Created
November 15, 2016 20:34
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merge3
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-module(z). | |
-export([t/0, merge/3]). | |
merge(F, L, R) -> | |
L1 = lists:sort(maps:to_list(L)), | |
L2 = lists:sort(maps:to_list(R)), | |
merge(F, L1, L2, []). | |
merge(_F, [], [], Acc) -> maps:from_list(Acc); | |
merge(F, [{KX, VX}|Xs], [], Acc) -> | |
merge(F, Xs, [], f(KX, F(KX, {left, VX}), Acc)); | |
merge(F, [], [{KY, VY} | Ys], Acc) -> | |
merge(F, [], Ys, f(KY, F(KY, {right, VY}), Acc)); | |
merge(F, [{KX, VX}|Xs] = Left, [{KY,VY}|Ys] = Right, Acc) -> | |
if | |
KX < KY -> merge(F, Xs, Right, f(KX, F(KX, {left, VX}), Acc)); | |
KX > KY -> merge(F, Left, Ys, f(KY, F(KY, {right, VY}), Acc)); | |
KX =:= KY -> merge(F, Xs, Ys, f(KX, F(KX, {both, VX, VY}), Acc)) | |
end. | |
f(_K, undefined, Acc) -> Acc; | |
f(K, {ok, R}, Acc) -> [{K, R} | Acc]. | |
t() -> | |
Map1 = #{ a => 1, b => 2 }, | |
Map2 = #{ b => 3, c => 3 }, | |
Fun1 = fun | |
(_K, {left, V}) -> {ok, V}; | |
(_K, {right, V}) -> {ok, V}; | |
(_K, {both, V1, V2}) -> {ok, V1 + V2} | |
end, | |
#{ a := 1, b := 5, c := 3 } = merge(Fun1, Map1, Map2), | |
Map3 = #{ a => #{ b => 2, f=> #{}} }, | |
Map4 = #{ a=> #{b => 3, c => 4, d=> #{e=> 5}} }, | |
Fun2 = fun | |
F(_K, {left, V}) -> {ok, V}; | |
F(_K, {right, V}) -> {ok, V}; | |
F(_K, {both, L, R}) when is_map(L), is_map(R) -> {ok, merge(F, L, R)}; | |
F(_K, {both, L, R}) -> {ok, [L, R]} %% arbitrary choice | |
end, | |
#{a => #{b => [2,3],c => 4,d => #{e => 5},f => #{}}} = | |
merge(Fun2, Map3, Map4). | |
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