README.md

fblualib C++ utilities

This module provides a few C++ utilities wrapping the Lua API. #include <fblualib/LuaUtils.h>

The module provides a series of functions named (and organized) as follows: for a type Foo (see below as to what types are allowed), we have:

• luaGetFoo(lua_State* L, int index) returns a folly::Optional<Foo>, which is set (non-empty) if the element on the stack at the given index can be converted to a Foo and empty otherwise
• luaGetFooChecked(lua_State* L, int index) returns a Foo if the element on the stack at the given index can be converted to a Foo, and raises a Lua error otherwise
• luaGetFieldIfFoo(lua_State* L, int index, const char* field) behaves similarly to luaGetFoo, but retrieves the data from a string-keyed field in a Lua table at the given index
• luaGetFieldIfFooChecked(lua_State* L, int index, const char* field) behaves similarly to luaGetFooChecked, but retrieves a field as above

Possible types (values of Foo) are:

• String; the value type is folly::StringPiece
• Number<T>, templated by a numeric type; the value type is T (so luaGetNumber<float>(L, index), etc)
• Tensor<T>, templated by a numeric type; the value type is thpp::Tensor<T> (so luaGetTensor<float>(L, index), etc)

luaGetString* and luaGetNumber* support an extra bool strict argument (default false) indicating whether the data must be of the exact expected type (strict = true) or may be converted (strict = false); with strict = false, we will convert between numbers and strings, and will round floating-point values if integers are requested; with strict = true, we won't.

There is also luaPushTensor(lua_Stte* L, thpp::Tensor<T> tensor) which pushes a tensor on the stack (use the lua_* or luaL_* functions from the Lua standard library for other types).