mirror of
https://github.com/lua/lua.git
synced 2025-01-14 05:43:00 +08:00
'break' coded as 'goto' + small bug when closing multiple gotos
to the same label
This commit is contained in:
Roberto Ierusalimschy
parent
3f5b56c48b
commit
bf8b08295a
111
lparser.c
111
lparser.c
@ -1,5 +1,5 @@
|
||||
/*
|
||||
** $Id: lparser.c,v 2.102 2011/02/09 16:51:28 roberto Exp roberto $
|
||||
** $Id: lparser.c,v 2.103 2011/02/09 17:03:18 roberto Exp $
|
||||
** Lua Parser
|
||||
** See Copyright Notice in lua.h
|
||||
*/
|
||||
@ -41,7 +41,6 @@
|
||||
*/
|
||||
typedef struct BlockCnt {
|
||||
struct BlockCnt *previous; /* chain */
|
||||
int breaklist; /* list of jumps out of this loop */
|
||||
int firstlabel; /* index of first label in this block */
|
||||
int firstgoto; /* index of first pending goto in this block */
|
||||
lu_byte nactvar; /* # active locals outside the block */
|
||||
@ -380,16 +379,31 @@ static int findlabel (LexState *ls, int g) {
|
||||
}
|
||||
|
||||
|
||||
static int newlabelentry (LexState *ls, Labellist *l, TString *name,
|
||||
int line, int pc) {
|
||||
int n = l->n;
|
||||
luaM_growvector(ls->L, l->arr, n, l->size, Labeldesc, MAX_INT, "labels");
|
||||
l->arr[n].name = name;
|
||||
l->arr[n].line = line;
|
||||
l->arr[n].nactvar = ls->fs->nactvar;
|
||||
l->arr[n].pc = pc;
|
||||
l->n++;
|
||||
return n;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
** check whether new label 'lb' matches any pending goto in current
|
||||
** check whether new label 'lb' matches any pending gotos in current
|
||||
** block; solves forward jumps
|
||||
*/
|
||||
static void findgotos (LexState *ls, Labeldesc *lb) {
|
||||
int i;
|
||||
Dyndata *dyd = ls->dyd;
|
||||
for (i = ls->fs->bl->firstgoto; i < dyd->gt.n; i++) {
|
||||
int i = ls->fs->bl->firstgoto;
|
||||
while (i < dyd->gt.n) {
|
||||
if (eqstr(dyd->gt.arr[i].name, lb->name))
|
||||
closegoto(ls, i, lb);
|
||||
else
|
||||
i++;
|
||||
}
|
||||
}
|
||||
|
||||
@ -419,7 +433,6 @@ static void movegotosout (FuncState *fs, BlockCnt *bl) {
|
||||
|
||||
|
||||
static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
|
||||
bl->breaklist = NO_JUMP;
|
||||
bl->isloop = isloop;
|
||||
bl->nactvar = fs->nactvar;
|
||||
bl->firstlabel = fs->ls->dyd->label.n;
|
||||
@ -431,30 +444,48 @@ static void enterblock (FuncState *fs, BlockCnt *bl, lu_byte isloop) {
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
** create a label named "break" to resolve break statements
|
||||
*/
|
||||
static void breaklabel (LexState *ls) {
|
||||
TString *n = luaS_new(ls->L, "break");
|
||||
int l = newlabelentry(ls, &ls->dyd->label, n, 0, ls->fs->pc);
|
||||
findgotos(ls, &ls->dyd->label.arr[l]);
|
||||
}
|
||||
|
||||
/*
|
||||
** generates an error for an undefined 'goto'; choose appropriate
|
||||
** message when label name is a resserved word (which can only be 'break')
|
||||
*/
|
||||
static void undefgoto (LexState *ls, Labeldesc *gt) {
|
||||
const char *msg = (gt->name->tsv.reserved > 0)
|
||||
? "<%s> at line %d not inside a loop"
|
||||
: "label " LUA_QS " (<goto> at line %d) undefined";
|
||||
msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
|
||||
semerror(ls, msg);
|
||||
}
|
||||
|
||||
|
||||
static void leaveblock (FuncState *fs) {
|
||||
BlockCnt *bl = fs->bl;
|
||||
LexState *ls = fs->ls;
|
||||
fs->bl = bl->previous;
|
||||
removevars(fs, bl->nactvar);
|
||||
ls->dyd->label.n = bl->firstlabel; /* remove local labels */
|
||||
if (bl->previous) /* inner block? */
