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#! python 

# -*- coding: utf-8 -*- 

# 

# Copyright 2013-2019 European Commission (JRC); 

# Licensed under the EUPL (the 'Licence'); 

# You may not use this work except in compliance with the Licence. 

# You may obtain a copy of the Licence at: http://ec.europa.eu/idabc/eupl 

""" 

Hierarchical string-like objects useful for indexing, that can be rename/relocated at a later stage. 

 

.. autosummary:: 

 

Pstep 

pmods_from_tuples 

Pmod 

 

*Example*:: 

 

>>> from pandalone.mappings import pmods_from_tuples 

 

>>> pmods = pmods_from_tuples([ 

... ('', 'deeper/ROOT'), 

... ('/abc', 'ABC'), 

... ('/abc/foo', 'BAR'), 

... ]) 

>>> p = pmods.step() 

>>> p.abc.foo 

`BAR` 

>>> p._paths() 

['deeper/ROOT/ABC/BAR'] 

 

- TODO: Implements "anywhere" pmods(`//`). 

""" 

 

from collections import OrderedDict 

from copy import copy 

import logging 

import re 

 

import functools as ft 

from pandalone import utils 

from pandalone.pandata import ( 

iter_jsonpointer_parts_relaxed, 

JSchema, 

unescape_jsonpointer_part, 

escape_jsonpointer_part, 

) 

 

 

__commit__ = "" 

 

log = logging.getLogger(__name__) 

 

 

class Pmod(object): 

 

r""" 

A path-step mapping forming the pmods-hierarchy. 

 

- The :term:`pmods` denotes the hierarchy of all :term:`mappings`, 

that either *rename* or *relocate* path-steps. 

 

- A single :term:`mapping` transforms an "origin" path to 

a "destination" one (also called as "from" and "to" paths). 

 

- A mapping always transforms the *final* path-step, like that:: 

 

FROM_PATH TO_PATH RESULT_PATH 

--------- ------- ----------- 

/rename/path foo --> /rename/foo ## renaming 

/relocate/path foo/bar --> /relocate/foo/bar ## relocation 

'' a/b/c --> /a/b/c ## Relocate all paths. 

/ a/b/c --> /a/b/c ## Relocates 1st "empty-str" step. 

 

- The :term:`pmod` is the mapping of that single path-step. 

 

- It is possible to match fully on path-steps using regular-expressions, 

and then to use any captured-groups from the *final* step into 

the mapped value:: 

 

(/all(.*)/path, foo) + all_1/path --> /all_1/foo 

+ all_XYZ --> /all_XYZ ## no change 

(/all(.*)/path, foo\1) + all_1/path --> /all_1/foo_1 

 

If more than one regex match, they are merged in the order declared 

(the latest one overrides a previous one). 

 

- Any exact child-name matches are applied and merged after regexs. 

 

- Use :func:`pmods_from_tuples()` to construct the pmods-hierarchy. 

 

- The pmods are used internally by class:`Pstep` to correspond 

the component-paths of their input & output onto the actual 

value-tree paths. 

 

:ivar str _alias: (optional) the mapped-name of the pstep for 

this pmod 

:ivar dict _steps: {original_name --> pmod} 

:ivar OrderedDict _regxs: {regex_on_originals --> pmod} 

 

 

Example: 

 

.. Note:: 

Do not manually construct instances from this class! 

To construct a hierarchy use the :func:`pmods_from_tuples()`. 

 

You can either use it for massively map paths, either for *renaming* them:: 

 

>>> pmods = pmods_from_tuples([ 

... ('/a', 'A'), 

... ('/~b.*', r'BB\g<0>'), ## Previous match. 

... ('/~b.*/~c.(.*)', r'W\1ER'), ## Capturing-group(1) 

... ]) 

>>> pmods.map_paths(['/a', '/a/foo']) ## 1st rule 

['/A', '/A/foo'] 

 

>>> pmods.map_path('/big/stuff') ## 2nd rule 

'/BBbig/stuff' 

 

>>> pmods.map_path('/born/child') ## 2nd & 3rd rule 

'/BBborn/WildER' 

 

 

or to *relocate* them:: 

 

>>> pmods = pmods_from_tuples([ 

... ('/a', 'A/AA'), 

... ('/~b.*/~c(.*)', r'../C/\1'), 

... ('/~b.*/~.*/~r.*', r'/\g<0>'), 

... ]) 

>>> pmods.map_paths(['/a/foo', '/big/child', '/begin/from/root']) 

['/A/AA/foo', '/big/C/hild', '/root'] 

 

 

Here is how you relocate "root" 

(notice that the `''` path is the root):: 

 

>>> pmods = pmods_from_tuples([('', '/NEW/ROOT')]) 

>>> pmods.map_paths(['/a/foo', '']) 

['/NEW/ROOT/a/foo', '/NEW/ROOT'] 

 

""" 

 

__slots__ = ["_alias", "_steps", "_regxs"] 

 

def __init__(self, _alias=None, _steps={}, _regxs={}): 

""" 

Args passed only for testing, remember `_regxs` to be (k,v) tuple-list! 

