is_json implemented

src/jsx_verify.erl

@@ -0,0 +1,161 @@
+%% The MIT License
+
+%% Copyright (c) 2010 Alisdair Sullivan <alisdairsullivan@yahoo.ca>
+
+%% Permission is hereby granted, free of charge, to any person obtaining a copy
+%% of this software and associated documentation files (the "Software"), to deal
+%% in the Software without restriction, including without limitation the rights
+%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+%% copies of the Software, and to permit persons to whom the Software is
+%% furnished to do so, subject to the following conditions:
+
+%% The above copyright notice and this permission notice shall be included in
+%% all copies or substantial portions of the Software.
+
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+%% THE SOFTWARE.
+
+
+-module(jsx_verify).
+
+-export([is_json/2]).
+-export([init/1, handle_event/2]).
+
+
+-record(opts, {
+    repeated_keys = true
+}).
+
+-type opts() :: [].
+
+
+-spec is_json(Source::(binary() | list()), Opts::opts()) -> binary().
+    
+is_json(Source, Opts) when (is_binary(Source) andalso is_list(Opts))
+        orelse (is_list(Source) andalso is_list(Opts)) ->
+    try case (gen_json:parser(?MODULE, Opts, extract_opts(Opts)))(Source) of
+            {incomplete, _} -> false
+            ; true -> true
+        end
+    catch error:badarg -> false
+    end.
+
+
+
+init(Opts) -> {parse_opts(Opts), []}.
+
+
+parse_opts(Opts) -> parse_opts(Opts, #opts{}).
+
+parse_opts([{repeated_keys, Val}|Rest], Opts) when Val == true; Val == false ->
+    parse_opts(Rest, Opts#opts{repeated_keys = Val});
+parse_opts([repeated_keys|Rest], Opts) ->
+    parse_opts(Rest, Opts#opts{repeated_keys = true});
+parse_opts([_|Rest], Opts) ->
+    parse_opts(Rest, Opts);
+parse_opts([], Opts) ->
+    Opts.
+
+
+extract_opts(Opts) ->
+    extract_parser_opts(Opts, []).
+
+extract_parser_opts([], Acc) -> Acc;     
+extract_parser_opts([{K,V}|Rest], Acc) ->
+    case lists:member(K, [loose_unicode, escape_forward_slash, explicit_end]) of
+        true -> extract_parser_opts(Rest, [{K,V}] ++ Acc)
+        ; false -> extract_parser_opts(Rest, Acc)
+    end;
+extract_parser_opts([K|Rest], Acc) ->
+    case lists:member(K, [loose_unicode, escape_forward_slash, explicit_end]) of
+        true -> extract_parser_opts(Rest, [K] ++ Acc)
+        ; false -> extract_parser_opts(Rest, Acc)
+    end.
+
+
+handle_event(end_json, _) -> true;
+
+handle_event(_, {Opts, _} = State) when Opts#opts.repeated_keys == true -> State;
+
+handle_event(start_object, {Opts, Keys}) -> {Opts, [dict:new()] ++ Keys};
+handle_event(end_object, {Opts, [_|Keys]}) -> {Opts, Keys};
+
+handle_event({key, Key}, {Opts, [CurrentKeys|Keys]}) ->
+    case dict:is_key(Key, CurrentKeys) of
+        true -> erlang:error(badarg)
+        ; false -> {Opts, [dict:store(Key, blah, CurrentKeys)|Keys]}
+    end;
+
+handle_event(_, State) -> State.
+
+
+
+%% eunit tests
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+
+true_test_() ->
+    [
+        {"empty object", ?_assert(is_json(<<"{}">>, []) =:= true)},
+        {"empty array", ?_assert(is_json(<<"[]">>, []) =:= true)},
+        {"whitespace", 
+            ?_assert(is_json(<<" \n    \t   \r   [true]   \t    \n\r  ">>, 
+                    []
+                ) =:= true
+            )
+        },
+        {"nested terms", 
+            ?_assert(is_json(
+                    <<"[{ \"x\": [ {}, {}, {} ], \"y\": [{}] }, {}, [[[]]]]">>, 
+                    []
+                ) =:= true
+            )
+        },
+        {"numbers", 
+            ?_assert(is_json(
+                    <<"[ -1.0, -1, -0, 0, 1e-1, 1, 1.0, 1e1 ]">>, 
+                    []
+                ) =:= true
+            )
+        },
+        {"strings", 
+            ?_assert(is_json(
+                    <<"[ \"a\", \"string\", \"in\", \"multiple\", \"acts\" ]">>, 
+                    []
+                ) =:= true
+            )
+        },
+        {"literals", 
+            ?_assert(is_json(<<"[ true, false, null ]">>, []) =:= true)
+        },
+        {"nested objects", 
+            ?_assert(is_json(<<"{\"key\": { \"key\": true}}">>, []) =:= true)
+        },        
+        {"repeated key ok", ?_assert(is_json(<<"{\"key\": true, \"key\": true}">>, []) =:= true)},
+        {"nested repeated key", ?_assert(is_json(<<"{\"key\": { \"key\": true }}">>,
+            [{repeated_keys, false}]) =:= true)
+        }
+    ].
+
+false_test_() ->
+    [
+        {"unbalanced list", ?_assert(is_json(<<"[[[]]">>, []) =:= false)},
+        {"trailing comma", 
+            ?_assert(is_json(<<"[ true, false, null, ]">>, []) =:= false)
+        },
+        {"unquoted key", ?_assert(is_json(<<"{ key: false }">>, []) =:= false)},
+        {"repeated key", ?_assert(is_json(<<"{\"key\": true, \"key\": true}">>,
+            [{repeated_keys, false}]) =:= false)
+        },
+        {"nested repeated key", ?_assert(is_json(<<"{\"key\": { \"a\": true, \"a\": false }}">>,
+            [{repeated_keys, false}]) =:= false)
+        }
+    ].
+        
+    
+-endif.