Basic keys parsing

keysparsing.go

@@ -0,0 +1,55 @@
+// Parsing keys handling both bare and quoted keys.
+
+package toml
+
+import (
+	"bytes"
+	"fmt"
+)
+
+func parseKey(key string) ([]string, error) {
+	groups := []string{}
+	var buffer bytes.Buffer
+	inQuotes := false
+	escapeNext := false
+	for _, char := range key {
+		if escapeNext {
+			buffer.WriteRune(char)
+			escapeNext = false
+			continue
+		}
+		switch char {
+		case '\\':
+			escapeNext = true
+			continue
+		case '"':
+			inQuotes = !inQuotes
+		case '.':
+			if inQuotes {
+				buffer.WriteRune(char)
+			} else {
+				groups = append(groups, buffer.String())
+				buffer.Reset()
+			}
+		default:
+			if !inQuotes && !isValidBareChar(char) {
+				return nil, fmt.Errorf("invalid bare character: %c", char)
+			}
+			buffer.WriteRune(char)
+		}
+	}
+	if inQuotes {
+		return nil, fmt.Errorf("mismatched quotes")
+	}
+	if escapeNext {
+		return nil, fmt.Errorf("unfinished escape sequence")
+	}
+	if buffer.Len() > 0 {
+		groups = append(groups, buffer.String())
+	}
+	return groups, nil
+}
+
+func isValidBareChar(r rune) bool {
+	return isAlphanumeric(r) || r == '-'
+}