--[[

	Terra build system, C header generator and LuaJIT ffi binding generator.
	Written by Cosmin Apreutesei. Public Domain.

Features:

	* compiles and links shared libraries.
	* creates C header files and LuaJIT ffi bindings.
	* supports structs, methods, global functions and global vars.
	* dependent struct and function pointer types are declared automatically.
	* tuples and function pointers are typedef'ed with friendly unique names.
	* struct typedefs are anonymous (except when forward declarations are
	  needed because of circular references) which allows the same struct
	  definition to appear in multiple ffi bindings without raising an error.
	* auto-assigns methods to types via ffi.metatype.
	* enables getters and setters via ffi.metatype.
	* publishes global numbers and bitmask values as enums.
	* diff-friendly deterministic output.

Terra type and function object attributes for controlling the output:

	* `cname`   : type/function name override.
	* `opaque`  : declare a type but don't define it.
	* `cprefix` : prefix method names.
	* `private` : tag method as private.
	* `public_methods`: specify which methods to publish.
	* `const_args`: specify which args have the const qualifier.

Conventions:

	* method names that start with an underscore are private by default.

Usage:

	local lib = require'terra.binder'.lib

	MyStruct.cname = 'my_struct_t'
	MyStruct.opaque = true
	MyStruct.methods.myMethod.cname = 'my_method'
	MyStruct.public_methods = {foo=1,bar=1,...}
	MyFunc.cname = 'my_func'
	MyOverloadedFunc.cname = {'my_func', 'my_func2'}
	MyFuncPointer.type.cname = 'myfunc_callback_t'
	MyFunc.const_args = {nil, true} --make arg#2 const (for passing Lua strings)

	local mylib = lib'mylib'

	mylib(MyStruct) --publish Terra struct MyStruct and its dependent types.
	mylib(MyFunc)   --publish Terra function MyFunc and its dependent types.
	mylib(_M, 'SP_', 'CP_') --publish all SP_FOO enums as CP_FOO.
	mylib(_M)       --publish all all-uppercase keys from _M as C enums.

	mylib:build{
		linkto = {'lib1', 'lib2', ...},
		optimize = false,  --for faster compile time when developing.
	}
	mylib:gen_ffi_binding()
	mylib:gen_c_header()

Note:

	C and LuaJIT ffi cannot handle all types of circular struct dependencies
	that Terra can handle, in particular you can't declare a struct with
	forward-declared struct fields (unlike Terra, C eager-completes types).
	This means that you might need to add some types manually in some rare cases.

]]

See the source code for more info.