Remove hg dep

modules/mahonia/mbcs.go

@@ -0,0 +1,92 @@
+package mahonia
+
+// Generic converters for multibyte character sets.
+
+// An mbcsTrie contains the data to convert from the character set to Unicode.
+// If a character would be encoded as "\x01\x02\x03", its unicode value would be found at t.children[1].children[2].children[3].rune
+// children either is nil or has 256 elements.
+type mbcsTrie struct {
+	// For leaf nodes, the Unicode character that is represented.
+	char rune
+
+	// For non-leaf nodes, the trie to decode the remainder of the character.
+	children []mbcsTrie
+}
+
+// A MBCSTable holds the data to convert to and from Unicode.
+type MBCSTable struct {
+	toUnicode   mbcsTrie
+	fromUnicode map[rune]string
+}
+
+// AddCharacter adds a character to the table. rune is its Unicode code point,
+// and bytes contains the bytes used to encode it in the character set.
+func (table *MBCSTable) AddCharacter(c rune, bytes string) {
+	if table.fromUnicode == nil {
+		table.fromUnicode = make(map[rune]string)
+	}
+
+	table.fromUnicode[c] = bytes
+
+	trie := &table.toUnicode
+	for i := 0; i < len(bytes); i++ {
+		if trie.children == nil {
+			trie.children = make([]mbcsTrie, 256)
+		}
+
+		b := bytes[i]
+		trie = &trie.children[b]
+	}
+
+	trie.char = c
+}
+
+func (table *MBCSTable) Decoder() Decoder {
+	return func(p []byte) (c rune, size int, status Status) {
+		if len(p) == 0 {
+			status = NO_ROOM
+			return
+		}
+
+		if p[0] == 0 {
+			return 0, 1, SUCCESS
+		}
+
+		trie := &table.toUnicode
+		for trie.char == 0 {
+			if trie.children == nil {
+				return 0xfffd, 1, INVALID_CHAR
+			}
+			if len(p) < size+1 {
+				return 0, 0, NO_ROOM
+			}
+
+			trie = &trie.children[p[size]]
+			size++
+		}
+
+		c = trie.char
+		status = SUCCESS
+		return
+	}
+}
+
+func (table *MBCSTable) Encoder() Encoder {
+	return func(p []byte, c rune) (size int, status Status) {
+		bytes := table.fromUnicode[c]
+		if bytes == "" {
+			if len(p) > 0 {
+				p[0] = '?'
+				return 1, INVALID_CHAR
+			} else {
+				return 0, NO_ROOM
+			}
+		}
+
+		if len(p) < len(bytes) {
+			return 0, NO_ROOM
+		}
+
+		return copy(p, bytes), SUCCESS
+	}
+}