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%D \module
%D   [       file=spac-hor,
%D        version=2009.10.16, % 1997.03.31, was core-spa.tex
%D          title=\CONTEXT\ Spacing Macros,
%D       subtitle=Horizontal,
%D         author=Hans Hagen,
%D           date=\currentdate,
%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
%C
%C This module is part of the \CONTEXT\ macro||package and is
%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
%C details.

\writestatus{loading}{ConTeXt Spacing Macros / Horizontal}

\unprotect

\registerctxluafile{spac-hor}{}

\let        \parfillrightskip \parfillskip
\newskip    \parfillleftskip
\newconstant\parfillleftmode

\let\v_spac_indentation_current\empty % amount/keyword

\newdimen \d_spac_indentation_par
\parindent\d_spac_indentation_par % for the show

\newconditional\c_spac_indentation_indent_first \settrue\c_spac_indentation_indent_first
\newconstant   \c_spac_indentation_toggle_state

%D After a blank or comparable situation (left side floats) we
%D need to check if the next paragraph has to be indented.

\unexpanded\def\presetindentation
  {\doifoutervmode{\ifconditional\c_spac_indentation_indent_first\else\spac_indentation_variant_no\fi}}

\unexpanded\def\setupindenting
  {\doifelsenextoptionalcs\spac_indentation_setup_options\spac_indentation_setup_size}

% \unexpanded\def\spac_indentation_setup_size
%   {\assigndimension\v_spac_indentation_current\d_spac_indentation_par{1\emwidth}{1.5\emwidth}{2\emwidth}}

\unexpanded\def\spac_indentation_setup_size
  {\assigndimension\v_spac_indentation_current\d_spac_indentation_par{1\emwidth}{1.5\emwidth}{2\emwidth}%
   \ifzeropt\parindent\else
     \parindent\d_spac_indentation_par\relax % new per 2019-04-12 : just in case it has been set beforehand
   \fi}

\let\synchronizeindenting\spac_indentation_setup_size

\let\m_spac_indentation_options\empty

\def\spac_indentation_setup_options[#1]%
  {\edef\m_spac_indentation_options{#1}% comma separated list
   \ifx\m_spac_indentation_options\empty \else
     \spac_indentation_setup_indeed
   \fi}

\def\spac_indentation_setup_indeed
  {% not here: \settrue\c_spac_indentation_indent_first
   % not here: \parindent\d_spac_indentation_par
   % not here: \c_spac_indentation_toggle_state\zerocount
   \processcommacommand[\m_spac_indentation_options]\spac_indentation_apply_step_one % catch small, medium, etc
   \processcommacommand[\m_spac_indentation_options]\spac_indentation_apply_step_two % catch rest
   \ifzeropt\parindent\else
     \doifemptytoks\everypar\spac_indentation_set_everypar
   \fi
   \ifconditional\c_spac_indentation_indent_first
     \spac_indentation_variant_yes % better than: \let\checkindentation\relax
   \else
     \spac_indentation_variant_no
   \fi
   \spac_indentation_check_toggle}

\def\spac_indentation_set_everypar
  {\everypar{\checkindentation}}

\unexpanded\def\useindentingparameter#1% faster local variant
  {\edef\m_spac_indentation_options{#1\c!indenting}%
   \ifx\m_spac_indentation_options\empty \else
     \spac_indentation_setup_indeed
   \fi}

% \def\spac_indentation_apply_step_one#1%
%   {\ifcsname\??indentingmethod#1\endcsname
%      % case two
%    \else
%      \edef\v_spac_indentation_current{#1}% single entry in list
%      \let\normalindentation\v_spac_indentation_current
%      \spac_indentation_setup_size
%    \fi}
%
% \def\spac_indentation_apply_step_two#1%
%   {\ifcsname\??indentingmethod#1\endcsname
%      \csname\??indentingmethod#1\endcsname
%    \else
%      % case one
%    \fi}

% \defineindenting[whatever][yes,2cm]
% %defineindenting[whatever][yes,-2cm]
%
% \setupindenting[yes,-2em] \input ward \par
% \setupindenting[yes,2em]  \input ward \par
% \setupindenting[whatever] \input ward \par

\installcorenamespace {indentingpreset}

\unexpanded\def\defineindenting
  {\dodoubleargument\spac_indenting_define}

\def\spac_indenting_define[#1][#2]% todo: mixes
  {\setevalue{\??indentingpreset#1}{#2}}

% \def\spac_indentation_apply_step_one_nested#1%
%   {\expandafter\processcommacommand\expandafter[\csname\??indentingpreset#1\endcsname]\spac_indentation_apply_step_one}
%
% \def\spac_indentation_apply_step_two_nested#1%
%   {\expandafter\processcommacommand\expandafter[\csname\??indentingpreset#1\endcsname]\spac_indentation_apply_step_two}
%
% \def\spac_indentation_apply_step_one#1%
%   {\ifcsname\??indentingpreset#1\endcsname
%      \spac_indentation_apply_step_one_nested{#1}%
%    \else\ifcsname\??indentingmethod#1\endcsname
%      % case two
%    \else
%      \edef\v_spac_indentation_current{#1}% single entry in list
%      \let\normalindentation\v_spac_indentation_current
%      \spac_indentation_setup_size
%    \fi\fi}
%
% \def\spac_indentation_apply_step_two#1%
%   {\ifcsname\??indentingpreset#1\endcsname
%      \spac_indentation_apply_step_two_nested{#1}%
%    \else\ifcsname\??indentingmethod#1\endcsname
%      \lastnamedcs
%    \else
%      % case one
%    \fi\fi}

\def\spac_indentation_apply_step_one_nested
  {\expandafter\processcommacommand\expandafter[\lastnamedcs]\spac_indentation_apply_step_one}

\def\spac_indentation_apply_step_two_nested
  {\expandafter\processcommacommand\expandafter[\lastnamedcs]\spac_indentation_apply_step_two}

\def\spac_indentation_apply_step_one#1%
  {\ifcsname\??indentingpreset#1\endcsname
     \spac_indentation_apply_step_one_nested
   \else\ifcsname\??indentingmethod#1\endcsname
     % case two
   \else
     \edef\v_spac_indentation_current{#1}% single entry in list
     \let\normalindentation\v_spac_indentation_current
     \spac_indentation_setup_size
   \fi\fi}

\def\spac_indentation_apply_step_two#1%
  {\ifcsname\??indentingpreset#1\endcsname
     \spac_indentation_apply_step_two_nested
   \else\ifcsname\??indentingmethod#1\endcsname
     \lastnamedcs
   \else
     % case one
   \fi\fi}

\unexpanded\def\indenting % kind of obsolete
  {\doifelsenextoptionalcs\spac_indentation_setup_options\relax}

% use \noindentation to suppress next indentation

\installcorenamespace{indentingmethod}

\unexpanded\def\installindentingmethod#1#2%
  {\setvalue{\??indentingmethod#1}{#2}}

\installindentingmethod \v!no    {\parindent\zeropoint}
\installindentingmethod \v!not   {\parindent\zeropoint}

\installindentingmethod \v!first {\settrue\c_spac_indentation_indent_first}
\installindentingmethod \v!next  {\setfalse\c_spac_indentation_indent_first}

\installindentingmethod \v!yes   {\parindent\d_spac_indentation_par\relax} % not \indent !
\installindentingmethod \v!always{\parindent\d_spac_indentation_par\relax} % not \indent !

