ? as a YAML key indicator only before space or EOL

colour/colour_test.go

@@ -172,6 +172,8 @@ func TestYAMLEdges(t *testing.T) {
 			"    - <key>pem</>: |\n        <str>-----BEGIN CERTIFICATE-----</>\n        <str>MIIB</>\n      <key>ttl</>: <str>768h</>\n  <key>n</>: <num>1</>\n",
 		"w: one two\n\n  42\n# c\nn: 1\n": "<key>w</>: <str>one two</>\n\n  <str>42</>\n<com># c</>\n<key>n</>: <num>1</>\n",
 		"q: 'it''s\n  ok: y' # c\n":       "<key>q</>: <str>'it''s</>\n  <str>ok: y'</> <com># c</>\n",
+		"?q: ?v\n?n:\n  a: 1\n  b: |\n    x\nd: 2\n": "<key>?q</>: <str>?v</>\n<key>?n</>:\n  <key>a</>: <num>1</>\n" +
+			"  <key>b</>: |\n    <str>x</>\n<key>d</>: <num>2</>\n",
 	}
 	for in, want := range cases {
 		if got := render(t, yamlF, in); got != want {

colour/yaml.go

@@ -129,10 +129,12 @@ func yamlNode(out *bytes.Buffer, s string) (int, byte) {
 // not a key/value pair.
 func keyEnd(s string) int {
 	end := 0
-	switch s[0] {
-	case '"', '\'':
+	switch {
+	case s[0] == '"' || s[0] == '\'':
 		end = quoteEnd(s)
-	case '[', '{', '&', '*', '!', '|', '>', '?', '%', '@', '`':
+	case s[0] == '?' && (len(s) == 1 || s[1] == ' '):
+		return 0
+	case strings.IndexByte("[{&*!|>%@`", s[0]) >= 0:
 		return 0
 	default:
 		for i := 0; i < len(s); i++ {