# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility
import re
regex = r"""
# Define the opening and closing elements before the recursion occurs
(?(DEFINE)
(?<open_curly>\{)
(?<close_curly>\})
(?<open_square>\[)
(?<close_square>\])
(?P<open_pascal>(?i:\bbegin\b))
(?P<close_pascal>(?i:\bend\b))
(?P<open_lua>--\[)
(?P<close_lua>--\])
(?<open>\g'open_curly'|\g'open_square'|\g'open_pascal'|\g'open_lua')
(?<close>\g'close_curly'|\g'close_square'|\g'close_pascal'|\g'close_lua')
)
# Match the opening element
(\g'open'
(?>
# For recursion, don't match either the opening
# or closing element
(?!\g'open'|\g'close')(.)
|
# Recurse this captured pattern
(?-1)
)*
# Match the closing element
\g'close')
"""
test_str = ("EVENLY BALANCED curly braces\n\n"
"{{{}}}\n"
"{ test1 { test2 { test3 { test4 } } } }\n\n"
"UNEVENLY BALANCED curly braces\n"
"{{{{}}}\n"
"{ test1 { test2 { test3 { test4 } } } } }\n\n"
"MULTI-LINE EVENLY BALANCED curly braces\n"
"{\n"
"}\n\n"
"MULTI-LINE UNEVENLY BALANCED curly braces\n"
"{{\n"
"}\n\n\n"
"EVENLY BALANCED square braces\n"
"[ test1 [ test2 [ test3 [ test4 ] ] ] ]\n\n"
"EVENLY BALANCED square and curly braces\n"
"{ test1 [ test2 { test3 [ test4 ] } ] }\n\n"
"UNEVENLY BALANCED square and curly braces\n"
"{ test1 [ test2 { test3 [ test4 ] } } ]\n")
matches = re.finditer(regex, test_str, re.VERBOSE)
for matchNum, match in enumerate(matches, start=1):
print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group()))
for groupNum in range(0, len(match.groups())):
groupNum = groupNum + 1
print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum)))
# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html