An SV can be created and loaded with one command. There are five types of
values that can be loaded: an integer value (IV), an unsigned integer
value (UV), a double (NV), a string (PV), and another scalar (SV).
+("PV" stands for "Pointer Value". You might think that it is misnamed
+because it is described as pointing only to strings. However, it is
+possible to have it point to other things. For example, inversion
+lists, used in regular expression data structures, are scalars, each
+consisting of an array of UVs which are accessed through PVs. But,
+using it for non-strings requires care, as the underlying assumption of
+much of the internals is that PVs are just for strings. Often, for
+example, a trailing NUL is tacked on automatically. The non-string use
+is documented only in this paragraph.)
The seven routines are:
SV *s;
STRLEN len;
- char * ptr;
+ char *ptr;
ptr = SvPV(s, len);
foo(ptr, len);
The current kinds of Magic Virtual Tables are:
- mg_type
- (old-style char and macro) MGVTBL Type of magic
- -------------------------- ------ -------------
- \0 PERL_MAGIC_sv vtbl_sv Special scalar variable
- # PERL_MAGIC_arylen vtbl_arylen Array length ($#ary)
- % PERL_MAGIC_rhash (none) extra data for restricted
- hashes
- . PERL_MAGIC_pos vtbl_pos pos() lvalue
- : PERL_MAGIC_symtab (none) extra data for symbol
- tables
- < PERL_MAGIC_backref vtbl_backref for weak ref data
- @ PERL_MAGIC_arylen_p (none) to move arylen out of
- XPVAV
- A PERL_MAGIC_overload vtbl_amagic %OVERLOAD hash
- a PERL_MAGIC_overload_elem vtbl_amagicelem %OVERLOAD hash element
- B PERL_MAGIC_bm vtbl_regexp Boyer-Moore
- (fast string search)
- c PERL_MAGIC_overload_table vtbl_ovrld Holds overload table
- (AMT) on stash
- D PERL_MAGIC_regdata vtbl_regdata Regex match position data
- (@+ and @- vars)
- d PERL_MAGIC_regdatum vtbl_regdatum Regex match position data
- element
- E PERL_MAGIC_env vtbl_env %ENV hash
- e PERL_MAGIC_envelem vtbl_envelem %ENV hash element
- f PERL_MAGIC_fm vtbl_regdata Formline ('compiled'
- format)
- G PERL_MAGIC_study vtbl_regdata study()ed string
- g PERL_MAGIC_regex_global vtbl_mglob m//g target
- H PERL_MAGIC_hints vtbl_hints %^H hash
- h PERL_MAGIC_hintselem vtbl_hintselem %^H hash element
- I PERL_MAGIC_isa vtbl_isa @ISA array
- i PERL_MAGIC_isaelem vtbl_isaelem @ISA array element
- k PERL_MAGIC_nkeys vtbl_nkeys scalar(keys()) lvalue
- L PERL_MAGIC_dbfile (none) Debugger %_<filename
- l PERL_MAGIC_dbline vtbl_dbline Debugger %_<filename
- element
- N PERL_MAGIC_shared (none) Shared between threads
- n PERL_MAGIC_shared_scalar (none) Shared between threads
- o PERL_MAGIC_collxfrm vtbl_collxfrm Locale transformation
- P PERL_MAGIC_tied vtbl_pack Tied array or hash
- p PERL_MAGIC_tiedelem vtbl_packelem Tied array or hash element
- q PERL_MAGIC_tiedscalar vtbl_packelem Tied scalar or handle
- r PERL_MAGIC_qr vtbl_regexp precompiled qr// regex
- S PERL_MAGIC_sig (none) %SIG hash
- s PERL_MAGIC_sigelem vtbl_sigelem %SIG hash element
- t PERL_MAGIC_taint vtbl_taint Taintedness
- U PERL_MAGIC_uvar vtbl_uvar Available for use by
- extensions
- u PERL_MAGIC_uvar_elem (none) Reserved for use by
- extensions
- V PERL_MAGIC_vstring (none) SV was vstring literal
- v PERL_MAGIC_vec vtbl_vec vec() lvalue
- w PERL_MAGIC_utf8 vtbl_utf8 Cached UTF-8 information
- x PERL_MAGIC_substr vtbl_substr substr() lvalue
- y PERL_MAGIC_defelem vtbl_defelem Shadow "foreach" iterator
- variable / smart parameter
- vivification
- ] PERL_MAGIC_checkcall (none) inlining/mutation of call
- to this CV
- ~ PERL_MAGIC_ext (none) Available for use by
- extensions
+=for comment
+This table is generated by regen/mg_vtable.pl. Any changes made here
+will be lost.
