users/23829: add and coument file-split-chars style

ChangeLog

@@ -1,3 +1,8 @@
+2019-01-08  Peter Stephenson  <p.stephenson@samsung.com>
+
+	* users/23829: Completion/Unix/Type/_path_files,
+	Doc/Zsh/compsys.yo: Add and document file-split-chars style.
+
 2018-01-05  dana  <dana@dana.is>
 
 	* unposted: Config/version.mk, NEWS: Update for 5.6.2-test-3

Completion/Unix/Type/_path_files

@@ -2,6 +2,11 @@
 
 local -a match mbegin mend
 
+local splitchars
+if zstyle -s ":completion:${curcontext}:" file-split-chars splitchars; then
+  compset -P "*[${(q)splitchars}]"
+fi
+
 # Look for glob qualifiers.  Do this first:  if we're really
 # in a glob qualifier, we don't actually want to expand
 # the earlier part of the path.  We can't expand inside

Doc/Zsh/compsys.yo

@@ -1568,6 +1568,16 @@ contains the string `tt(follow)', timestamps are associated with the
 targets of symbolic links; the default is to use the timestamps
 of the links themselves.
 )
+kindex(file-split-chars, completion style)
+item(tt(file-split-chars))(
+A set of characters that will cause em(all) file completions for
+the given context to be split at the point where any of the characters
+occurs.  A typical use is to set the style to tt(:); then everything
+up to and including the last tt(:) in the string so far is ignored when
+completing files.  As this is quite heavy-handed, it is usually
+preferable to update completion functions for contexts where this
+behaviour is useful.
+)
 kindex(filter, completion style)
 item(tt(filter))(
 The tt(ldap) plugin of email address completion (see tt(_email_addresses)) uses