Implemented runes

src/build/core/Number.go

@@ -0,0 +1,36 @@
+package core
+
+import (
+	"strconv"
+	"unicode/utf8"
+
+	"git.akyoto.dev/cli/q/src/build/errors"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// Number tries to convert the token into a numeric value.
+func (f *Function) Number(t token.Token) (int, byte, error) {
+	switch t.Kind {
+	case token.Number:
+		number, err := strconv.Atoi(t.Text(f.File.Bytes))
+		return number, 8, err
+
+	case token.Rune:
+		r := t.Bytes(f.File.Bytes)
+		r = r[1 : len(r)-1]
+
+		if len(r) == 0 {
+			return 0, 0, errors.New(errors.InvalidRune, f.File, t.Position+1)
+		}
+
+		number, size := utf8.DecodeRune(r)
+
+		if len(r) > size {
+			return 0, 0, errors.New(errors.InvalidRune, f.File, t.Position+1)
+		}
+
+		return int(number), byte(size), nil
+	}
+
+	return 0, 0, errors.New(errors.InvalidNumber, f.File, t.Position)
+}