Function get_expression

src/licensedcode/match_spdx_lid.py:154–193

Return an Expression object by parsing the `text` string using the ``licensing`` reference Licensing. Use the ``expression_symbols`` mapping of {lowered key: LicenseSymbol} if provided. Otherwise use the standard SPDX license symbols. Note that an expression is ALWAYS returned

(text, licensing, expression_symbols, unknown_symbol)

def get_expression(text, licensing, expression_symbols, unknown_symbol):
    """
    Return an Expression object by parsing the `text` string using the
    ``licensing`` reference Licensing.

    Use the ``expression_symbols`` mapping of {lowered key: LicenseSymbol} if
    provided. Otherwise use the standard SPDX license symbols.

    Note that an expression is ALWAYS returned: if the parsing fails or some
    other error happens somehow, this function returns instead a bare
    expression made of only "unknown-spdx" symbol.
    """
    _prefix, text = prepare_text(text)
    if not text:
        return
    expression = None
    try:
        expression = _parse_expression(
            text=text,
            licensing=licensing,
            expression_symbols=expression_symbols,
            unknown_symbol=unknown_symbol,
        )
    except Exception:
        try:
            # Try to parse again using a lenient recovering parsing process such
            # as for plain space or comma-separated list of licenses (e.g.
            # UBoot)
            expression = _reparse_invalid_expression(
                text=text,
                licensing=licensing,
                expression_symbols=expression_symbols,
                unknown_symbol=unknown_symbol,
            )
        except Exception:
            pass

    if expression is None:
        expression = unknown_symbol
    return expression


# Some older SPDX ids are deprecated and therefore no longer referenced in