new perldelta

[perl5.git] / av.h

diff --git a/av.h b/av.h
index 488e098..6e0b24d 100644 (file)
--- a/av.h
+++ b/av.h
@@ -1,7 +1,7 @@
 /*    av.h
  *
 /*    av.h
  *

- *    Copyright (C) 1991, 1992, 1993, 1995, 1996, 1997, 1998, 1999,
- *    2000, 2001, 2002, 2005, by Larry Wall and others
+ *    Copyright (C) 1991, 1992, 1993, 1995, 1996, 1997, 1998, 1999, 2000,
+ *    2001, 2002, 2005, 2006, 2007, 2008, by Larry Wall and others

  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.
  *
  *    You may distribute under the terms of either the GNU General Public
  *    License or the Artistic License, as specified in the README file.


@@ -9,60 +9,37 @@
  */
 
 struct xpvav {
  */
 
 struct xpvav {

-    IV         this_space;
-    SSize_t    xav_fill;       /* Index of last element present */
-    SSize_t    xav_max;        /* max index for which array has space */
-    union {
-       struct {
-           void *xnv_p1;       /* pointer to beginning of C array of SVs */
-           union {
-               void *xnv_p2;
-               IV xnv_i2;
-           }   xnv_u2;
-       }       xnv_s;
-       NV      xnvu_nv;
-    }          xnv_u;
-    MAGIC*     xmg_magic;      /* magic for scalar array */

     HV*                xmg_stash;      /* class package */
     HV*                xmg_stash;      /* class package */

-};
-
-#if !defined(PERL_EXPERIMENTAL_LAYOUT)
-typedef struct xpvav xpvav_allocated;
-#else
-typedef struct {
+    union _xmgu        xmg_u;

     SSize_t    xav_fill;       /* Index of last element present */
     SSize_t    xav_max;        /* max index for which array has space */
     SSize_t    xav_fill;       /* Index of last element present */
     SSize_t    xav_max;        /* max index for which array has space */

-    union {
-       NV      xnvu_nv;
-       struct {
-           void *xnv_p1;       /* pointer to beginning of C array of SVs */
-           union {
-               void *xnv_p2;
-               IV xnv_i2;
-           }   xnv_u2;
-       }       xnv_s;
-    }          xnv_u;
-    MAGIC*     xmg_magic;      /* magic for scalar array */
-    HV*                xmg_stash;      /* class package */
-} xpvav_allocated;
-#endif
+    SV**       xav_alloc;      /* pointer to beginning of C array of SVs */
+};

 
 

-/* SV**        xav_alloc; */
-#define xav_alloc xnv_u.xnv_s.xnv_p1

 /* SV* xav_arylen; */
 /* SV* xav_arylen; */

-#define xav_arylen xnv_u.xnv_s.xnv_u2.xnv_p2
-
-/* AVf_REAL is set for all AVs whose xav_array contents are refcounted.
- * Some things like "@_" and the scratchpad list do not set this, to
- * indicate that they are cheating (for efficiency) by not refcounting
- * the AV's contents.
- * 
- * AVf_REIFY is only meaningful on such "fake" AVs (i.e. where AVf_REAL
+
+/* SVpav_REAL is set for all AVs whose xav_array contents are refcounted
+ * and initialized such that any element can be retrieved as a SV*.
+ * Such AVs may be referred to as "real" AVs. Examples include regular
+ * perl arrays, tiedarrays (since v5.16), and padlist AVs.
+ *
+ * Some things do not set SVpav_REAL, to indicate that they are cheating
+ * (for efficiency) by not refcounting the AV's contents or ensuring that
+ * all elements are safe for arbitrary access. This type of AV may be
+ * referred to as "fake" AVs. Examples include "@_" (unless tied), the
+ * scratchpad list, and the backrefs list on an object or stash.
+ *
+ * SVpav_REIFY is only meaningful on such "fake" AVs (i.e. where SVpav_REAL

  * is not set).  It indicates that the fake AV is capable of becoming
  * real if the array needs to be modified in some way.  Functions that
  * modify fake AVs check both flags to call av_reify() as appropriate.
  *
  * is not set).  It indicates that the fake AV is capable of becoming
  * real if the array needs to be modified in some way.  Functions that
  * modify fake AVs check both flags to call av_reify() as appropriate.
  *

