add vendoring

vendor/github.com/jhillyerd/enmime/internal/stringutil/split.go

@@ -0,0 +1,45 @@
+package stringutil
+
+const escape = '\\'
+
+// SplitUnquoted slices s into all substrings separated by sep and returns a slice of
+// the substrings between those separators.
+//
+// If s does not contain sep and sep is not empty, SplitUnquoted returns a
+// slice of length 1 whose only element is s.
+//
+// It ignores sep present inside quoted runs.
+func SplitUnquoted(s string, sep rune, quote rune) []string {
+	return splitUnquoted(s, sep, quote, false)
+}
+
+// SplitAfterUnquoted slices s into all substrings after each instance of sep and
+// returns a slice of those substrings.
+//
+// If s does not contain sep and sep is not empty, SplitAfterUnquoted returns
+// a slice of length 1 whose only element is s.
+//
+// It ignores sep present inside quoted runs.
+func SplitAfterUnquoted(s string, sep rune, quote rune) []string {
+	return splitUnquoted(s, sep, quote, true)
+}
+
+func splitUnquoted(s string, sep rune, quote rune, preserveSep bool) []string {
+	ixs := FindUnquoted(s, sep, quote)
+	if len(ixs) == 0 {
+		return []string{s}
+	}
+
+	start := 0
+	result := make([]string, 0, len(ixs)+1)
+	for _, ix := range ixs {
+		end := ix
+		if preserveSep {
+			end++
+		}
+		result = append(result, s[start:end])
+		start = ix + 1
+	}
+
+	return append(result, s[start:])
+}