__main__.py 文件源码

def explore_frontier(sig, data_type, metric, max_size):
    # closure for binding sig and rules easily
    expand = producers.generate_expander(sig)
    # generate appropriate starting node based on type
    start_node = producers.e.Un(producers.parse_type(data_type))
    frontier = [(metric(start_node), start_node)]
    # go hog wild
    while True:
        # pull expression off heap, check expansions
        m, expr = heapq.heappop(frontier)
        expansions = expand(expr)
        # if there are expansions, just add them back in
        if expansions:
            for new_expr in expansions:
                heapq.heappush(frontier, (metric(new_expr), new_expr) )
        # if there aren't any expansions and the program is closed, we're done
        elif len(expr._values_from_kind("un")) == 0:
            yield m[0], expr

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# now we treat this module as a script - time to execute!
#------------------------------------------------------------------------------