Add named parameters support

SQLite supports named parameters in either of these forms:
- $NAME
- :NAME
- @NAME

These parameters should be supplied to the query either in a form of a map
or as a list, the key is always iodata:
- #{":myparam" => "value"}
- [{"$myparam", 1}]
- [{text, "@myparam", "value"}]

CONTRIBUTERS

@@ -10,3 +10,4 @@
 
 Aleph Archives 
 Qing Liang <qing.liang.cn@gmail.com>
+Dmitry Matveyev <public@greenfork.me>

c_src/esqlite3_nif.c

@@ -753,6 +753,38 @@ esqlite_bind_null(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
     return make_atom(env, "ok");
 }
 
+static ERL_NIF_TERM
+esqlite_bind_parameter_index(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+    esqlite3_stmt *stmt;
+    ErlNifBinary bin;
+    int index;
+    ERL_NIF_TERM eos = enif_make_int(env, 0);
+
+    if(argc != 2) {
+        return enif_make_badarg(env);
+    }
+
+    if(!enif_get_resource(env, argv[0], esqlite3_stmt_type, (void **) &stmt)) {
+        return enif_make_badarg(env);
+    }
+
+    if(!stmt->statement) {
+        return enif_raise_exception(env, make_atom(env, "no_prepared_statement"));   
+    }
+
+    if(!enif_inspect_iolist_as_binary(env, enif_make_list2(env, argv[1], eos), &bin)) {
+        return enif_make_badarg(env);
+    }
+
+    index = sqlite3_bind_parameter_index(stmt->statement, bin.data);
+    if(index == 0) {
+        return enif_make_atom(env, "error");
+    }
+
+    return make_ok_tuple(env, enif_make_int(env, index));
+}
+
 static ERL_NIF_TERM
 esqlite_step(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 {
@@ -1202,6 +1234,7 @@ static ErlNifFunc nif_funcs[] = {
     {"bind_text", 3, esqlite_bind_text},
     {"bind_blob", 3, esqlite_bind_blob},
     {"bind_null", 2, esqlite_bind_null},
+    {"bind_parameter_index", 2, esqlite_bind_parameter_index},
 
     {"step", 1, esqlite_step, ERL_NIF_DIRTY_JOB_IO_BOUND},
     {"reset", 1, esqlite_reset},

src/esqlite3.erl

@@ -295,8 +295,17 @@ prepare(#esqlite3{db=Connection}, Sql, PrepareFlags) ->
 %% @doc Bind an array of values as parameters of a prepared statement
 -spec bind(Statement, Args) -> Result when
       Statement :: esqlite3_stmt(),
-      Args :: list(),
+      Args :: list() | map(),
       Result :: ok | {error, _}.
+%% Named parameters
+bind(#esqlite3_stmt{}=Statement, Args) when is_map(Args) ->
+    bind(Statement, maps:to_list(Args));
+bind(#esqlite3_stmt{}=Statement, [{_Type, _ParameterName, _Value} | _] = Args) ->
+    bind2(Statement, Args);
+bind(#esqlite3_stmt{}=Statement, [{ParameterName, _Value} | _] = Args)
+        when is_binary(ParameterName); is_list(ParameterName) ->
+    bind2(Statement, Args);
+%% Anonymous parameters
 bind(#esqlite3_stmt{}=Statement, Args) when is_list(Args) ->
     bind1(Statement, 1, Args).
 
@@ -310,6 +319,33 @@ bind1(Statement, Column, [Arg | Args]) ->
             Error
     end.
 
+bind2(_Statement, []) ->
+    ok;
+bind2(#esqlite3_stmt{stmt=Stmt}=Statement, [{Type, ParameterName, Value} | Args]) ->
+    case esqlite3_nif:bind_parameter_index(Stmt, ParameterName) of
+        {ok, Column} ->
+            case bind_arg(Statement, Column, {Type, Value}) of
+                ok ->
+                    bind2(Statement, Args);
+                {error, _}=Error ->
+                    Error
+            end;
+        error ->
+            {error, named_parameter_not_found}
+    end;
+bind2(#esqlite3_stmt{stmt=Stmt}=Statement, [{ParameterName, Value} | Args]) ->
+    case esqlite3_nif:bind_parameter_index(Stmt, ParameterName) of
+        {ok, Column} ->
+            case bind_arg(Statement, Column, Value) of
+                ok ->
+                    bind2(Statement, Args);
+                {error, _}=Error ->
+                    Error
+            end;
+        error ->
+            {error, named_parameter_not_found}
+    end.
+
 % Bind with automatic tyoe conversion
 bind_arg(Statement, Column, undefined) ->
     bind_null(Statement, Column);

src/esqlite3_nif.erl

@@ -42,6 +42,7 @@
     bind_text/3,
     bind_blob/3,
     bind_null/2,
+    bind_parameter_index/2,
 
     step/1,
 
@@ -194,6 +195,13 @@ bind_blob(_Statement, _Index, _Value) ->
 bind_null(_Statement, _Index) ->
     erlang:nif_error(nif_library_not_loaded).
 
+-spec bind_parameter_index(Statement, ParameterName) -> Result when
+      Statement :: esqlite3_stmt_ref(),
+      ParameterName :: iodata(),
+      Result :: {ok, integer()} | error.
+bind_parameter_index(_Statement, _ParameterName) ->
+    erlang:nif_error(nif_library_not_loaded).
+
 -spec step(Statement) -> StepResult when
       Statement :: esqlite3_stmt_ref(),
       StepResult :: row() | '$done' | error().

test/esqlite_test.erl

@@ -281,6 +281,26 @@ bind_for_queries_test() ->
 
     ok.
 
+named_bind_for_queries_test() ->
+    {ok, Db} = esqlite3:open(":memory:"),
+
+    ok = esqlite3:exec(Db, "begin;"),
+    ok = esqlite3:exec(Db, "create table test_table(one varchar(10), two int);"),
+    ok = esqlite3:exec(Db, "commit;"),
+
+    ?assertEqual([[1]], esqlite3:q(Db, <<"SELECT count(type) FROM sqlite_master WHERE type='table' AND name=:name;">>,
+                                   [{<<":name">>, "test_table"}])),
+    ?assertEqual([[1]], esqlite3:q(Db, <<"SELECT count(type) FROM sqlite_master WHERE type='table' AND name=$name;">>,
+                                   [{"$name", test_table}])),
+    ?assertEqual([[1]], esqlite3:q(Db, <<"SELECT count(type) FROM sqlite_master WHERE type='table' AND name=@name;">>,
+                                   [{"@name", <<"test_table">>}])),
+    ?assertEqual([[1]], esqlite3:q(Db, <<"SELECT count(type) FROM sqlite_master WHERE type='table' AND name=:name;">>,
+                                   #{":name" => test_table})),
+    ?assertEqual([[1]], esqlite3:q(Db, <<"SELECT count(type) FROM sqlite_master WHERE type='table' AND name=:name;">>,
+                                   [{text, ":name", "test_table"}])),
+
+    ok.
+
 column_names2_test() ->
     {ok, Db} = esqlite3:open(":memory:"),
     ok = esqlite3:exec(Db, "begin;"),