 

.. Note:: Volatile arg-defaults (empty dicts) are knowingly used , 

to preserve memory; should never append in them! 

 

""" 

self._alias = _alias 

self._steps = _steps 

if _regxs: 

self._regxs = OrderedDict((re.compile(k), v) for k, v in _regxs) 

else: 

self._regxs = _regxs 

 

def step(self, pname="", alias=None): 

""" 

Create a new :class:`Pstep` having as mappings this pmod. 

 

If no `pname` specified, creates a *root* pstep. 

 

Delegates to :meth:`Pstep.__new__()`. 

""" 

return Pstep(pname, _proto_or_pmod=self, alias=alias) 

 

def _append_into_steps(self, key): 

""" 

Inserts a child-mappings into `_steps` dict. 

 

:param str key: the step-name to add 

""" 

 

cpmod = None 

d = self._steps 

if not d: 

self._steps = d = {} # Do not modify init-defaults. 

else: 

cpmod = d.get(key) 

if not cpmod: 

d[key] = cpmod = Pmod() 

 

return cpmod 

 

def _append_into_regxs(self, key): 

""" 

Inserts a child-mappings into `_steps` dict. 

 

:param str key: the regex-pattern to add 

""" 

key = re.compile(key) 

cpmod = None 

d = self._regxs 

if not d: 

self._regxs = d = OrderedDict() # Do not modify init-defaults. 

else: 

cpmod = d.get(key) 

if cpmod: 

# Remove it, to append it at then end. 

del d[key] 

if not cpmod: 

cpmod = Pmod() 

d[key] = cpmod 

 

return cpmod 

 

def _override_steps(self, other): 

""" 

Override this pmod's '_steps' dict with other's, recursively. 

 

Same as :meth:`_override_regxs()` but without caring for order. 

""" 

 

opmods = other._steps 

if opmods: 

spmods = self._steps 

if spmods: 

# Like ``spmods.copy().update()`` but 

# recursive `_merge()` on common items. 

# 

spmods = spmods.copy() 

for name, opmod in opmods.items(): 

spmod = spmods.get(name) 

if spmod: 

opmod = spmod._merge(opmod) 

spmods[name] = opmod # Share other-pmod if not mine. 

opmods = spmods 

 

# Share other dict if self hadn't its own. 

self._steps = opmods 

 

def _override_regxs(self, other): 

""" 

Override this pmod's `_regxs` dict with other's, recursively. 

 

- It may "share" (crosslink) the dict and/or its child-pmods 

between the two pmod args (`self` and `other`). 

- No dict is modified (apart from self, which must have been cloned 

previously by :meth:`Pmod._merge()`), to avoid side-effects 

in case they were "shared". 

- It preserves dict-ordering so that `other` order takes precedence 

(its elements are the last ones). 

 

:param Pmod self: contains the dict that would be overridden 

:param Pmod other: contains the dict with the overrides 

""" 

 

opmods = other._regxs 

if opmods: 

spmods = self._regxs 

if spmods: 

# Like ``spmods.copy().update()`` but 

# with recursive `_merge()` on common items, 

# and preserve order. 

# 

opairs = [] 

for name, opmod in opmods.items(): 

spmod = spmods.get(name) 

if spmod: 

mpmod = spmod._merge(opmod) 

else: 

mpmod = opmod # Share other-pmod. 

opairs.append((name, mpmod)) 

 

okeys = opmods.keys() 

spairs = [ 

(name, spmod) # Share self-pmod. 

for name, spmod in spmods.items() 

if name not in okeys 

] 

 

opmods = type(spmods)(spairs + opairs) 

 

# Share other dict if self hadn't its own. 

self._regxs = opmods 

 

def _merge(self, other): 

""" 

Clone and override all its props with props from other-pmod, recursively. 

 

Although it does not modify this, the `other` or their children pmods, 

it may "share" (crosslink) them, so pmods MUST NOT be modified later. 

 

:param Pmod other: contains the dicts with the overrides 

:return: the cloned merged pmod 

:rtype: Pmod 

 

Examples: 

 

Look how `_steps` are merged:: 

 

>>> pm1 = Pmod(_alias='pm1', _steps={ 

... 'a':Pmod(_alias='A'), 'c':Pmod(_alias='C')}) 

>>> pm2 = Pmod(_alias='pm2', _steps={ 

... 'b':Pmod(_alias='B'), 'a':Pmod(_alias='AA')}) 

>>> pm = pm1._merge(pm2) 

>>> sorted(pm._steps.keys()) 

['a', 'b', 'c'] 

 

 

And here it is `_regxs` merging, which preserves order:: 

 

>>> pm1 = Pmod(_alias='pm1', 

... _regxs=[('d', Pmod(_alias='D')), 

... ('a', Pmod(_alias='A')), 

... ('c', Pmod(_alias='C'))]) 

>>> pm2 = Pmod(_alias='pm2', 

... _regxs=[('b', Pmod(_alias='BB')), 

... ('a', Pmod(_alias='AA'))]) 

 

>>> pm1._merge(pm2) 

pmod('pm2', OrderedDict([(re.compile('d'), pmod('D')), 

(re.compile('c'), pmod('C')), 

(re.compile('b'), pmod('BB')), 

(re.compile('a'), pmod('AA'))])) 

 

>>> pm2._merge(pm1) 

pmod('pm1', OrderedDict([(re.compile('b'), pmod('BB')), 

(re.compile('d'), pmod('D')), 

(re.compile('a'), pmod('A')), 

(re.compile('c'), pmod('C'))])) 

""" 

self = copy(self) 

if other._alias is not None: 

self._alias = other._alias 

self._override_steps(other) 

self._override_regxs(other) 

 

return self 

 

def _match_regxs(self, cstep): 

"""Return (pmod, regex.match) for those child-pmods matching `cstep`.""" 

