Added map and foreach support on queries

src/esqlite3.erl

@@ -28,6 +28,8 @@
 	 bind/2, bind/3, 
 	 close/1, close/2]).
 
+-export([q/2, map/3, foreach/3]).
+
 -define(DEFAULT_TIMEOUT, infinity).
 
 %% @doc Opens a sqlite3 database mentioned in Filename.
@@ -40,43 +42,95 @@ open(Filename) ->
 %%
 %% @spec open(string(), timeout()) -> {ok, connection()} | {error, error_message()}
 open(Filename, Timeout) ->
-    {ok, Db} = esqlite3_nif:start(),
+    {ok, Connection} = esqlite3_nif:start(),
 
     Ref = make_ref(),
-    ok = esqlite3_nif:open(Db, Ref, self(), Filename),
+    ok = esqlite3_nif:open(Connection, Ref, self(), Filename),
     case receive_answer(Ref, Timeout) of
 	ok ->
-	    {ok, Db};
+	    {ok, Connection};
 	Other ->
 	    {error, Other}
     end.
 
-%% @doc Execute Sql statement
+%% @doc Execute a sql statement, returns a list with tuples. 
+q(Sql, Connection) ->
+    {ok, Statement} = prepare(Sql, Connection),
+    do_steps(Statement).
+
+%% 
+map(F, Sql, Connection) ->
+    {ok, Statement} = prepare(Sql, Connection),
+    map_s(F, Statement).
+
+%% 
+foreach(F, Sql, Connection) ->
+    {ok, Statement} = prepare(Sql, Connection),
+    foreach_s(F, Statement).
+
 %%
-%% @spec exec(connection(), iolist()) -> integer() |  {error, error_message()}
-exec(Db, Sql) ->
-    exec(Db, Sql, ?DEFAULT_TIMEOUT).
+foreach_s(F, Statement) ->    
+    case try_step(Statement, 0) of
+	'$done' -> ok;
+	Row when is_tuple(Row) ->
+	    F(Row),
+	    foreach_s(F, Statement)
+    end.    
+
+%%
+map_s(F, Statement) ->
+    case try_step(Statement, 0) of
+	'$done' ->
+	    [];
+	Row -> 
+	    [F(Row) | map_s(F, Statement)]
+    end.
+
+%%    
+do_steps(Statement) ->
+    case try_step(Statement, 0) of
+	'$done' -> 
+	    [];
+	Row when is_tuple(Row) ->
+	    [Row | do_steps(Statement)]
+    end.  
+
+try_step(_Statement, Tries) when Tries > 5 ->
+    throw(too_many_tries);
+try_step(Statement, Tries) ->
+    case esqlite3:step(Statement) of
+	'$busy' -> 
+	    try_step(Statement, Tries + 1);
+	Something -> 
+	    Something
+    end.
+	    
+%% @doc Execute Sql statement, returns the number of affected rows.
+%%
+%% @spec exec(iolist(), connection()) -> integer() |  {error, error_message()}
+exec(Sql, Connection) ->
+    exec(Sql, Connection, ?DEFAULT_TIMEOUT).
 
 %% @doc Execute 
 %%
-%% @spec exec(connection(), iolist(), timeout()) -> integer() | {error, error_message()}
-exec(Db, Sql, Timeout) ->
+%% @spec exec(iolist(), connection(), timeout()) -> integer() | {error, error_message()}
+exec(Sql, Connection, Timeout) ->
     Ref = make_ref(),
-    ok = esqlite3_nif:exec(Db, Ref, self(), add_eos(Sql)),
+    ok = esqlite3_nif:exec(Connection, Ref, self(), add_eos(Sql)),
     receive_answer(Ref, Timeout).
 
 %% @doc Prepare a statement
 %%
-%% @spec prepare(connection(), iolist()) -> {ok, prepared_statement()} | {error, error_message()}
-prepare(Db, Sql) ->
-    prepare(Db, Sql, ?DEFAULT_TIMEOUT).
+%% @spec prepare(iolost(), connection()) -> {ok, prepared_statement()} | {error, error_message()}
+prepare(Sql, Connection) ->
+    prepare(Sql, Connection, ?DEFAULT_TIMEOUT).
 
 %% @doc
 %%
-%% @spec(connection(), iolist(), timeout()) -> {ok, prepared_statement()} | {error, error_message()}
-prepare(Db, Sql, Timeout) ->
+%% @spec(iolist(), connection(), timeout()) -> {ok, prepared_statement()} | {error, error_message()}
+prepare(Sql, Connection, Timeout) ->
     Ref = make_ref(),
-    ok = esqlite3_nif:prepare(Db, Ref, self(), add_eos(Sql)),
+    ok = esqlite3_nif:prepare(Connection, Ref, self(), add_eos(Sql)),
     receive_answer(Ref, Timeout).
 
 %% @doc Step
@@ -110,21 +164,20 @@ bind(Stmt, Args, Timeout) ->
 %% @doc Close the database
 %%
 %% @spec close(connection()) -> ok | {error, error_message()}
-close(Db) ->
-    close(Db, ?DEFAULT_TIMEOUT).
+close(Connection) ->
+    close(Connection, ?DEFAULT_TIMEOUT).
 
 %% @doc Close the database
 %%
 %% @spec close(connection(), integer()) -> ok | {error, error_message()}
-close(Db, Timeout) ->
+close(Connection, Timeout) ->
     Ref = make_ref(),
-    ok = esqlite3_nif:close(Db, Ref, self()),
+    ok = esqlite3_nif:close(Connection, Ref, self()),
     receive_answer(Ref, Timeout).
 
 %% Internal functions
-
-add_eos(String) when is_list(String) ->
-    [String, 0].
+add_eos(IoList) ->
+    [IoList, 0].
 
 receive_answer(Ref, Timeout) ->
     receive