lib/encoder: add encoding of square brackets

docs/content/overview.md

@@ -280,6 +280,7 @@ will show you the defaults for the backends.
 | RightSpace | SPACE on the right of a string |
 | SingleQuote | `'` |
 | Slash | `/` |
+| SquareBracket | `[`, `]` |
 
 To take a specific example, the FTP backend's default encoding is
 

lib/encoder/encoder.go

@@ -63,6 +63,7 @@ const (
 	EncodeRightCrLfHtVt                          // Trailing CR LF HT VT
 	EncodeInvalidUtf8                            // Invalid UTF-8 bytes
 	EncodeDot                                    // . and .. names
+	EncodeSquareBracket                          // []
 
 	// Synthetic
 	EncodeWin         = EncodeColon | EncodeQuestion | EncodeDoubleQuote | EncodeAsterisk | EncodeLtGt | EncodePipe // :?"*<>|
@@ -120,6 +121,7 @@ func init() {
 	alias("None", EncodeZero)
 	alias("Slash", EncodeSlash)
 	alias("LtGt", EncodeLtGt)
+	alias("SquareBracket", EncodeSquareBracket)
 	alias("DoubleQuote", EncodeDoubleQuote)
 	alias("SingleQuote", EncodeSingleQuote)
 	alias("BackQuote", EncodeBackQuote)
@@ -315,6 +317,13 @@ func (mask MultiEncoder) Encode(in string) string {
 					return true
 				}
 			}
+			if mask.Has(EncodeSquareBracket) { // []
+				switch r {
+				case '[', ']',
+					'［', '］':
+					return true
+				}
+			}
 			if mask.Has(EncodeQuestion) { // ?
 				switch r {
 				case '?',
@@ -473,6 +482,17 @@ func (mask MultiEncoder) Encode(in string) string {
 				continue
 			}
 		}
+		if mask.Has(EncodeSquareBracket) { // []
+			switch r {
+			case '[', ']':
+				out.WriteRune(r + fullOffset)
+				continue
+			case '［', '］':
+				out.WriteRune(QuoteRune)
+				out.WriteRune(r)
+				continue
+			}
+		}
 		if mask.Has(EncodeQuestion) { // ?
 			switch r {
 			case '?':
@@ -713,6 +733,13 @@ func (mask MultiEncoder) Decode(in string) string {
 					return true
 				}
 			}
+			if mask.Has(EncodeSquareBracket) { // []
+				switch r {
+				case '［', '］':
+					return true
+				}
+			}
+
 			if mask.Has(EncodeQuestion) { // ?
 				switch r {
 				case '？':
@@ -857,6 +884,17 @@ func (mask MultiEncoder) Decode(in string) string {
 				continue
 			}
 		}
+		if mask.Has(EncodeSquareBracket) { // []
+			switch r {
+			case '［', '］':
+				if unquote {
+					out.WriteRune(r)
+				} else {
+					out.WriteRune(r - fullOffset)
+				}
+				continue
+			}
+		}
 		if mask.Has(EncodeQuestion) { // ?
 			switch r {
 			case '？':

lib/encoder/internal/gen/main.go

@@ -42,6 +42,7 @@ var maskBits = []struct {
 	{encoder.EncodeSingleQuote, "EncodeSingleQuote"},
 	{encoder.EncodeBackQuote, "EncodeBackQuote"},
 	{encoder.EncodeLtGt, "EncodeLtGt"},
+	{encoder.EncodeSquareBracket, "EncodeSquareBracket"},
 	{encoder.EncodeDollar, "EncodeDollar"},
 	{encoder.EncodeDoubleQuote, "EncodeDoubleQuote"},
 	{encoder.EncodeColon, "EncodeColon"},
@@ -105,6 +106,11 @@ var allMappings = []mapping{{
 	}, []rune{
 		'＜', '＞',
 	}}, {
+	encoder.EncodeSquareBracket, []rune{
+		'[', ']',
+	}, []rune{
+		'［', '］',
+	}}, {
 	encoder.EncodeDoubleQuote, []rune{
 		'"',
 	}, []rune{