add attempt_atom flag

add attempt_atom flag, which is compatable with

  jsx:decode(Bin, [{label, attempt_atom}])

c_src/decoder.c

@@ -53,6 +53,7 @@ typedef struct {
     int             is_partial;
     int             return_maps;
     int             return_trailer;
+    int             attempt_atom;
     ERL_NIF_TERM    null_term;
 
     char*           p;
@@ -82,6 +83,7 @@ dec_new(ErlNifEnv* env)
     d->is_partial = 0;
     d->return_maps = 0;
     d->return_trailer = 0;
+    d->attempt_atom = 0;
     d->null_term = d->atoms->atom_null;
 
     d->p = NULL;
@@ -623,20 +625,41 @@ make_empty_object(ErlNifEnv* env, int ret_map)
     return enif_make_tuple1(env, enif_make_list(env, 0));
 }
 
+ERL_NIF_TERM
+key_attempt_atom(ErlNifEnv* env, ERL_NIF_TERM key) {
+    ERL_NIF_TERM keyatom;
+    ErlNifBinary keybin;
+    // maximum atom length is 255 bytes
+    char keybuf[256];
+
+    if(enif_inspect_binary(env, key, &keybin) && keybin.size < sizeof(keybuf)) {
+        memcpy(keybuf, keybin.data, keybin.size);
+        keybuf[keybin.size] = 0;
+        if(enif_make_existing_atom(env, keybuf, &keyatom, ERL_NIF_LATIN1)) {
+            return keyatom;
+        }
+    }
+    return key;
+}
+
 int
-make_object(ErlNifEnv* env, ERL_NIF_TERM pairs, ERL_NIF_TERM* out, int ret_map)
+make_object(ErlNifEnv* env, ERL_NIF_TERM pairs, ERL_NIF_TERM* out, int ret_map, int attempt_atom)
 {
     ERL_NIF_TERM ret;
     ERL_NIF_TERM key;
     ERL_NIF_TERM val;
 
 #if MAP_TYPE_PRESENT
+
     if(ret_map) {
         ret = enif_make_new_map(env);
         while(enif_get_list_cell(env, pairs, &val, &pairs)) {
             if(!enif_get_list_cell(env, pairs, &key, &pairs)) {
                 assert(0 == 1 && "Unbalanced object pairs.");
             }
+            if(attempt_atom) {
+                key = key_attempt_atom(env, key);
+            }
             if(!enif_make_map_put(env, ret, key, val, &ret)) {
                 return 0;
             }
@@ -651,6 +674,9 @@ make_object(ErlNifEnv* env, ERL_NIF_TERM pairs, ERL_NIF_TERM* out, int ret_map)
         if(!enif_get_list_cell(env, pairs, &key, &pairs)) {
             assert(0 == 1 && "Unbalanced object pairs.");
         }
+        if(attempt_atom) {
+            key = key_attempt_atom(env, key);
+        }
         val = enif_make_tuple2(env, key, val);
         ret = enif_make_list_cell(env, val, ret);
     }
@@ -720,6 +746,8 @@ decode_init(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
             d->null_term = d->atoms->atom_nil;
         } else if(get_null_term(env, val, &(d->null_term))) {
             continue;
+        } else if(enif_compare(val, d->atoms->atom_attempt_atom) == 0) {
+            d->attempt_atom = 1;
         } else {
             return enif_make_badarg(env);
         }
@@ -984,7 +1012,7 @@ decode_iter(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
                         }
                         dec_pop(d, st_object);
                         dec_pop(d, st_value);
-                        if(!make_object(env, curr, &val, d->return_maps)) {
+                        if(!make_object(env, curr, &val, d->return_maps, d->attempt_atom)) {
                             ret = dec_error(d, "internal_object_error");
                             goto done;
                         }

c_src/jiffy.c

@@ -32,6 +32,7 @@ load(ErlNifEnv* env, void** priv, ERL_NIF_TERM info)
     st->atom_use_nil = make_atom(env, "use_nil");
     st->atom_null_term = make_atom(env, "null_term");
     st->atom_escape_forward_slashes = make_atom(env, "escape_forward_slashes");
+    st->atom_attempt_atom = make_atom(env, "attempt_atom");
 
     // Markers used in encoding
     st->ref_object = make_atom(env, "$object_ref$");

c_src/jiffy.h

@@ -35,6 +35,7 @@ typedef struct {
     ERL_NIF_TERM    atom_use_nil;
     ERL_NIF_TERM    atom_null_term;
     ERL_NIF_TERM    atom_escape_forward_slashes;
+    ERL_NIF_TERM    atom_attempt_atom;
 
     ERL_NIF_TERM    ref_object;
     ERL_NIF_TERM    ref_array;

src/jiffy.erl

@@ -39,6 +39,7 @@
 -type decode_option() :: return_maps
                         | use_nil
                         | return_trailer
+                        | attempt_atom
                         | {null_term, any()}
                         | {bytes_per_iter, non_neg_integer()}
                         | {bytes_per_red, non_neg_integer()}.

test/jiffy_16_attempt_atom_tests.erl

@@ -0,0 +1,32 @@
+% This file is part of Jiffy released under the MIT license.
+% See the LICENSE file for more information.
+
+-module(jiffy_16_attempt_atom_tests).
+
+-include_lib("eunit/include/eunit.hrl").
+
+attempt_atom_test_() ->
+    Opts = [attempt_atom],
+    _ = key_is_atom,
+    Cases = [
+        {<<"{\"key_no_atom\":1}">>, {[{<<"key_no_atom">>, 1}]}},
+        {<<"{\"key_is_atom\":1}">>, {[{key_is_atom, 1}]}}
+    ],
+    {"Test attempt_atom", lists:map(fun({Data, Result}) ->
+        ?_assertEqual(Result, jiffy:decode(Data, Opts))
+    end, Cases)}.
+
+-ifndef(JIFFY_NO_MAPS).
+
+attempt_atom_map_test_() ->
+    Opts = [attempt_atom, return_maps],
+    _ = key_is_atom,
+    Cases = [
+        {<<"{\"key_no_atom\":1}">>, #{<<"key_no_atom">> => 1}},
+        {<<"{\"key_is_atom\":1}">>, #{key_is_atom => 1}}
+    ],
+    {"Test attempt_atom_map", lists:map(fun({Data, Result}) ->
+        ?_assertEqual(Result, jiffy:decode(Data, Opts))
+    end, Cases)}.
+
+-endif.