\installindentingmethod \v!never {\parindent\zeropoint\relax     % no \indent !
                                  \c_spac_indentation_toggle_state\zerocount}

\installindentingmethod \v!odd   {\c_spac_indentation_toggle_state\plusone}
\installindentingmethod \v!even  {\c_spac_indentation_toggle_state\plustwo}

\installindentingmethod \v!normal{\ifx\normalindentation\empty\else
                                    \let\v_spac_indentation_current\normalindentation
                                    \spac_indentation_setup_size
                                  \fi}

\installindentingmethod \v!reset {\settrue\c_spac_indentation_indent_first
                                  \parindent\zeropoint
                                  \c_spac_indentation_toggle_state\zerocount}

\installindentingmethod \v!toggle{\parindent\ifzeropt\parindent
                                    \d_spac_indentation_par
                                  \else
                                    \zeropoint
                                  \fi\relax}

\unexpanded\def\noindenting{\indenting[\v!no, \v!next ]}
\unexpanded\def\doindenting{\indenting[\v!yes,\v!first]}

%D Here come the handlers (still rather messy ... we need states).

\newif\ifindentation \indentationtrue  % will become a mode

\let\checkindentation\relax

\installmacrostack\checkindentation
\installmacrostack\ifindentation

\def\spac_indentation_remove
  {\ifzeropt\parindent \else
     \begingroup
     \setbox\scratchbox\lastbox
     \endgroup
   \fi}

\def\spac_indentation_kill_indeed
  {\global\indentationfalse
   \spac_indentation_remove}

\def\spac_indentation_do_toggle_indeed
  {\global\indentationfalse
   \glet\checkindentation\spac_indentation_no_toggle_indeed
   \spac_indentation_remove}

\def\spac_indentation_no_toggle_indeed
  {\global\indentationtrue
   \glet\checkindentation\spac_indentation_do_toggle_indeed}

\def\spac_indentation_do_indeed
  {\global\indentationtrue}

\def\spac_indentation_do_toggle
  {\glet\checkindentation\spac_indentation_do_toggle_indeed}

\def\spac_indentation_no_toggle
  {\glet\checkindentation\spac_indentation_no_toggle_indeed}

\def\spac_indentation_check_toggle
  {\ifcase\c_spac_indentation_toggle_state
     % nothing
   \or
     \spac_indentation_no_toggle
   \or
     \spac_indentation_do_toggle
   \fi}

\def\spac_indentation_variant_yes
  {\glet\checkindentation\spac_indentation_do_indeed}

\def\spac_indentation_no_next_check
  {\spac_indentation_remove
   \glet\checkindentation\spac_indentation_do_indeed}

\def\spac_indentation_variant_no % made global
  {\ifinpagebody \else
     \global\indentationfalse
     \glet\checkindentation\spac_indentation_no_next_check
   \fi}

\def\nonoindentation % bv bij floats
  {\ifinpagebody \else
     \global\indentationtrue
     \glet\checkindentation\spac_indentation_do_indeed
   \fi}

\def\spac_indentation_variant_force
  {\ifvmode \ifzeropt\parindent \else
     % was : \hskip\parindent
     % can be: \indent
     % but we test:
     \noindent\hskip\parindent
   \fi \fi}

\appendtoks
    \push_macro_checkindentation
    \push_macro_ifindentation
\to \everypushsomestate

\appendtoks
    \pop_macro_ifindentation
    \pop_macro_checkindentation
\to \everypopsomestate

% public:

\let\indentation  \spac_indentation_variant_force
\let\noindentation\spac_indentation_variant_no    % public
\let\doindentation\spac_indentation_variant_yes   % public

\def\dontrechecknextindentation              % public (in macros)
  {\glet\dorechecknextindentation\relax}

\let\dorechecknextindentation\relax          % public (in macros)

\unexpanded\def\spac_indentation_check_next_indentation
  {\glet\dorechecknextindentation\relax
   \doifelsenextchar\par\donothing\spac_indentation_variant_no} % messy check as next is seldom \par

\def\spac_indentation_variant_auto
  {\glet\dorechecknextindentation\spac_indentation_check_next_indentation}

%D This one sets up the local indentation behaviour (i.e. either or not
%D a next paragraph will be indented).

\installcorenamespace{indentnext}

\unexpanded\def\checknextindentation[#1]%
  {\begincsname\??indentnext#1\endcsname}

\unexpanded\def\useindentnextparameter#1% new, the more efficient variant
  {\edef\p_indentnext{#1\c!indentnext}%
   \ifx\p_indentnext\empty\else
     \begincsname\??indentnext\p_indentnext\endcsname
   \fi}

\letvalue{\??indentnext       }\donothing
\letvalue{\??indentnext\v!yes }\spac_indentation_variant_yes
\letvalue{\??indentnext\v!no  }\spac_indentation_variant_no
\letvalue{\??indentnext\v!auto}\spac_indentation_variant_auto

%D An example of usage:
%D
%D \starttyping
%D \setupindenting[small,yes]
%D
%D \setupitemize [indentnext=auto]
%D \setuptyping  [indentnext=auto]
%D \setupformulas[indentnext=auto]
%D
%D \input tufte \startitemize \item itemize \stopitemize
%D \input tufte \startitemize \item itemize \stopitemize
%D \input tufte \startitemize \item itemize \stopitemize
%D
%D \page
%D
%D \input tufte
%D \starttyping
%D verbatim
%D \stoptyping
%D
%D \input tufte
%D \starttyping
%D verbatim
%D \stoptyping
%D
%D \input tufte
%D \starttyping
%D verbatim
%D \stoptyping
%D
%D \page
%D
%D \input tufte \startformula a = b \stopformula
%D \input tufte \startformula a = b \stopformula
%D \input tufte \startformula a = b \stopformula
%D \stoptyping

