From 64efae0fa4fd96910ae58a220c101df9543e0922 Mon Sep 17 00:00:00 2001
From: Ulrike Fischer <fischer@troubleshooting-tex.de>
Date: Thu, 19 Mar 2020 19:42:58 +0100
Subject: [PATCH] working on destinations

---
 hgeneric-experimental.def | 24 +++++++++------
 hyperreflinktypes.tex     | 65 +++++++++++++++++++++++++++++++++------
 2 files changed, 70 insertions(+), 19 deletions(-)

diff --git a/hgeneric-experimental.def b/hgeneric-experimental.def
index c7809f78..bb0e7abf 100644
--- a/hgeneric-experimental.def
+++ b/hgeneric-experimental.def
@@ -63,6 +63,9 @@
 \Hy@unicodetrue
 \let\HyPsd@pdfencoding\HyPsd@pdfencoding@unicode
 
+\providecommand*\@pdfview{XYZ}
+
+%%%%%%%%%%
 % variants
 \cs_generate_variant:Nn \pdf_object_write:nn {nx}
 \cs_generate_variant:Nn \pdf_catalog_gput:nn {nx}
@@ -312,6 +315,9 @@
 
 
 \ExplSyntaxOn
+%these patterns are used in hyperref checks.
+%it is unclear if they are really useful and if a backend support is
+%needed.
 \str_case:VnF \c_sys_backend_str
  {
    { pdfmode }
@@ -357,7 +363,7 @@
 
 \Hy@DisableOption{pdfversion}%
 
-%ocg colorlinks should be done as in ocgx. This here
+% ocg colorlinks should be done as in ocgx. This here
 % are boxes ...
 \legacy_if:nTF {Hy@ocgcolorlinks}
   {
@@ -468,11 +474,9 @@
 % default:
 \pdf_link_margin:n { 1pt }
 
-
 \ExplSyntaxOff
 
-\providecommand*\@pdfview{XYZ}
-
+\ExplSyntaxOn
 \newcommand\Hy@pstringDest{}
 
 \Hy@WrapperDef\new@pdflink#1{% #1 is a destination name.
@@ -482,7 +486,8 @@
   \Hy@SaveLastskip
   \Hy@VerboseAnchor{#1}%
   \Hy@pstringdef\Hy@pstringDest{\HyperDestNameFilter{#1}}%
-  \Hy@DestName\Hy@pstringDest\@pdfview
+  %\Hy@DestName\Hy@pstringDest\@pdfview
+  \pdf_destination:nf { \Hy@pstringDest } { \@pdfview } %types??
   \Hy@RestoreLastskip
   \ifhmode
     \spacefactor\@savsf
@@ -490,12 +495,13 @@
 }
 \let\pdf@endanchor\@empty
 
+\ExplSyntaxOff
 \ExplSyntaxOn
 
-\cs_new_protected:Npn \Hy@DestName #1 #2 % #1= name #2= fit options
-  {
-    \pdf_destination:nf {#1}{#2}
-  }
+%\cs_new_protected:Npn \Hy@DestName #1 #2 % #1= name #2= fit options
+%  {
+%    \pdf_destination:nf {#1}{#2}
+%  }
 
 \ExplSyntaxOff
 \def\Hy@undefinedname{UNDEFINED}
diff --git a/hyperreflinktypes.tex b/hyperreflinktypes.tex
index b7db35a2..e31ed914 100644
--- a/hyperreflinktypes.tex
+++ b/hyperreflinktypes.tex
@@ -1,22 +1,67 @@
-\hyper@linkstart : 
-   in hyperref.sty!
+%%%%%%%%%%%%%%%%%%
+Internal links
+%%%%%%%%%%%%%%%%%
+
+\hyper@linkstart :
+   defined in driver, 
+   used in hyperref.sty!
    two arguments!
    first : color (will ignore it ...)
    second: destination name
    \hyper@linkstart{link}{\Hy@footnote@currentHref}
-   \hyper@linkstart{cite}{cite.#1}%        
+   \hyper@linkstart{cite}{cite.#1}%
    \hyper@linkstart{link}{\Hy@tocdestname} (toc)
 
- internal command 
+ internal command
   \find@pdflink{#1}{#2}
+   defined in driver,
+   used only in driver
   ->  \pdf_link_begin_goto:nnw { link } { #2 }
       \expandafter\Hy@colorlink\csname @#1color\endcsname
-      
+
 \hyper@link
-   three arguments, basically \hyper@linkstart/\hyperlinkend with
-   content as third argument. 
-   Used in \hyper@link@ - > 
+   three arguments, basically \hyper@linkstart/\hyper@linkend with
+   content as third argument.
+   Used in \hyper@link@ - >
     \hyper@@link[cite]
     \hyper@@link[link]
-    #1 either link or cite     
- 
\ No newline at end of file
+    #1 either link or cite
+    
+%%%%%%%%%%%%%%%%%%%%%
+
+\hyper@anchor, \hyper@anchorstart, \hyper@anchorend :
+  defined in driver,
+  used in hyperref.sty
+  one argument: destination name    
+  
+  Uses
+  \hyper@anchorstart{Doc-Start}\hyper@anchorend
+  \hyper@anchorstart{\@currentHref}\hyper@anchorend in \hyper@refstepcounter and various environments
+  inside the definition of \hyper@@anchor: \hyper@@anchor is used in various environments where text is involved and
+  typically in combination with nesting. (Very) old version of hyperref.dtx suggest that anchorcolor which does nothing
+  now was involved here.
+  \def\hypertarget#1#2{%
+  \ifHy@nesting
+    \hyper@@anchor{#1}{#2}%
+  \else
+    \hyper@@anchor{#1}{\relax}#2%
+  \fi
+}
+  
+  Internalcommand
+   \new@pdflink #1 
+   defined in driver
+   used only in driver
+   argument is destination name, "Fit" argument is got through \@pdfview
+
+
+%%%% 
+nesting
+
+The documentation writes about "nesting":
+Allows links to be nested; no drivers currently support this.
+
+All places in the code where \ifHy@nesting is used are about anchors, not links.
+\ifHy@nesting is false in all drivers, so actually nowhere the true code is used. 
+
+It is unclear if nesting can be used, and what use it would have.
\ No newline at end of file