lua line numbers after multiple calls to loadbuffer - lua

Question

I load two strings with loadbuffer into one lua_state.
if( luaL_loadbuffer( L, str.c_str(), str.size(), "line") != 0 )
{
printf( "%s\n", lua_tostring ((lua_State *)L, -1));
}
lua_pcall(L, 0, 0, 0);
if( luaL_loadbuffer( L, str2.c_str(), str2.size(), "line2") != 0 )
{
printf( "%s\n", lua_tostring ((lua_State *)L, -1));
}
lua_pcall(L, 0, 0, 0);
For example:
function f ()
print( "Hello World!")
end
and
function g ()
f(
end
The forgotten ) in the second string throws an error:
[string "line2"]:9: unexpected Symbol
But 9 is the line number from string 1 plus string 2. The line number should be 3.
Is there a way to reset the line number counter before call to loadbuffer?

Answer 1

I guess this link describes your situation:
http://www.corsix.org/content/common-lua-pitfall-loading-code
You are loading two chunks of information, calling the chunks will put them consecutive into the global table. The lua_pcall(L, 0, 0, 0); is not calling your f() and g(), but is constructing your lua code sequential.
Your code could possibly be simplified to:
if (luaL_dostring(L, str.c_str()))
{
printf("%s\n", lua_tostring (L, -1));
}
if (luaL_dostring(L, str2.c_str()));
{
printf("%s\n", lua_tostring (L, -1));
}
which also protects against calling a chunk when it fails to load;

Answer 2

You are right Enigma, the code from str2 is appended consecutive. A breakpoint in
static void statement (LexState *ls) {
in lparser.cpp shows LexState.linenumber to be 5 and 7 for str, and 5, 7, 14 and 16 for str2.
So str is lexed and added to the VM twice.
I will find a different way to put a script made of multiple files into one VM.

Answer 3

Just if someone would need it too.
Add this function to lauxlib.h
LUALIB_API int (luaL_loadbuffers) (lua_State *L, size_t count, const char **buff, size_t *sz,
const char **name, const char *mode);
and to lauxlib.c
#include"lzio.h"
#include"ldo.h"
#include"ltable.h"
#include"lgc.h"
LUALIB_API int luaL_loadbuffers (lua_State *L, size_t count, const char **buff, size_t *sz,
const char **name, const char *mode)
{
ZIO z;
int status;
int i;
for( i=0; i<count; i++)
{
LoadS ls;
ls.s = buff[i];
ls.size = sz[i];
lua_lock(L);
luaZ_init(L, &z, getS, &ls);
status = luaD_protectedparser(L, &z, name[i], mode);
if (status == LUA_OK) { /* no errors? */
LClosure *f = clLvalue(L->top - 1); /* get newly created function */
if (f->nupvalues == 1) { /* does it have one upvalue? */
/* get global table from registry */
Table *reg = hvalue(&G(L)->l_registry);
const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
/* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
setobj(L, f->upvals[0]->v, gt);
luaC_barrier(L, f->upvals[0], gt);
} // == 1
lua_pcall( L, 0, 0, 0);
}
lua_unlock(L);
if( status != LUA_OK )
break;
}
return status;
}
Every string/file gets its own line numnbering.
It is just a copy, almost, of lua_load in lapi.c. So easy to adjust in a new release of LUA.