tiny.pluck.bdd.WeightedSampler

1pub const WeightedSampler = struct {2    allocator: Allocator,3    manager: *Manager,4    bdd: Bdd,5    params: *const WmcParams,6    cache: WmcDenseCache,7    var_bdds: []Bdd,8    total_wmc: f64,910    pub fn init(11        allocator: Allocator,12        manager: *Manager,13        bdd: Bdd,14        params: *const WmcParams,15    ) !WeightedSampler {16        const var_bdds = try allocator.alloc(Bdd, manager.numVars());17        errdefer allocator.free(var_bdds);18        for (var_bdds, 0..) |*var_bdd, label| {19            var_bdd.* = try manager.getOrInsert(Node.init(@intCast(label), Bdd.FALSE, Bdd.TRUE));20        }2122        var cache = try WmcDenseCache.init(allocator, manager.nodes.items.len);23        errdefer cache.deinit();24        const total_wmc = wmcHelper(manager, bdd, params, &cache);25        return WeightedSampler{26            .allocator = allocator,27            .manager = manager,28            .bdd = bdd,29            .params = params,30            .cache = cache,31            .var_bdds = var_bdds,32            .total_wmc = total_wmc,33        };34    }3536    pub fn deinit(self: *WeightedSampler) void {37        self.cache.deinit();38        self.allocator.free(self.var_bdds);39    }4041    pub fn sample(self: *WeightedSampler, rng: std.Random) Allocator.Error!WeightedSampleResult {42        if (self.bdd.isTrue()) {43            return WeightedSampleResult{44                .sample = Bdd.TRUE,45                .probability = 1.0,46            };47        }48        if (self.bdd.isFalse() or self.total_wmc == 0.0) {49            return WeightedSampleResult{50                .sample = Bdd.FALSE,51                .probability = 0.0,52            };53        }5455        return try weightedSampleFromCache(self.manager, self.bdd, self.params, rng, 1.0, &self.cache, self.var_bdds);56    }57};