JezK
Edit File: actions.py
# actions.py from .exceptions import ParseException from .util import col class OnlyOnce: """ Wrapper for parse actions, to ensure they are only called once. """ def __init__(self, method_call): from .core import _trim_arity self.callable = _trim_arity(method_call) self.called = False def __call__(self, s, l, t): if not self.called: results = self.callable(s, l, t) self.called = True return results raise ParseException(s, l, "OnlyOnce obj called multiple times w/out reset") def reset(self): """ Allow the associated parse action to be called once more. """ self.called = False def match_only_at_col(n): """ Helper method for defining parse actions that require matching at a specific column in the input text. """ def verify_col(strg, locn, toks): if col(locn, strg) != n: raise ParseException(strg, locn, "matched token not at column {}".format(n)) return verify_col def replace_with(repl_str): """ Helper method for common parse actions that simply return a literal value. Especially useful when used with :class:`transform_string<ParserElement.transform_string>` (). Example:: num = Word(nums).set_parse_action(lambda toks: int(toks[0])) na = one_of("N/A NA").set_parse_action(replace_with(math.nan)) term = na | num term[1, ...].parse_string("324 234 N/A 234") # -> [324, 234, nan, 234] """ return lambda s, l, t: [repl_str] def remove_quotes(s, l, t): """ Helper parse action for removing quotation marks from parsed quoted strings. Example:: # by default, quotation marks are included in parsed results quoted_string.parse_string("'Now is the Winter of our Discontent'") # -> ["'Now is the Winter of our Discontent'"] # use remove_quotes to strip quotation marks from parsed results quoted_string.set_parse_action(remove_quotes) quoted_string.parse_string("'Now is the Winter of our Discontent'") # -> ["Now is the Winter of our Discontent"] """ return t[0][1:-1] def with_attribute(*args, **attr_dict): """ Helper to create a validating parse action to be used with start tags created with :class:`make_xml_tags` or :class:`make_html_tags`. Use ``with_attribute`` to qualify a starting tag with a required attribute value, to avoid false matches on common tags such as ``<TD>`` or ``<DIV>``. Call ``with_attribute`` with a series of attribute names and values. Specify the list of filter attributes names and values as: - keyword arguments, as in ``(align="right")``, or - as an explicit dict with ``**`` operator, when an attribute name is also a Python reserved word, as in ``**{"class":"Customer", "align":"right"}`` - a list of name-value tuples, as in ``(("ns1:class", "Customer"), ("ns2:align", "right"))`` For attribute names with a namespace prefix, you must use the second form. Attribute names are matched insensitive to upper/lower case. If just testing for ``class`` (with or without a namespace), use :class:`with_class`. To verify that the attribute exists, but without specifying a value, pass ``with_attribute.ANY_VALUE`` as the value. Example:: html = ''' <div> Some text <div type="grid">1 4 0 1 0</div> <div type="graph">1,3 2,3 1,1</div> <div>this has no type</div> </div> ''' div,div_end = make_html_tags("div") # only match div tag having a type attribute with value "grid" div_grid = div().set_parse_action(with_attribute(type="grid")) grid_expr = div_grid + SkipTo(div | div_end)("body") for grid_header in grid_expr.search_string(html): print(grid_header.body) # construct a match with any div tag having a type attribute, regardless of the value div_any_type = div().set_parse_action(with_attribute(type=with_attribute.ANY_VALUE)) div_expr = div_any_type + SkipTo(div | div_end)("body") for div_header in div_expr.search_string(html): print(div_header.body) prints:: 1 4 0 1 0 1 4 0 1 0 1,3 2,3 1,1 """ if args: attrs = args[:] else: attrs = attr_dict.items() attrs = [(k, v) for k, v in attrs] def pa(s, l, tokens): for attrName, attrValue in attrs: if attrName not in tokens: raise ParseException(s, l, "no matching attribute " + attrName) if attrValue != with_attribute.ANY_VALUE and tokens[attrName] != attrValue: raise ParseException( s, l, "attribute {!r} has value {!r}, must be {!r}".format( attrName, tokens[attrName], attrValue ), ) return pa with_attribute.ANY_VALUE = object() def with_class(classname, namespace=""): """ Simplified version of :class:`with_attribute` when matching on a div class - made difficult because ``class`` is a reserved word in Python. Example:: html = ''' <div> Some text <div class="grid">1 4 0 1 0</div> <div class="graph">1,3 2,3 1,1</div> <div>this <div> has no class</div> </div> ''' div,div_end = make_html_tags("div") div_grid = div().set_parse_action(with_class("grid")) grid_expr = div_grid + SkipTo(div | div_end)("body") for grid_header in grid_expr.search_string(html): print(grid_header.body) div_any_type = div().set_parse_action(with_class(withAttribute.ANY_VALUE)) div_expr = div_any_type + SkipTo(div | div_end)("body") for div_header in div_expr.search_string(html): print(div_header.body) prints:: 1 4 0 1 0 1 4 0 1 0 1,3 2,3 1,1 """ classattr = "{}:class".format(namespace) if namespace else "class" return with_attribute(**{classattr: classname}) # pre-PEP8 compatibility symbols replaceWith = replace_with removeQuotes = remove_quotes withAttribute = with_attribute withClass = with_class matchOnlyAtCol = match_only_at_col