config.py

#!/usr/bin/python3

from  pyparsing import Keyword, QuotedString, Suppress, Regex, OneOrMore, Group
from  pyparsing import lineno

def checkSubdirectory(s, l, t):
    if t[0].startswith('/'):
        raise Exception('Subdirectory expected at line %d" %s' %
                        (lineno(l, s), t[0]))
def checkDirectory(s, l, t):
    if not t[0].startswith('/'):
        raise Exception('Directory expected at line %d" %s' %
                        (lineno(l, s), t[0]))
    
_subdirectory_ = (
    Regex('[._a-zA-Z0-9/]+') |
    QuotedString('"') |
    QuotedString("'")
).setParseAction(checkSubdirectory)
_directory_ = (
    Regex('[._a-zA-Z0-9/]+') |
    QuotedString('"') |
    QuotedString("'")
).setParseAction(checkDirectory)
_host_and_directory_ = (
    Regex('[A-Za-z][A-Za-z0-9-.]*')('host') +
    Suppress(':') +
    _directory_('path')
)
_client_ = (
    Regex('@?[A-Za-z][A-Za-z0-9-.]') | QuotedString('"') | QuotedString("'")
)
_options_ = (
    Regex('[a-z][a-z_,]*') | QuotedString('"') | QuotedString("'")
)
_client_export_ = (
    _client_('host') + _options_('options')
)
_export_entry_ = (
    _subdirectory_('path') +
    Suppress('[') +
    Group(OneOrMore(Group(_client_export_)))('client') +
    Suppress(']')
)
_primary_ = (
    Suppress(Keyword('primary')) + 
    Suppress('{') +
    Suppress(Keyword('attributes'))  +
    ( QuotedString('"') | QuotedString("'") )('attributes') +
    Group(_host_and_directory_)('mount') +
    Suppress(Keyword('export')) +
    Suppress('{') +
    Group(OneOrMore(Group(_export_entry_)))('export') +
    Suppress('}') +
    Suppress('}') 
)
_backup_entry_ = (
     Group(_host_and_directory_)('mount') +
    Suppress('[') +
    Group(OneOrMore(_subdirectory_)).setResultsName('path') +
    Suppress(']')
)
_backup_ = (
    Suppress(Keyword('backup')) +
    Suppress('{') +
    Group(OneOrMore(Group(_backup_entry_)))('entry') +
    Suppress('}')
)
_secondary_ = (
    Suppress(Keyword('secondary')) +
    Suppress('{') +
    Group(OneOrMore(Group(_backup_)))('backup') +
    Suppress('}')
)
_config_ = (
    Group(_primary_)('primary') +
    Group(_secondary_)('secondary')
)

def parse(s):
    return _config_.parseString(s)

if __name__ == '__main__':
    import sys
    from  pyparsing import ParseException

    config = open(sys.argv[1]).read()
    try:
        config1 = parse(config)
    except ParseException as e:
        lines = config.split('\n')
        print('\n'.join(lines[0:e.lineno]))
        print('%s^ %s' % (' ' * e.col, e))
        raise
        pass
    config2 = parse(config)
    print(config1.dump())
    print(config1.asList() == config2.asList())