 

return [ 

(rpmod, match) 

for rpmod, match in ( 

(rpmod, re.fullmatch(regex, cstep)) 

for regex, rpmod in self._regxs.items() 

) 

if match 

] 

 

def descend(self, cstep): 

r""" 

Return child-pmod with merged any exact child with all matched regexps, along with its alias regex-expaned. 

 

:param str cstep: the child path-step cstep of the pmod to return 

:return: the merged-child pmod, along with the alias; 

both might be None, if nothing matched, or no alias. 

:rtype: tuple(Pmod, str) 

 

Example:: 

 

>>> pm = Pmod( 

... _steps={'a': Pmod(_alias='A')}, 

... _regxs=[(r'a\w*', Pmod(_alias='AWord')), 

... (r'a(\d*)', Pmod(_alias=r'A_\1')), 

... ]) 

>>> pm.descend('a') 

(pmod('A'), 'A') 

 

>>> pm.descend('abc') 

(pmod('AWord'), 'AWord') 

 

>>> pm.descend('a12') 

(pmod('A_\\1'), 'A_12') 

 

>>> pm.descend('BAD') 

(None, None) 

 

 

Notice how children of regexps are merged together:: 

 

>>> pm = Pmod( 

... _steps={'a': 

... Pmod(_alias='A', _steps={1: 11})}, 

... _regxs=[ 

... (r'a\w*', Pmod(_alias='AWord', 

... _steps={2: Pmod(_alias=22)})), 

... (r'a\d*', Pmod(_alias='ADigit', 

... _steps={3: Pmod(_alias=33)})), 

... ]) 

>>> sorted(pm.descend('a')[0]._steps) ## All children and regexps match. 

[1, 2, 3] 

 

>>> pm.descend('aa')[0]._steps ## Only r'a\w*' matches. 

{2: pmod(22)} 

 

>>> sorted(pm.descend('a1')[0]._steps ) ## Both regexps matches. 

[2, 3] 

 

So it is possible to say:: 

 

>>> pm.descend('a1')[0].alias(2) 

22 

>>> pm.descend('a1')[0].alias(3) 

33 

>>> pm.descend('a1')[0].descend('BAD') 

(None, None) 

>>> pm.descend('a$') 

(None, None) 

 

but it is better to use :meth:`map_path()` for this. 

""" 

alias = None 

 

cpmod = self._steps.get(cstep) 

pmods = self._match_regxs(cstep) 

 

if cpmod and cpmod._alias is not None: 

alias = cpmod._alias 

else: 

for rpmod, match in reversed(pmods): 

if rpmod._alias is not None: 

alias = match.expand(rpmod._alias) 

break 

pmods = [pmod for pmod, _ in pmods] 

if cpmod: 

pmods.append(cpmod) 

 

if pmods: 

return (ft.reduce(Pmod._merge, pmods), alias) 

return (None, None) 

 

def alias(self, cstep): 

""" 

Like :meth:`descend()` but without merging child-pmods. 

 

:return: the expanded alias from child/regexs or None 

""" 

cpmod = self._steps.get(cstep) 

if cpmod and cpmod._alias is not None: 

return cpmod._alias 

 

pmods = self._match_regxs(cstep) 

 

for rpmod, match in reversed(pmods): 

if rpmod._alias is not None: 

return match.expand(rpmod._alias) 

 

def map_path(self, path): 

r""" 

Maps a '/rooted/path' using all aliases while descending its child pmods. 

 

It uses any aliases on all child pmods if found. 

 

:param str path: a rooted path to transform 

:return: the rooted mapped path or '/' if path was '/' 

:rtype: str or None 

 

Examples:: 

 

>>> pmods = pmods_from_tuples([ 

... ('/a', 'A/AA'), 

... ('/~a(\\w*)', r'BB\1'), 

... ('/~a\\w*/~d.*', r'D \g<0>'), 

... ('/~a(\\d+)', r'C/\1'), 

... ('/~a(\\d+)/~(c.*)', r'CC-/\1'), # The 1st group is ignored! 

... ('/~a\\d+/~e.*', r'/newroot/\g<0>'), # Rooted mapping. 

