=item C<regnode_charclass>
-Character classes are represented by C<regnode_charclass> structures,
-which have a four-byte argument and then a 32-byte (256-bit) bitmap
-indicating which characters are included in the class.
+Bracketed character classes are represented by C<regnode_charclass>
+structures, which have a four-byte argument and then a 32-byte (256-bit)
+bitmap indicating which characters in the Latin1 range are included in
+the class.
regnode_charclass U32 arg1;
char bitmap[ANYOF_BITMAP_SIZE];
-=item C<regnode_charclass_class>
+Various flags whose names begin with C<ANYOF_> are used for special
+situations. Above Latin1 matches and things not known until run-time
+are stored in L</Perl's pprivate structure>.
+
+=item C<regnode_charclass_posixl>
There is also a larger form of a char class structure used to represent
-POSIX char classes called C<regnode_charclass_class> which has an
-additional 4-byte (32-bit) bitmap indicating which POSIX char classes
+POSIX char classes under C</l> matching,
+called C<regnode_charclass_posixl> which has an
+additional 32-bit bitmap indicating which POSIX char classes
have been included.
- regnode_charclass_class U32 arg1;
+ regnode_charclass_posixl U32 arg1;
char bitmap[ANYOF_BITMAP_SIZE];
- char classflags[ANYOF_CLASSBITMAP_SIZE];
+ U32 classflags;
=back
added to the program. However, one complication is that reg() returns NULL
for parsing C<(?:)> syntax for embedded modifiers, setting the flag
C<TRYAGAIN>. The C<TRYAGAIN> propagates upwards until it is captured, in
-some cases by by C<regatom()>, but otherwise unconditionally by
+some cases by C<regatom()>, but otherwise unconditionally by
C<regbranch()>. Hence it will never be returned by C<regbranch()> to
C<reg()>. This flag permits patterns such as C<(?i)+> to be detected as
errors (I<Quantifier follows nothing in regex; marked by <-- HERE in m/(?i)+
and the second being running the regop interpreter.
If we can tell that there is no valid start point then we don't bother running
-interpreter at all. Likewise, if we know from the analysis phase that we
+the interpreter at all. Likewise, if we know from the analysis phase that we
cannot detect a short-cut to the start position, we go straight to the
interpreter.
UTF-8 properly, both at compile time and at execution time, including
when the string and pattern are mismatched.
-The following comment in F<regcomp.h> gives an example of exactly how
-tricky this can be:
-
- Two problematic code points in Unicode casefolding of EXACT nodes:
-
- U+0390 - GREEK SMALL LETTER IOTA WITH DIALYTIKA AND TONOS
- U+03B0 - GREEK SMALL LETTER UPSILON WITH DIALYTIKA AND TONOS
-
- which casefold to
-
- Unicode UTF-8
-
- U+03B9 U+0308 U+0301 0xCE 0xB9 0xCC 0x88 0xCC 0x81
- U+03C5 U+0308 U+0301 0xCF 0x85 0xCC 0x88 0xCC 0x81
-
- This means that in case-insensitive matching (or "loose matching",
- as Unicode calls it), an EXACTF of length six (the UTF-8 encoded
- byte length of the above casefolded versions) can match a target
- string of length two (the byte length of UTF-8 encoded U+0390 or
- U+03B0). This would rather mess up the minimum length computation.
-
- What we'll do is to look for the tail four bytes, and then peek
- at the preceding two bytes to see whether we need to decrease
- the minimum length by four (six minus two).
-
- Thanks to the design of UTF-8, there cannot be false matches:
- A sequence of valid UTF-8 bytes cannot be a subsequence of
- another valid sequence of UTF-8 bytes.
-
-
=head2 Base Structures
The C<regexp> structure described in L<perlreapi> is common to all
-regex engines. Two of its fields that are intended for the private use
+regex engines. Two of its fields are intended for the private use
of the regex engine that compiled the pattern. These are the
C<intflags> and pprivate members. The C<pprivate> is a void pointer to
an arbitrary structure whose use and management is the responsibility
implement things such as the stringification of C<qr//>.
-The other structure is pointed to be the C<regexp> struct's
+The other structure is pointed to by the C<regexp> struct's
C<pprivate> and is in addition to C<intflags> in the same struct
considered to be the property of the regex engine which compiled the
regular expression;
=item C<data>
-This field points at a reg_data structure, which is defined as follows
+This field points at a C<reg_data> structure, which is defined as follows
struct reg_data {
U32 count;
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