1 files changed, 156 insertions, 0 deletions
diff --git a/modules/mahonia/gb18030.go b/modules/mahonia/gb18030.go
new file mode 100644
index 00000000..d2759250
--- /dev/null
+++ b/modules/mahonia/gb18030.go
@@ -0,0 +1,156 @@
+package mahonia
+
+import (
+	"sync"
+)
+
+// Converters for GB18030 encoding.
+
+func init() {
+	RegisterCharset(&Charset{
+		Name: "GB18030",
+		NewDecoder: func() Decoder {
+			gb18030Once.Do(buildGB18030Tables)
+			return decodeGB18030Rune
+		},
+		NewEncoder: func() Encoder {
+			gb18030Once.Do(buildGB18030Tables)
+			return encodeGB18030Rune
+		},
+	})
+}
+
+func decodeGB18030Rune(p []byte) (r rune, size int, status Status) {
+	if len(p) == 0 {
+		status = NO_ROOM
+		return
+	}
+
+	b := p[0]
+	if b < 128 {
+		return rune(b), 1, SUCCESS
+	}
+
+	if len(p) < 2 {
+		status = NO_ROOM
+		return
+	}
+
+	if p[0] < 0x81 || p[0] > 0xfe {
+		return 0xfffd, 1, INVALID_CHAR
+	}
+
+	if p[1] >= 0x40 {
+		// 2-byte character
+		c := uint16(p[0])<<8 + uint16(p[1])
+		r = rune(gbkToUnicode[c])
+		if r == 0 {
+			r = gbkToUnicodeExtra[c]
+		}
+
+		if r != 0 {
+			return r, 2, SUCCESS
+		}
+	} else if p[1] >= 0x30 {
+		// 4-byte character
+		if len(p) < 4 {
+			return 0, 0, NO_ROOM
+		}
+		if p[2] < 0x81 || p[2] > 0xfe || p[3] < 0x30 || p[3] > 0x39 {
+			return 0xfffd, 1, INVALID_CHAR
+		}
+
+		code := uint32(p[0])<<24 + uint32(p[1])<<16 + uint32(p[2])<<8 + uint32(p[3])
+		lin := gb18030Linear(code)
+
+		if lin <= maxGB18030Linear {
+			r = rune(gb18030LinearToUnicode[lin])
+			if r != 0 {
+				return r, 4, SUCCESS
+			}
+		}
+
+		for _, rng := range gb18030Ranges {
+			if lin >= rng.firstGB && lin <= rng.lastGB {
+				return rng.firstRune + rune(lin) - rune(rng.firstGB), 4, SUCCESS
+			}
+		}
+	}
+
+	return 0xfffd, 1, INVALID_CHAR
+}
+
+func encodeGB18030Rune(p []byte, r rune) (size int, status Status) {
+	if len(p) == 0 {
+		status = NO_ROOM
+		return
+	}
+
+	if r < 128 {
+		p[0] = byte(r)
+		return 1, SUCCESS
+	}
+
+	if len(p) < 2 {
+		status = NO_ROOM
+		return
+	}
+
+	var c uint16
+	if r < 0x10000 {
+		c = unicodeToGBK[r]
+	} else {
+		c = unicodeToGBKExtra[r]
+	}
+
+	if c != 0 {
+		p[0] = byte(c >> 8)
+		p[1] = byte(c)
+		return 2, SUCCESS
+	}
+
+	if len(p) < 4 {
+		return 0, NO_ROOM
+	}
+
+	if r < 0x10000 {
+		f := unicodeToGB18030[r]
+		if f != 0 {
+			p[0] = byte(f >> 24)
+			p[1] = byte(f >> 16)
+			p[2] = byte(f >> 8)
+			p[3] = byte(f)
+			return 4, SUCCESS
+		}
+	}
+
+	for _, rng := range gb18030Ranges {
+		if r >= rng.firstRune && r <= rng.lastRune {
+			lin := rng.firstGB + uint32(r) - uint32(rng.firstRune)
+			p[0] = byte(lin/(10*126*10)) + 0x81
+			p[1] = byte(lin/(126*10)%10) + 0x30
+			p[2] = byte(lin/10%126) + 0x81
+			p[3] = byte(lin%10) + 0x30
+			return 4, SUCCESS
+		}
+	}
+
+	p[0] = 0x1a
+	return 1, INVALID_CHAR
+}
+
+var gb18030Once sync.Once
+
+// Mapping from gb18039Linear values to Unicode.
+var gb18030LinearToUnicode []uint16
+
+var unicodeToGB18030 []uint32
+
+func buildGB18030Tables() {
+	gb18030LinearToUnicode = make([]uint16, maxGB18030Linear+1)
+	unicodeToGB18030 = make([]uint32, 65536)
+	for _, data := range gb18030Data {
+		gb18030LinearToUnicode[gb18030Linear(data.gb18030)] = data.unicode
+		unicodeToGB18030[data.unicode] = data.gb18030
+	}
+}