|
"""Bash-style brace expansion""" |
|
import re |
|
import string |
|
import sys |
|
from itertools import chain, product |
|
|
|
__version__ = '0.1.7' |
|
|
|
__all__ = ['braceexpand', 'alphabet', 'UnbalancedBracesError'] |
|
|
|
class UnbalancedBracesError(ValueError): pass |
|
|
|
PY3 = sys.version_info[0] >= 3 |
|
|
|
if PY3: |
|
xrange = range |
|
|
|
alphabet = string.ascii_uppercase + string.ascii_lowercase |
|
|
|
int_range_re = re.compile(r'^(-?\d+)\.\.(-?\d+)(?:\.\.-?(\d+))?$') |
|
char_range_re = re.compile(r'^([A-Za-z])\.\.([A-Za-z])(?:\.\.-?(\d+))?$') |
|
|
|
|
|
def braceexpand(pattern, escape=True): |
|
"""braceexpand(pattern) -> iterator over generated strings |
|
|
|
Returns an iterator over the strings resulting from brace expansion |
|
of pattern. This function implements Brace Expansion as described in |
|
bash(1), with the following limitations: |
|
|
|
* A pattern containing unbalanced braces will raise an |
|
UnbalancedBracesError exception. In bash, unbalanced braces will either |
|
be partly expanded or ignored. |
|
|
|
* A mixed-case character range like '{Z..a}' or '{a..Z}' will not |
|
include the characters '[]^_`' between 'Z' and 'a'. |
|
|
|
When escape is True (the default), characters in pattern can be |
|
prefixed with a backslash to cause them not to be interpreted as |
|
special characters for brace expansion (such as '{', '}', ','). |
|
To pass through a a literal backslash, double it ('\\\\'). |
|
|
|
When escape is False, backslashes in pattern have no special |
|
meaning and will be preserved in the output. |
|
|
|
Examples: |
|
|
|
>>> from braceexpand import braceexpand |
|
|
|
# Integer range |
|
>>> list(braceexpand('item{1..3}')) |
|
['item1', 'item2', 'item3'] |
|
|
|
# Character range |
|
>>> list(braceexpand('{a..c}')) |
|
['a', 'b', 'c'] |
|
|
|
# Sequence |
|
>>> list(braceexpand('index.html{,.backup}')) |
|
['index.html', 'index.html.backup'] |
|
|
|
# Nested patterns |
|
>>> list(braceexpand('python{2.{5..7},3.{2,3}}')) |
|
['python2.5', 'python2.6', 'python2.7', 'python3.2', 'python3.3'] |
|
|
|
# Prefixing an integer with zero causes all numbers to be padded to |
|
# the same width. |
|
>>> list(braceexpand('{07..10}')) |
|
['07', '08', '09', '10'] |
|
|
|
# An optional increment can be specified for ranges. |
|
>>> list(braceexpand('{a..g..2}')) |
|
['a', 'c', 'e', 'g'] |
|
|
|
# Ranges can go in both directions. |
|
>>> list(braceexpand('{4..1}')) |
|
['4', '3', '2', '1'] |
|
|
|
# Numbers can be negative |
|
>>> list(braceexpand('{2..-1}')) |
|
['2', '1', '0', '-1'] |
|
|
|
# Unbalanced braces raise an exception. |
|
>>> list(braceexpand('{1{2,3}')) |
|
Traceback (most recent call last): |
|
... |
|
UnbalancedBracesError: Unbalanced braces: '{1{2,3}' |
|
|
|
# By default, the backslash is the escape character. |
|
>>> list(braceexpand(r'{1\\{2,3}')) |
|
['1{2', '3'] |
|
|
|
# Setting 'escape' to False disables backslash escaping. |
|
>>> list(braceexpand(r'\\{1,2}', escape=False)) |
|
['\\\\1', '\\\\2'] |
|
|
|
""" |
|
