From 7b271baae19db1528fbe6621bdf50af89a5a336b Mon Sep 17 00:00:00 2001
From: Hans Hagen <pragma@wxs.nl>
Date: Fri, 22 Feb 2019 20:29:46 +0100
Subject: 2019-02-22 19:43:00

---
 tex/context/base/mkiv/strc-blk.mkiv | 128 +++++++++++++++++++++++++++++-------
 1 file changed, 104 insertions(+), 24 deletions(-)

(limited to 'tex/context/base/mkiv/strc-blk.mkiv')

diff --git a/tex/context/base/mkiv/strc-blk.mkiv b/tex/context/base/mkiv/strc-blk.mkiv
index c42bb25ec..e52198721 100644
--- a/tex/context/base/mkiv/strc-blk.mkiv
+++ b/tex/context/base/mkiv/strc-blk.mkiv
@@ -34,48 +34,125 @@
 
 \appendtoks
     \clf_definestructureblock{\currentblock}%
-    \setuevalue{\e!begin\currentblock}{\dodoubleempty\strc_blocks_begin[\currentblock]}%
-    \setuevalue{\e!end  \currentblock}{}%
+    \setuevalue{\e!begin\currentblock}{\strc_blocks_begin{\currentblock}}%
+    \letvalue  {\e!end  \currentblock}\donothing
 \to \everydefineblock
 
-\unexpanded\def\strc_blocks_begin[#1][#2]%
-  {\normalexpanded{\buff_pickup{@block@}{\e!begin#1}{\e!end#1}}
-     {}% before
-     {\clf_savestructureblock{#1}{#2}{@block@}}%
-     \plusone}% after
+% The naive way:
+%
+% \unexpanded\def\strc_blocks_begin#1%
+%   {\dotripleempty\strc_blocks_begin_indeed[#1]}
+%
+% \unexpanded\def\strc_blocks_begin_indeed[#1][#2][#3]%
+%   {\normalexpanded{\buff_pickup{\??block}{\e!begin#1}{\e!end#1}}
+%      {}%
+%      {\clf_savestructureblock{#1}{#2}{#3}{\??block}}%
+%      \plusone}%
+%
+% We need to prevent too much lookahead which will gobble newlines
+% that are needed for buffers. See blocks-002.tex as example.
+
+% maybe: systemmode "block:<name>"
+
+\let\m_block   \empty
+\let\m_subblock\empty
+
+\unexpanded\def\strc_blocks_begin#1%
+  {\edef\m_block   {#1}%
+   \let \m_subblock\empty
+   \doifelsenextoptionalcs\strc_blocks_begin_yes\strc_blocks_begin_nop}
+
+\unexpanded\def\strc_blocks_begin_yes[#1]%
+  {\doifelseassignmentcs{#1}%
+     \strc_blocks_begin_indeed
+     \strc_blocks_begin_tagged
+     {#1}}
+
+\unexpanded\def\strc_blocks_begin_tagged#1%
+  {\edef\m_subblock{#1}%
+   \doifelsenextoptionalcs\strc_blocks_begin_yes_yes\strc_blocks_begin_nop}
+
+\unexpanded\def\strc_blocks_begin_yes_yes[#1]%
+  {\strc_blocks_begin_indeed{#1}}
+
+\unexpanded\def\strc_blocks_begin_nop
+  {\strc_blocks_begin_indeed{}}
+
+\unexpanded\def\strc_blocks_begin_indeed#1%
+  {\normalexpanded{\buff_pickup{\??block}{\e!begin\m_block}{\e!end\m_block}}%
+     {}%
+     {\clf_savestructureblock{\m_block}{\m_subblock}{#1}{\??block}}%
+     \plusone}
 
 \let\strc_blocks_setup\relax
 
+\newconstant   \c_strc_blocks_index
+\newconditional\c_strc_blocks_display
+
 \unexpanded\def\dostarthiddenblock % called at lua end
-  {\startnointerference
-   \dostartnormalblock}
+  {\begingroup
+   \visiblefalse % blocks float
+   \startnointerference
+   \strc_start_block}
 
 \unexpanded\def\dostophiddenblock % called at lua end
-  {\dostopnormalblock
-   \stopnointerference}
+  {\strc_stop_block
+   \stopnointerference
+   \endgroup}
+
+\unexpanded\def\dostartnormalblock % called at lua end
+  {\begingroup
+   \visibletrue
+   \strc_start_block}
 
-\unexpanded\def\dostartnormalblock#1% called at lua end
-  {\bgroup
-   \visibletrue  % will change
-   \edef\currentblock{#1}%
+\unexpanded\def\dostopnormalblock % called at lua end
+  {\strc_stop_block
+   \endgroup}
+
+\def\strc_start_block#1#2%
+  {\edef\currentblock{#2}%
+   \c_strc_blocks_index#1\relax
    \strc_blocks_setup
    \let\strc_blocks_setup\relax
-   \blockparameter\c!before
-   \useblockstyleandcolor\c!style\c!color % maybe moev one line up (font spacing)
-   \blockparameter\c!inner % better \c!setups
+   \edef\p_alternative{\blockparameter\c!alternative}%
+   \ifx\p_alternative\v!text
+      \setfalse\c_strc_blocks_display
+   \else
+      \settrue\c_strc_blocks_display
+   \fi
+   \ifconditional\c_strc_blocks_display
+      \blockparameter\c!before
+   \fi
+   \begingroup
+   \usesetupsparameter\blockparameter\relax
+   \dostarttagged\t!block\currentblock
+   \useblockstyleandcolor\c!style\c!color
+   \blockparameter\c!inner % old
+   \ifconditional\c_strc_blocks_display
+     \usealignparameter\blockparameter
+   \else
+     \blockparameter\c!left
+   \fi
    \ignorespaces}
 
-\unexpanded\def\dostopnormalblock % called at lua end
+\def\strc_stop_block
   {\removeunwantedspaces
-   \blockparameter\c!after
-   \par % todo: alternative = text, paragraph
-   \egroup}
+   \ifconditional\c_strc_blocks_display
+     \par
+   \else
+     \blockparameter\c!right
+   \fi
+   \dostoptagged
+   \endgroup
+   \ifconditional\c_strc_blocks_display
+     \blockparameter\c!after
+   \fi}
 
 \def\strc_blocks_set_state[#1][#2][#3]% state name tag
   {\clf_setstructureblockstate{#1}{#2}{#3}}
 
 \def\strc_blocks_select[#1][#2][#3][#4]% state name tag setups
-  {\bgroup
+  {\begingroup
    \doifelseassignment{#3}
      {\getparameters[\??blocktemp][\c!criterium=\v!text,#3]%
       \def\strc_blocks_setup{\setupcurrentblock[#3]}%
@@ -83,7 +160,10 @@
      {\getparameters[\??blocktemp][\c!criterium=\v!text,#4]%
       \def\strc_blocks_setup{\setupcurrentblock[#4]}%
       \clf_selectstructureblock{#1}{#2}{#3}{\csname\??blocktemp\c!criterium\endcsname}}%
-   \egroup}
+   \endgroup}
+
+\def\blockuservariable#1%
+  {\clf_structureblockuservariable\c_strc_blocks_index{#1}}
 
 % hide   : save, if [+] also hidden execute
 % keep   : save and normal execute
-- 
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