forgot to add file

server/drafty/grapheme.go

@@ -0,0 +1,81 @@
+package drafty
+
+import (
+	"github.com/rivo/uniseg"
+)
+
+// graphemes is a container holding lengths of graphemes in a string.
+type graphemes struct {
+	// The original string.
+	original string
+
+	// Sizes of grapheme clusters within the original string.
+	sizes []byte
+}
+
+// prepareGraphemes returns a parsed grapheme container by splitting the string into grapheme clusters
+// and saving their lengths.
+func prepareGraphemes(str string) *graphemes {
+	// Split the string into grapheme clusters and save the size of each cluster.
+	sizes := make([]byte, 0, len(str))
+	for state, remaining, cluster := -1, str, ""; len(remaining) > 0; {
+		cluster, remaining, _, state = uniseg.StepString(remaining, state)
+		sizes = append(sizes, byte(len(cluster)))
+	}
+
+	return &graphemes{
+		original: str,
+		sizes:    sizes,
+	}
+}
+
+// length returns the number of grapheme clusters in the original string.
+func (g *graphemes) length() int {
+	if g == nil {
+		return 0
+	}
+	return len(g.sizes)
+}
+
+// string returns the original string from which the grapheme was created from.
+func (g *graphemes) string() string {
+	if g == nil {
+		return ""
+	}
+	return g.original
+}
+
+// slice returns a new grapheme iterator containing graphemes from 'start' to 'end'.
+func (g *graphemes) slice(start, end int) *graphemes {
+
+	// Convert grapheme offsets to string offsets.
+	s := 0
+	for i := 0; i < start; i++ {
+		s += int(g.sizes[i])
+	}
+	e := s
+	for i := start; i < end; i++ {
+		e += int(g.sizes[i])
+	}
+
+	if e == 0 {
+		println("G= ", g)
+	}
+
+	return &graphemes{
+		original: g.original[s:e],
+		sizes:    g.sizes[start:end],
+	}
+}
+
+// append appends 'other' grapheme iterator to 'g' iterator and returns g.
+// If g is nil, 'other' is returned.
+func (g *graphemes) append(other *graphemes) *graphemes {
+	if g == nil {
+		return other
+	}
+
+	g.original += other.original
+	g.sizes = append(g.sizes, other.sizes...)
+	return g
+}