WARNING: Internal function which is subject to change

\cond INTERNAL

Uses an existing buffer to hold the parsed AST, if it fits. The specified buffer must not be deallocated until after the document is parsed and the A

Creates a dynamic_allocation policy with the given initial AST and stack buffer sizes.

Creates an empty, zero-sized view.

HACK: This is a re-implemented version of a similar function on sajson::value. We should modify it to either share a common helper, or remove it compl