Backport __ from v- #557
Comments
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Here is a first attempt to backport it from ksh 93v- 2013-08-07. The changes all involve First backport attemptdiff --git a/src/cmd/ksh93/include/name.h b/src/cmd/ksh93/include/name.h
index 74684894f..91a89858b 100644
--- a/src/cmd/ksh93/include/name.h
+++ b/src/cmd/ksh93/include/name.h
@@ -84,6 +84,7 @@ struct Namref
{
Namval_t *np;
Namval_t *table;
+ Namval_t *oldnp;
Dt_t *root;
char *sub;
#if SHOPT_FIXEDARRAY
@@ -153,6 +154,7 @@ struct Ufunction
#define nv_reftree(n) ((n)->nvalue.nrp->root)
#define nv_reftable(n) ((n)->nvalue.nrp->table)
#define nv_refsub(n) ((n)->nvalue.nrp->sub)
+#define nv_refoldnp(n) ((n)->nvalue.nrp->oldnp)
#if SHOPT_FIXEDARRAY
# define nv_refindex(n) ((n)->nvalue.nrp->curi)
# define nv_refdimen(n) ((n)->nvalue.nrp->dim)
@@ -206,6 +208,7 @@ extern void nv_outnode(Namval_t*,Sfio_t*, int, int);
extern int nv_subsaved(Namval_t*, int);
extern void nv_typename(Namval_t*, Sfio_t*);
extern void nv_newtype(Namval_t*);
+extern Namval_t *nv_typeparent(Namval_t*);
extern int nv_istable(Namval_t*);
extern size_t nv_datasize(Namval_t*, size_t*);
extern Namfun_t *nv_mapchar(Namval_t*, const char*);
diff --git a/src/cmd/ksh93/include/shell.h b/src/cmd/ksh93/include/shell.h
index 7efad5109..b5b49a36a 100644
--- a/src/cmd/ksh93/include/shell.h
+++ b/src/cmd/ksh93/include/shell.h
@@ -285,6 +285,7 @@ struct Shell_s
Namval_t *namespace; /* current active namespace */
Namval_t *last_table; /* last table used in last nv_open */
Namval_t *prev_table; /* previous table used in nv_open */
+ Namval_t *oldnp; /* last valid parent node */
Sfio_t *outpool; /* output stream pool */
long timeout; /* read timeout */
unsigned int curenv; /* current subshell number */
diff --git a/src/cmd/ksh93/sh/name.c b/src/cmd/ksh93/sh/name.c
index 580205a88..80b6d1c46 100644
--- a/src/cmd/ksh93/sh/name.c
+++ b/src/cmd/ksh93/sh/name.c
@@ -704,6 +704,18 @@ static char *stack_extend(const char *cname, char *cp, int n)
return (char*)name;
}
+static Namval_t *nv_parentnode(Namval_t *np)
+{
+ Namval_t *mp = np;
+ if(nv_istable(np))
+ return nv_parent(np);
+ if(mp=nv_typeparent(np))
+ return mp;
+ if((mp= (Namval_t*)np->nvenv))
+ return mp;
+ return np;
+}
+
Namval_t *nv_create(const char *name, Dt_t *root, int flags, Namfun_t *dp)
{
char *sub=0, *cp=(char*)name, *sp, *xp;
@@ -872,6 +884,9 @@ Namval_t *nv_create(const char *name, Dt_t *root, int flags, Namfun_t *dp)
if(c)
*sp = c;
top = 0;
+ if(np && !nv_isattr(np,NV_MINIMAL) && sh.oldnp && !np->nvenv && sh.oldnp!=np)
+ np->nvenv = (char*)sh.oldnp;
+ sh.oldnp = np;
if(isref)
{
#if SHOPT_FIXEDARRAY
@@ -898,6 +913,8 @@ Namval_t *nv_create(const char *name, Dt_t *root, int flags, Namfun_t *dp)
n = nv_refindex(np);
dim = nv_refdimen(np);
#endif /* SHOPT_FIXEDARRAY */
+ if(sh.oldnp = nv_refoldnp(np))
+ sh.oldnp = (Namval_t*)sh.oldnp->nvenv;
np = nv_refnode(np);
#if SHOPT_FIXEDARRAY
if(n)
@@ -1208,7 +1225,25 @@ Namval_t *nv_create(const char *name, Dt_t *root, int flags, Namfun_t *dp)
return np;
cp++;
break;
+ case '_':
+ if(cp[1]=='_' && (cp[2]==0 || cp[2]=='.') && sh.oldnp)
+ {
+ cp += 2;
+ dp->last = cp;
+ nvcache.ok = 0;
+ sh.oldnp = np = nv_parentnode(sh.oldnp);
+ if(*cp==0)
+ return np;
+ sp = nv_name(np);
+ c = strlen(sp);
+ dp->nofree |= 1;
+ name = copystack(sp,cp,NULL);
+ cp = (char*)name+c+1;
+ break;
+ }
+ /* FALLTHROUGH */
default:
+ sh.oldnp = np;
