diff -r d6dbd5d50d43 -r 426054465916 src/XMLNameCodec.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/XMLNameCodec.h	Wed Dec 30 01:28:45 2020 +0100
@@ -0,0 +1,127 @@
+/**
+ * Relational pipes
+ * Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <sstream>
+#include <iomanip>
+#include <stdexcept>
+
+#include <glibmm-2.4/glibmm/ustring.h>
+
+namespace relpipe {
+namespace in {
+namespace xmltable {
+
+class XMLNameCodec {
+private:
+	static const char DEFAULT_ESCAPING_CHARACTER = '_';
+	const char esc;
+	const bool namespaceAware;
+
+	bool between(gunichar codepoint, gunichar start, gunichar end) {
+		return codepoint >= start && codepoint <= end;
+	}
+
+	/**
+	 * https://www.w3.org/TR/REC-xml/#NT-NameStartChar
+	 *
+	 * @param codepoint unicode character
+	 * @return whether this character is allowed at the beginning of a XML name
+	 */
+	bool isValidNameStartChar(gunichar codepoint) {
+		// NameStartChar  ::= ":" | [A-Z] | "_" | [a-z] 
+		//   | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF]
+		//   | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF]
+		//   | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]
+		return (codepoint == ':' && !namespaceAware) || between(codepoint, 'A', 'Z') || codepoint == '_' || between(codepoint, 'a', 'z')
+				|| between(codepoint, 0xC0, 0xD6) || between(codepoint, 0xD8, 0xF6) || between(codepoint, 0xF8, 0x2FF) || between(codepoint, 0x370, 0x37D) || between(codepoint, 0x37F, 0x1FFF)
+				|| between(codepoint, 0x200C, 0x200D) || between(codepoint, 0x2070, 0x218F) || between(codepoint, 0x2C00, 0x2FEF) || between(codepoint, 0x3001, 0xD7FF)
+				|| between(codepoint, 0xF900, 0xFDCF) || between(codepoint, 0xFDF0, 0xFFFD) || between(codepoint, 0x10000, 0xEFFFF);
+	}
+
+	/**
+	 * https://www.w3.org/TR/REC-xml/#NT-NameChar
+	 *
+	 * @param codepoint unicode character
+	 * @return whether this character is allowed in a XML name
+	 */
+	bool isValidNameChar(gunichar codepoint) {
+		// NameChar       ::= NameStartChar | "-" | "." | [0-9] 
+		//   | #xB7
+		//   | [#x0300-#x036F] | [#x203F-#x2040]
+		return isValidNameStartChar(codepoint) || codepoint == '-' || codepoint == '.' || between(codepoint, '0', '9')
+				|| codepoint == 0xB7
+				|| between(codepoint, 0x0300, 0x036F) || between(codepoint, 0x203F, 0x2040);
+	}
+
+public:
+
+	XMLNameCodec() : XMLNameCodec(DEFAULT_ESCAPING_CHARACTER, true) {
+	}
+
+	/**
+	 * @param escapingCharacter must be valid character allowed not only in the middle of the XML name but also as the
+	 * first character of the name
+	 * @param namespaceAware colon character is reserved as a separator of the prefix and the local name, see
+	 * https://www.w3.org/TR/REC-xml-names/#NT-NCName
+	 * @throws std::invalid_argument if escapingCharacter is not valid
+	 */
+	XMLNameCodec(const char escapingCharacter, const bool namespaceAware) : esc(escapingCharacter), namespaceAware(namespaceAware) {
+		// TODO: allow also characters like #xB7 and add another escaping if they occur at the beginning of the name?
+		if (!isValidNameStartChar(esc)) {
+			throw std::invalid_argument("The character „" + std::to_string(escapingCharacter) + "“ is not allowed at the beginning of a XML name and thus not usable for escaping");
+		}
+	}
+
+	virtual ~XMLNameCodec() {
+	}
+
+	/**
+	 * @param name any string
+	 * @return valid name of XML element or attribute
+	 */
+	Glib::ustring encode(Glib::ustring name) {
+		if (name.empty()) {
+			return Glib::ustring(1, esc);
+		} else {
+			std::stringstream result;
+
+			for (int i = 0; i < name.size(); i++) {
+				gunichar codepoint = name[i];
+				if (codepoint == esc) {
+					result.put(esc);
+					result.put(esc);
+					continue;
+				} else if ((i == 0 && isValidNameStartChar(codepoint)) || (i > 0 && isValidNameChar(codepoint))) {
+					result << Glib::ustring(1, codepoint);
+					continue;
+				}
+
+				result.put(esc);
+				result << Glib::ustring::format(std::hex, std::setfill(L'0'), std::setw(2), codepoint);
+				result.put(esc);
+			}
+
+			return result.str();
+		}
+	}
+
+};
+
+}
+}
+}