util.sqlite3: Deduplicate query methods

There were 3 very similar methods:
-   :execute()
-   :execute_query()
-   :execute_update()

The first one returns the prepared statement and is mainly used
internally in the library for CREATE statements.

The later two only really differ in how the results are returned.
Those two are one main method and one small one that only picks out the
iterator.

util/sqlite3.lua

@@ -9,6 +9,7 @@ local type = type
 local t_concat = table.concat;
 local t_insert = table.insert;
 local s_char = string.char;
+local array = require "prosody.util.array";
 local log = require "prosody.util.logger".init("sql");
 
 local lsqlite3 = require "lsqlite3";
@@ -194,13 +195,6 @@ function engine:execute(sql, ...)
 	return stmt;
 end
 
-local result_mt = {
-	__index = {
-	affected = function(self) return self.__affected; end;
-	rowcount = function(self) return self.__rowcount; end;
-	},
-};
-
 local function iterator(table)
 	local i = 0;
 	return function()
@@ -212,6 +206,23 @@ local function iterator(table)
 	end
 end
 
+local result_mt = {
+	__len = function(self)
+		return self.__rowcount;
+	end;
+	__index = {
+		affected = function(self)
+			return self.__affected;
+		end;
+		rowcount = function(self)
+			return self.__rowcount;
+		end;
+	};
+	__call = function(self)
+		return iterator(self.__data);
+	end;
+};
+
 local function debugquery(where, sql, ...)
 	local i = 0; local a = {...}
 	sql = sql:gsub("\n?\t+", " ");
@@ -225,7 +236,7 @@ local function debugquery(where, sql, ...)
 	end)));
 end
 
-function engine:execute_query(sql, ...)
+function engine:execute_update(sql, ...)
 	local prepared = self.prepared;
 	local stmt = prepared[sql];
 	if stmt and stmt:isopen() then
@@ -235,38 +246,20 @@ function engine:execute_query(sql, ...)
 	end
 	local ret = stmt:bind_values(...);
 	if ret ~= lsqlite3.OK then error(self.conn:errmsg()); end
-	local data, ret = {}
-	while stmt:step() == ROW do
-		t_insert(data, stmt:get_values());
+	local data = array();
+	for row in stmt:rows() do
+		data:push(array(row));
 	end
 	-- FIXME Error handling, BUSY, ERROR, MISUSE
 	if stmt:reset() == lsqlite3.OK then
 		prepared[sql] = stmt;
 	end
-	return setmetatable({ __data = data }, { __index = result_mt.__index, __call = iterator(data) });
-end
-function engine:execute_update(sql, ...)
-	local prepared = self.prepared;
-	local stmt = prepared[sql];
-	if not stmt or not stmt:isopen() then
-		stmt = assert(self.conn:prepare(sql));
-	else
-		prepared[sql] = nil;
-	end
-	local ret = stmt:bind_values(...);
-	if ret ~= lsqlite3.OK then error(self.conn:errmsg()); end
-	local rowcount = 0;
-	repeat
-		ret = stmt:step();
-		if ret == lsqlite3.ROW then
-			rowcount = rowcount + 1;
-		end
-	until ret ~= lsqlite3.ROW;
 	local affected = self.conn:changes();
-	if stmt:reset() == lsqlite3.OK then
-		prepared[sql] = stmt;
-	end
-	return setmetatable({ __affected = affected, __rowcount = rowcount }, result_mt);
+	return setmetatable({ __affected = affected; __rowcount = #data; __data = data }, result_mt);
+end
+
+function engine:execute_query(sql, ...)
+	return self:execute_update(sql, ...)()
 end
 
 engine.insert = engine.execute_update;