... ]) 

 

>>> pmods.map_path('/a') 

'/A/AA' 

 

>>> pmods.map_path('/a_hi') 

'/BB_hi' 

 

>>> pmods.map_path('/a12') 

'/C/12' 

 

>>> pmods.map_path('/a12/etc') 

'/newroot/etc' 

 

Notice how children from *all* matching prior-steps are merged:: 

 

>>> pmods.map_path('/a12/dow') 

'/C/12/D dow' 

>>> pmods.map_path('/a12/cow') 

'/C/12/CC-/cow' 

 

 

To map *root* use '' which matches before the 1st slash('/'):: 

 

>>> pmods = pmods_from_tuples([('', 'New/Root'),]) ## Relative 

>>> pmods 

pmod({'': pmod('New/Root')}) 

 

>>> pmods.map_path('/for/plant') 

'New/Root/for/plant' 

 

>>> pmods_from_tuples([('', '/New/Root'),]).map_path('/for/plant') 

'/New/Root/for/plant' 

 

.. Note:: 

Using slash('/') for "from" path will NOT map *root*:: 

 

>>> pmods = pmods_from_tuples([('/', 'New/Root'),]) 

>>> pmods 

pmod({'': pmod({'': pmod('New/Root')})}) 

 

>>> pmods.map_path('/for/plant') 

'/for/plant' 

 

>>> pmods.map_path('//for/plant') 

'/New/Root/for/plant' 

 

'/root' 

 

but '' always remains unchanged (whole document):: 

 

>>> pmods.map_path('') 

'' 

 

""" 

is_folder = len(path) > 1 and path.endswith("/") 

if is_folder: 

path = path[:-1] 

 

steps = tuple(iter_jsonpointer_parts_relaxed(path)) 

if self._alias is None: 

nsteps = () 

else: 

nsteps = tuple(iter_jsonpointer_parts_relaxed(self._alias)) 

 

if steps: 

pmod = self 

# Separate last-step from loop below, since 

# merged child-pmods in `descend` are not needed. 

# 

for step in steps[:-1]: 

if pmod: 

pmod, alias = pmod.descend(step) 

if alias is not None: 

if alias.startswith("."): 

nsteps += (step,) 

step = alias 

# XXX: Monkey business here. 

if len(step) > 1 and step.endswith("/"): 

step = step[:-1] 

nsteps += tuple(iter_jsonpointer_parts_relaxed(step)) 

 

final_step = steps[-1] 

if pmod: 

alias = pmod.alias(final_step) 

if alias is not None: 

if alias.startswith("."): 

nsteps += (final_step,) 

final_step = alias 

# XXX: Monkey business here. 

is_folder = len(final_step) > 1 and final_step.endswith("/") 

if is_folder: 

final_step = final_step[:-1] 

nsteps += tuple(iter_jsonpointer_parts_relaxed(final_step)) 

 

npath = _join_paths(*nsteps) 

 

if is_folder: 

path += "%s/" % path 

 

return npath 

 

def map_paths(self, paths): 

return [self.map_path(p) for p in paths] 

 

def __repr__(self): 

args = [ 

repr(a) for a in [self._alias, self._steps, self._regxs] if a or a == "" 

] 

 

args = ", ".join(args) 

return "pmod({})".format(args) 

 

def __eq__(self, o): 

try: 

return (self._alias, self._steps, self._regxs) == ( 

o._alias, 

o._steps, 

o._regxs, 

) 

except: 

return False 

 

 

def pmods_from_tuples(pmods_tuples): 

""" 

Turns a list of 2-tuples into a *pmods* hierarchy. 

 

- Each tuple defines the renaming-or-relocation of the *final* part 

of some component path onto another one into value-trees, such as:: 

 

(/rename/path, foo) --> rename/foo 

(relocate/path, foo/bar) --> relocate/foo/bar 

 

 

- The "from" path may be: 

- relative, 

- absolute(starting with `/`), or 

- "anywhere"(starting with `//`). 

 

- In case a "step" in the "from" path starts with tilda(`~`), 

it is assumed to be a regular-expression, and it is removed from it. 

The "to" path can make use of any "from" capture-groups:: 

 

('/~all(.*)/path', 'foo') 

(r'~some[\d+]/path', 'foo\1') 

('//~all(.*)/path', 'foo') 

 

 

 

:param list(tuple(str, str) pmods_tuples: 

:return: a root pmod 

:rtype: Pmod 

 

 

Example:: 

 

>>> pmods_from_tuples([ 

... ('/a', 'A1/A2'), 

... ('/a/b', 'B'), 

... ]) 

pmod({'': pmod({'a': pmod('A1/A2', {'b': pmod('B')})})}) 

 

>>> pmods_from_tuples([ 

... ('/~a*', 'A1/A2'), 

... ('/a/~b[123]', 'B'), 

... ]) 

pmod({'': pmod({'a': 

pmod(OrderedDict([(re.compile('b[123]'), pmod('B'))]))}, 

OrderedDict([(re.compile('a*'), pmod('A1/A2'))]))}) 

 

 

This is how you map *root*:: 

 

>>> pmods = pmods_from_tuples([ 

... ('', 'relative/Root'), ## Make all paths relatives. 

... ('/a/b', '/Rooted/B'), ## But map `b` would be "rooted". 

