Function set_input 

pub fn set_input(
    state: &mut LuaState,
    ls: &mut LexState,
    z: ZIO,
    source: GcRef<LuaString>,
    firstchar: i32,
) -> Result<(), LuaError>

Initialise ls for lexing a new chunk from stream z.

C source

// C: void luaX_setinput (lua_State *L, LexState *ls, ZIO *z,
//                         TString *source, int firstchar) {
//   ls->t.token = 0;
//   ls->L = L;
//   ls->current = firstchar;
//   ls->lookahead.token = TK_EOS;  /* no look-ahead token */
//   ls->z = z;
//   ls->fs = NULL;
//   ls->linenumber = 1;
//   ls->lastline = 1;
//   ls->source = source;
//   ls->envn = luaS_newliteral(L, LUA_ENV);  /* get env name */
//   luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);
// }