import re import tuned.logs from tuned.utils.commands import commands log = tuned.logs.get() cmd = commands() class Parser(): """ Parser used for expanding strings containing functions. """ def __init__(self, repository): self._repository = repository def _parse_init(self, s = ""): self._cnt = 0 self._str = s self._len = len(s) self._stack = [] self._esc = False def _curr_char(self): return self._str[self._cnt] if self._cnt < self._len else "" def _curr_substr(self, _len): return self._str[self._cnt:self._cnt + _len] def _push_pos(self, esc): self._stack.append((esc, self._cnt)) def _sub(self, a, b, s): self._str = self._str[:a] + s + self._str[b + 1:] self._len = len(self._str) self._cnt += len(s) - (b - a + 1) if self._cnt < 0: self._cnt = 0 def _process_func(self, _from): sl = re.split(r'(?<!\\):', self._str[_from:self._cnt]) if sl[0] != "${f": return sl = [str(v).replace(r"\:", ":") for v in sl] if not re.match(r'\w+$', sl[1]): log.error("invalid function name '%s'" % sl[1]) return try: f = self._repository.load_func(sl[1]) except ImportError: log.error("function '%s' not implemented" % sl[1]) return s = f.execute(sl[2:]) log.debug("${f:%s} expands to: '%s'" % (":".join(sl[1:]), s)) if s is None: return self._sub(_from, self._cnt, s) def _process(self, s): self._parse_init(s) while self._cnt < self._len: if self._curr_char() == "}": try: si = self._stack.pop() except IndexError: log.error("invalid variable syntax, non pair '}' in: '%s'" % s) return self._str # if not escaped if not si[0]: self._process_func(si[1]) elif self._curr_substr(2) == "${": self._push_pos(self._esc) if self._curr_char() == "\\": self._esc = True else: self._esc = False self._cnt += 1 if len(self._stack): log.error("invalid variable syntax, non pair '{' in: '%s'" % s) return self._str def expand(self, s): if s is None or s == "": return s # expand functions and convert all \${f:*} to ${f:*} (unescape) return re.sub(r'\\(\${f:.*})', r'\1', self._process(s))