... ]) 

>>> pmods 

pmod({'': 

pmod('relative/Root', 

{'a': pmod({'b': 

pmod('/Rooted/B')})})}) 

 

>>> pmods.map_path('/a/c') 

'relative/Root/a/c' 

 

>>> pmods.map_path('/a/b') 

'/Rooted/B' 

 

 

But note that '/' maps the 1st "empty-str" step after root:: 

 

>>> pmods_from_tuples([ 

... ('/', 'New/Root'), 

... ]) 

pmod({'': pmod({'': pmod('New/Root')})}) 

 

 

TODO: Implement "anywhere" matches. 

""" 

root = Pmod() 

for i, (f, t) in enumerate(pmods_tuples): 

if (f, t) == ("", "") or f is None or t is None: 

msg = 'pmod-tuple #%i of %i: Invalid "from-to" tuple (%r, %r).' 

log.warning(msg, i + 1, len(pmods_tuples), f, t) 

continue 

 

pmod = root 

for srcstep in iter_jsonpointer_parts_relaxed(f): 

is_regex = srcstep.startswith("~") 

if is_regex: 

pmod = pmod._append_into_regxs(srcstep[1:]) 

else: 

pmod = pmod._append_into_steps(srcstep) 

 

pmod._alias = t 

 

return root 

 

 

def _append_step(steps, step): 

""" 

Joins `step` at the right of `steps`, respecting '/', '..', '.', ''. 

 

:param tuple steps: where to append into 

("absolute" when 1st-element is '') 

:param str step: what to append 

(may be: ``'foo', '.', '..', ''``) 

:rtype: tuple 

 

.. Note:: 

The empty-string('') is the "root" for both `steps` and `step`. 

An empty-tuple `steps` is considered "relative", equivalent to dot(`.`). 

 

 

Example:: 

 

>>> _append_step((), 'a') 

('a',) 

 

>>> _append_step(('a', 'b'), '..') 

('a',) 

 

>>> _append_step(('a', 'b'), '.') 

('a', 'b') 

 

 

Not that an "absolute" path has the 1st-step empty(`''`), 

(so the previous paths above were all "relative"):: 

 

>>> _append_step(('a', 'b'), '') 

('',) 

 

>>> _append_step(('',), '') 

('',) 

 

>>> _append_step((), '') 

('',) 

 

 

Dot-dots preserve "relative" and "absolute" paths, respectively, 

and hence do not coalesce when at the left:: 

 

>>> _append_step(('',), '..') 

('',) 

 

>>> _append_step(('',), '.') 

('',) 

 

>>> _append_step(('a',), '..') 

() 

 

>>> _append_step((), '..') 

('..',) 

 

>>> _append_step(('..',), '..') 

('..', '..') 

 

>>> _append_step((), '.') 

() 

 

 

 

Single-dots('.') just dissappear:: 

 

>>> _append_step(('.',), '.') 

() 

 

>>> _append_step(('.',), '..') 

('..',) 

 

""" 

assert isinstance(steps, tuple), (steps, step) 

assert not step or isinstance(step, str), (steps, step) 

 

if step == "": 

return ("",) 

 

_last_pair_choices = { 

(".",): (), 

("..",): ("..",), 

(".", "."): (), 

(".", ".."): ("..",), 

("..", "."): ("..",), 

("..", ".."): ("..", ".."), 

("", "."): ("",), 

("", ".."): ("",), 

} 

 

try: 

last_pair = steps[-1:] + (step,) 

steps = steps[:-1] + _last_pair_choices[last_pair] 

except KeyError: 

if step == ".": 

pass 

elif step == "..": 

steps = steps[:-1] 

else: 

steps += (step,) 

 

return steps 

 

 

def _join_paths(*steps): 

""" 

Joins all path-steps in a single string, respecting ``'/', '..', '.', ''``. 

 

:param str steps: single json-steps, from left to right 

:rtype: str 

 

.. Note:: 

If you use :func:`iter_jsonpointer_parts_relaxed()` to generate 

path-steps, the "root" is signified by the empty(`''`) step; 

not the slash(`/`)! 

 

Hence a lone slash(`/`) gets splitted to an empty step after "root" 

like that: ``('', '')``, which generates just "root"(`''`). 

 

Therefore a "folder" (i.e. `some/folder/`) when splitted equals 

``('some', 'folder', '')``, which results again in the "root"(`''`)! 

 

 

Examples:: 

 

>>> _join_paths('r', 'a', 'b') 

'r/a/b' 

 

>>> _join_paths('', 'a', 'b', '..', 'bb', 'cc') 

'/a/bb/cc' 

 

>>> _join_paths('a', 'b', '.', 'c') 

'a/b/c' 

 

 

An empty-step "roots" the remaining path-steps:: 

 

>>> _join_paths('a', 'b', '', 'r', 'aa', 'bb') 

'/r/aa/bb' 

 

 

All `steps` have to be already "splitted":: 

 

>>> _join_paths('a', 'b', '../bb') 

'a/b/../bb' 

 

 

Dot-doting preserves "relative" and "absolute" paths, respectively:: 

 

>>> _join_paths('..') 

