continue patch (help needed)
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- Subject: continue patch (help needed)
- From: Asko Kauppi <asko.kauppi@...>
- Date: Sat, 9 Apr 2005 21:52:28 +0300
The old "continue patch" is for Lua 5.0 code. It covers three files,
llex.h, llex.c, and lparser.c (where most of the fun is).
The change of for counter scope in >5.0 Lua makes me unaware, where
exactly to place the patched line. Let's see:
This is the original Lua 5.0.2 portion (with patch addition marked):
static void forbody (LexState *ls, int base, int line, int nvars, int
isnum) {
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, nvars); /* scope for all variables */
check(ls, TK_DO);
enterblock(fs, &bl, 1); /* loop block */
prep = luaK_getlabel(fs);
block(ls);
>>> luaK_patchtohere(fs, bl.continuelist);
luaK_patchtohere(fs, prep-1);
endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars - 3);
luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */
luaK_patchlist(fs, (isnum) ? endfor : luaK_jump(fs), prep);
leaveblock(fs);
}
This is 5.1w4 'modern' portion with both A and B tried (but neither
worked):
static void forbody (LexState *ls, int base, int line, int nvars, int
isnum) {
/* forbody -> DO block */
BlockCnt bl;
FuncState *fs = ls->fs;
int prep, endfor;
adjustlocalvars(ls, 3); /* control variables */
checknext(ls, TK_DO);
prep = luaK_codeAsBx(fs, (isnum ? OP_FORPREP : OP_TFORPREP), base,
NO_JUMP);
enterblock(fs, &bl, 0); /* scope for declared variables */
adjustlocalvars(ls, nvars);
luaK_reserveregs(fs, nvars);
block(ls);
>>> A: luaK_patchtohere(fs, bl.continuelist);
leaveblock(fs); /* end of scope for declared variables */
>>> B: luaK_patchtohere(fs, bl.continuelist);
luaK_patchtohere(fs, prep);
endfor = (isnum) ? luaK_codeAsBx(fs, OP_FORLOOP, base, NO_JUMP) :
luaK_codeABC(fs, OP_TFORLOOP, base, 0, nvars);
luaK_fixline(fs, line); /* pretend that `OP_FOR' starts the loop */
luaK_patchlist(fs, (isnum ? endfor : luaK_jump(fs)), prep + 1);
}
When 'continue' within a for loop is met, the execution goes into
eternal loop (or so it seems..)
-ak