abstracted internal state of the `jsx_to_term' handler
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alisdair sullivan
parent
1909687aff
commit
62914f422a
1 changed files with 105 additions and 22 deletions
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@ -25,6 +25,7 @@
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-export([to_term/2]).
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-export([init/1, handle_event/2]).
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-export([start_object/1, start_array/1, finish/1, insert/2, insert/3]).
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-record(config, {
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@ -70,33 +71,20 @@ parse_config([], Config) ->
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Config.
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init(Config) -> {[[]], parse_config(Config)}.
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init(Config) -> {[], parse_config(Config)}.
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handle_event(end_json, {[[Terms]], _Config}) -> Terms;
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handle_event(end_json, {Term, _Config}) -> Term;
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handle_event(start_object, {Terms, Config}) -> {[[]|Terms], Config};
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handle_event(end_object, {[[], {key, Key}, Last|Terms], Config}) ->
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{[[{Key, [{}]}] ++ Last] ++ Terms, Config};
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handle_event(end_object, {[Object, {key, Key}, Last|Terms], Config}) ->
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{[[{Key, lists:reverse(Object)}] ++ Last] ++ Terms, Config};
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handle_event(end_object, {[[], Last|Terms], Config}) ->
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{[[[{}]] ++ Last] ++ Terms, Config};
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handle_event(end_object, {[Object, Last|Terms], Config}) ->
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{[[lists:reverse(Object)] ++ Last] ++ Terms, Config};
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handle_event(start_object, {Stack, Config}) -> {start_object(Stack), Config};
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handle_event(end_object, {Stack, Config}) -> {finish(Stack), Config};
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handle_event(start_array, {Terms, Config}) -> {[[]|Terms], Config};
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handle_event(end_array, {[List, {key, Key}, Last|Terms], Config}) ->
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{[[{Key, lists:reverse(List)}] ++ Last] ++ Terms, Config};
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handle_event(end_array, {[List, Last|Terms], Config}) ->
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{[[lists:reverse(List)] ++ Last] ++ Terms, Config};
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handle_event(start_array, {Stack, Config}) -> {start_array(Stack), Config};
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handle_event(end_array, {Stack, Config}) -> {finish(Stack), Config};
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handle_event({key, Key}, {Terms, Config}) -> {[{key, format_key(Key, Config)}] ++ Terms, Config};
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handle_event({key, Key}, {Stack, Config}) -> {insert(format_key(Key, Config), Stack), Config};
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handle_event({_, Event}, {[{key, Key}, Last|Terms], Config}) ->
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{[[{Key, Event}] ++ Last] ++ Terms, Config};
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handle_event({_, Event}, {[Last|Terms], Config}) ->
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{[[Event] ++ Last] ++ Terms, Config}.
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handle_event({_, Event}, {Stack, Config}) -> {insert(Event, Stack), Config}.
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format_key(Key, Config) ->
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@ -113,6 +101,44 @@ format_key(Key, Config) ->
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end.
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%% internal state is a stack of in progress objects/arrays
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%% `[Current, Parent, Grandparent,...OriginalAncestor]`
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%% an object has the representation on the stack of
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%% `{object, [{NthKey, NthValue}, {NMinus1Key, NthMinus1Value},...{FirstKey, FirstValue}]}`
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%% of if there's a key with a yet to be matched value
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%% `{object, Key, [{NthKey, NthValue},...]}`
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%% an array looks like
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%% `{array, [NthValue, NthMinus1Value,...FirstValue]}`
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%% allocate a new object on top of the stack
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start_object(Stack) -> [{object, []}] ++ Stack.
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%% allocate a new array on top of the stack
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start_array(Stack) -> [{array, []}] ++ Stack.
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%% finish an object or array and insert it into the parent object if it exists
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finish([{object, []}]) -> [{}];
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finish([{object, []}|Rest]) -> insert([{}], Rest);
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finish([{object, Pairs}]) -> lists:reverse(Pairs);
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finish([{object, Pairs}|Rest]) -> insert(lists:reverse(Pairs), Rest);
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finish([{array, Values}]) -> lists:reverse(Values);
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finish([{array, Values}|Rest]) -> insert(lists:reverse(Values), Rest);
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finish(_) -> erlang:error(badarg).
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%% insert a value when there's no parent object or array
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insert(Value, []) -> Value;
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%% insert a key or value into an object or array, autodetects the 'right' thing
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insert(Key, [{object, Pairs}|Rest]) -> [{object, Key, Pairs}] ++ Rest;
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insert(Value, [{object, Key, Pairs}|Rest]) -> [{object, [{Key, Value}] ++ Pairs}] ++ Rest;
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insert(Value, [{array, Values}|Rest]) -> [{array, [Value] ++ Values}] ++ Rest;
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insert(_, _) -> erlang:error(badarg).
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%% insert a key/value pair into an object
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insert(Key, Value, [{object, Pairs}|Rest]) -> [{object, [{Key, Value}] ++ Pairs}] ++ Rest;
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insert(_, _, _) -> erlang:error(badarg).
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%% eunit tests
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@ -158,13 +184,70 @@ format_key_test_() ->
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].
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rep_manipulation_test_() ->
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[
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{"allocate a new object on an empty stack", ?_assertEqual(
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[{object, []}],
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start_object([])
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)},
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{"allocate a new object on a stack", ?_assertEqual(
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[{object, []}, {object, []}],
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start_object([{object, []}])
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)},
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{"allocate a new array on an empty stack", ?_assertEqual(
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[{array, []}],
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start_array([])
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)},
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{"allocate a new array on a stack", ?_assertEqual(
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[{array, []}, {object, []}],
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start_array([{object, []}])
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)},
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{"insert a key into an object", ?_assertEqual(
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[{object, key, []}, junk],
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insert(key, [{object, []}, junk])
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)},
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{"insert a value into an object", ?_assertEqual(
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[{object, [{key, value}]}, junk],
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insert(value, [{object, key, []}, junk])
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)},
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{"insert a value into an array", ?_assertEqual(
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[{array, [value]}, junk],
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insert(value, [{array, []}, junk])
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)},
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{"insert a key/value pair into an object", ?_assertEqual(
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[{object, [{key, value}, {x, y}]}, junk],
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insert(key, value, [{object, [{x, y}]}, junk])
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)},
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{"finish an object with no ancestor", ?_assertEqual(
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[{a, b}, {x, y}],
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finish([{object, [{x, y}, {a, b}]}])
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)},
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{"finish an empty object", ?_assertEqual(
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[{}],
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finish([{object, []}])
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)},
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{"finish an object with an ancestor", ?_assertEqual(
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[{object, [{key, [{a, b}, {x, y}]}, {foo, bar}]}],
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finish([{object, [{x, y}, {a, b}]}, {object, key, [{foo, bar}]}])
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)},
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{"finish an array with no ancestor", ?_assertEqual(
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[a, b, c],
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finish([{array, [c, b, a]}])
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)},
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{"finish an array with an ancestor", ?_assertEqual(
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[{array, [[a, b, c], d, e, f]}],
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finish([{array, [c, b, a]}, {array, [d, e, f]}])
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)}
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].
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handle_event_test_() ->
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Data = jsx:test_cases(),
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[
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{
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Title, ?_assertEqual(
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Term,
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lists:foldl(fun handle_event/2, {[[]], #config{}}, Events ++ [end_json])
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lists:foldl(fun handle_event/2, {[], #config{}}, Events ++ [end_json])
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)
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} || {Title, _, Term, Events} <- Data
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].
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