commit bf8b08295aa2f4b66aeb7d8313d464ccd80c0b0c
parent 3f5b56c48b51b0e4e2c439f1d0bf717b018c1aee
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Thu, 10 Feb 2011 12:50:17 -0200
'break' coded as 'goto' + small bug when closing multiple gotos
to the same label
Diffstat:
| M | lparser.c | | | 111 | +++++++++++++++++++++++++++++++++++++------------------------------------------ |
1 file changed, 52 insertions(+), 59 deletions(-)
diff --git a/lparser.c b/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 */
