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