lib/encoder: add Exclamation mark encoding

docs/content/overview.md

@@ -369,6 +369,7 @@ will show you the defaults for the backends.
 | Dollar | `$` | `＄` |
 | Dot | `.` or `..` as entire string | `．`, `．．` |
 | DoubleQuote | `"` | `＂` |
+| Exclamation | `!` | `！` |
 | Hash | `#` | `＃` |
 | InvalidUtf8 | An invalid UTF-8 character (e.g. latin1) | `<60>` |
 | LeftCrLfHtVt | CR 0x0D, LF 0x0A, HT 0x09, VT 0x0B on the left of a string | `␍`, `␊`, `␉`, `␋` |

lib/encoder/encoder.go

@@ -64,6 +64,7 @@ const (
 	EncodeDot                        // . and .. names
 	EncodeSquareBracket              // []
 	EncodeSemicolon                  // ;
+	EncodeExclamation                // !
 
 	// Synthetic
 	EncodeWin         = EncodeColon | EncodeQuestion | EncodeDoubleQuote | EncodeAsterisk | EncodeLtGt | EncodePipe // :?"*<>|
@@ -124,6 +125,7 @@ func init() {
 	alias("LtGt", EncodeLtGt)
 	alias("SquareBracket", EncodeSquareBracket)
 	alias("Semicolon", EncodeSemicolon)
+	alias("Exclamation", EncodeExclamation)
 	alias("DoubleQuote", EncodeDoubleQuote)
 	alias("SingleQuote", EncodeSingleQuote)
 	alias("BackQuote", EncodeBackQuote)
@@ -336,6 +338,12 @@ func (mask MultiEncoder) Encode(in string) string {
 					return true
 				}
 			}
+			if mask.Has(EncodeExclamation) { // !
+				switch r {
+				case '!', '！':
+					return true
+				}
+			}
 			if mask.Has(EncodeQuestion) { // ?
 				switch r {
 				case '?',
@@ -516,6 +524,17 @@ func (mask MultiEncoder) Encode(in string) string {
 				continue
 			}
 		}
+		if mask.Has(EncodeExclamation) { // !
+			switch r {
+			case '!':
+				out.WriteRune(r + fullOffset)
+				continue
+			case '！':
+				out.WriteRune(QuoteRune)
+				out.WriteRune(r)
+				continue
+			}
+		}
 		if mask.Has(EncodeQuestion) { // ?
 			switch r {
 			case '?':
@@ -772,7 +791,12 @@ func (mask MultiEncoder) Decode(in string) string {
 					return true
 				}
 			}
-
+			if mask.Has(EncodeExclamation) { // !
+				switch r {
+				case '！':
+					return true
+				}
+			}
 			if mask.Has(EncodeQuestion) { // ?
 				switch r {
 				case '？':
@@ -939,6 +963,17 @@ func (mask MultiEncoder) Decode(in string) string {
 				continue
 			}
 		}
+		if mask.Has(EncodeExclamation) { // !
+			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

@@ -45,6 +45,7 @@ var maskBits = []struct {
 	{encoder.EncodeLtGt, "EncodeLtGt"},
 	{encoder.EncodeSquareBracket, "EncodeSquareBracket"},
 	{encoder.EncodeSemicolon, "EncodeSemicolon"},
+	{encoder.EncodeExclamation, "EncodeExclamation"},
 	{encoder.EncodeDollar, "EncodeDollar"},
 	{encoder.EncodeDoubleQuote, "EncodeDoubleQuote"},
 	{encoder.EncodeColon, "EncodeColon"},
@@ -118,6 +119,11 @@ var allMappings = []mapping{{
 	}, []rune{
 		'；',
 	}}, {
+	encoder.EncodeExclamation, []rune{
+		'!',
+	}, []rune{
+		'！',
+	}}, {
 	encoder.EncodeDoubleQuote, []rune{
 		'"',
 	}, []rune{