texinfo/contrib/texifont/fattr.tex

% font set              Computer Modern, Latin Modern, Bera
%   font family         CMRoman, CMTypewriter, CMSansSerif
%
% font feature          slant, weight, width
%   font attribute      sl, it, bold, cond
%
% fontfile
%
% Font features and attributes:
%
%     size              design point size
%     encoding          ot1, oml, oms, omx, t1, ts1, t2a
%     slant             up, sl, it, ui, cursive
%     weight            lt, med, semib, bold, bx,
%     width             cond, normal, ext
%     figures           oldfigures, liningfigures
%     caps              normalcaps, allcaps, smallcaps, nocaps

\catcode`@=11
%
% \fsz:CMRoman/<OT1>/<up>/<med>/<normal>/<liningfigures>/<normalcaps>
% ->
% cmr5/5,cmr7/7,cmr8/8,cmr9/9,cmr10/10,cmr12/12,cmr17/17,.
%
% {CMRoman}{b}{bx}
% {OML,CMRoman}{m}{up}
% {OML,CMRoman}{bx}{up}
% {OML,CMRoman}{b}{bx}
% {CMSans}{it}{sl}
% {CMSans}{b}{bx}
% {CMSans,OML}{}{CMRoman}
% {ConcreteRoman}{b}{LMSans,b}
% {OT1,CMMath}{}{CMRoman,n}
% {OMX,CMMath}{bx}{m}
%

\input eplain

%
%
%
% Font-related logging.  Meanings of \ftracelevel values are:
%
%   0 - none
%   1 - warning
%   2 - debug
%   3 - verbose
\newcount\ftracelevel
\ftracelevel=1
%
\def\f@warning{\f@trace0}%
\def\f@debug  {\f@trace1}%
\def\f@verbose{\f@trace2}%
\def\f@trace#1{%
  \ifnum#1<\ftracelevel
    \expandafter\message
  \else
    \expandafter\gobble
  \fi
}%
%
%
%
% Defining new fonts.
%
% \newfont MAG-FACTOR FILE-NAME DESIGN-SIZE [ATTRIBUTES]
%
% If ATTRIBUTES is not given, will reuse ATTRIBUTES from the
% last \newfont call with ATTRIBUTES given.  To define a font with
% empty attributes, pass \empty or {} for ATTRIBUTES.
\let\newfont@last@attributes\empty
%
{\catcode`\^^M=12 % Comment out all line ends from now on.
\gdef\newfont{\begingroup \catcode`\^^M=12 \@newfont}%
\gdef\@newfont#1 #2 #3^^M{\endgroup%
  \def\newfont@mag{#1}%
  \def\newfont@fname{#2}%
  \@new@font#3 ^^M%
}%
\gdef\@new@font #1 #2^^M{% DESIGN-SIZE [ATTRIBUTES]
  \get@dimen{#1}% Convert font size into a dimen.
  \if^^M#2^^M% Assume #2 contains no (leading) ^^Ms.
    % #2 is empty, continue to use the current \newfont@last@attributes.
  \else%
    \@new@font@#2^^M% Redefine \newfont@last@attributes, removing the space.
  \fi%
  \def@newfont%
}%
\gdef\@new@font@#1 ^^M{\def\newfont@last@attributes{#1}}%
}%
%
%\def\def@newfont{%
%  \message{^^J.\newfont@mag.\newfont@fname.\the\dimen@.\newfont@last@attributes.}%
%}%
%
\def\def@newfont{%
  % Empty \ff@temp0, \ff@temp1, ..., \ff@temp<MAX-ITEM-IDX>.
  \ff@temp@reset
  \for\ff@temp@i:=\newfont@last@attributes\do{%
    \f@get@af\ff@temp@i
    \expandafter\edef\csname ff@temp\tempb\endcsname{\tempa\space}%
  }%
  % Combine all \f@temp<X> into \f@name.
  \edef\f@name{f:\ff@temp@collect}%
  \expandafter\let\expandafter\temp \csname \f@name \endcsname
  %
  \ifx\temp\relax
    \let\do\relax
    \expandafter\xdef\csname\f@name\endcsname
      {\do \the\dimen@ \space \newfont@mag\space {\newfont@fname}}%
    \f@debug{^^J\the\inputlineno: Started font def with
             "\csname \f@name\endcsname".}%
  \else
    \edef\newfont@size{\the\dimen@}%
    \divide\dimen@ by1000
    \multiply\dimen@ by\newfont@mag\relax
    \let\newfont@prefix\empty
    \let\do\newfont@insert
    % Try inserting the new size.
