Lua Firebird UDF

luafbudf is a tiny library to use a Lua interpreter within a Firebird database. This library doesn't add scripting support to Firebird's Engine, just make it available for ad-hoc scripts.

This library registers a set of UDF functions that accept a variable number of arguments. The functions are named lua, lua1, lua2, ..., lua8, accepting zero, one, two to eight arguments (Firebird don't support varargs).

The usage is very simple. Just execute the .sql on your Firebird Database and invoke the script as:

select lua( 'return 2 + 2 * 2' ) from rdb$database;
select lua2( 'local a, b = ...; return math.pow( a, b )', 42, 3 ) from rdb$database;
select lua2( '@math.pow', 42, 3 ) from rdb$database;

If the script source starts with an at symbol @, then Lua UDF will try to traverse the path and find a suitable function:

select lua1( '@foo.bar.baz', 42 ) from rdb$database;

Is the equivalent to return foo.bar.baz( 42 ). If the field member contain dots, then a special case is provided:

select lua1( '@foo[lorem.ipsum]baz', 42 ) from rdb$database;

Is the equivalent to return foo[ "lorem.ipsum" ].baz( 42 ). There is no special syntax to method call.

As a convenience, Lua UDF exports a global table named pkg that is a wrapper to the require function. This way, you can do things like:

select lua2( '@pkg[socket.http]request', URL, POSTDATA ) from webservices;

Instead of

select lua2( 'return require "socket.http".request( ... )', URL, POSTDATA ) from webservices;

Whilst it may seen unnecessary, the former sugar avoids to parse the source script for every tuple in the relation.

Important due to a bug in the Firebird API, these UDF functions can not accept DATE, TIME nor TIMESTAMP values.