1 files changed, 128 insertions, 0 deletions
diff --git a/vietoaq/vietoaq.go b/vietoaq/vietoaq.go
new file mode 100644
index 0000000..b4375e7
--- /dev/null
+++ b/vietoaq/vietoaq.go
@@ -0,0 +1,128 @@
+package vietoaq
+
+import (
+	"regexp"
+	"strings"
+
+	"golang.org/x/text/unicode/norm"
+)
+
+var (
+	toneMap = "\u0304\u0301\u0308\u0309\u0302\u0300\u0303"
+	vietoaqMap = [7][2]rune{
+		{'r', 'l'}, {'p', 'b'}, {'x', 'z'}, {'n', 'm'}, {'t', 'd'}, {'k', 'g'}, {'f', 'v'}}
+	RegularSyllable = regexp.MustCompile(
+	  `([bcdfghjklmnprstz']?|[cs]h)`    + // onset
+	  `([aeiuoyı])`                     + // first vowel of nucleus
+	  `([` + toneMap + `]?)`            + // tone
+	  `([aeiouyı]{0,2})`                + // remaining nucleus vowels
+	  `(q?)`                            ) // regular coda
+	VietoaqSyllable = regexp.MustCompile(
+	  `([bcdfghjklmnprstxz]|[cs]h)`     + // onset
+	  `([aeiuoy]{1,3})`                 + // nucleus
+	  `([qrlpbxznmtdkgfv]?)`            ) // Vietoaq coda
+)
+
+func toTransform(syll []string, padding bool) string {
+	onset, vow, tone, vows, coda :=
+		syll[1], syll[2], syll[3], syll[4], syll[5]
+	if onset == "" || onset == "'" {
+		onset = "x"
+	}
+	if tone != "" {
+		var qful int
+		if coda == "q" {
+			qful = 1
+		} else {
+			qful = 0
+		}
+		coda = string(vietoaqMap[strings.Index(toneMap, tone) / 2][qful])
+	}
+	return onset + strings.ReplaceAll(vow + vows, "ı", "i") + coda
+}
+
+func fromTransform(syll []string, padding bool) string {
+	onset, vow, tone, vows, coda :=
+		syll[1], syll[2][0:1], "", syll[2][1:], syll[3]
+	if coda != "" && coda != "q" {
+		codaRune := rune(coda[0])
+		var ii, jj int
+		for i, arr := range vietoaqMap {
+			for j, char := range arr {
+				if char == codaRune {
+					ii, jj = i, j
+					break
+				}
+			}
+		}
+		if jj == 1 {
+			coda = "q"
+		} else {
+			coda = ""
+		}
+		tone = string([]rune(toneMap)[ii])
+		if onset == "x" {
+			onset = ""
+		}
+	} else if vow == "i" {
+		vow = "ı"
+	}
+	if onset == "x" {
+		if padding || tone != "" {
+			onset = ""
+		} else {
+			onset = "'"
+		}
+	}
+	return onset + norm.NFC.String(vow + tone) +
+		strings.ReplaceAll(vows, "i", "ı") + coda
+}
+
+func To(regular string) string {
+	return syllableTransform(regular, RegularSyllable, toTransform)
+}
+
+func From(vietoaq string) string {
+	return syllableTransform(vietoaq, VietoaqSyllable, fromTransform)
+}
+
+func syllableTransform(input string, r *regexp.Regexp,
+	transform func([]string, bool)string) string {
+	interleaved := Syllables(strings.ToLower(norm.NFD.String(input)), r)
+	var sb strings.Builder
+	for i, s := range interleaved {
+		if i % 2 == 1 {
+			sb.WriteString(transform(s, interleaved[i - 1][0] != "" || i == 1))
+		} else {
+			sb.WriteString(s[0])
+		}
+	}
+	return norm.NFC.String(sb.String())
+}
+
+// returns an array of junk and Toaq, interleaved
+func Syllables(s string, r *regexp.Regexp) [][]string {
+	acc := [][]string{}
+	for {
+		bounds := r.FindStringSubmatchIndex(s)
+		if bounds == nil {
+			break
+		}
+		preemptive := r.FindStringSubmatchIndex(s[bounds[1] - 1:])
+		if preemptive != nil && preemptive[0] == 0 &&
+			bounds[len(bounds) - 1] - bounds[len(bounds) - 2] > 0 {
+			bounds[1]--
+			bounds[len(bounds) - 1]--
+		}
+		acc = append(acc, []string{s[:bounds[0]]})
+		ln := len(bounds) / 2
+		contentful := make([]string, ln)
+		for j := 0; j < ln; j++ {
+			contentful[j] = s[bounds[2 * j]:bounds[2 * j + 1]]
+		}
+		acc = append(acc, contentful)
+		s = s[bounds[1]:]
+	}
+	acc = append(acc, []string{s})
+	return acc
+}