    \temp\relax
    % If the new size hasn't been inserted, append it now.
    \ifx\do\newfont@insert
      \let\do\relax
      \expandafter\xdef\csname\f@name\endcsname {%
        \newfont@prefix \do \newfont@size\space \newfont@mag\space {\newfont@fname}%
      }%
      \f@debug{^^J\the\inputlineno: Updated font def to
               "\csname \f@name\endcsname".}%
    \fi
  \fi
}%
%
% \newfont@insert FONT-SIZE MAG-FACTOR FILE-NAME
%
% Insert new font file into the list of font files in \newfont@prefix,
% preserving ascending order of scaled design sizes.
%
% Pass in new font's design size in \newfont@size, mag factor
% in \newfont@mag, font file name in \newfont@fname, pre-computed
% scaled size in \dimen@.
\def\newfont@insert#1 #2 #3{%
  \toks@=\expandafter{\newfont@prefix}%
  % We are comparing scaled font sizes, not design sizes.
  \dimen@ii=#1\divide\dimen@ii by1000 \multiply\dimen@ii by#2\relax
  %
  \ifdim \dimen@ii < \dimen@
    % Not inserting yet, go on to the next font file.
    \edef\newfont@prefix{\the\toks@ \noexpand\do #1 #2 {#3}}%
  \else
    % Time to insert the new font file.  If we are adding a font file
    % for the same design size/mag factor, the new def will override
    % the old, but give out a warning.
    \def\newfont@next{\noexpand\do #1 #2 {#3}}%
    \ifnum #2=\newfont@mag
      \ifdim #1=\newfont@size
        \f@warning{^^J\the\inputlineno: Warning: Replacing font "#3" (#1@#2)
          with font "\newfont@fname" (\newfont@size @\newfont@mag).}%
        \let\newfont@next\empty
      \fi
    \fi
    \edef\newfont@prefix{\the\toks@
      \noexpand\do \newfont@size \space \newfont@mag \space {\newfont@fname}%
      \newfont@next}%
    % No need to parse further, just append the rest of the list.
    \expandafter\newfont@append
  \fi
}%
%
\def\newfont@append#1\relax{%
  \let\do\relax
  \expandafter\xdef\csname\f@name\endcsname {\newfont@prefix #1}%
  \f@debug{^^J\the\inputlineno: Updated font def to
           "\csname \f@name\endcsname".}%
}%
%
%
%
% Defining new font features and attributes.
%
\newcount\fcacheidx % Font cache index.
\newcount\ffeatcount % Font feature count.
% We'll build up the following as we add font features.
\let\ff@reset\empty
\let\ff@collect\empty
\let\ff@temp@reset\empty
\let\ff@temp@collect\empty
%
% \newfontattr FONTFEATURE FONTATTR
\def\newfontattr #1 #2 {%
  % Define a new font attribute, if it's not defined yet.
  \expandafter\ifx\csname fa:#2\endcsname \relax
  \else
    \errmessage{Font attribute "#2" already defined as part
      of font feature "\csname ff@\csname faf:#2\endcsname\endcsname"}%
  \fi
  \expandafter\xdef\csname fa:#2\endcsname{\the\fcacheidx}%
  \expandafter\xdef\csname fa@\the\fcacheidx\endcsname{#2}%
  % Invalidate current font cache (and update index for the next font
  % attribute).
  \global\advance\fcacheidx by1
  %
  % Define a new font feature, if it's not defined yet.
  \expandafter\ifx\csname ff:#1\endcsname \relax
    \expandafter\xdef\csname ff:#1\endcsname{\the\ffeatcount}%
    \expandafter\xdef\csname ff@\the\ffeatcount\endcsname{#1}%
    % Update \ff@reset to clear the new font feature cell \ffN.
    \toks@=\expandafter{\ff@reset}%
    \xdef\ff@reset{\the\toks@
      \let\expandafter\noexpand\csname ff\the\ffeatcount\endcsname
        \noexpand\empty}%
    % Update \ff@temp@reset to clear the new font feature cell \ff@tempN.
    \toks@=\expandafter{\ff@temp@reset}%
    \xdef\ff@temp@reset{\the\toks@
      \let\expandafter\noexpand\csname ff@temp\the\ffeatcount\endcsname
        \noexpand\empty}%
    % Update \ff@collect to include the new font feature cell \ffN.
    \toks@=\expandafter{\ff@collect}%
    \xdef\ff@collect{\the\toks@
      ^^A\expandafter\noexpand\csname ff\the\ffeatcount\endcsname}%
    % Update \ff@temp@collect to include the new font feature cell \ffN.