+
+=for mg_vtable.pl begin
+ mg_type
+ (old-style char and macro) MGVTBL Type of magic
+ -------------------------- ------ -------------
+ \0 PERL_MAGIC_sv vtbl_sv Special scalar variable
+ # PERL_MAGIC_arylen vtbl_arylen Array length ($#ary)
+ % PERL_MAGIC_rhash (none) extra data for restricted
+ hashes
+ . PERL_MAGIC_pos vtbl_pos pos() lvalue
+ : PERL_MAGIC_symtab (none) extra data for symbol
+ tables
+ < PERL_MAGIC_backref vtbl_backref for weak ref data
+ @ PERL_MAGIC_arylen_p (none) to move arylen out of XPVAV
+ B PERL_MAGIC_bm vtbl_regexp Boyer-Moore
+ (fast string search)
+ c PERL_MAGIC_overload_table vtbl_ovrld Holds overload table
+ (AMT) on stash
+ D PERL_MAGIC_regdata vtbl_regdata Regex match position data
+ (@+ and @- vars)
+ d PERL_MAGIC_regdatum vtbl_regdatum Regex match position data
+ element
+ E PERL_MAGIC_env vtbl_env %ENV hash
+ e PERL_MAGIC_envelem vtbl_envelem %ENV hash element
+ f PERL_MAGIC_fm vtbl_regdata Formline
+ ('compiled' format)
+ g PERL_MAGIC_regex_global vtbl_mglob m//g target
+ H PERL_MAGIC_hints vtbl_hints %^H hash
+ h PERL_MAGIC_hintselem vtbl_hintselem %^H hash element
+ I PERL_MAGIC_isa vtbl_isa @ISA array
+ i PERL_MAGIC_isaelem vtbl_isaelem @ISA array element
+ k PERL_MAGIC_nkeys vtbl_nkeys scalar(keys()) lvalue
+ L PERL_MAGIC_dbfile (none) Debugger %_<filename
+ l PERL_MAGIC_dbline vtbl_dbline Debugger %_<filename
+ element
+ N PERL_MAGIC_shared (none) Shared between threads
+ n PERL_MAGIC_shared_scalar (none) Shared between threads
+ o PERL_MAGIC_collxfrm vtbl_collxfrm Locale transformation
+ P PERL_MAGIC_tied vtbl_pack Tied array or hash
+ p PERL_MAGIC_tiedelem vtbl_packelem Tied array or hash element
+ q PERL_MAGIC_tiedscalar vtbl_packelem Tied scalar or handle
+ r PERL_MAGIC_qr vtbl_regexp precompiled qr// regex
+ S PERL_MAGIC_sig (none) %SIG hash
+ s PERL_MAGIC_sigelem vtbl_sigelem %SIG hash element
+ t PERL_MAGIC_taint vtbl_taint Taintedness
+ U PERL_MAGIC_uvar vtbl_uvar Available for use by
+ extensions
+ u PERL_MAGIC_uvar_elem (none) Reserved for use by
+ extensions
+ V PERL_MAGIC_vstring (none) SV was vstring literal
+ v PERL_MAGIC_vec vtbl_vec vec() lvalue
+ w PERL_MAGIC_utf8 vtbl_utf8 Cached UTF-8 information
+ x PERL_MAGIC_substr vtbl_substr substr() lvalue
+ y PERL_MAGIC_defelem vtbl_defelem Shadow "foreach" iterator
+ variable / smart parameter
+ vivification
+ ] PERL_MAGIC_checkcall vtbl_checkcall inlining/mutation of call
+ to this CV
+ ~ PERL_MAGIC_ext (none) Available for use by
+ extensions
+
+=for mg_vtable.pl end
When an uppercase and lowercase letter both exist in the table, then the
uppercase letter is typically used to represent some kind of composite type
In general, you either have to know what you're dealing with, or you
have to guess. The API function C<is_utf8_string> can help; it'll tell
you if a string contains only valid UTF-8 characters. However, it can't
-do the work for you. On a character-by-character basis, C<is_utf8_char>
+do the work for you. On a character-by-character basis,
+C<is_utf8_char_buf>
will tell you whether the current character in a string is valid UTF-8.
=head2 How does UTF-8 represent Unicode characters?
whether the byte can be encoded as a single byte even in UTF-8):
U8 *utf;
+ U8 *utf_end; /* 1 beyond buffer pointed to by utf */
UV uv; /* Note: a UV, not a U8, not a char */
+ STRLEN len; /* length of character in bytes */
if (!UTF8_IS_INVARIANT(*utf))
/* Must treat this as UTF-8 */
- uv = utf8_to_uv(utf);
+ uv = utf8_to_uvchr_buf(utf, utf_end, &len);
else
/* OK to treat this character as a byte */
uv = *utf;
-You can also see in that example that we use C<utf8_to_uv> to get the
-value of the character; the inverse function C<uv_to_utf8> is available
+You can also see in that example that we use C<utf8_to_uvchr_buf> to get the
+value of the character; the inverse function C<uvchr_to_utf8> is available
for putting a UV into UTF-8:
if (!UTF8_IS_INVARIANT(uv))
/* Must treat this as UTF8 */
- utf8 = uv_to_utf8(utf8, uv);
+ utf8 = uvchr_to_utf8(utf8, uv);
else
/* OK to treat this character as a byte */
*utf8++ = uv;
=item *
-If a string is UTF-8, B<always> use C<utf8_to_uv> to get at the value,
+If a string is UTF-8, B<always> use C<utf8_to_uvchr_buf> to get at the value,
unless C<UTF8_IS_INVARIANT(*s)> in which case you can use C<*s>.
=item *
When writing a character C<uv> to a UTF-8 string, B<always> use
-C<uv_to_utf8>, unless C<UTF8_IS_INVARIANT(uv))> in which case
+C<uvchr_to_utf8>, unless C<UTF8_IS_INVARIANT(uv))> in which case
you can use C<*s = uv>.
=item *