Pass 2 at perldelta: add some changes since 5.7.2.

[p5sagit/p5-mst-13.2.git] / pod / perlunicode.pod

diff --git a/pod/perlunicode.pod b/pod/perlunicode.pod
index 277238e..6606ecd 100644 (file)
--- a/pod/perlunicode.pod
+++ b/pod/perlunicode.pod
@@ -20,7 +20,7 @@ Other encodings can be converted to perl's encoding on input, or from
 perl's encoding on output by use of the ":encoding(...)" layer.
 See L<open>.
 
-To mark the Perl source itself as being in an particular encoding,
+To mark the Perl source itself as being in a particular encoding,
 see L<encoding>.
 
 =item Regular Expressions
@@ -275,6 +275,8 @@ have their directionality defined:
     BidiWS      Whitespace
     BidiON      Other Neutrals
 
+=back
+
 =head2 Scripts
 
 The scripts available for C<\p{In...}> and C<\P{In...}>, for example
@@ -481,6 +483,8 @@ below list that have the C<Block> appended).
    Yi Radicals
    Yi Syllables
 
+=over 4
+
 =item *
 
 The special pattern C<\X> match matches any extended Unicode sequence
@@ -563,7 +567,7 @@ than one Unicode character
 
 =back
 
-What doesn't yet work are the followng cases:
+What doesn't yet work are the following cases:
 
 =over 8
 
@@ -628,14 +632,23 @@ Level 1 - Basic Unicode Support
         [ 1] \x{...}
         [ 2] \N{...}
         [ 3] . \p{Is...} \P{Is...}
-        [ 4] now scripts (see UTR#24 Script Names) in  addition to blocks
+        [ 4] now scripts (see UTR#24 Script Names) in addition to blocks
         [ 5] have negation
-        [ 6] can use look-ahead to emulate subtracion
+        [ 6] can use look-ahead to emulate subtraction (*)
         [ 7] include Letters in word characters
         [ 8] see UTR#21 Case Mappings: Perl implements 1:1 mappings
         [ 9] see UTR#13 Unicode Newline Guidelines
         [10] should do ^ and $ also on \x{2028} and \x{2029}
 
+(*) Instead of [\u0370-\u03FF-[{UNASSIGNED}]] as suggested by the TR
+18 you can use negated lookahead: to match currently assigned modern
+Greek characters use for example
+
+               /(?!\p{Cn})[\x{0370}-\x{03ff}]/
+
+In other words: the matched character must not be a non-assigned
+character, but it must be in the block of modern Greek characters.
+
 =item *
 
 Level 2 - Extended Unicode Support
@@ -681,6 +694,31 @@ length (1 to 6 bytes, current character allocations require 4 bytes),
 byteorder independent encoding.  For ASCII, UTF-8 is transparent
 (and we really do mean 7-bit ASCII, not any 8-bit encoding).
 
+The following table is from Unicode 3.1.
+
+ Code Points            1st Byte  2nd Byte  3rd Byte  4th Byte
+
+   U+0000..U+007F       00..7F   
+   U+0080..U+07FF       C2..DF    80..BF   
+   U+0800..U+0FFF       E0        A0..BF    80..BF  
+   U+1000..U+FFFF       E1..EF    80..BF    80..BF  
+  U+10000..U+3FFFF      F0        90..BF    80..BF    80..BF
+  U+40000..U+FFFFF      F1..F3    80..BF    80..BF    80..BF
+ U+100000..U+10FFFF     F4        80..8F    80..BF    80..BF
+
+Or, another way to look at it, as bits:
+
+ Code Points                    1st Byte   2nd Byte  3rd Byte  4th Byte
+
+                    0aaaaaaa     0aaaaaaa
+            00000bbbbbaaaaaa     110bbbbb  10aaaaaa
+            ccccbbbbbbaaaaaa     1110cccc  10bbbbbb  10aaaaaa
+  00000dddccccccbbbbbbaaaaaa     11110ddd  10cccccc  10bbbbbb  10aaaaaa
+
+As you can see, the continuation bytes all begin with C<10>, and the
+leading bits of the start byte tells how many bytes the are in the
+encoded character.
+
 =item UTF-16, UTF-16BE, UTF16-LE, Surrogates, and BOMs (Byte Order Marks)
 
 UTF-16 is a 2 or 4 byte encoding.  The Unicode code points
@@ -769,7 +807,7 @@ for more discussion of the issues.
 
 =head1 SEE ALSO
 
-L<encoding>, L<Encode>, L<open>, L<bytes>, L<utf8>, L<perlretut>,
-L<perlvar/"${^WIDE_SYSTEM_CALLS}">
+L<perluniintro>, L<encoding>, L<Encode>, L<open>, L<utf8>, L<bytes>,
+L<perlretut>, L<perlvar/"${^WIDE_SYSTEM_CALLS}">
 
 =cut