1. Added #ifdef extern "C" to public header files.
2. Changed variables that are key words in c++, to different names (like ns instead of namespace).
3. Changed char* to const char* for constant strings.
* Reduced memory for attribute and body objects, see `XML_NEW_DIFFERENTIATE` compile-time option.
* Optimized cbuf handling in parsing and xml2cbuf functions.
* Optimized xml scanner to read strings rather than single chars
* Optimized xml_merge for the case of disjunct trees.
w-level general upgrades and as a complement to module-specific upgrade.
* Called on startup after initial XML parsing, but before module-specific upgrades
* Enabled by definign the `.ca_datastore_upgrade`
* [General-purpose upgrade documentation](https://clixon-docs.readthedocs.io/en/latest/backend.html#ge
neral-purpose)
* JSON parse error messages change from ` on line x: syntax error,..` to `json_parse: line x: syntax err
or`
* Unknown-element error message is more descriptive, eg from `namespace is: urn:example:clixon` to: `Fai
led to find YANG spec of XML node: x with parent: xp in namespace urn:example:clixon`.
* C-API parse and validation API more capable
* `xml_spec_populate` family of functions extended with three-value return values
* -1: error, 0: parse OK, 1: parse and YANG binding OK.
* `xml_parse` and `json_parse` API changes
* Three value returns: -1: error, 0: parse OK, 1: parse and YANG binding OK.
* Extended `xml_parse_file2` and `xml_parse_string2` extended API functions with all options available.
* New concept called `yang_bind` that defines how XML symbols are bound to YANG after parsing
* Existing API same except `xml_parse_file` `endtag` argument moved to `xml_parse_file2`
* C-API: Added instrumentation: `xml_size` and `xml_stats_get`.
* Fixed: Enabling modstate (CLICON_XMLDB_MODSTATE), changing a revision on a yang, and restarting made the backend daemon exit at start (thanks Matt)
* Also: ensure to load `ietf-yang-library.yang ` if CLICON_XMLDB_MODSTATE is set
* Renamed yang file `ietf-netconf-notification@2008-07-01.yang` to `clixon-rfc5277`.
* Cligen uses posix regex while yang uses XSD. It differs in some aspects. A translator function has been added for `\d` -> `[0-9]` translation, there may be more.
* [ietf-netconf-notification@2008-07-01.yang validation problem #62](https://github.com/clicon/clixon/issues/62)
* For backward compatibility, load of startup and running set CLICON_XML_NS_STRICT to false temporarily.
* Added three-valued return values for several validate functions where -1 is fatal error, 0 is validation failed and 1 is validation OK.
* This includes: `xmldb_put`, `xml_yang_validate_all`, `xml_yang_validate_add`, `xml_yang_validate_rpc`, `api_path2xml`, `api_path2xpath`
* Added new xml functions for specific types: `xml_child_nr_notype`, `xml_child_nr_notype`, `xml_child_i_type`, `xml_find_type`.
* Added urn:ietf:params:netconf:capability:yang-library:1.0
* Thanks SCadilhac for helping out, see https://github.com/clicon/clixon/issues/39
* uri_percent_encode() and xml_chardata_encode() changed to use stdarg parameters
* The previous XPATH imlementation was very restricted.
* The only function implemented is the Yang extension "current()". No other functions are implemented (eg last(), count()).
