208 lines
6.3 KiB
Python
208 lines
6.3 KiB
Python
|
# 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
|