% maybe an everyforgetparindent

\unexpanded\def\forgetparindent
  {\settrue\c_spac_indentation_indent_first % recently added
   \d_spac_indentation_par\zeropoint
   \parindent\zeropoint
   \let\v_spac_indentation_current\v!none}

\appendtoks
    \forgetparindent
\to \everyforgetall

\unexpanded\def\forgethorizontalstretch
  {\emergencystretch\zeropoint}

\appendtoks
    \forgethorizontalstretch
\to \everyforgetall % needed in pagebody

%D Helper:

\unexpanded\def\softbreak
  {\relax\ifhmode\hskip\parfillskip\break\fi}

%D \macros
%D   {frenchspacing,nonfrenchspacing}
%D
%D Somehow \type{\frenchspacing} can lead to hyphenation between dashes so we now
%D have \type {\newfrenchspacing} (moved from \type {syst-chr}). Maybe it's not
%D needed any more.

%D Hm ... todo:

\installcorenamespace{spacecodemethod}

\sfcode`\)=\zerocount
\sfcode`\'=\zerocount
\sfcode`\]=\zerocount

\def\spac_spacecodes_set_fixed#1%
  {\sfcode`\.#1\relax \sfcode`\,#1\relax
   \sfcode`\?#1\relax \sfcode`\!#1\relax
   \sfcode`\:#1\relax \sfcode`\;#1\relax}

\def\spac_spacecodes_set_stretch
  {\sfcode`\.3000 \sfcode`\,1250
   \sfcode`\?3000 \sfcode`\!3000
   \sfcode`\:2000 \sfcode`\;1500 }

\unexpanded\def\frenchspacing   {\spac_spacecodes_set_fixed\plusthousand}
\unexpanded\def\newfrenchspacing{\spac_spacecodes_set_fixed{1050}}
\unexpanded\def\nonfrenchspacing{\spac_spacecodes_set_stretch}

\unexpanded\def\installspacingmethod#1#2{\setvalue{\??spacecodemethod#1}{#2}}

\installspacingmethod \empty    {}                  % keep values
\installspacingmethod \v!fixed  {\frenchspacing   } % equal spaces everywhere
\installspacingmethod \v!packed {\newfrenchspacing} % slighly more after punctuation
\installspacingmethod \v!broad  {\nonfrenchspacing} % more depending on what punctuation

\unexpanded\def\setupspacing
  {\doifelsenextoptionalcs\spac_spacecodes_setup_yes\spac_spacecodes_setup_nop}

\def\spac_spacecodes_setup_yes[#1]%
  {\begincsname\??spacecodemethod#1\endcsname
   \updateraggedskips}

\def\spac_spacecodes_setup_nop
  {\updateraggedskips}

%D Here's a tweak .. if needed one can configure it in the configuration
%D so that initialization happens more efficient.
%D
%D \starttyping
%D \startoverlay
%D     {
%D         \green
%D         \enabledirectives[characters.spaceafteruppercase=normal]%
%D         \vbox{\hsize 5em x. X\par x.\ X\par X. X\par X.\ X\par}
%D     } {
%D         \blue
%D         \enabledirectives[characters.spaceafteruppercase=traditional]%
%D         \vbox{\hsize 5em x. X\par x.\ X\par X. X\par X.\ X\par}
%D     }
%D \stopoverlay
%D \stoptyping

% This is not needed, as \updateraggedskips is taking care of it:

\let\synchronizespacecodes\spac_spacecodes_setup_nop % \relax

% \dorecurse{100}{\recurselevel\spacefactor 800 \space} \par
% \dorecurse{100}{\recurselevel\spacefactor1200 \space} \par
% \dorecurse{100}{\recurselevel\spacefactor 800 \normalspaceprimitive} \par
% \dorecurse{100}{\recurselevel\spacefactor1200 \normalspaceprimitive} \par

% When we don't add the % here, we effectively get \<endlinechar> and
% since we have by default \def\^^M{\ } we get into a loop.

\let\normalspaceprimitive=\ % space-comment is really needed

%D As the \type{\ } is convenient in:
%D
%D \starttyping
%D \TEX\space x\crlf
%D \TEX\      x\crlf
%D \TEX{}     x\crlf
%D \stoptyping
%D
%D from now on we treat it as a normal space and not as a space with \type
%D {sfcode} 1000.

\unexpanded\def\specialspaceprimitive
  {\begingroup
   % so, no fancy extra spacing after: foo i.e.\ bar
   \nonfrenchspacing\normalspaceprimitive
   \endgroup}

\unexpanded\def\normalnotobeyedspace
  {\mathortext\normalspaceprimitive\specialspaceprimitive} % no \dontleavehmode\space (else no frenchspacing)

\let\ =\normalnotobeyedspace

% Because I strip spaces at the end of lines (in the editor) we need a bit of
% a trick to define slash+newline, so \space and \<newline> are the same

% We need to be careful with \ and \space and the definition of ~ which uses \ as
% we need to associate unicode spacing with it. There is some messy aspect that
% I forgot to note down so I will revision the \ once I ran into it again.

% \ruledhbox spread 10pt {\frenchspacing    xx xx\ X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx xx\ X}
% \ruledhbox spread 10pt {\frenchspacing    xx xx X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx xx X}
% \ruledhbox spread 10pt {\frenchspacing    xx xx~X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx xx~X}

% \ruledhbox spread 10pt {\frenchspacing    xx dr.\ X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx dr.\ X}
% \ruledhbox spread 10pt {\frenchspacing    xx dr. X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx dr. X}
% \ruledhbox spread 10pt {\frenchspacing    xx dr.~X}
% \ruledhbox spread 10pt {\nonfrenchspacing xx dr.~X}

\unexpanded\def\nonbreakablespace{\penalty\plustenthousand\normalspaceprimitive} % no space in math

\letcatcodecommand \ctxcatcodes \tildeasciicode \nonbreakablespace % overloaded later

           \def\space          { }
\unexpanded\def\removelastspace{\ifhmode\unskip\fi}
\unexpanded\def\nospace        {\removelastspace\ignorespaces}