dp->last = cp;
if((c = mbchar(cp)) && !isaletter(c))
return np;
@@ -3384,6 +3419,7 @@ void nv_setref(Namval_t *np, Dt_t *hp, int flags)
np->nvalue.nrp = sh_newof(0,struct Namref,1,sizeof(Dtlink_t));
np->nvalue.nrp->np = nq;
np->nvalue.nrp->root = hp;
+ np->nvalue.nrp->oldnp = sh.oldnp;
if(ep)
{
#if SHOPT_FIXEDARRAY
@@ -3531,14 +3567,17 @@ char *nv_name(Namval_t *np)
if(!nv_isattr(np,NV_MINIMAL|NV_EXPORT) && np->nvenv)
{
Namval_t *nq= sh.last_table, *mp= (Namval_t*)np->nvenv;
- if(np==sh.last_table)
- sh.last_table = 0;
- if(nv_isarray(mp))
- sfprintf(sh.strbuf,"%s[%s]",nv_name(mp),np->nvname);
- else
- sfprintf(sh.strbuf,"%s.%s",nv_name(mp),np->nvname);
- sh.last_table = nq;
- return sfstruse(sh.strbuf);
+ if(!strchr(np->nvname,'.') || nv_type(mp) || (nv_isarray(mp) && (cp=nv_getsub(mp)) && strcmp(np->nvname,cp)==0))
+ {
+ if(np==sh.last_table)
+ sh.last_table = 0;
+ if(nv_isarray(mp))
+ sfprintf(sh.strbuf,"%s[%s]",nv_name(mp),np->nvname);
+ else
+ sfprintf(sh.strbuf,"%s.%s",nv_name(mp),np->nvname);
+ sh.last_table = nq;
+ return sfstruse(sh.strbuf);
+ }
}
if(nv_istable(np))
sh.last_table = nv_parent(np);
diff --git a/src/cmd/ksh93/sh/nvtree.c b/src/cmd/ksh93/sh/nvtree.c
index 3aca14e51..b42e12cda 100644
--- a/src/cmd/ksh93/sh/nvtree.c
+++ b/src/cmd/ksh93/sh/nvtree.c
@@ -704,6 +704,8 @@ static void outval(char *name, const char *vname, struct Walk *wp)
if(fp = nv_stack(np,NULL))
free(fp);
np->nvfun = 0;
+ if(!nv_isattr(np,NV_MINIMAL))
+ np->nvenv = 0;
return;
}
for(xp=fp->next; xp; xp = xp->next)
@@ -1004,7 +1006,9 @@ static char *walk_tree(Namval_t *np, Namval_t *xp, int flags)
sh.var_tree = dp;
if(nq && mq)
{
+ char *nvenv = mq->nvenv;
nv_clone(nq,mq,flags|NV_RAW);
+ mq->nvenv = nvenv;
if(flags&NV_MOVE)
nv_delete(nq,walk.root,0);
}
diff --git a/src/cmd/ksh93/sh/nvtype.c b/src/cmd/ksh93/sh/nvtype.c
index 56db5998a..21e1db54d 100644
--- a/src/cmd/ksh93/sh/nvtype.c
+++ b/src/cmd/ksh93/sh/nvtype.c
@@ -447,9 +447,12 @@ static Namfun_t *clone_type(Namval_t* np, Namval_t *mp, int flags, Namfun_t *fp)
nv_addnode(nr,1);
if(pp->strsize<0)
continue;
- _nv_unset(nr,0);
- if(!nv_isattr(nr,NV_MINIMAL))
- nv_delete(nr,sh.last_root,0);
+ if(nr != (Namval_t*)np->nvenv)
+ {
+ _nv_unset(nr,0);
+ if(!nv_isattr(nr,NV_MINIMAL))
+ nv_delete(nr,sh.last_root,0);
+ }
}
else if(nv_isattr(nq,NV_RDONLY) && !nq->nvalue.cp && !nv_isattr(nq,NV_INTEGER))
{
@@ -1509,3 +1512,14 @@ int sh_outtype(Sfio_t *out)
dtinsert(sh.var_base,L_ARGNOD);
return 0;
}
+
+Namval_t *nv_typeparent(Namval_t *np)
+{
+ Namchld_t *fp;
+ Namtype_t *tp;
+ if(fp = (Namchld_t*)nv_hasdisc(np,&chtype_disc))
+ return fp->ptype->parent;
+ if(tp = (Namtype_t*)nv_hasdisc(np,&type_disc))
+ return tp->parent;
+ return 0;
+}
diff --git a/src/cmd/ksh93/sh/subshell.c b/src/cmd/ksh93/sh/subshell.c
index 25e92cdee..3e216bf08 100644
--- a/src/cmd/ksh93/sh/subshell.c
+++ b/src/cmd/ksh93/sh/subshell.c
@@ -349,7 +349,7 @@ static void nv_restore(struct subshell *sp)
}
nv_setsize(mp,nv_size(np));
if(!(flags&NV_MINIMAL))
- mp->nvenv = np->nvenv;
+ mp->nvenv = nv_isnull(mp) ? 0 : np->nvenv;
mp->nvfun = np->nvfun;
if(np->nvfun && nofree)
np->nvfun->nofree = nofree;The patch makes your example script work: typeset -a a=(zero one)
a[3]=three a[4]=four