|
||||
movegotosout(fs, bl); /* update pending gotos to outer block */
|
||||
else if (bl->firstgoto < ls->dyd->gt.n) { /* pending gotos in outer block? */
|
||||
Labeldesc *gt = &ls->dyd->gt.arr[bl->firstgoto];
|
||||
const char *msg = luaO_pushfstring(ls->L,
|
||||
"label " LUA_QS " (<goto> at line %d) undefined",
|
||||
getstr(gt->name), gt->line);
|
||||
semerror(ls, msg);
|
||||
}
|
||||
if (bl->previous && bl->upval) {
|
||||
/* create a 'jump to here' to close upvalues */
|
||||
int j = luaK_jump(fs);
|
||||
luaK_patchclose(fs, j, bl->nactvar);
|
||||
luaK_patchtohere(fs, j);
|
||||
}
|
||||
if (bl->isloop)
|
||||
breaklabel(ls); /* close pending breaks */
|
||||
fs->bl = bl->previous;
|
||||
removevars(fs, bl->nactvar);
|
||||
lua_assert(bl->nactvar == fs->nactvar);
|
||||
fs->freereg = fs->nactvar; /* free registers */
|
||||
luaK_patchtohere(fs, bl->breaklist);
|
||||
ls->dyd->label.n = bl->firstlabel; /* remove local labels */
|
||||
if (bl->previous) /* inner block? */
|
||||
movegotosout(fs, bl); /* update pending gotos to outer block */
|
||||
else if (bl->firstgoto < ls->dyd->gt.n) /* pending gotos in outer block? */
|
||||
undefgoto(ls, &ls->dyd->gt.arr[bl->firstgoto]); /* error */
|
||||
}
|
||||
|
||||
|
||||
@ -1070,7 +1101,6 @@ static void block (LexState *ls) {
|
||||
BlockCnt bl;
|
||||
enterblock(fs, &bl, 0);
|
||||
statlist(ls);
|
||||
lua_assert(bl.breaklist == NO_JUMP);
|
||||
leaveblock(fs);
|
||||
}
|
||||
|
||||
@ -1159,44 +1189,6 @@ static int cond (LexState *ls) {
|
||||
}
|
||||
|
||||
|
||||
/* code a break statement. The last 'if' decides the need to close
|
||||
upvalues when leaving the block. If the block has upvalues, it
|
||||
must be closed. If it has local variables and any label
|
||||
before the break, those variables must be closed too, as they
|
||||
may be used as upvalues after the break and through a goto
|
||||
be exited through this break.
|
||||
*/
|
||||
static void breakstat (LexState *ls) {
|
||||
FuncState *fs = ls->fs;
|
||||
BlockCnt *bl = fs->bl;
|
||||
int upval = 0;
|
||||
while (bl && !bl->isloop) {
|
||||
upval |= bl->upval;
|
||||
bl = bl->previous;
|
||||
}
|
||||
if (!bl)
|
||||
semerror(ls, "no loop to break");
|
||||
luaK_concat(fs, &bl->breaklist, luaK_jump(fs));
|
||||
if (upval ||
|
||||
(fs->nactvar > bl->nactvar &&
|
||||
ls->dyd->label.n > bl->firstlabel))
|
||||
luaK_patchclose(fs, bl->breaklist, bl->nactvar);
|
||||
}
|
||||
|
||||
|
||||
static int newlabelentry (LexState *ls, Labellist *l, TString *name,
|
||||
int line, int pc) {
|
||||
int n = l->n;
|
||||
luaM_growvector(ls->L, l->arr, l->n, l->size, Labeldesc, MAX_INT, "labels");
|
||||
l->arr[n].name = name;
|
||||
l->arr[n].line = line;
|
||||
l->arr[n].nactvar = ls->fs->nactvar;
|
||||
l->arr[n].pc = pc;
|
||||
l->n++;
|
||||
return n;
|
||||
}
|
||||
|
||||
|
||||
static void gotostat (LexState *ls, TString *label, int line) {
|
||||
/* create new entry for this goto */
|
||||
int g = newlabelentry(ls, &ls->dyd->gt, label, line, luaK_jump(ls->fs));
|
||||
@ -1551,7 +1543,8 @@ static int statement (LexState *ls) {
|
||||
}
|
||||
case TK_BREAK: { /* stat -> breakstat */
|
||||
luaX_next(ls); /* skip BREAK */
|
||||
breakstat(ls);
|
||||
/* code it as "goto 'break'" */
|
||||
gotostat(ls, luaS_new(ls->L, "break"), line);
|
||||
return 1; /* must be last statement */
|
||||
}
|
||||
case TK_GOTO: { /* stat -> 'goto' NAME */
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user