\ifdefined\nospaces
    \unexpanded\def\nospacing{\normalnospaces\plusone}
    \unexpanded\def\dospacing{\normalnospaces\zerocount}
\else
    \unexpanded\def\nospacing{\spaceskip\scaledpoint     \xspaceskip\zeropoint}
    \unexpanded\def\dospacing{\spaceskip\currentspaceskip\xspaceskip\zeropoint} % what
\fi

\ifdefined\softhyphen \else
    \let\softhyphen\explicitdiscretionary
\fi

\cldcontext{"\string\\unexpanded\string\\def\string\\\string\n{\string\\space}"}
%cldcontext{"\string\\let\string\\\string\n=\string\\space"}

% in tables we need:
%
% \def\fixedspace   {\hskip.5em\relax}
%
% but, since not all fonts have .5em digits:

\unexpanded\def\fixedspace
  {\setbox\scratchbox\hpack{\mathortext{0}{0}}% was \hbox
   \hskip\wd\scratchbox\relax}

\unexpanded\def\fixedspaces
  {\letcatcodecommand \ctxcatcodes \tildeasciicode\fixedspace
   \let~\fixedspace} % we need to renew it

\appendtoks
    \let~\space
    \let\ \space
\to \everysimplifycommands

\newsignal\s_spac_keep_unwanted_space

\unexpanded\def\keepunwantedspaces
  {\ifhmode
     \ifdim\lastskip=\s_spac_keep_unwanted_space\else
        \hskip\s_spac_keep_unwanted_space\relax
     \fi
   \fi}

\unexpanded\def\removeunwantedspaces
  {\ifhmode
     \expandafter \spac_helpers_remove_unwantedspace
   \fi}

\def\spac_helpers_remove_unwantedspace
  {\ifnum\lastnodetype=\gluenodecode
     \ifdim\lastskip=\s_spac_keep_unwanted_space\relax
       \unskip
     \else
       \unskip
       \doubleexpandafter\spac_helpers_remove_unwantedspace
     \fi
   \fi}

\unexpanded\def\onlynonbreakablespace
  {\ifdim\lastskip=\interwordspace
     \unskip
     \nonbreakablespace
   \fi
   \ignorespaces}

% \startbuffer
% \startlines \tt \fixedspaces
%  0~1~~2~~~3~~~~4~~~~~5
%  0~~~~~~~~~~~~~~~~~~~5
% $0~1~~2~~~3~~~~4~~~~~5$
% $0~~~~~~~~~~~~~~~~~~~5$
% \stoplines
%
% \starttabulate[|~|]
% \NC  0~1~~2~~~3~~~~4~~~~~5  \NC \NR \NC  0~~~~~~~~~~~~~~~~~~~5  \NC \NR
% \NC $0~1~~2~~~3~~~~4~~~~~5$ \NC \NR \NC $0~~~~~~~~~~~~~~~~~~~5$ \NC \NR
% \stoptabulate
%
% \starttable[||]
% \NC  0~1~~2~~~3~~~~4~~~~~5  \NC \AR \NC  0~~~~~~~~~~~~~~~~~~~5  \NC \AR
% \NC $0~1~~2~~~3~~~~4~~~~~5$ \NC \AR \NC $0~~~~~~~~~~~~~~~~~~~5$ \NC \AR
% \stoptable
% \stopbuffer
%
% \setupbodyfont[cmr] \getbuffer
% \setupbodyfont[lbr] \getbuffer

%D A couple of plain macros:

\ifdefined\thinspace \else

    \unexpanded\def\thinspace   {\kern .16667\emwidth}
    \unexpanded\def\negthinspace{\kern-.16667\emwidth}
    \unexpanded\def\enspace     {\kern     .5\emwidth}

\fi

\ifdefined\quad \else

    \unexpanded\def\enskip{\hskip.5\emwidth\relax}
    \unexpanded\def\quad  {\hskip  \emwidth\relax}
    \unexpanded\def\qquad {\hskip 2\emwidth\relax}

\fi

\unexpanded\def\negenspace{\kern-.5\emwidth}
\unexpanded\def\negemspace{\kern-  \emwidth}

\let\emspace\quad

\unexpanded\def\charspace{ } % the unexpandable \space (as space can also be delimiter for numbers)

\unexpanded\def\quads
  {\dosingleempty\spac_quads}

\def\spac_quads[#1]%
  {\zwj\dorecurse{\iffirstargument#1\else\plusthree\fi}{\hskip\emwidth\zwj}}

% Suggested by GB (not the name -):

\def\rapfillskip{.5\hsize plus .092\hsize minus .5\hsize} % D.A.'s value

% Bovendien definieren we enkele extra \fill's:

\unexpanded\def\hfilll   {\hskip\zeropoint\s!plus1\s!filll\relax}
\unexpanded\def\vfilll   {\vskip\zeropoint\s!plus1\s!filll\relax}

%unexpanded\def\hfilneg  {\hskip\zeropoint\s!plus-1\s!fil\relax}
\unexpanded\def\hfillneg {\hskip\zeropoint\s!plus-1\s!fill\relax}
\unexpanded\def\hfilllneg{\hskip\zeropoint\s!plus-1\s!filll\relax}
%unexpanded\def\vfilneg  {\vskip\zeropoint\s!plus-1\s!fil\relax}
\unexpanded\def\vfillneg {\vskip\zeropoint\s!plus-1\s!fill\relax}
\unexpanded\def\vfilllneg{\vskip\zeropoint\s!plus-1\s!filll\relax}

\unexpanded\def\tfskip    {\begingroup\tf\hskip\emwidth\endgroup}
\unexpanded\def\dotfskip#1{\begingroup\tf\hskip      #1\endgroup} % used elsewhere

% maybe we should hash the analysis

\installcorenamespace{narrower}
\installcorenamespace{narrowermethod}

\newskip\s_spac_narrower_left
\newskip\s_spac_narrower_right
\newskip\s_spac_narrower_middle

\installcommandhandler \??narrower {narrower} \??narrower

\setupnarrower
  [\c!before=\endgraf,
   \c!after=\endgraf,
   \c!left=1.5\emwidth,
   \c!right=1.5\emwidth,
   \c!middle=1.5\emwidth,
   \c!default=\v!middle]

\appendtoks
   \setuevalue{\e!start\currentnarrower}{\spac_narrower_start{\currentnarrower}}%
   \setuevalue{\e!stop \currentnarrower}{\spac_narrower_stop}%
\to \everydefinenarrower

\unexpanded\def\installnarrowermethod#1#2%
  {\setvalue{\??narrowermethod#1}{#2}}