printf '%s ' "${a[@]/~(E)^/${!__}=}"; echoOutput before patch: However, the patch also causes a few regression test failures: Of course I may well have missed something while backporting this, so please do verify the patch against the 93v- commit linked above. There should also be a fix for it in ksh 93v- 2013-08-29 ("Fixed __ to work in nested types") but I haven't managed to isolated that from all the other changes in that commit yet. I suspect the fix involves an (ab)use of the NV_EXPORT attribute. It's so unfortunate they never kept changes in distinct commits :/ |
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Having said all that, I'm not convinced this is worth integrating into ksh 93u+m. I don't think an interesting hack is worth it when it comes with "the usual assortment of bewildering bugs that obfuscate its intended purpose"; we prioritise fixing bugs here, so I'd like to avoid introducing any where possible. In the example: typeset -a a=(zero one)
a[3]=three a[4]=four
for i in "${!a[@]}"
do printf 'a[%d]=%s ' i "${a[i]}"
done; echo…and that works on every ksh93, and makes for much more legible and understandable code. As for the use in types, in the mailing list thread, you mentioned a workaround that you called "nasty":
I could be convinced to backport |
…on the other hand, that turns out to be a pre-existing quirk of ksh, and not something introduced by this patch. whereas: I would consider the ksh93 behaviour to be clearly a bug, but there are probably scripts that depend on it. :-/ |
It's definitely a feature. The other shells just chose not to implement it for whatever reason. It's required in order to access sub-matches from |
I did not (and still don't) understand Irek and other's objections in that thread. I created that thread due to the misbehavior of From that thread...
Is that even true. If so why? Why
I have no clue what was meant here. A type is nothing like a compound variable other than superficially borrowing bits of the compound assignment grammar for their definitions. Predefined discipline functions? What? I didn't even use a compound variable in that example and
What on earth is a type tree? Why would a type have a parent? Compound variables sure. I think the |
__has many uses for accessing things that you can't get to any other way. I can't name them all because I almost certainly haven't discovered all that it does. In some contexts it behaves as a self-reference as you would expect_to be used for, while in others it has a "parent-of-self" function.One interesting use is to access the current element during a replacement expansion:
Examples of other places where __ does "something":
.sh.mathfunction definitionstypeset -Tobjects.shnamespaceTo name a few. It also has the usual assortment of bewildering bugs that obfuscate its intended purpose.
The origin of
__was a thread in which I pointed out that_within a get/set discipline should reference the current object analogous to the way "properties" or "accessors" work in other languages. https://marc.info/?l=ast-users&m=137448362609866&w=4Evidently this usage conflicted with other people's ideas about what it should do, so
__was added to refer to the parent object in contexts where hierarchical structures apply. It seems to have been extended for other uses, none of which are documented, of course.EDIT: Later in that thread I commented that
__should work like python'ssuper()or something. No clue what I was thinking there. That's nonsense unless ksh adopts a multiple inheritance scheme, which I wouldn't propose. :/The text was updated successfully, but these errors were encountered: