algebra.py 文件源码

def _addVars(x, children):
    # import pdb; pdb.set_trace()
    if isinstance(x, Variable):
        return set([x])
    elif isinstance(x, CompValue):
        x["_vars"] = set(reduce(operator.or_, children, set()))
        if x.name == "Bind":
            return set([x.var])
        elif x.name == 'SubSelect':
            if x.projection:
                s = set(v.var or v.evar for v in x.projection)
            else:
                s = set()

            return s
    return reduce(operator.or_, children, set())