Merge pull request #6 from moyamo/yowsup-2

Add parser for spectrum configuration file
This commit is contained in:
dazzzl 2016-04-12 17:15:40 +02:00
commit 7f71b56988
1 changed files with 118 additions and 0 deletions

118
config.py Normal file
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# I'm guessing this is the format of the spectrum config file in BNF
# <config_file> ::= <line>*
# <line> ::= <space>* <expr> <space>* <newline> | <space*>
# <expr> ::= <section> | <assignment>
# <section> ::= [<identifier>*]
# <assignment> ::= <identifier> <space>* = <space>* <value>
class SpectrumConfig:
"""
Represents spectrum2 configuration options.
"""
def __init__(self, path_to_config_file):
"""
Initialises configuration file.
Args:
path_to_config_file: The absolute path to the configuration file.
"""
self.config_path = path_to_config_file
self.options = self.loadConfig(self.config_path)
# Load backend_logging information
self.options.update(self.loadConfig(self['logging.backend_config']))
def loadConfig(self, file_name):
section = {'a': ""} # Current section heading,
# It's a dictionary because variables in python closures can't be
# assigned to.
options = dict()
# Recursive descent parser
def consume_spaces(line):
i = 0
for c in line:
if c != ' ':
break
i += 1
return line[i:]
def read_identifier(line):
i = 0
for c in line:
if c == ' ' or c==']' or c=='[' or c=='=':
break
i += 1
# no identifier
if i == 0:
return (None, 'No identifier')
return (line[:i], line[i:])
def parse_section(line):
if len(line) == 0 or line[0] != '[':
return (None, 'expected [')
line = line[1:]
identifier, line = read_identifier(line)
if len(line) == 0 or line[0] != ']' or identifier is None:
return (None, line)
return (identifier, line[1:])
def parse_assignment(line):
key, line = read_identifier(line)
if key is None:
return (None, None, line)
line = consume_spaces(line)
if len(line) == 0 or line[0] != '=':
return (None, None, 'Expected =')
line = consume_spaces(line[1:])
value = line[:-1]
return (key, value, '\n')
def expr(line):
sec, newline = parse_section(line)
if sec is not None:
section['a'] = sec
else:
key, value, newline = parse_assignment(line)
if key is not None:
if section['a'] != '':
options[section['a'] + '.' + key] = value
else:
options[key] = value
else:
return (None, newline)
return (newline, None)
def parse_line(line, line_number):
line = consume_spaces(line)
if line == '\n':
return
newline, error = expr(line)
if newline is None:
raise ConfigParseError(str(line_number) + ': ' + error + ': ' + repr(line))
newline = consume_spaces(newline)
if newline != '\n':
raise ConfigParseError(str(line_number) + ': Expected newline got ' + repr(newline))
def strip_comments(line):
i = 0
for c in line:
if c == '#' or c == '\n':
break
i += 1
return line[:i] + '\n'
with open(file_name, 'r') as f:
i = 1
while True:
line = f.readline()
if line == '':
break
parse_line(strip_comments(line), i)
i += 1
return options
def __getitem__(self, key):
return self.options[key]
class ConfigParseError(Exception):
pass