- * Note that the Perl stack and @DB::args have neither flag set. (Thus,
+ * av_reify() transforms a fake AV into a real one through two actions.
+ * Allocated but unpopulated elements are initialized to make them safe for
+ * arbitrary retrieval and the reference counts of populated elements are
+ * incremented.
+ *
+ * Note that the Perl stack has neither flag set. (Thus,

  * items that go on the stack are never refcounted.)
  *
  * These internal details are subject to change any time.  AV
  * items that go on the stack are never refcounted.)
  *
  * These internal details are subject to change any time.  AV


@@ -71,26 +48,38 @@ typedef struct {
  */
 
 /*
  */
 
 /*

-=head1 Handy Values
-
-=for apidoc AmU||Nullav
+=for apidoc ADmnU||Nullav

 Null AV pointer.
 
 Null AV pointer.
 

-=head1 Array Manipulation Functions
+(deprecated - use C<(AV *)NULL> instead)
+
+=for apidoc Am|SSize_t|AvFILL|AV* av
+Same as C<L</av_top_index>> or C<L</av_tindex>>.

 
 

-=for apidoc Am|int|AvFILL|AV* av
-Same as C<av_len()>.  Deprecated, use C<av_len()> instead.
+=for apidoc Cm|SSize_t|AvFILLp|AV* av
+
+If the array C<av> is empty, this returns -1; otherwise it returns the maximum
+value of the indices of all the array elements which are currently defined in
+C<av>.  It does not handle magic, hence the C<p> private indication in its name.
+
+=for apidoc Am|SV**|AvARRAY|AV* av
+Returns a pointer to the AV's internal SV* array.
+
+This is useful for doing pointer arithmetic on the array.
+If all you need is to look up an array element, then prefer C<av_fetch>.

 
 =cut
 */
 
 
 =cut
 */
 

-#define Nullav Null(AV*)
+#ifndef PERL_CORE
+#  define Nullav Null(AV*)
+#endif

 
 

-#define AvARRAY(av)    ((av)->sv_u.sv_array)
-#define AvALLOC(av)    (*((SV***)&((XPVAV*)  SvANY(av))->xav_alloc))
+#define AvARRAY(av)    ((av)->sv_u.svu_array)
+#define AvALLOC(av)    ((XPVAV*)  SvANY(av))->xav_alloc

 #define AvMAX(av)      ((XPVAV*)  SvANY(av))->xav_max
 #define AvFILLp(av)    ((XPVAV*)  SvANY(av))->xav_fill
 #define AvMAX(av)      ((XPVAV*)  SvANY(av))->xav_max
 #define AvFILLp(av)    ((XPVAV*)  SvANY(av))->xav_fill

-#define AvARYLEN(av)   (*((SV**)&((XPVAV*)  SvANY(av))->xav_arylen))
+#define AvARYLEN(av)   (*Perl_av_arylen_p(aTHX_ MUTABLE_AV(av)))

 
 #define AvREAL(av)     (SvFLAGS(av) & SVpav_REAL)
 #define AvREAL_on(av)  (SvFLAGS(av) |= SVpav_REAL)
 
 #define AvREAL(av)     (SvFLAGS(av) & SVpav_REAL)
 #define AvREAL_on(av)  (SvFLAGS(av) |= SVpav_REAL)


@@ -101,19 +90,129 @@ Same as C<av_len()>.  Deprecated, use C<av_len()> instead.
 #define AvREIFY_off(av)        (SvFLAGS(av) &= ~SVpav_REIFY)
 #define AvREIFY_only(av)       (AvREAL_off(av), SvFLAGS(av) |= SVpav_REIFY)
 
 #define AvREIFY_off(av)        (SvFLAGS(av) &= ~SVpav_REIFY)
 #define AvREIFY_only(av)       (AvREAL_off(av), SvFLAGS(av) |= SVpav_REIFY)
 

+

 #define AvREALISH(av)  (SvFLAGS(av) & (SVpav_REAL|SVpav_REIFY))
                                           
 #define AvREALISH(av)  (SvFLAGS(av) & (SVpav_REAL|SVpav_REIFY))
                                           

-#define AvFILL(av)     ((SvRMAGICAL((SV *) (av))) \
-                         ? mg_size((SV *) av) : AvFILLp(av))
+#define AvFILL(av)     ((SvRMAGICAL((const SV *) (av))) \
+                         ? mg_size(MUTABLE_SV(av)) : AvFILLp(av))
+#define av_top_index(av) AvFILL(av)
+#define av_tindex(av)    av_top_index(av)
+
+/* Note that it doesn't make sense to do this:
+ *      SvGETMAGIC(av); IV x = av_tindex_nomg(av);
+ */
+#   define av_top_index_skip_len_mg(av)                                     \
+                            (__ASSERT_(SvTYPE(av) == SVt_PVAV) AvFILLp(av))
+#   define av_tindex_skip_len_mg(av)  av_top_index_skip_len_mg(av)

 
 #define NEGATIVE_INDICES_VAR "NEGATIVE_INDICES"
 
 /*
 
 #define NEGATIVE_INDICES_VAR "NEGATIVE_INDICES"
 
 /*

- * Local variables:
- * c-indentation-style: bsd
- * c-basic-offset: 4
- * indent-tabs-mode: t
- * End:
- *
- * ex: set ts=8 sts=4 sw=4 noet:
+
+Note that there are both real and fake AVs; see the beginning of this file and
+'av.c'
+
+=for apidoc newAV
+=for apidoc_item newAV_alloc_x
+=for apidoc_item newAV_alloc_xz
+
+These all create a new AV, setting the reference count to 1.  If you also know
+the initial elements of the array with, see L</C<av_make>>.
+
+As background, an array consists of three things:
+
+=over
+
+=item 1.
+
+A data structure containing information about the array as a whole, such as its
+size and reference count.
+
+=item 2.
+
+A C language array of pointers to the individual elements.  These are treated
+as pointers to SVs, so all must be castable to SV*.
+
+=item 3.
+
+The individual elements themselves.  These could be, for instance, SVs and/or
+AVs and/or HVs, etc.
+
+=back
+
+An empty array need only have the first data structure, and all these functions
+create that.  They differ in what else they do, as follows:
+
+=over
+
+=item C<newAV> form
+
+=for comment
+'form' above and below is because otherwise have two =items with the same name,
+can't link to them.
+
+This does nothing beyond creating the whole-array data structure.
+The Perl equivalent is approximately S<C<my @array;>>
+
+This is useful when the minimum size of the array could be zero (perhaps there
+are likely code paths that will entirely skip using it).
+
+If the array does get used, the pointers data structure will need to be
+allocated at that time.  This will end up being done by L</av_extend>>,
+either explicitly:
+
+    av_extend(av, len);
+
+or implicitly when the first element is stored:
+
+    (void)av_store(av, 0, sv);
+
+Unused array elements are typically initialized by C<av_extend>.
+
+=item C<newAV_alloc_x> form
+
+This effectively does a C<newAV> followed by also allocating (uninitialized)
+space for the pointers array.  This is used when you know ahead of time the
+likely minimum size of the array.  It is more efficient to do this than doing a
+plain C<newAV> followed by an C<av_extend>.
+
+Of course the array can be extended later should it become necessary.
+
+C<size> must be at least 1.
+
+=item C<newAV_alloc_xz> form
+
+This is C<newAV_alloc_x>, but initializes each pointer in it to NULL.  This
+gives added safety to guard against them being read before being set.
+
+C<size> must be at least 1.
+
+=back
+
+The following examples all result in an array that can fit four elements
+(indexes 0 .. 3):
+
+    AV *av = newAV();
+    av_extend(av, 3);
+
+    AV *av = newAV_alloc_x(4);
+
+    AV *av = newAV_alloc_xz(4);
+
+In contrast, the following examples allocate an array that is only guaranteed
+to fit one element without extending:
+
+    AV *av = newAV_alloc_x(1);
+    AV *av = newAV_alloc_xz(1);
+
+=cut
+
+*/
+
+#define newAV()        MUTABLE_AV(newSV_type(SVt_PVAV))
+#define newAV_alloc_x(size)  av_new_alloc(size,0)
+#define newAV_alloc_xz(size) av_new_alloc(size,1)
+
+/*
+ * ex: set ts=8 sts=4 sw=4 et:

  */
  */