Function _parse

Lib/re/_parser.py:511–884

(source, state, verbose, nested, first=False)

    return subpattern

def _parse(source, state, verbose, nested, first=False):
    # parse a simple pattern
    subpattern = SubPattern(state)

    # precompute constants into local variables
    subpatternappend = subpattern.append
    sourceget = source.get
    sourcematch = source.match
    _len = len
    _ord = ord

    while True:

        this = source.next
        if this is None:
            break # end of pattern
        if this in "|)":
            break # end of subpattern
        sourceget()

        if verbose:
            # skip whitespace and comments
            if this in WHITESPACE:
                continue
            if this == "#":
                while True:
                    this = sourceget()
                    if this is None or this == "\n":
                        break
                continue

        if this[0] == "\\":
            code = _escape(source, this, state)
            subpatternappend(code)

        elif this not in SPECIAL_CHARS:
            subpatternappend((LITERAL, _ord(this)))

        elif this == "[":
            here = source.tell() - 1
            # character set
            set = []
            setappend = set.append
##          if sourcematch(":"):
##              pass # handle character classes
            if source.next == '[':
                import warnings
                warnings.warn(
                    'Possible nested set at position %d' % source.tell(),
                    FutureWarning, stacklevel=nested + 6
                )
            negate = sourcematch("^")
            # check remaining characters
            while True:
                this = sourceget()
                if this is None:
                    raise source.error("unterminated character set",
                                       source.tell() - here)