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https://github.com/marianoguerra/erldn

edn format parser for the erlang platform
https://github.com/marianoguerra/erldn

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edn format parser for the erlang platform

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README 

        
erldn - an edn parser for the erlang platform

=============================================



erldn is a parser for the `edn specification `_.



implemented using leex and yecc, tested with eunit.



this is a low level parser, it gives you an erlang data structure where you

have to decide how will you actually represent things like maps, sets, vectors

since each person may have a different need, no imposition here.



Build

-----



::



    ./rebar compile



Test

----



::



    ./rebar eunit



Use

---



::



    1> erldn:parse_str("{}").

    {ok,{map,[]}}



    2> erldn:parse_str("1").

    {ok,1}



    3> erldn:parse_str("true").

    {ok,true}



    4> erldn:parse_str("nil").

    {ok,nil}



    5> erldn:parse_str("[1 true nil]").

    {ok,{vector,[1,true,nil]}}



    6> erldn:parse_str("(1 true nil :foo)").

    {ok,[1,true,nil,foo]}



    7> erldn:parse_str("(1 true nil :foo ns/foo)").

    {ok,[1,true,nil,foo,{symbol,'ns/foo'}]}



    8> erldn:parse_str("#{1 true nil :foo ns/foo}").

    {ok,{set,[1,true,nil,foo,{symbol,'ns/foo'}]}}



    9> erldn:parse_str("#myapp/Person {:first \"Fred\" :last \"Mertz\"}").

    {ok,{tag,'myapp/Person',

             {map,[{first,"Fred"},{last,"Mertz"}]}}}

             10> erldn:parse_str("#{1 true #_ nil :foo ns/foo}").

             {ok,{set,[1,true,{ignore,nil},foo,{symbol,'ns/foo'}]}}

             11> erldn:parse_str("#{1 true #_ 42 :foo ns/foo}").

             {ok,{set,[1,true,{ignore,42},foo,{symbol,'ns/foo'}]}}



     % to_string



     10> {ok, Result} = erldn:parse_str("{:a 42}").

     {ok,{map,[{a,42}]}}



     11> io:format("~s~n", [erldn:to_string(Result)]).

     {:a 42}

     ok



     % to_erlang



     12> erldn:to_erlang(element(2, erldn:parse_str("[1, nil, :nil, \"asd\"]"))).

     [1,nil,nil,<<"asd">>]



API

---



parse_str/1

    parses a string with edn into an erlang data structure maintaining all

    the details from the original edn



to_string/1

    converts the result from *parse_str/1* into an edn string representation



to_erlang/1

    converts the result from *parse_str/1* into an erlang-friendly version of

    itself; see "To Erlang Mappings" below.



to_erlang/2

    like *to_erlang/1* but accepts a tuplelist as a second argument with a

    tag as the first argument and a function `(fun (Tag, Value, OtherHandlers) -> .. end)`

    as the second of each pair to handle tagged values.

    

check the unit tests for usage examples.



Type Mappings

-------------



=============== ========================================================

edn             erlang

=============== ========================================================

integer         integer

float           float

boolean         boolean

nil             nil (atom)

char            tagged integer -> {char, }}

string          binary string (utf-8)

list            list

vector          tagged list -> {vector, [...]}

map             tagged property list -> {map, [{key1, val1}, ...]}

set             tagged list -> {set, [...]} (not made unique on parsing)

symbol          tagged atom -> {symbol, }

tagged elements tagged tuple with tag and value -> {tag, Symbol, Value}

=============== ========================================================



To Erlang Mappings

------------------



The `to_erlang` function transforms the incoming data structure into a more

erlang-friendly data structure, but this can't be converted back to a string

without transforming it again. The mappings by default are:



=============== ========================================================

edn             erlang

=============== ========================================================

integer         integer

float           float

boolean         boolean

char            string

nil (atom)      nil (atom)

nil (symbol)    nil (atom)

binary string   binary string

list            list

vector          list

map             dict (dict module)

set             set (sets module)

symbol          stay the same

tagged elements call registered handler for that tag, fail if not found

=============== ========================================================



TODO

----



nothing that I can think of!



Notes

-----



* since keywords are mapped to atoms and nil is mapped to the nil atom, if

  the nil keyword is encountered it will be mapped to {keyword, nil}.



Author

------



marianoguerra



License

-------



MIT + optional beer for the author if you meet me



Notes to myself

---------------



::



    make clean

    make

    MIX_EXS=package.exs mix hex.publish