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Editing: expect.py
import time from .exceptions import EOF, TIMEOUT class Expecter(object): def __init__(self, spawn, searcher, searchwindowsize=-1): self.spawn = spawn self.searcher = searcher # A value of -1 means to use the figure from spawn, which should # be None or a positive number. if searchwindowsize == -1: searchwindowsize = spawn.searchwindowsize self.searchwindowsize = searchwindowsize self.lookback = None if hasattr(searcher, 'longest_string'): self.lookback = searcher.longest_string def do_search(self, window, freshlen): spawn = self.spawn searcher = self.searcher if freshlen > len(window): freshlen = len(window) index = searcher.search(window, freshlen, self.searchwindowsize) if index >= 0: spawn._buffer = spawn.buffer_type() spawn._buffer.write(window[searcher.end:]) spawn.before = spawn._before.getvalue()[ 0:-(len(window) - searcher.start)] spawn._before = spawn.buffer_type() spawn._before.write(window[searcher.end:]) spawn.after = window[searcher.start:searcher.end] spawn.match = searcher.match spawn.match_index = index # Found a match return index elif self.searchwindowsize or self.lookback: maintain = self.searchwindowsize or self.lookback if spawn._buffer.tell() > maintain: spawn._buffer = spawn.buffer_type() spawn._buffer.write(window[-maintain:]) def existing_data(self): # First call from a new call to expect_loop or expect_async. # self.searchwindowsize may have changed. # Treat all data as fresh. spawn = self.spawn before_len = spawn._before.tell() buf_len = spawn._buffer.tell() freshlen = before_len if before_len > buf_len: if not self.searchwindowsize: spawn._buffer = spawn.buffer_type() window = spawn._before.getvalue() spawn._buffer.write(window) elif buf_len < self.searchwindowsize: spawn._buffer = spawn.buffer_type() spawn._before.seek( max(0, before_len - self.searchwindowsize)) window = spawn._before.read() spawn._buffer.write(window) else: spawn._buffer.seek(max(0, buf_len - self.searchwindowsize)) window = spawn._buffer.read() else: if self.searchwindowsize: spawn._buffer.seek(max(0, buf_len - self.searchwindowsize)) window = spawn._buffer.read() else: window = spawn._buffer.getvalue() return self.do_search(window, freshlen) def new_data(self, data): # A subsequent call, after a call to existing_data. spawn = self.spawn freshlen = len(data) spawn._before.write(data) if not self.searchwindowsize: if self.lookback: # search lookback + new data. old_len = spawn._buffer.tell() spawn._buffer.write(data) spawn._buffer.seek(max(0, old_len - self.lookback)) window = spawn._buffer.read() else: # copy the whole buffer (really slow for large datasets). spawn._buffer.write(data) window = spawn.buffer else: if len(data) >= self.searchwindowsize or not spawn._buffer.tell(): window = data[-self.searchwindowsize:] spawn._buffer = spawn.buffer_type() spawn._buffer.write(window[-self.searchwindowsize:]) else: spawn._buffer.write(data) new_len = spawn._buffer.tell() spawn._buffer.seek(max(0, new_len - self.searchwindowsize)) window = spawn._buffer.read() return self.do_search(window, freshlen) def eof(self, err=None): spawn = self.spawn spawn.before = spawn._before.getvalue() spawn._buffer = spawn.buffer_type() spawn._before = spawn.buffer_type() spawn.after = EOF index = self.searcher.eof_index if index >= 0: spawn.match = EOF spawn.match_index = index return index else: spawn.match = None spawn.match_index = None msg = str(spawn) msg += '\nsearcher: %s' % self.searcher if err is not None: msg = str(err) + '\n' + msg exc = EOF(msg) exc.__cause__ = None # in Python 3.x we can use "raise exc from None" raise exc def timeout(self, err=None): spawn = self.spawn spawn.before = spawn._before.getvalue() spawn.after = TIMEOUT index = self.searcher.timeout_index if index >= 0: spawn.match = TIMEOUT spawn.match_index = index return index else: spawn.match = None spawn.match_index = None msg = str(spawn) msg += '\nsearcher: %s' % self.searcher if err is not None: msg = str(err) + '\n' + msg exc = TIMEOUT(msg) exc.__cause__ = None # in Python 3.x we can use "raise exc from None" raise exc def errored(self): spawn = self.spawn spawn.before = spawn._before.getvalue() spawn.after = None spawn.match = None spawn.match_index = None def expect_loop(self, timeout=-1): """Blocking expect""" spawn = self.spawn if timeout is not None: end_time = time.time() + timeout try: idx = self.existing_data() if idx is not None: return idx while True: # No match at this point if (timeout is not None) and (timeout < 0): return self.timeout() # Still have time left, so read more data incoming = spawn.read_nonblocking(spawn.maxread, timeout) if self.spawn.delayafterread is not None: time.sleep(self.spawn.delayafterread) idx = self.new_data(incoming) # Keep reading until exception or return. if idx is not None: return idx if timeout is not None: timeout = end_time - time.time() except EOF as e: return self.eof(e) except TIMEOUT as e: return self.timeout(e) except: self.errored() raise class searcher_string(object): '''This is a plain string search helper for the spawn.expect_any() method. This helper class is for speed. For more powerful regex patterns see the helper class, searcher_re. Attributes: eof_index - index of EOF, or -1 timeout_index - index of TIMEOUT, or -1 After a successful match by the search() method the following attributes are available: start - index into the buffer, first byte of match end - index into the buffer, first byte after match match - the matching string itself ''' def __init__(self, strings): '''This creates an instance of searcher_string. This argument 'strings' may be a list; a sequence of strings; or the EOF or TIMEOUT types. ''' self.eof_index = -1 self.timeout_index = -1 self._strings = [] self.longest_string = 0 for n, s in enumerate(strings): if s is EOF: self.eof_index = n continue if s is TIMEOUT: self.timeout_index = n continue self._strings.append((n, s)) if len(s) > self.longest_string: self.longest_string = len(s) def __str__(self): '''This returns a human-readable string that represents the state of the object.''' ss = [(ns[0], ' %d: %r' % ns) for ns in self._strings] ss.append((-1, 'searcher_string:')) if self.eof_index >= 0: ss.append((self.eof_index, ' %d: EOF' % self.eof_index)) if self.timeout_index >= 0: ss.append((self.timeout_index, ' %d: TIMEOUT' % self.timeout_index)) ss.sort() ss = list(zip(*ss))[1] return '\n'.join(ss) def search(self, buffer, freshlen, searchwindowsize=None): '''This searches 'buffer' for the first occurrence of one of the search strings. 'freshlen' must indicate the number of bytes at the end of 'buffer' which have not been searched before. It helps to avoid searching the same, possibly big, buffer over and over again. See class spawn for the 'searchwindowsize' argument. If there is a match this returns the index of that string, and sets 'start', 'end' and 'match'. Otherwise, this returns -1. ''' first_match = None # 'freshlen' helps a lot here. Further optimizations could # possibly include: # # using something like the Boyer-Moore Fast String Searching # Algorithm; pre-compiling the search through a list of # strings into something that can scan the input once to # search for all N strings; realize that if we search for # ['bar', 'baz'] and the input is '...foo' we need not bother # rescanning until we've read three more bytes. # # Sadly, I don't know enough about this interesting topic. /grahn for index, s in self._strings: if searchwindowsize is None: # the match, if any, can only be in the fresh data, # or at the very end of the old data offset = -(freshlen + len(s)) else: # better obey searchwindowsize offset = -searchwindowsize n = buffer.find(s, offset) if n >= 0 and (first_match is None or n < first_match): first_match = n best_index, best_match = index, s if first_match is None: return -1 self.match = best_match self.start = first_match self.end = self.start + len(self.match) return best_index class searcher_re(object): '''This is regular expression string search helper for the spawn.expect_any() method. This helper class is for powerful pattern matching. For speed, see the helper class, searcher_string. Attributes: eof_index - index of EOF, or -1 timeout_index - index of TIMEOUT, or -1 After a successful match by the search() method the following attributes are available: start - index into the buffer, first byte of match end - index into the buffer, first byte after match match - the re.match object returned by a successful re.search ''' def __init__(self, patterns): '''This creates an instance that searches for 'patterns' Where 'patterns' may be a list or other sequence of compiled regular expressions, or the EOF or TIMEOUT types.''' self.eof_index = -1 self.timeout_index = -1 self._searches = [] for n, s in enumerate(patterns): if s is EOF: self.eof_index = n continue if s is TIMEOUT: self.timeout_index = n continue self._searches.append((n, s)) def __str__(self): '''This returns a human-readable string that represents the state of the object.''' #ss = [(n, ' %d: re.compile("%s")' % # (n, repr(s.pattern))) for n, s in self._searches] ss = list() for n, s in self._searches: ss.append((n, ' %d: re.compile(%r)' % (n, s.pattern))) ss.append((-1, 'searcher_re:')) if self.eof_index >= 0: ss.append((self.eof_index, ' %d: EOF' % self.eof_index)) if self.timeout_index >= 0: ss.append((self.timeout_index, ' %d: TIMEOUT' % self.timeout_index)) ss.sort() ss = list(zip(*ss))[1] return '\n'.join(ss) def search(self, buffer, freshlen, searchwindowsize=None): '''This searches 'buffer' for the first occurrence of one of the regular expressions. 'freshlen' must indicate the number of bytes at the end of 'buffer' which have not been searched before. See class spawn for the 'searchwindowsize' argument. If there is a match this returns the index of that string, and sets 'start', 'end' and 'match'. Otherwise, returns -1.''' first_match = None # 'freshlen' doesn't help here -- we cannot predict the # length of a match, and the re module provides no help. if searchwindowsize is None: searchstart = 0 else: searchstart = max(0, len(buffer) - searchwindowsize) for index, s in self._searches: match = s.search(buffer, searchstart) if match is None: continue n = match.start() if first_match is None or n < first_match: first_match = n the_match = match best_index = index if first_match is None: return -1 self.start = first_match self.match = the_match self.end = self.match.end() return best_index
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