regexec.c: Remove no longer needed comments

These comments gave the derivation of the published Unicode algorithm
for determining what goes into \X to how it is actually implemented.

The new version of the Unicode text will be much more like what we've
implemented, so the derivation is no longer necessary; and is about to
be obsolete because of the Unicode document, and some changes to how we
process.

diff --git a/regexec.c b/regexec.c
index 57f47ce..39a504f 100644 (file)
--- a/regexec.c
+++ b/regexec.c
@@ -3922,36 +3922,6 @@ S_regmatch(pTHX_ regmatch_info *reginfo, regnode *prog)
                Control is:         [ GCB_Control  CR  LF ]
                Hangul-syllable is: ( T+ | ( L* ( L | ( LVT | ( V | LV ) V* ) T* ) ))
 
-              The discussion below shows how the code for CLUMP is derived
-              from this regex.  Note that most of these concepts are from
-              property values of the Grapheme Cluster Boundary (GCB) property.
-              No code point can have multiple property values for a given
-              property.  Thus a code point in Prepend can't be in Control, but
-              it must be in !Control.  This is why Control above includes
-              GCB_Control plus CR plus LF.  The latter two are used in the GCB
-              property separately, and so can't be in GCB_Control, even though
-              they logically are controls.  Control is not the same as gc=cc,
-              but includes format and other characters as well.
-
-              The Unicode definition of Hangul-syllable is:
-                  L+
-                  | (L* ( ( V | LV ) V* | LVT ) T*)
-                  | T+ 
-                 )
-              Each of these is a value for the GCB property, and hence must be
-              disjoint, so the order they are tested is immaterial, so the
-              above can safely be changed to
-                  T+
-                  | L+
-                  | (L* ( LVT | ( V | LV ) V*) T*)
-
-              The last two terms can be combined like this:
-                  L* ( L | (( LVT | ( V | LV ) V*) T*))
-
-              That means that if we have seen any L's at all we can quit
-              there, but if the next character is an LVT, a V, or an LV we
-              should keep going.
-
               There is a subtlety with Prepend* which showed up in testing.
               Note that the Begin, and only the Begin is required in:
                | Prepend* Begin Extend*