1 files changed, 124 insertions, 0 deletions
diff --git a/modules/mahonia/iso2022jp.go b/modules/mahonia/iso2022jp.go
new file mode 100644
index 00000000..c8de6fc8
--- /dev/null
+++ b/modules/mahonia/iso2022jp.go
@@ -0,0 +1,124 @@
+package mahonia
+
+import (
+	"unicode/utf8"
+)
+
+// converters for ISO-2022-JP encoding
+
+const esc = 27
+
+func init() {
+	type jpEncoding int
+	const (
+		ascii jpEncoding = iota
+		jisX0201Roman
+		jisX0208
+	)
+
+	RegisterCharset(&Charset{
+		Name: "ISO-2022-JP",
+		NewDecoder: func() Decoder {
+			encoding := ascii
+			return func(p []byte) (c rune, size int, status Status) {
+				if len(p) == 0 {
+					return 0, 0, NO_ROOM
+				}
+
+				b := p[0]
+				if b == esc {
+					if len(p) < 3 {
+						return 0, 0, NO_ROOM
+					}
+					switch p[1] {
+					case '(':
+						switch p[2] {
+						case 'B':
+							encoding = ascii
+							return 0, 3, STATE_ONLY
+
+						case 'J':
+							encoding = jisX0201Roman
+							return 0, 3, STATE_ONLY
+						}
+
+					case '$':
+						switch p[2] {
+						case '@', 'B':
+							encoding = jisX0208
+							return 0, 3, STATE_ONLY
+						}
+					}
+				}
+
+				switch encoding {
+				case ascii:
+					if b > 127 {
+						return utf8.RuneError, 1, INVALID_CHAR
+					}
+					return rune(b), 1, SUCCESS
+
+				case jisX0201Roman:
+					if b > 127 {
+						return utf8.RuneError, 1, INVALID_CHAR
+					}
+					switch b {
+					case '\\':
+						return 0xA5, 1, SUCCESS
+					case '~':
+						return 0x203E, 1, SUCCESS
+					}
+					return rune(b), 1, SUCCESS
+
+				case jisX0208:
+					return jis0208Table.DecodeLow(p)
+				}
+				panic("unreachable")
+			}
+		},
+		NewEncoder: func() Encoder {
+			jis0208Table.Reverse()
+			encoding := ascii
+			return func(p []byte, c rune) (size int, status Status) {
+				if len(p) == 0 {
+					return 0, NO_ROOM
+				}
+
+				if c < 128 {
+					if encoding != ascii {
+						if len(p) < 4 {
+							return 0, NO_ROOM
+						}
+						p[0], p[1], p[2] = esc, '(', 'B'
+						p[3] = byte(c)
+						encoding = ascii
+						return 4, SUCCESS
+					}
+					p[0] = byte(c)
+					return 1, SUCCESS
+				}
+
+				if c > 65535 {
+					return 0, INVALID_CHAR
+				}
+				jis := jis0208Table.FromUnicode[c]
+				if jis == [2]byte{0, 0} && c != rune(jis0208Table.Data[0][0]) {
+					return 0, INVALID_CHAR
+				}
+
+				if encoding != jisX0208 {
+					if len(p) < 3 {
+						return 0, NO_ROOM
+					}
+					p[0], p[1], p[2] = esc, '$', 'B'
+					encoding = jisX0208
+					return 3, STATE_ONLY
+				}
+
+				p[0] = jis[0] + 0x21
+				p[1] = jis[1] + 0x21
+				return 2, SUCCESS
+			}
+		},
+	})
+}