ADT queries!

Dominik Madarász
Dominik Madarász

Hi there!

With the release of 16.1.1 version of zpl you are now able to perform URI like queries on ADT nodes.

New functionality

The new function zpl_adt_get takes a URI which specifies how we should perform a lookup on an ADT node. The following features are present:

  • nested lookup
    • "a/b/c" would look through nodes to fetch the c node.
  • nested conditional lookup
    • "arr/[foo=123]/bar" would scan the arr array node to find an object element which field foo would be of value 123, it would then fetch a node inside called bar.
  • index-based lookup
    • "arr/3" would fetch the 4th element of array node arr.
  • value-based lookup
    • "arr/[apple]" would fetch an element of array node arr with value apple.

Example call:

  zpl_json_object *node = zpl_adt_get(document, "foo/bar/baz");
  // node variable is now a pointer to the node called `baz` or null pointer if lookup has failed.

As we can see, this new function reduces the amount of code needed to perform lookups on ADT nodes. It is also much more readable and easy to understand.

Feel free to check out the json_get.c example code.

We also plan to implement a sscanf alike addition to this API later on, example:

  zpl_adt_get(obj, "/settings/title:%s/x:%d/y:%d/modes/[name=enhanced]:%n", title_str, &x, &y, node_ptr);

Parser improvements

The new version also offers an ability to disable extra parsing logic to reduce memory footprint and improve parsing speed, the macro switch responsible for this change is ZPL_PARSER_DISABLE_ANALYSIS. Note it strips certain features that would ensure data format consistency on exports, use only when you want to perform fast raw imports!

See you next time!