return (_flatten(t, escape) for t in parse_pattern(pattern, escape)) |
|
|
|
|
|
def parse_pattern(pattern, escape): |
|
|
|
start = 0 |
|
pos = 0 |
|
bracketdepth = 0 |
|
items = [] |
|
|
|
|
|
while pos < len(pattern): |
|
if escape and pattern[pos] == '\\': |
|
pos += 2 |
|
continue |
|
elif pattern[pos] == '{': |
|
if bracketdepth == 0 and pos > start: |
|
|
|
items.append([pattern[start:pos]]) |
|
start = pos |
|
bracketdepth += 1 |
|
elif pattern[pos] == '}': |
|
bracketdepth -= 1 |
|
if bracketdepth == 0: |
|
|
|
expr = pattern[start+1:pos] |
|
item = parse_expression(expr, escape) |
|
if item is None: |
|
items.extend([['{'], parse_pattern(expr, escape), ['}']]) |
|
else: |
|
items.append(item) |
|
start = pos + 1 |
|
pos += 1 |
|
|
|
if bracketdepth != 0: |
|
raise UnbalancedBracesError("Unbalanced braces: '%s'" % pattern) |
|
|
|
if start < pos: |
|
|
|
items.append([pattern[start:]]) |
|
|
|
return product(*items) |
|
|
|
|
|
def parse_expression(expr, escape): |
|
int_range_match = int_range_re.match(expr) |
|
if int_range_match: |
|
return make_int_range(*int_range_match.groups()) |
|
|
|
char_range_match = char_range_re.match(expr) |
|
if char_range_match: |
|
return make_char_range(*char_range_match.groups()) |
|
|
|
return parse_sequence(expr, escape) |
|
|
|
|
|
def parse_sequence(seq, escape): |
|
|
|
start = 0 |
|
pos = 0 |
|
bracketdepth = 0 |
|
items = [] |
|
|
|
|
|
while pos < len(seq): |
|
if escape and seq[pos] == '\\': |
|
pos += 2 |
|
continue |
|
elif seq[pos] == '{': |
|
bracketdepth += 1 |
|
elif seq[pos] == '}': |
|
bracketdepth -= 1 |
|
elif seq[pos] == ',' and bracketdepth == 0: |
|
items.append(parse_pattern(seq[start:pos], escape)) |
|
start = pos + 1 |
|
pos += 1 |
|
|
|
if bracketdepth != 0 or not items: |
|
return None |
|
|
|
|
|
items.append(parse_pattern(seq[start:], escape)) |
|
return chain(*items) |
|
|
|
|
|
def make_int_range(start, end, step=None): |
|
if any([s.startswith(('0', '-0')) |
|
for s in (start, end) if s not in ('0', '-0')]): |
|
padding = max(len(start), len(end)) |
|
else: |
|
padding = 0 |
|
step = (int(step) or 1) if step else 1 |
|
start = int(start) |
|
end = int(end) |
|
r = xrange(start, end+1, step) if start < end else \ |
|
xrange(start, end-1, -step) |
|
fmt = '%0{}d'.format(padding) |
|
return (fmt % i for i in r) |
|
|
|
|
|
def make_char_range(start, end, step=None): |
|
step = (int(step) or 1) if step else 1 |
|
start = alphabet.index(start) |
|
end = alphabet.index(end) |
|
if start < end: |
|
return alphabet[start:end+1:step] |
|
else: |
|
end = end or -len(alphabet) |
|
return alphabet[start:end-1:-step] |
|
|
|
|
|
escape_re = re.compile(r'\\(.)') |
|
|
|
def _flatten(t, escape): |
|
l = [] |
|
for item in t: |
|
if isinstance(item, tuple): l.extend(_flatten(item, escape)) |
|
else: l.append(item) |
|
s = ''.join(l) |
|
|
|
return escape_re.sub(r'\1', s) if escape else s |
|
|
|
|
|
if __name__ == '__main__': |
|
import doctest |
|
import sys |
|
failed, _ = doctest.testmod(optionflags=doctest.IGNORE_EXCEPTION_DETAIL) |
|
if failed: |
|
sys.exit(1) |
|
|