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from .exceptions import ParseException |
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from .util import col, replaced_by_pep8 |
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class OnlyOnce: |
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""" |
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Wrapper for parse actions, to ensure they are only called once. |
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""" |
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def __init__(self, method_call): |
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from .core import _trim_arity |
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self.callable = _trim_arity(method_call) |
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self.called = False |
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def __call__(self, s, l, t): |
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if not self.called: |
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results = self.callable(s, l, t) |
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self.called = True |
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return results |
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raise ParseException(s, l, "OnlyOnce obj called multiple times w/out reset") |
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def reset(self): |
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""" |
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Allow the associated parse action to be called once more. |
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""" |
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self.called = False |
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def match_only_at_col(n): |
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""" |
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Helper method for defining parse actions that require matching at |
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a specific column in the input text. |
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""" |
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def verify_col(strg, locn, toks): |
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if col(locn, strg) != n: |
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raise ParseException(strg, locn, f"matched token not at column {n}") |
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return verify_col |
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def replace_with(repl_str): |
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""" |
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Helper method for common parse actions that simply return |
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a literal value. Especially useful when used with |
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:class:`transform_string<ParserElement.transform_string>` (). |
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Example:: |
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num = Word(nums).set_parse_action(lambda toks: int(toks[0])) |
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na = one_of("N/A NA").set_parse_action(replace_with(math.nan)) |
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term = na | num |
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term[1, ...].parse_string("324 234 N/A 234") # -> [324, 234, nan, 234] |
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""" |
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return lambda s, l, t: [repl_str] |
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def remove_quotes(s, l, t): |
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""" |
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Helper parse action for removing quotation marks from parsed |
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quoted strings. |
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Example:: |
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# by default, quotation marks are included in parsed results |
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quoted_string.parse_string("'Now is the Winter of our Discontent'") # -> ["'Now is the Winter of our Discontent'"] |
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# use remove_quotes to strip quotation marks from parsed results |
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quoted_string.set_parse_action(remove_quotes) |
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quoted_string.parse_string("'Now is the Winter of our Discontent'") # -> ["Now is the Winter of our Discontent"] |
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""" |
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return t[0][1:-1] |
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def with_attribute(*args, **attr_dict): |
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""" |
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Helper to create a validating parse action to be used with start |
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tags created with :class:`make_xml_tags` or |
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:class:`make_html_tags`. Use ``with_attribute`` to qualify |
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a starting tag with a required attribute value, to avoid false |
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matches on common tags such as ``<TD>`` or ``<DIV>``. |
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Call ``with_attribute`` with a series of attribute names and |
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values. Specify the list of filter attributes names and values as: |
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- keyword arguments, as in ``(align="right")``, or |
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- as an explicit dict with ``**`` operator, when an attribute |
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name is also a Python reserved word, as in ``**{"class":"Customer", "align":"right"}`` |
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- a list of name-value tuples, as in ``(("ns1:class", "Customer"), ("ns2:align", "right"))`` |
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For attribute names with a namespace prefix, you must use the second |
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form. Attribute names are matched insensitive to upper/lower case. |
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If just testing for ``class`` (with or without a namespace), use |
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:class:`with_class`. |
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To verify that the attribute exists, but without specifying a value, |
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pass ``with_attribute.ANY_VALUE`` as the value. |
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Example:: |
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html = ''' |
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<div> |
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Some text |
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<div type="grid">1 4 0 1 0</div> |
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<div type="graph">1,3 2,3 1,1</div> |
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<div>this has no type</div> |
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</div> |
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''' |
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div,div_end = make_html_tags("div") |
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# only match div tag having a type attribute with value "grid" |
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div_grid = div().set_parse_action(with_attribute(type="grid")) |
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grid_expr = div_grid + SkipTo(div | div_end)("body") |
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for grid_header in grid_expr.search_string(html): |
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print(grid_header.body) |
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# construct a match with any div tag having a type attribute, regardless of the value |
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div_any_type = div().set_parse_action(with_attribute(type=with_attribute.ANY_VALUE)) |
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div_expr = div_any_type + SkipTo(div | div_end)("body") |
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for div_header in div_expr.search_string(html): |
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print(div_header.body) |
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prints:: |
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1 4 0 1 0 |
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1 4 0 1 0 |
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1,3 2,3 1,1 |
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""" |
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if args: |
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attrs = args[:] |
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else: |
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attrs = attr_dict.items() |
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attrs = [(k, v) for k, v in attrs] |
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def pa(s, l, tokens): |
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for attrName, attrValue in attrs: |
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if attrName not in tokens: |
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raise ParseException(s, l, "no matching attribute " + attrName) |
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if attrValue != with_attribute.ANY_VALUE and tokens[attrName] != attrValue: |
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raise ParseException( |
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s, |
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l, |
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f"attribute {attrName!r} has value {tokens[attrName]!r}, must be {attrValue!r}", |
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) |
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return pa |
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with_attribute.ANY_VALUE = object() |
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def with_class(classname, namespace=""): |
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""" |
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Simplified version of :class:`with_attribute` when |
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matching on a div class - made difficult because ``class`` is |
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a reserved word in Python. |
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Example:: |
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html = ''' |
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<div> |
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Some text |
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<div class="grid">1 4 0 1 0</div> |
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<div class="graph">1,3 2,3 1,1</div> |
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<div>this <div> has no class</div> |
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</div> |
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''' |
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div,div_end = make_html_tags("div") |
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div_grid = div().set_parse_action(with_class("grid")) |
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grid_expr = div_grid + SkipTo(div | div_end)("body") |
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for grid_header in grid_expr.search_string(html): |
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print(grid_header.body) |
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div_any_type = div().set_parse_action(with_class(withAttribute.ANY_VALUE)) |
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div_expr = div_any_type + SkipTo(div | div_end)("body") |
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for div_header in div_expr.search_string(html): |
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print(div_header.body) |
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prints:: |
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1 4 0 1 0 |
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1 4 0 1 0 |
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1,3 2,3 1,1 |
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""" |
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classattr = f"{namespace}:class" if namespace else "class" |
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return with_attribute(**{classattr: classname}) |
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replaceWith = replaced_by_pep8("replaceWith", replace_with) |
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removeQuotes = replaced_by_pep8("removeQuotes", remove_quotes) |
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withAttribute = replaced_by_pep8("withAttribute", with_attribute) |
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withClass = replaced_by_pep8("withClass", with_class) |
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matchOnlyAtCol = replaced_by_pep8("matchOnlyAtCol", match_only_at_col) |
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