'..' 

 

>>> _join_paths('a', '..') 

'.' 

 

>>> _join_paths('a', '..', '..', '..') 

'../..' 

 

>>> _join_paths('', 'a', '..', '..') 

'' 

 

 

Some more special cases:: 

 

>>> _join_paths('..', 'a') 

'../a' 

 

>>> _join_paths('', '.', '..', '..') 

'' 

 

>>> _join_paths('.', '..') 

'..' 

 

>>> _join_paths('..', '.', '..') 

'../..' 

 

.. seealso:: _append_step 

""" 

nsteps = ft.reduce(_append_step, steps, ()) 

if not nsteps: 

return "." 

else: 

return "/".join(nsteps) 

 

 

_forbidden_pstep_attrs = ("get_values", "Series") 

""" 

Psteps attributes excluded from magic-creation, because searched by pandas's indexing code. 

""" 

 

 

def _clone_attrs(obj): 

"""Clone deeply any collection attributes of the passed-in object.""" 

attrs = vars(obj).copy() 

ccsteps = attrs.get("_csteps", None) 

if ccsteps: 

attrs["_csteps"] = ccsteps.copy() 

ctags = attrs["_tags"] 

if ctags: 

attrs["_tags"] = attrs["_tags"].copy() 

return attrs 

 

 

class Pstep(str): 

 

""" 

Automagically-constructed *relocatable* paths for accessing data-tree. 

 

The "magic" autocreates psteps as they referenced, making writing code 

that access data-tree paths, natural, while at the same time the "model" 

of those tree-data gets discovered. 

 

Each pstep keeps internally the *name* of a data-tree step, which, 

when created through recursive referencing, concedes with parent's 

branch leading to this step. That name can be modified with :class:`Pmod` 

so the same data-accessing code can refer to differently-named values 

int the data-tree. 

 

:ivar dict _csteps: the child-psteps by their name (default `None`) 

:ivar dict _pmod: path-modifications used to construct this and 

relayed to children (default `None`) 

:ivar int _locked: one of 

- :const:`Pstep.CAN_RELOCATE` (default), 

- :const:`Pstep.CAN_RENAME`, 

- :const:`Pstep.LOCKED` (neither from the above). 

:ivar set _tags: A set of strings (default `()`) 

:ivar dict _schema: json-schema data. 

 

See :meth:`__new__()` for interal constructor. 

 

**Usage:** 

 

- Use a :meth:`Pmod.pstep()` to construct a *root* pstep from mappings. 

Specify a string argument to construct a relative pstep-hierarchy. 

 

- Just referencing (non_private) attributes, creates them. 

 

- Private attributes and functions (starting with ``_``) exist for 

specific operations (ie for specifying json-schema, or 

for collection all paths). 

 

- Assignments are only allowed for string-values, or to private attributes:: 

 

>>> p = Pstep() 

>>> p.assignments = 12 

Traceback (most recent call last): 

AssertionError: Cannot assign '12' to '/assignments! 

 

>>> p._but_hidden = 'Ok' 

 

- Use :meth:`_paths()` to get all defined paths so far. 

 

- Construction:: 

 

>>> Pstep() 

`` 

>>> Pstep('a') 

`a` 

 

Notice that pstesps are surrounded with the back-tick char('`'). 

 

- Paths are created implicitely as they are referenced:: 

 

>>> m = {'a': 1, 'abc': 2, 'cc': 33} 

>>> p = Pstep('a') 

>>> assert m[p] == 1 

>>> assert m[p.abc] == 2 

>>> assert m[p.a321.cc] == 33 

 

>>> sorted(p._paths()) 

['a/a321/cc', 'a/abc'] 

 

 

- Any "path-mappings" or "pmods" maybe specified during construction:: 

 

>>> from pandalone.mappings import pmods_from_tuples 

 

>>> pmods = pmods_from_tuples([ 

... ('', 'deeper/ROOT'), 

... ('/abc', 'ABC'), 

... ('/abc/foo', 'BAR'), 

... ]) 

>>> p = pmods.step() 

>>> p.abc.foo 

`BAR` 

>>> p._paths() 

['deeper/ROOT/ABC/BAR'] 

 

- but exceptions are thrown if mapping any step marked as "locked": 

 

>>> p.abc.foo._locked ## 3: CAN_RELOCATE 

3 

 

>>> p.abc.foo._lock ## Screams, because `foo` is already mapped. 

Traceback (most recent call last): 

ValueError: Cannot rename/relocate 'foo'-->'BAR' due to LOCKED! 

 

- .. Warning:: 

Creating an empty(`''`) step in some paths will "root" the path:: 

 

>>> p = Pstep() 

>>> _ = p.a1.b 

>>> _ = p.A2 

>>> p._paths() 

['/A2', '/a1/b'] 

 

>>> _ = p.a1.a2.c 

>>> _ = p.a1.a2 = '' 

>>> p._paths() 

['/A2', '/a1/b', '/c'] 

 

""" 

 

CAN_RELOCATE = 3 

CAN_RENAME = 1 

LOCKED = 0 

 

@staticmethod 

def _lockstr(lock): 

if lock >= Pstep.CAN_RELOCATE: 

return "CAN_RELOCATE" 

if Pstep.LOCKED <= lock < Pstep.CAN_RELOCATE: 

return "LOCKED" 

return "LOCKED" 

 

def __new__(cls, pname="", _proto_or_pmod=None, alias=None): 

""" 

Constructs a string with str-content which may comes from the mappings. 

