Function _parse_expression

src/licensedcode/match_spdx_lid.py:226–268

Return a LicenseExpression object by parsing the `text` string using the ``licensing`` reference Licensing. Return None or raise an exception on errors. Use the ``expression_symbols`` mapping of {lowered key: LicenseSymbol} if provided. Otherwise use the standard SPDX license s

(text, licensing, expression_symbols, unknown_symbol)

def _parse_expression(text, licensing, expression_symbols, unknown_symbol):
    """
    Return a LicenseExpression object by parsing the `text` string using the
    ``licensing`` reference Licensing. Return None or raise an exception on
    errors.

    Use the ``expression_symbols`` mapping of {lowered key: LicenseSymbol} if
    provided. Otherwise use the standard SPDX license symbols.
    """
    if not text:
        return
    text = text.lower()
    expression = licensing.parse(text, simple=True)

    if expression is None:
        return

    # substitute old SPDX symbols with new ones if any
    old_expressions_subs = get_old_expressions_subs_table(licensing)
    updated = expression.subs(old_expressions_subs)

    # collect known symbols and build substitution table: replace known symbols
    # with a symbol wrapping a known license and unkown symbols with the
    # unknown-spdx symbol
    symbols_table = {}

    def _get_matching_symbol(_symbol):
        return expression_symbols.get(_symbol.key.lower(), unknown_symbol)

    for symbol in licensing.license_symbols(updated, unique=True, decompose=False):
        if isinstance(symbol, LicenseWithExceptionSymbol):
            # we have two symbols:make a a new symbo, from that
            new_with = LicenseWithExceptionSymbol(
                license_symbol=_get_matching_symbol(symbol.license_symbol),
                exception_symbol=_get_matching_symbol(symbol.exception_symbol)
            )

            symbols_table[symbol] = new_with
        else:
            symbols_table[symbol] = _get_matching_symbol(symbol)

    symbolized = updated.subs(symbols_table)
    return symbolized


def _reparse_invalid_expression(