Lua

This repo is a clone of the official Lua repository https://github.com/lua/lua, where I publish my own changes and improvements.

This branch implements…

Direct enumeration of collections in Lua for in loops.

This branch adds support for direct for..in enumeration in Lua, for any type of collection: Lua tables and native collections implemented as userdata, without having to call pair() or ipair(), in the for-in statement.

For example, you can now write:

for var1, var2, var3 in collection do
    -- do some stuff
end

Direct for..in enumeration can be customized by defining a "__forgen" metamethod that shall return the 3 values needed by the generic for loop: an iterator function, a state, and the initial value of the iterator variable.

If no "__forgen" metamethod is defined and the collection is a Lua table, direct for..in enumeration is equivalent to calling the standard Lua library function pair().

Internally, a new Lua op-code 'OP_TFORPREP' has been added, that replaces the initial JMP instruction when initializing a generic for loop. When executed, this opcode checks for the presence of a "__forgen" metamethod in the loop base object and calls it if present.