\unexpanded\def\spac_narrower_method_analyze#1%
  {\ifcsname\??narrowermethod#1\endcsname
     \lastnamedcs
   \else
     \global\advance\s_spac_narrower_middle#1\relax
   \fi}

\def\spac_narrower_initialize[#1]% hm, can be dorepeat directly
  {\dorepeatwithcommand[#1]\spac_narrower_method_analyze}

\installnarrowermethod  \v!left   {\global\advance\s_spac_narrower_left   \narrowerparameter\c!left  \relax}
\installnarrowermethod  \v!middle {\global\advance\s_spac_narrower_middle \narrowerparameter\c!middle\relax}
\installnarrowermethod  \v!right  {\global\advance\s_spac_narrower_right  \narrowerparameter\c!right \relax}
\installnarrowermethod{-\v!left  }{\global\advance\s_spac_narrower_left  -\narrowerparameter\c!left  \relax}
\installnarrowermethod{-\v!middle}{\global\advance\s_spac_narrower_middle-\narrowerparameter\c!middle\relax}
\installnarrowermethod{-\v!right }{\global\advance\s_spac_narrower_right -\narrowerparameter\c!right \relax}
\installnarrowermethod  \v!reset  {\global        \s_spac_narrower_left   \zeropoint
                                   \global        \s_spac_narrower_middle \zeropoint
                                   \global        \s_spac_narrower_right  \zeropoint\relax}
\installnarrowermethod \v!none    {}
\installnarrowermethod \v!reverse {} % never seen

\unexpanded\def\spac_narrower_start#1%
  {\begingroup
   \edef\currentnarrower{#1}%
   \dosingleempty\spac_narrower_start_indeed}

\unexpanded\def\spac_narrower_start_indeed[#1]%
  {\iffirstargument
     \spac_narrower_start_apply{#1}%
   \else
     \spac_narrower_start_apply{\narrowerparameter\v!default}%
   \fi}

\newskip\s_spac_narrower_left_last
\newskip\s_spac_narrower_right_last
\newconditional\s_spac_narrower_last_swap

\def\spac_narrower_start_apply#1%
  {\narrowerparameter\c!before
   \global\s_spac_narrower_left  \zeropoint
   \global\s_spac_narrower_right \zeropoint
   \global\s_spac_narrower_middle\zeropoint
   \edef\askednarrower{#1}%
   \ifx\askednarrower\v!reverse
     \ifconditional\s_spac_narrower_last_swap
       \leftskip \s_spac_narrower_right_last
       \rightskip\s_spac_narrower_left_last
       \setfalse\s_spac_narrower_last_swap
     \else
       \leftskip \s_spac_narrower_left_last
       \rightskip\s_spac_narrower_right_last
       \settrue\s_spac_narrower_last_swap
     \fi
   \else
     \normalexpanded{\processcommalistwithparameters[\askednarrower]}\spac_narrower_initialize
     \advance\leftskip \dimexpr\s_spac_narrower_left +\s_spac_narrower_middle\relax
     \advance\rightskip\dimexpr\s_spac_narrower_right+\s_spac_narrower_middle\relax
   \fi
   \seteffectivehsize}

\unexpanded\def\spac_narrower_stop
  {\narrowerparameter\c!after
   \normalexpanded{%
      \endgroup
      \s_spac_narrower_left_last \the\leftskip \relax
      \s_spac_narrower_right_last\the\rightskip\relax
      \ifconditional\s_spac_narrower_last_swap
        \setfalse\s_spac_narrower_last_swap
      \else
        \settrue\s_spac_narrower_last_swap
      \fi
   }}

\unexpanded\def\startnarrower
  {\dosingleempty\spac_narrower_start_basic}

\unexpanded\def\spac_narrower_start_basic[#1]%
  {\begingroup
   \let\currentnarrower\empty
   \iffirstargument
     \spac_narrower_start_apply{#1}%
   \else
     \spac_narrower_start_apply{\narrowerparameter\v!default}%
   \fi}

\let\stopnarrower\spac_narrower_stop

\unexpanded\def\startnarrow % current how
  {\begingroup
   \dodoubleempty\spac_narrower_start_named}

% \def\spac_narrower_start_named[#1][#2]%
%   {\edef\currentnarrower{#1}%
%    \ifsecondargument
%      \spac_narrower_start_apply{#2}%
%    \else
%      \spac_narrower_start_apply{\narrowerparameter\v!default}%
%    \fi}

\def\spac_narrower_start_named
  {\ifsecondargument
      \expandafter\spac_narrower_start_named_two
   \else
      \expandafter\spac_narrower_start_named_one
   \fi}

\def\spac_narrower_start_named_one[#1]%
  {\doifelseassignment{#1}\spac_narrower_start_named_one_yes\spac_narrower_start_named_one_nop[#1]}

\def\spac_narrower_start_named_one_yes[#1][#2]% [settings] []
  {\setupcurrentnarrower[#1]%
   \spac_narrower_start_apply{\narrowerparameter\v!default}}

\def\spac_narrower_start_named_one_nop[#1][#2]% [tag] []
  {\edef\currentnarrower{#1}%
   \spac_narrower_start_apply{\narrowerparameter\v!default}}

\def\spac_narrower_start_named_two[#1]%
  {\doifelseassignment{#1}\spac_narrower_start_named_settings_how\spac_narrower_start_named_tag_unknown[#1]}

\def\spac_narrower_start_named_settings_how[#1][#2]% [settings] [how]
  {\setupcurrentnarrower[#1]%
   \spac_narrower_start_apply{#2}}

\def\spac_narrower_start_named_tag_unknown[#1][#2]% [tag] [...]
  {\doifelseassignment{#2}\spac_narrower_start_named_tag_settings\spac_narrower_start_named_tag_how[#1][#2]}

\def\spac_narrower_start_named_tag_settings[#1][#2]% [tag] [settings]
  {\edef\currentnarrower{#1}%
   \setupcurrentnarrower[#2]%
   \spac_narrower_start_apply{\narrowerparameter\v!default}}

\def\spac_narrower_start_named_tag_how[#1][#2]% [tag] [how]
  {\edef\currentnarrower{#1}%
   \spac_narrower_start_apply{#2}}

\let\stopnarrow\spac_narrower_stop

\newdimen\d_spac_effective_hsize     \def\effectivehsize    {\hsize}
\newdimen\d_spac_effective_leftskip  \def\effectiveleftskip {\dimexpr\leftskip \relax}
\newdimen\d_spac_effective_rightskip \def\effectiverightskip{\dimexpr\rightskip\relax}

