Use of xs:integer() on right side of arrow operator seems to give error "elementpath.exceptions.ElementPathTypeError: 'xs:integer' constructor function at line 1, column 37: [err:XPST0017] Wrong number of arguments"

[martin-honnen]

I have the Python script

from elementpath import select

from elementpath.xpath3 import XPath3Parser

from xml.etree import ElementTree

root = ElementTree.XML('<root><term>12.</term></root>')

result = select(root, "term", parser=XPath3Parser)

print(result)

result = select(root, "term => substring-before('.') => xs:integer()", parser=XPath3Parser)

print(result)

which fails on the second select call with the traceback shown below.

I think in terms of XPath 3.1 the expression term => substring-before('.') => xs:integer() is fine.

Traceback (most recent call last):
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\arrow-operator-test2.py", line 13, in <module>
    result = select(root, "term => substring-before('.') => xs:integer()", parser=XPath3Parser)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\xpath_selectors.py", line 53, in select
    root_token = _parser.parse(path)
                 ^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\xpath2\xpath2_parser.py", line 508, in parse
    root_token = super(XPath1Parser, self).parse(source)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\tdop.py", line 497, in parse
    root_token = self.expression()
                 ^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\tdop.py", line 627, in expression
    left = self.token.led(left)
           ^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\xpath31\_xpath31_operators.py", line 242, in led_arrow_operator
    self[:] = left, self.parser.expression(80)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\tdop.py", line 627, in expression
    left = self.token.led(left)
           ^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\xpath1\_xpath1_operators.py", line 186, in led
    self[:] = left, self.parser.expression(95)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\tdop.py", line 624, in expression
    left = self.token.nud()
           ^^^^^^^^^^^^^^^^
  File "C:\Users\marti\PycharmProjects\ElementPathArrowOperatorTest1\.venv\Lib\site-packages\elementpath\xpath2\xpath2_parser.py", line 260, in nud_
    raise self.error('XPST0017') from None
elementpath.exceptions.ElementPathTypeError: 'xs:integer' constructor function at line 1, column 37: [err:XPST0017] Wrong number of arguments

[brunato]

Found the problem, a skip of arguments check is needed in nud() method for constructors, e.g.:

@method('string')
def nud_string_type_and_function(self: XPathConstructor) -> XPathConstructor:
    if not self.parser.parse_arguments:
        return self

    try:
        self.parser.advance('(')
        if self.label != 'function' or self.parser.next_token.symbol != ')':
            self[0:] = self.parser.expression(5),
        self.parser.advance(')')
    except ElementPathSyntaxError as err:
        raise self.error('XPST0017', err)
    else:
        return self

Instead this should be a syntax error:

"term => element()"

thank you

[brunato]

Hi @martin-honnen,
a fix for this is available with v4.7.0.

[martin-honnen]

Thanks, @brunato.