 

These are the valid argument combinations:: 

 

pname='attr_name', 

pname='attr_name', _alias='Mass [kg]' 

 

pname='attr_name', _proto_or_pmod=Pmod 

 

pname='attr_name', _proto_or_pmod=Pstep 

pname='attr_name', _proto_or_pmod=Pstep, _alias='Mass [kg]' 

 

 

:param str pname: 

this pstep's name which must coincede with the name of 

the parent-pstep's attribute holding this pstep. 

It is stored at `_orig` and if no `alias` and unmapped by pmod, 

this becomes the `alias`. 

:param Pmod or Pstep _proto_or_pmod: 

It can be either: 

 

- the mappings for this pstep, 

- another pstep to clone attributes from 

(used when replacing an existing child-pstep), or 

- None. 

 

The mappings will apply only if :meth:`Pmod.descend()` 

match `pname` and will derrive the alias. 

:param str alias: 

Will become the super-str object when no mappaings specified 

(`_proto_or_pmod` is a dict from some prototype pstep) 

It gets jsonpointer-escaped if it exists 

(see :func:`pandata.escape_jsonpointer_part()`) 

""" 

pmod = None 

attrs = None 

if _proto_or_pmod: 

if isinstance(_proto_or_pmod, Pmod): 

pmod, m_alias = _proto_or_pmod.descend(pname) 

if alias is None and m_alias: 

# TODO: Add Escape-path TCs. 

alias = unescape_jsonpointer_part(m_alias) 

else: 

assert isinstance(_proto_or_pmod, Pstep), ( 

"Invalid type(%s) for `_proto_or_pmod`!" % _proto_or_pmod 

) 

attrs = _clone_attrs(_proto_or_pmod) 

if alias is None: 

alias = pname 

self = str.__new__(cls, alias) 

self.__dict__ = attrs or { 

"_orig": pname, 

"_pmod": pmod, 

"_csteps": None, 

"_locked": Pstep.CAN_RELOCATE, 

"_tags": (), 

} 

 

return self 

 

def __make_cstep(self, ckey, alias=None, existing_cstep=None): 

csteps = self._csteps 

if not csteps: 

self._csteps = csteps = {} 

else: 

if existing_cstep is None: 

existing_cstep = csteps.get(ckey, None) 

# Update my mappings for `b` when ``self.b = "foo"``. 

# 

if alias is not None: 

pmod = self._pmod 

if pmod: 

pmod._alias = alias 

else: 

self._pmod = Pmod(_alias=alias) 

csteps[ckey] = child = Pstep(ckey, existing_cstep or self._pmod, alias) 

 

return child 

 

def __getattr__(self, attr): 

try: 

return str.__getattr__(self, attr) 

except AttributeError as ex: 

if attr.startswith("_") or attr in _forbidden_pstep_attrs: 

raise 

csteps = self._csteps 

child = csteps and csteps.get(attr, None) 

return child or self.__make_cstep(attr) 

 

def __setattr__(self, attr, value): 

if attr.startswith("_"): 

str.__setattr__(self, attr, value) 

elif isinstance(value, Pstep): 

self.__make_cstep(attr, existing_cstep=value) 

elif isinstance(value, str): 

self.__make_cstep(attr, alias=value) 

else: 

raise self._ex_invalid_assignment(attr, value) 

 

def __dir__(self): 

d = super(str, self).__dir__() 

if self._csteps: 

d = sorted(d + list(self._csteps.keys())) 

return d 

 

def _ex_invalid_assignment(self, cpname, value): 

msg = "Cannot assign '%s' to '%s/%s!" 

return AssertionError(msg % (value, self, cpname)) 

 

def __repr__(self): 

return "`%s`" % self 

 

@property 

def _locked(self): 

""" 

Gets `_locked` internal flag or scream on set, when step already renamed/relocated 

 

Prefer using one of :attr:`_fix` or :attr:`_lock` instead. 

 

:param locked: One of :attr:`CAN_RELOCATE`, :attr:`CAN_RENAME`, 

:attr:`LOCKED`. 

:raise: ValueError when stricter lock-value on a renamed/relocated pstep 

""" 

return vars(self)["_locked"] 

 

@_locked.setter 

def _locked(self, lock_state): 

if self != self._orig: 

if lock_state < Pstep.CAN_RENAME or ( 

lock_state < Pstep.CAN_RELOCATE and "/" in self 

): 

msg = "Cannot rename/relocate '%s'-->'%s' due to %s!" 

raise ValueError(msg % (self._orig, self, Pstep._lockstr(lock_state))) 

vars(self)["_locked"] = int(lock_state) 

 

@property 

def _fix(self): 

"""Sets :attr:`locked` = `CAN_RENAME`. 

