split_escaped.go

func splitEscaped(s string, sep, esc rune) []string {
	var pos int
	a := strings.FieldsFunc(s, func(r rune) bool {
		escaped := pos > 0 && rune(s[pos-1]) == esc
		pos++
		return r == sep && !escaped
	})
	for i, s := range a {
		a[i] = strings.ReplaceAll(s, string(esc)+string(sep), string(sep))
	}
	return a
}

func TestSplitEscaped(t *testing.T) {
	tt := []struct {
		s        string
		sep, esc rune
		splitted []string
	}{
		{
			s:        "",
			sep:      ',',
			esc:      '\\',
			splitted: []string{},
		},
		{
			s:        "1,2,3",
			sep:      ',',
			esc:      '\\',
			splitted: []string{"1", "2", "3"},
		},
		{
			s:        "1,2\\,3",
			sep:      ',',
			esc:      '\\',
			splitted: []string{"1", "2,3"},
		},
	}
	for _, tc := range tt {
		name := fmt.Sprintf("s=%s sep=%s esc=%s", tc.s, string(tc.sep), string(tc.esc))
		t.Run(name, func(t *testing.T) {
			result := splitEscaped(tc.s, tc.sep, tc.esc)
			if !reflect.DeepEqual(result, tc.splitted) {
				t.Fatalf("expected %v, got: %v", tc.splitted, result)
			}
		})
	}
}