\unexpanded\def\seteffectivehsize
  {\setlocalhsize
   \d_spac_effective_hsize    \localhsize
   \d_spac_effective_leftskip 1\leftskip
   \d_spac_effective_rightskip1\rightskip
   \let\effectivehsize    \d_spac_effective_hsize
   \let\effectiveleftskip \d_spac_effective_leftskip
   \let\effectiverightskip\d_spac_effective_rightskip}

\installcorenamespace{skipadaptionleft}
\installcorenamespace{skipadaptionright}

\newskip\leftskipadaption
\newskip\rightskipadaption

\setvalue{\??skipadaptionleft \v!yes     }{\ifzeropt\d_spac_indentation_par\narrowerparameter\c!left\else\d_spac_indentation_par\fi}
\letvalue{\??skipadaptionleft \v!no      }\zeropoint
\letvalue{\??skipadaptionleft \empty     }\zeropoint
\setvalue{\??skipadaptionright\v!yes     }{\narrowerparameter\c!right}
\letvalue{\??skipadaptionright\v!no      }\zeropoint
\letvalue{\??skipadaptionright\empty     }\zeropoint

% \setvalue{\??skipadaptionleft \v!standard}{\ifzeropt\d_spac_indentation_par\narrowerparameter\c!left\else\d_spac_indentation_par\fi}
% \setvalue{\??skipadaptionright\v!standard}{\narrowerparameter\c!right}

\letcsnamecsname\csname\??skipadaptionleft \v!standard\endcsname\csname\??skipadaptionleft \v!yes\endcsname
\letcsnamecsname\csname\??skipadaptionright\v!standard\endcsname\csname\??skipadaptionright\v!yes\endcsname

% \unexpanded\def\dosetleftskipadaption #1{\leftskipadaption \ifcsname\??skipadaptionleft #1\endcsname\csname\??skipadaptionleft #1\endcsname\else#1\fi\relax}
% \unexpanded\def\dosetrightskipadaption#1{\rightskipadaption\ifcsname\??skipadaptionright#1\endcsname\csname\??skipadaptionright#1\endcsname\else#1\fi\relax}

\unexpanded\def\dosetleftskipadaption #1{\leftskipadaption \ifcsname\??skipadaptionleft #1\endcsname\lastnamedcs\else#1\fi\relax}
\unexpanded\def\dosetrightskipadaption#1{\rightskipadaption\ifcsname\??skipadaptionright#1\endcsname\lastnamedcs\else#1\fi\relax}

\unexpanded\def\doadaptleftskip #1{\normalexpanded{\dosetleftskipadaption {#1}}\advance\leftskip \leftskipadaption }
\unexpanded\def\doadaptrightskip#1{\normalexpanded{\dosetrightskipadaption{#1}}\advance\rightskip\rightskipadaption}

\unexpanded\def\forgetbothskips
  {\leftskip\zeropoint
   \rightskip\zeropoint
   \relax}

\appendtoks
    \forgetbothskips
\to \everyforgetall

% in spac-ver.mkiv
%
% \unexpanded\def\forgetparskip
%   {\s_spac_whitespace_parskip\zeropoint
%    \parskip\zeropoint
%    \let\v_spac_whitespace_current\v!none}
%
% \appendtoks
%     \forgetparskip
% \to \everyforgetall

%D Tolerance (can also be set with align):

\installcorenamespace{tolerancemethods}

\unexpanded\def\installtolerancemethod#1#2#3%
  {\setvalue{\??tolerancemethods#1:#2}{#3}}

\installtolerancemethod \v!vertical   \v!verystrict   {\let\bottomtolerance\empty}
\installtolerancemethod \v!vertical   \v!strict       {\def\bottomtolerance{.050}}
\installtolerancemethod \v!vertical   \v!tolerant     {\def\bottomtolerance{.075}}
\installtolerancemethod \v!vertical   \v!verytolerant {\def\bottomtolerance{.100}}

\installtolerancemethod \v!horizontal \v!stretch      {\emergencystretch\bodyfontsize}
\installtolerancemethod \v!horizontal \v!space        {\spaceskip.5em\s!plus.25em\s!minus.25em\relax}
\installtolerancemethod \v!horizontal \v!verystrict   {\tolerance\plustwohundred}
\installtolerancemethod \v!horizontal \v!strict       {\tolerance1500 }
\installtolerancemethod \v!horizontal \v!tolerant     {\tolerance3000 }
\installtolerancemethod \v!horizontal \v!verytolerant {\tolerance4500 }

\appendetoks
     \pretolerance\plushundred
     \tolerance   \plustwohundred
\to\everyforgetall

\def\spac_tolerances_step_vertical  #1{\csname\??tolerancemethods\v!vertical  :#1\endcsname}
\def\spac_tolerances_step_horizontal#1{\csname\??tolerancemethods\v!horizontal:#1\endcsname}

\unexpanded\def\setuptolerance
  {\dosingleargument\spac_tolerances_setup}

\def\spac_tolerances_setup[#1]%
  {\doifelseinset\v!vertical{#1}%
     {\processcommacommand[#1]\spac_tolerances_step_vertical  }
     {\processcommacommand[#1]\spac_tolerances_step_horizontal}}

%D \macros
%D   {pushindentation,popindentation}
%D
%D The pushing and popping is done by:

\newbox\b_spac_indentations_a
\newbox\b_spac_indentations_b

\unexpanded\def\pushindentation
  {\begingroup
   \ifhmode
     \unskip
     \setbox\b_spac_indentations_a\lastbox       % get \strut if present
     \unskip
     \setbox\b_spac_indentations_b\lastbox       % get \indent generated box
     \unskip
   \else
     \dontleavehmode % was \hskip\zeropoint      % switch to horizontal mode
     \unskip
     \setbox\b_spac_indentations_a\lastbox       % get \indent generated box
     \setbox\b_spac_indentations_b\emptybox
   \fi}

\unexpanded\def\popindentation
  {\box\b_spac_indentations_b
   \box\b_spac_indentations_a
   \endgroup}

%D The only complication lays in \type{\strut}. In \PLAIN\
%D \TEX\ a \type{\strut} is defined as:
%D
%D \starttyping
%D \def\strut%
%D   {\relax\ifmmode\copy\strutbox\else\unhcopy\strutbox\fi}
%D \stoptyping
%D
%D But what is a \type{\strut}? Normally it's a rule of width
%D zero, but when made visual, it's a rule and a negative skip.
%D The mechanism for putting things in the margins described
%D here cannot handle this situation very well. One
%D characteristic of \type{\strut} is that the \type{\unhcopy}
%D results in entering horizontal mode, which in return leads
%D to some indentation.
%D
%D To serve our purpose a bit better, the macro \type{\strut}
%D can be redefined as:
%D
%D \starttyping
%D \def\strut
%D   {\relax\ifmmode\else\hskip0pt\fi\copy\strutbox}
%D \stoptyping
%D
%D Or more compatible:
%D
%D \starttyping
%D \def\strut
%D   {\relax\ifmmode
%D      \copy\strutbox
%D    \else
%D      \bgroup\setbox\strutbox=\hbox{\box\strutbox}\unhcopy\strutbox\egroup
%D    \fi}
%D \stoptyping
%D
%D In \CONTEXT\ however we save some processing time by putting
%D an extra \type{\hbox} around the \type{\strutbox}.