:return: self 

:raise: ValueError if step has been relocated pstep 

""" 

self._locked = Pstep.CAN_RENAME 

return self 

 

@property 

def _lock(self): 

"""Set :attr:`locked` = `LOCKED`. 

:return: self, for chained use 

:raise: ValueError if step has been renamed/relocated pstep 

""" 

self._locked = Pstep.LOCKED 

return self 

 

def _tag(self, tag): 

"""Add a "tag" for this pstep. 

 

:return: self, for chained use 

""" 

tags = self._tags 

if tags: 

tags.add(tag) 

else: 

self._tags = set([tag]) 

 

return self 

 

def _tag_remove(self, tag): 

"""Delete a "tag" from this pstep. 

 

:return: self, for chained use 

""" 

tags = self._tags 

if tags: 

tags.discard(tag) 

 

return self 

 

def _steps(self, keys=False, tag=None): 

csteps = self._csteps 

if not csteps: 

return [] 

if keys: 

return csteps.keys() 

return csteps.values() 

 

def _paths(self, with_orig=False, tag=None): 

""" 

Return all children-paths (str-list) constructed so far, in a list. 

 

:param bool with_orig: wheter to include also orig-path, for debug. 

:param str tag: If not 'None', fetches all paths with `tag` 

in their last step. 

:rtype: [str] 

 

 

Examples:: 

 

>>> p = Pstep() 

>>> _ = p.a1._tag('inp').b._tag('inp').c 

>>> _ = p.a2.b2 

 

>>> p._paths() 

['/a1/b/c', '/a2/b2'] 

 

>>> p._paths(tag='inp') 

['/a1', '/a1/b'] 

 

 

For debugging set `with_orig` to `True`:: 

 

>>> pmods = pmods_from_tuples([ 

... ('', 'ROOT'), 

... ('/a', 'A/AA'), 

... ]) 

>>> p = pmods.step() 

>>> _ = p.a.b 

>>> p._paths(with_orig=True) 

['(-->ROOT)/(a-->A/AA)/b'] 

 

""" 

 

def append_orig(s): 

orig = s._orig 

return "(%s-->%s)" % (orig, s) if s != orig else s 

 

paths = [] 

for path in self._iter_hierarchy(): 

send = path[-1] 

if (tag and tag in send._tags) or (not tag and not send._csteps): 

if with_orig: 

path = [append_orig(s) for s in path] 

paths.append(_join_paths(*path)) 

 

return sorted(set(paths)) 

 

def _derrive_map_tuples(self): 

""" 

Recursively extract ``(cmap --> alias)`` pairs from the pstep-hierarchy. 

 

:param list pairs: Where to append subtree-paths built. 

:param tuple prefix_steps: branch currently visiting 

:rtype: [(str, str)] 

""" 

 

def orig_paths(psteps): 

return [p._orig for p in psteps] 

 

map_pairs = ( 

(_join_paths(*orig_paths(p)), str(p[-1])) for p in self._iter_hierarchy() 

) 

return sorted(map_pairs, key=lambda p: p[0]) 

 

def _iter_hierarchy(self, prefix_steps=()): 

""" 

Breadth-first traversing of pstep-hierarchy. 

 

:param tuple prefix_steps: Builds here branch currently visiting. 

:return: yields the visited pstep along with its path (including it) 

:rtype: (Pstep, [Pstep]) 

""" 

prefix_steps += (self,) 

yield prefix_steps 

 

csteps = self._csteps 

if csteps: 

for v in csteps.values(): 

for p in v._iter_hierarchy(prefix_steps): 

yield p 

 

@property 

def _schema(self): 

"""Updates json-schema-v4 on this pstep (see :class:`JSchema`).""" 

 

# Lazy create it 

# (clients should check before`_schema_exists()`) 

# 

sdict = vars(self) 

jschema = sdict.get("_schema") 

if jschema is None: 

sdict["_schema"] = jschema = JSchema() 

 

return jschema 

 

def _schema_exists(self): 

"""Always use this to avoid needless schema-instantiations.""" 

return "_schema" in vars(self) 

 

 

def pstep_from_df(columns_df, name_col="names"): 

""" 

Creates a :class:`Pstep` instances from a dataframe. 

 

:param pd.DataFrame columns_df: 

pstep's mapped-names in `name_col` column, indexed by paths, and 

any additional pstep-attributes in the rest columns. 

 

example:: 

 

======== ========= =================== 

paths names renames 

======== ========= =================== 

/A foo ['FOO', 'LL'] 

/B bar [] 

======== ========= =================== 

""" 

p = pmods_from_tuples(zip(columns_df.index, columns_df[name_col])).step() 

cdf = columns_df.drop(name_col, axis=1, errors="ignore") 

attributes = cdf.columns 

for rows in cdf.itertuples(): 

path, *attr_values = rows 

cstep = getattr(p, path[1:]) 

for attr, aval in zip(attributes, attr_values): 

setattr(cstep, "_%s" % attr, aval) 

 

return p 

 

 

if __name__ == "__main__": # pragma: no cover 

raise NotImplementedError