| Prefix | Header | Abstraction |
|---|---|---|
luaL_ |
lauxlib.h |
Auxiliary library (extends public API) |
luaK_ |
lcode.h |
Code generator |
| N/A | lctype.h |
Replacement for ctype.h |
luaG_ |
ldebug.h |
Debug hooks? |
luaD_ |
ldo.h |
Calls; register-window stack |
luaF_ |
lfunc.h |
Closures and free varibles (“upvalues”) |
luaC_ |
lgc.h |
Garbage collection |
luaX_ |
llex.h |
Lexical analysis |
| N/A | llimits.h |
Sizes, limits, numeric-operation macros |
luaM_ |
lmem.h |
Allocation |
luaO_ |
lobject.h |
Key representations: Values, type tags, conversions |
| N/A | lopcodes.h |
Instruction decoding; opcode table |
| N/A | lparser.h |
Parser; classification of names |
luaE_ |
lstate.h |
Interpreter state; call stack |
luaS_ |
lstring.h |
Strings |
luaH_ |
ltable.h |
(Hash) tables |
luaT_ |
ltm.h |
Tag methods (metamethods) |
lua_ |
lua.h |
Public (C) API |
| N/A | luaconf.h |
Configuration for portability (uninteresting) |
luaopen_ |
lualib.h |
Access to standard libraries |
luaV_ |
lvm.h |
Bytecode interpreter & operations |
luaZ_ |
lzio.h |
Buffered streams |
Before tackling any code, read this documentation:
The section on Lua Stack and Registers in the Lua 5.3 Bytecode Reference
API documentation for these functions:
Note: When reading source code, you may want to use the Unix “tags” facility, which gives you a fast way to jump to the definition of any identifier. If you use Emacs or vi, look up the Unix commands etags or ctags.
On line 160 of header file lstate.h, understand these fields of the struct lua_State:
top, stack_last, and stack (type StkId is TValue *)ci and ncibase_cierrorJmpnCcallsOn line 65 of header file lstate.h, understand the CallInfo structure. Ignore fields having to do with yields.
On line 97 of lapi.c, read the implementation of lua_checkstack. Note differences between ci->top and L->top.
On line 60 of lapi.c, read the first two cases in the implementation of index2addr.
On line 1130 of lvm.c, read the implementation of the OP_CALL opcode, and also the implementation of luaD_precall on line 413 of ldo.c. Be prepared to compare the two main cases of luaD_precall. Ignore the “hook” code.
Finally, the implementation of pcall:
Starting on line 931 of lapi.c, read the implementation of lua_pcallk. Focus on the special case of lua_pcall, in which ctx is 0 and k is NULL. (Note: functions savestack and restorestack convert a stack index to and from an integer, which is then resilient to movement (reallocation) of the stack.)
Notice function f_call; it uses luaD_callnoyield and luaD_call as a roundabout way of getting to luaD_precall and luaV_execute.
On line 721 of ldo.c, read the implementation of luaD_pcall. Focus on the stack unwinding. Don’t get distracted by luaD_shrinkstack.
On line 136 of ldo.c, read the implementation of luaD_rawrunprotected. The LUAI_TRY macro calls setjmp, and it executes the body if setjmp returns 0, which happens on the first trip though. The outcome of the body is represented by the contents of field lj.status. During the execution of the protected call, this field is the same as L->errorJmp->status, which may be set to an error code by luaD_throw (just above). The final status is returned from luaD_rawrunprotected.
How is the Lua call stack represented?
How does it present an interleaving of Lua activations with C activations? What’s actually happening with the C stack?
How does the Lua call stack work with the register-window stack (also known as “the Lua stack”)?
In the virtual machine, how does the CALL instruction work?
In the API, how does function lua_call work?
How is the Lua primitive pcall implemented?