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#############################################################################
##
## Copyright (C) 2021 The Qt Company Ltd.
## Contact: https://www.qt.io/licensing/
##
## This file is part of Qt for Python.
##
## $QT_BEGIN_LICENSE:COMM$
##
## Commercial License Usage
## Licensees holding valid commercial Qt licenses may use this file in
## accordance with the commercial license agreement provided with the
## Software or, alternatively, in accordance with the terms contained in
## a written agreement between you and The Qt Company. For licensing terms
## and conditions see https://www.qt.io/terms-conditions. For further
## information use the contact form at https://www.qt.io/contact-us.
##
## $QT_END_LICENSE$
##
#############################################################################
from __future__ import print_function, absolute_import
"""
tool.py
Some useful stuff, see below.
On the function with_metaclass see the answer from Martijn Pieters on
https://stackoverflow.com/questions/18513821/python-metaclass-understanding-the-with-metaclass
"""
from textwrap import dedent
class SimpleNamespace(object):
# From types.rst, because the builtin is implemented in Python 3, only.
def __init__(self, **kwargs):
self.__dict__.update(kwargs)
def __repr__(self):
keys = sorted(self.__dict__)
items = ("{}={!r}".format(k, self.__dict__[k]) for k in keys)
return "{}({})".format(type(self).__name__, ", ".join(items))
def __eq__(self, other):
return self.__dict__ == other.__dict__
try:
from types import SimpleNamespace
except ImportError:
pass
def build_brace_pattern(level, separators=""):
"""
Build a brace pattern upto a given depth
The brace pattern parses any pattern with round, square, curly, or angle
brackets. Inside those brackets, any characters are allowed.
The structure is quite simple and is recursively repeated as needed.
When separators are given, the match stops at that separator.
Reason to use this instead of some Python function:
The resulting regex is _very_ fast!
A faster replacement would be written in C, but this solution is
sufficient when the nesting level is not too large.
Because of the recursive nature of the pattern, the size grows by a factor
of 4 at every level, as does the creation time. Up to a level of 6, this
is below 10 ms.
There are other regex engines available which allow recursive patterns,
avoiding this problem completely. It might be considered to switch to
such an engine if the external module is not a problem.
"""
def escape(str):
return "".join("\\" + c for c in str)
ro, rc = round = "()"
so, sc = square = "[]"
co, cc = curly = "CD" # we insert "{}", later...
ao, ac = angle = "<>"
qu, bs = '"', "\\"
all = round + square + curly + angle
__ = " "
ro, rc, so, sc, co, cc, ao, ac, separators, qu, bs, all = map(
escape, (ro, rc, so, sc, co, cc, ao, ac, separators, qu, bs, all))
no_brace_sep_q = r"[^{all}{separators}{qu}{bs}]".format(**locals())
no_quote = r"(?: [^{qu}{bs}] | {bs}. )*".format(**locals())
pattern = dedent(r"""
(
(?: {__} {no_brace_sep_q}
| {qu} {no_quote} {qu}
| {ro} {replacer} {rc}
| {so} {replacer} {sc}
| {co} {replacer} {cc}
| {ao} {replacer} {ac}
)+
)
""")
no_braces_q = "[^{all}{qu}{bs}]*".format(**locals())
repeated = dedent(r"""
{indent} (?: {__} {no_braces_q}
{indent} | {qu} {no_quote} {qu}
{indent} | {ro} {replacer} {rc}
{indent} | {so} {replacer} {sc}
{indent} | {co} {replacer} {cc}
{indent} | {ao} {replacer} {ac}
{indent} )*
""")
for idx in range(level):
pattern = pattern.format(replacer = repeated if idx < level-1 else no_braces_q,
indent = idx * " ", **locals())
return pattern.replace("C", "{").replace("D", "}")
# Copied from the six module:
def with_metaclass(meta, *bases):
"""Create a base class with a metaclass."""
# This requires a bit of explanation: the basic idea is to make a dummy
# metaclass for one level of class instantiation that replaces itself with
# the actual metaclass.
class metaclass(type):
def __new__(cls, name, this_bases, d):
return meta(name, bases, d)
@classmethod
def __prepare__(cls, name, this_bases):
return meta.__prepare__(name, bases)
return type.__new__(metaclass, 'temporary_class', (), {})
# eof
|