%D \starttyping
%D % \setuplayout[gridgrid=yes] \showgrid
%D
%D \startbuffer
%D test 1\crlf
%D test 2\crlf
%D
%D \crlf test 3
%D
%D test 4\crlf
%D test 5
%D
%D \crlf
%D \crlf
%D \crlf
%D test 6
%D \stopbuffer
%D
%D \hbox
%D   {\hsize5em
%D    \ruledvtop{\getbuffer}\enspace
%D    \ruledvtop{\showstruts\getbuffer}\enspace
%D    \hsize15em \setuptyping[before=,after=]%
%D    \ruledvtop{\typebuffer}}
%D \stoptyping

\unexpanded\def\justonespace{\removeunwantedspaces\space}
%unexpanded\def\justaperiod {\removeunwantedspaces.}
%unexpanded\def\justacomma  {\removeunwantedspaces,}

\installcorenamespace{hspace}

\unexpanded\def\ignorecrlf
  {\let\crlf\justonespace\let\\\crlf}

\unexpanded\def\definehspace
  {\dotripleempty\spac_hspaces_define}

\def\spac_hspaces_define[#1][#2][#3]% #1 = optional namespace
  {\ifthirdargument
     \setvalue{\??hspace#1:#2}{#3}%
   \else
     \setvalue{\??hspace:#1}{#2}%
   \fi}

\unexpanded\def\hspace
  {\dodoubleempty\spac_hspaces_insert}

\def\spac_hspaces_insert[#1][#2]%
  {\ifhmode
     \removeunwantedspaces
     \hskip % always a skip even when 0pt
       \ifsecondargument
         \hspaceamount{#1}{#2}%
       \else\iffirstargument
         \hspaceamount\empty{#1}%
       \else
         \hspaceamount\empty\s!default
       \fi\fi
     \expandafter\ignorespaces
   \fi}

\def\hspaceamount#1#2%
  {\dimexpr\ifcsname\??hspace#1:#2\endcsname\lastnamedcs\else\zeropoint\fi\relax}

\def\directhspaceamount#1%
  {\dimexpr\ifcsname\??hspace  :#1\endcsname\lastnamedcs\else\zeropoint\fi\relax}

% no installhspace here (this is already an old command)

\definehspace [\v!small]   [.25\emspaceamount]
\definehspace [\v!medium]  [.5\emspaceamount]
\definehspace [\v!big]     [1\emspaceamount]
\definehspace [\v!normal]  [1\spaceamount]
\definehspace [\v!default] [\spaceamount]
\definehspace [\v!none]    [\zeropoint]

%D Taken from Taco's math module (cq. \AMS\ macros), but
%D adapted to \type {\hspace}:

\unexpanded\def\textormathspace         #1#2#3{\ifmmode\mskip#1#2\else\kern #1\hspaceamount\empty{#3}\fi\relax}
\unexpanded\def\textormathspacecommand  #1#2#3{\ifmmode\mskip#1#2\else#3\fi\relax}
\unexpanded\def\breakabletextormathspace#1#2#3{\ifmmode\mskip#1#2\else\hskip#1\hspaceamount\empty{#3}\fi\relax}

\newmuskip\hairmuskip \hairmuskip=.15mu

\unexpanded\def\hairspace    {\textormathspace+\hairmuskip{.5}}
\unexpanded\def\thinspace    {\textormathspace+\thinmuskip 1}
%unexpanded\def\medspace     {\textormathspace+\medmuskip  2}      % 4/18 em
\unexpanded\def\thickspace   {\textormathspace+\thickmuskip3}
\unexpanded\def\neghairspace {\textormathspace-\thinmuskip{.5}}
\unexpanded\def\negthinspace {\textormathspace-\thinmuskip 1}
\unexpanded\def\negmedspace  {\textormathspace-\medmuskip  2}
\unexpanded\def\negthickspace{\textormathspace-\thickmuskip3}

\unexpanded\edef\medspace    {\textormathspacecommand+\medmuskip{\Uchar"205F}}

% needed for unicode:

%unexpanded\def\breakablethinspace      {\breakabletextormathspace+\thinmuskip1}
%unexpanded\def\twoperemspace           {\hskip\dimexpr\emwidth/2\relax} % == \enspace
%unexpanded\def\threeperemspace         {\hskip\dimexpr\emwidth/3\relax}
%unexpanded\def\fourperemspace          {\hskip\dimexpr\emwidth/4\relax}
%unexpanded\def\fiveperemspace          {\hskip\dimexpr\emwidth/5\relax} % goodie
%unexpanded\def\sixperemspace           {\hskip\dimexpr\emwidth/6\relax}
%unexpanded\def\figurespace             {\begingroup\setbox\scratchbox\hbox{0}\hskip\wd\scratchbox\endgroup} % there is a command for this
%unexpanded\def\punctuationspace        {\begingroup\setbox\scratchbox\hbox{.}\hskip\wd\scratchbox\endgroup}
%unexpanded\def\ideographicspace        {\hskip\dimexpr\emwidth/1\relax}
%unexpanded\def\ideographichalffillspace{\hskip\dimexpr\emwidth/2\relax}
%unexpanded\def\nobreakspace            {\penalty\plustenthousand\kern\interwordspace}
%unexpanded\def\narrownobreakspace      {\penalty\plustenthousand\thinspace}
%unexpanded\def\zerowidthnobreakspace   {\penalty\plustenthousand\kern\zeropoint}
%unexpanded\def\zerowidthspace          {\hskip\zeropoint}

\definehspace[.5][.1250\emwidth] % hair
\definehspace[1] [.1667\emwidth] % thin
\definehspace[2] [.2222\emwidth] % med
\definehspace[3] [.2777\emwidth] % thick

\let \, \thinspace
\let \: \medspace
\let \; \thickspace
\let \! \negthinspace

% plain ...
%
% \ifdefined\> \else \unexpanded\def\>{\mskip \medmuskip  }                                \fi
% \ifdefined\* \else \unexpanded\def\*{\discretionary{\thinspace\the\textfont2\char2}{}{}} \fi

\def\flexiblespaceamount#1#2#3%
         {#1\interwordspace
   \s!plus#2\interwordstretch
  \s!minus#3\interwordshrink}

\def\fixedspaceamount#1%
  {#1\interwordspace}

% moved from page-lin
%
% the following code is used in startlines\stoplines
%
% do we need \normalspaceprimitive here?

