otf.pack.tree: In memory trees#

Convert to and from Node.

otf.pack convert directly between different types and doesn’t have any intermediate representation of values. Having access to a simple representation makes it easier to write tests and debug application.

This is the easiest way to programmatically check what a python object looks like when it’s reduced:

>>> v = (1, 2)
>>> explode([(1, 2)])
[Custom(constructor='tuple', args=([1, 2],), kwargs={})]

You can also leverage this module to check other reducers:

>>> import otf.pack.text
>>> otf.pack.reduce_text("{4: I.do_not.exist(1)}", NodeBuilder())
{4: Custom(constructor='I.do_not.exist', args=(1,), kwargs={})}

API:#

otf.pack.tree.Node = int | float | None | str | bytes | bool | otf.pack.tree.Custom | otf.pack.tree.Reference | otf.pack.tree.Mapping | dict[typing.Any, typing.Any] | list[typing.Any]#
class otf.pack.tree.Mapping(data)#

A key value container

Usually mapping are represented as dictionaries:

>>> explode({None: "empty"})  # All the exploded keys are hashable
{None: 'empty'}

When the reduced value cannot be safely represented as a dictionary (because some keys are not hashable) we use a Mapping :

>>> from pprint import pp
>>> pp(explode({(): "empty"}), width=60)
Mapping(data=[(Custom(constructor='tuple',
                      args=([],),
                      kwargs={}),
               'empty')])

Note that the mapping cannot implement the collections.Mapping interface because it might contain duplicate keys:

>>> v1 = (1,)
>>> v2 = (2,)
>>> e = explode({1: v1, v1: v2, v2: 2})
>>> pp(e, width=60)
Mapping(data=[(1,
               Custom(constructor='tuple',
                      args=([1],),
                      kwargs={})),
              (Reference(offset=3),
               Custom(constructor='tuple',
                      args=([2],),
                      kwargs={})),
              (Reference(offset=3), 2)])
Parameters

data (list[tuple[Node, Node]]) –

class otf.pack.tree.Reference(offset)#

Denotes a shared reference.

This is a reference to the object that appeared offset nodes ago in a depth first traversal of the tree.

Parameters

offset (int) –

class otf.pack.tree.Custom(constructor, *args, **kwargs)#

Denotes a type with a custom de-serialisation function

Parameters

  • constructor (str) – The name of the function used to do the implosion of custom types

  • value (Node) – A serialisable value that can be passed as an argument to constructor to recreate the original value

class otf.pack.tree.NodeBuilder#

A base.Accumulator used to build Node

otf.pack.tree.explode(v)#

Convert an object to a Node

Parameters

v –

otf.pack.tree.implode(v)#

Reconstruct the object represented by a Node

Parameters

v –