manchester

Evaluate Manchester syntax

This module compiles restrictions and logical constructs in Manchester syntax into Owlready2 classes. The main function in this module is manchester.evaluate(), see its docstring for usage example.

Pyparsing is used under the hood for parsing.

ManchesterError

Bases: EMMOntoPyException

Raised on invalid Manchester notation.

Source code in ontopy/manchester.py

class ManchesterError(EMMOntoPyException):
    """Raised on invalid Manchester notation."""

evaluate(ontology, expr)

Evaluate expression in Manchester syntax.

Parameters:

Name	Type	Description	Default
ontology	owlready2.Ontology	The ontology within which the expression will be evaluated.	required
expr	str	Manchester expression to be evaluated.	required

Returns:

Type	Description
owlready2.Construct	An Owlready2 construct that corresponds to the expression.

Example:

from ontopy.manchester import evaluate from ontopy import get_ontology emmo = get_ontology.load()

restriction = evaluate(emmo, 'hasPart some Atom') cls = evaluate(emmo, 'Atom') expr = evaluate(emmo, 'Atom or Molecule')

Note

Logical expressions (with not, and and or) are supported as well as object property restrictions. For data properterties are only value restrictions supported so far.

Source code in ontopy/manchester.py

def evaluate(ontology: owlready2.Ontology, expr: str) -> owlready2.Construct:
    """Evaluate expression in Manchester syntax.

    Args:
        ontology: The ontology within which the expression will be evaluated.
        expr: Manchester expression to be evaluated.

    Returns:
        An Owlready2 construct that corresponds to the expression.

    Example:
    >>> from ontopy.manchester import evaluate
    >>> from ontopy import get_ontology
    >>> emmo = get_ontology.load()

    >>> restriction = evaluate(emmo, 'hasPart some Atom')
    >>> cls = evaluate(emmo, 'Atom')
    >>> expr = evaluate(emmo, 'Atom or Molecule')

    Note:
        Logical expressions (with `not`, `and` and `or`) are supported as
        well as object property restrictions.  For data properterties are
        only value restrictions supported so far.
    """

    # pylint: disable=invalid-name
    def _parse_literal(r):
        """Compiles literal to Owlready2 type."""
        if r.language:
            v = owlready2.locstr(r.string, r.language)
        elif r.number:
            v = r.number
        else:
            v = r.string
        return v

    # pylint: disable=invalid-name,no-else-return,too-many-return-statements
    # pylint: disable=too-many-branches
    def _eval(r):
        """Recursively evaluate expression produced by pyparsing into an
        Owlready2 construct."""

        def fneg(x):
            """Negates the argument if `neg` is true."""
            return owlready2.Not(x) if neg else x

        if isinstance(r, str):  # r is atomic, returns its owlready2 repr
            return ontology[r]
        neg = False  # whether the expression starts with "not"
        while r[0] == "not":
            r.pop(0)  # strip off the "not" and proceed
            neg = not neg

        if len(r) == 1:  # r is either a atomic or a parenthesised
            # subexpression that should be further evaluated
            if isinstance(r[0], str):
                return fneg(ontology[r[0]])
            else:
                return fneg(_eval(r[0]))
        elif r.op:  # r contains a logical operator: and/or
            ops = {"and": owlready2.And, "or": owlready2.Or}
            op = ops[r.op]
            if len(r) == 3:
                return op([fneg(_eval(r[0])), _eval(r[2])])
            else:
                arg1 = fneg(_eval(r[0]))
                r.pop(0)
                r.pop(0)
                return op([arg1, _eval(r)])
        elif r.objProp:  # r is a restriction
            if r[0] == "inverse":
                r.pop(0)
                prop = owlready2.Inverse(ontology[r[0]])
            else:
                prop = ontology[r[0]]
            rtype = r[1]
            if rtype == "Self":
                return fneg(prop.has_self())
            r.pop(0)
            r.pop(0)
            f = getattr(prop, rtype)
            if rtype == "value":
                return fneg(f(_eval(r)))
            elif rtype in ("some", "only"):
                return fneg(f(_eval(r)))
            elif rtype in ("min", "max", "exactly"):
                cardinality = r.pop(0)
                return fneg(f(cardinality, _eval(r)))
            else:
                raise ManchesterError(f"invalid restriction type: {rtype}")
        elif r.dataProp:  # r is a data property restriction
            prop = ontology[r[0]]
            rtype = r[1]
            r.pop(0)
            r.pop(0)
            f = getattr(prop, rtype)
            if rtype == "value":
                return f(_parse_literal(r))
            else:
                raise ManchesterError(
                    f"unimplemented data property restriction: "
                    f"{prop} {rtype} {r}"
                )
        else:
            raise ManchesterError(f"invalid expression: {r}")

    grammar = manchester_expression()
    return _eval(grammar.parseString(expr, parseAll=True))

manchester_expression()

Returns pyparsing grammar for a Manchester expression.

This function is mostly for internal use.

See also: https://www.w3.org/TR/owl2-manchester-syntax/

Source code in ontopy/manchester.py

def manchester_expression():
    """Returns pyparsing grammar for a Manchester expression.

    This function is mostly for internal use.

    See also: https://www.w3.org/TR/owl2-manchester-syntax/
    """
    # pylint: disable=global-statement,invalid-name,too-many-locals
    global GRAMMAR
    if GRAMMAR:
        return GRAMMAR

    # Subset of the Manchester grammar for expressions
    # It is based on https://www.w3.org/TR/owl2-manchester-syntax/
    # but allows logical constructs within restrictions (like Protege)
    ident = pp.Word(pp.alphas + "_:-", pp.alphanums + "_:-", asKeyword=True)
    uint = pp.Word(pp.nums)
    alphas = pp.Word(pp.alphas)
    string = pp.Word(pp.alphanums + ":")
    quotedString = (
        pp.QuotedString('"""', multiline=True) | pp.QuotedString('"')
    )("string")
    typedLiteral = pp.Combine(quotedString + "^^" + string("datatype"))
    stringLanguageLiteral = pp.Combine(quotedString + "@" + alphas("language"))
    stringLiteral = quotedString
    numberLiteral = pp.pyparsing_common.number("number")
    literal = (
        typedLiteral | stringLanguageLiteral | stringLiteral | numberLiteral
    )
    logOp = pp.oneOf(["and", "or"], asKeyword=True)
    expr = pp.Forward()
    restriction = pp.Forward()
    primary = pp.Keyword("not")[...] + (
        restriction | ident("cls") | pp.nestedExpr("(", ")", expr)
    )
    objPropExpr = (
        pp.Literal("inverse")
        + pp.Suppress("(")
        + ident("objProp")
        + pp.Suppress(")")
        | pp.Literal("inverse") + ident("objProp")
        | ident("objProp")
    )
    dataPropExpr = ident("dataProp")
    restriction <<= (
        objPropExpr + pp.Keyword("some") + expr
        | objPropExpr + pp.Keyword("only") + expr
        | objPropExpr + pp.Keyword("Self")
        | objPropExpr + pp.Keyword("value") + ident("individual")
        | objPropExpr + pp.Keyword("min") + uint + expr
        | objPropExpr + pp.Keyword("max") + uint + expr
        | objPropExpr + pp.Keyword("exactly") + uint + expr
        | dataPropExpr + pp.Keyword("value") + literal
    )
    expr <<= primary + (logOp("op") + expr)[...]

    GRAMMAR = expr
    return expr