\installcorenamespace{spacemethods}

\unexpanded\def\installspacemethod#1#2% needs to set \obeyedspace
  {\setvalue{\??spacemethods#1}{#2}}

\def\activatespacehandler#1%
  {\csname\??spacemethods\ifcsname\??spacemethods#1\endcsname#1\else\v!off\fi\endcsname}

\unexpanded\def\spac_spaces_checked_control{\mathortext\normalspace{\dontleavehmode{\tt\controlspace}}}%
\unexpanded\def\spac_spaces_checked_normal {\mathortext\normalspace{\dontleavehmode\normalspace}}%
\unexpanded\def\spac_spaces_checked_fixed  {\mathortext\normalspace{\dontleavehmode\fixedspace}}%

% hm, order matters when we \let in \obeyspaces

\installspacemethod \v!on
  {\obeyspaces
   \let\obeyedspace\spac_spaces_checked_control
   \let\ =\obeyedspace}

\installspacemethod \v!yes
  {\obeyspaces
   \let\obeyedspace\spac_spaces_checked_normal
   \let\ =\obeyedspace}

\installspacemethod \v!off % == default
  {\normalspaces
   \let\obeyedspace\normalspace
   \let\ =\normalspaceprimitive} % was \normalspace

\installspacemethod \v!fixed
  {\obeyspaces
   \let\obeyedspace\spac_spaces_checked_fixed
   \let\ =\obeyedspace}

\appendtoks
   \normalspaces % to be sure
\to \everybeforeoutput

%D A more robust variant of the \MKII\ one:
%D
%D \startbuffer
%D bla \TEX\autoinsertnextspace bla
%D bla \TEX\autoinsertnextspace (bla)
%D bla (\TEX\autoinsertnextspace) bla
%D bla \TEX\autoinsertnextspace\ bla
%D \stopbuffer
%D
%D \typebuffer \getbuffer

\unexpanded\def\autoinsertnextspace
  {\futurelet\nexttoken\spac_spaces_auto_insert_next}

\def\spac_spaces_auto_insert_next
  {\clf_autonextspace{\normalmeaning\nexttoken}} % todo, just consult nexttoken at the lua end

%D Moved from bib module:

\unexpanded\def\outdented#1%
  {\hskip-\hangindent#1\relax}

%D Beware: due to char-def this becomes an active character but that
%D might change sometime when we will replace all these specials to
%D node insertions. We might even expand it to utf then as it then
%D can be used in string comparison (not that much needed anyway).

% \chardef\zwnj="200C
% \chardef\zwj ="200D

% TODO (but used in languages):

\unexpanded\def\spac_glues_text_or_math#1#2%
  {\begingroup
   \ifmmode
     \mskip#1%
   \else
     \scratchdimen#1\hspaceamount\empty{#2}%
     \scratchskip\scratchdimen\s!plus.5\scratchdimen\s!minus.3\scratchdimen
     \hskip\scratchskip
   \fi
   \endgroup}

\unexpanded\def\thinglue {\spac_glues_text_or_math\thinmuskip \v!small}
\unexpanded\def\medglue  {\spac_glues_text_or_math\medmuskip  \v!medium}
\unexpanded\def\thickglue{\spac_glues_text_or_math\thickmuskip\v!big}

%D A rather unknown one:

\unexpanded\def\widened % moved from cont-new
  {\doifelsenextoptionalcs\spac_widened_yes\spac_widened_nop}

\def\spac_widened_yes[#1]#2{\hbox \s!spread       #1{\hss#2\hss}}
\def\spac_widened_nop    #1{\hbox \s!spread \emwidth{\hss#1\hss}}

\definecomplexorsimple\widened

%D For the moment here (used in page-txt):

\unexpanded\def\ignoredlinebreak{\unskip\space\ignorespaces}

%D \macros
%D   {startignorespaces}
%D
%D I'll probably forget that this one exists:
%D
%D \starttyping
%D \ruledhbox
%D   {\startignorespaces
%D      \def\oeps{a}
%D      \startignorespaces
%D        \def\oeps{a}
%D      \stopignorespaces
%D      \def\oeps{a}
%D    \stopignorespaces
%D    \oeps}
%D \stoptyping

\newsignal\s_spac_ignore_spaces
\newcount \c_spac_ignore_spaces

\unexpanded\def\startignorespaces
  {\advance\c_spac_ignore_spaces\plusone
   \ifcase\c_spac_ignore_spaces\or \ifhmode
     \hskip\s_spac_ignore_spaces
   \fi \fi
   \ignorespaces}

\unexpanded\def\stopignorespaces
  {\ifcase\c_spac_ignore_spaces \or
     \ifhmode
       \doloop\spac_ignore_spaces_body
     \fi
   \fi
   \advance\c_spac_ignore_spaces\minusone}

\def\spac_ignore_spaces_body
  {\ifzeropt\lastskip
     \exitloop
   \else\ifdim\lastskip=\s_spac_ignore_spaces
     \unskip
     \exitloop
   \else
     \unskip
   \fi\fi}

%D \macros
%D   {obeyfollowingtoken}

\def\obeyfollowingtoken{{}}  % end \cs scanning

%D Something new:

\unexpanded\def\interwordspacebefore{\wordboundary\zwnj\hskip\interwordspace\relax}
\unexpanded\def\interwordspaceafter {\hskip\interwordspace\relax\zwnj\wordboundary}

\unexpanded\def\interwordspacesbefore#1{\dofastloopcs{#1}\interwordspacebefore}
\unexpanded\def\interwordspacesafter #1{\dofastloopcs{#1}\interwordspaceafter}
\unexpanded\def\interwordspaces      #1{\wordboundary\zwnj\dofastloopcs{\numexpr#1+\minusone}\interwordspaceafter}

\protect \endinput