    \toks@=\expandafter{\ff@temp@collect}%
    \xdef\ff@temp@collect{\the\toks@
      ^^A\expandafter\noexpand\csname ff@temp\the\ffeatcount\endcsname}%
    % Set \ffN to \empty, otherwise it will be set to \relax the first
    % time we try to access it through \csname...\endcsname, and we
    % depend on it to be either a number or \empty.
    \global\expandafter\let\csname ff\the\ffeatcount\endcsname \empty
    %
    \global\advance\ffeatcount by1
    % We've added a new font feature, so we should invalidate current
    % font cache.  But we've already done so above when adding the new
    % font attribute.
    %\global\advance\fcacheidx by1
  \fi
  % Assign the font attribute to the font feature.
  \expandafter\xdef\csname faf:#2\endcsname{\csname ff:#1\endcsname}%
}%
%
% \newfontattrs FONTFEATURE FONTATTRIBUTE[,...]
\def\newfontattrs #1 #2 {%
  \for\temp:=#2\do{\newfontattr #1 {\temp} }%
}%
%
%
%
% Setting a font.
%
\newcount\f@base@mag \f@base@mag=1000
\newcount\f@count@
% Set a font based on the current values of \ff0, \ff1, ..., or
% execute #1 if such font is not defined.
\def\f@setfont#1{%
  \f@verbose{^^J\the\inputlineno: (Started search for a font.}%
  % Check the cache.
  \expandafter\let\expandafter\temp
    \csname f\the\fcacheidx:\the\f@cur@size:\ff@collect\endcsname
  \ifx\temp\relax
    % Not in the cache.
    \let\do\relax
    \expandafter\let\expandafter\temp \csname f:\ff@collect\endcsname
    \ifx\temp\relax
      \f@debug{^^JFont is not defined.}%
      #1% Execute the no-font action.
    \else
      \dimen@=\z@ % Fake previous size for the first font in the list.
      \let\f@fname\empty
      \let\do\f@search@size
      \global\dimen@i=\f@cur@size
      \temp\relax
      \ifnum\f@base@mag=\f@count@ \else
        \global\divide\dimen@i by\f@base@mag
        \global\multiply\dimen@i by\f@count@
      \fi
      \f@debug{Found font "\f@fname", mag factor \the\f@count@,
        scaled size \the\dimen@i.}%
      % Save it in the cache.
      \global \expandafter\font
        \csname f\the\fcacheidx:\the\f@cur@size:\ff@collect\endcsname
        \f@fname \space at\the\dimen@i
      % Set it.
      \csname f\the\fcacheidx:\the\f@cur@size:\ff@collect\endcsname
    \fi
  \else
    % Got a cache hit.
    \f@debug{Found font in the cache.}%
    \temp
  \fi
  \f@verbose{Ended search for a font.)}%
}%
%
% \f@search@size DESIGN-SIZE MAG-FACTOR FILE-NAME
%
% Pass in the desired font size in \dimen@i.  Font file name is saved
% in \f@fname, font's mag factor in \f@count@.
\def\f@search@size #1 #2 #3{%
  \f@verbose{Looking at font def "#3" (#1@#2).}%
  \dimen@ii=\dimen@ % Get the size of the previous font from the list.
  % Scale design size of the next font as per current base mag factor.
  \dimen@=#1\relax
  \ifnum#2=\f@base@mag \else
    \divide\dimen@ by\f@base@mag \multiply\dimen@ by#2\relax
  \fi
  % Calculate the "dividing" point size.
  \count@=\dimen@ % Don't clobber \dimen@.
  \advance\count@ by-\dimen@ii % Curr size - prev size.
  % Don't do the following line -- .3333*3pt < 1pt.
  %\advance\dimen@ii by.3333\count@ % 1/3 of the way from prev to curr.
  \divide\count@ by3
  \advance\dimen@ii by\count@ sp% 1/3 of the way from prev to curr.
  %
  \ifdim \dimen@i > \dimen@ii
    % The previous font's size is too small.  The current font might
    % or might not be the one we need, but we assume it is, in case
    % it's the last one in the list.
    \def\f@fname{#3}%
    \f@count@=#2\relax
  \else
    % The target size is close enough to the prev font's size, so we take that.
    \ifx\f@fname\empty
      % This is the case when we need a size smaller than the very
      % first font in the list.
      \def\f@fname{#3}%
      \f@count@=#2\relax
    \fi
    \expandafter\f@search@gobble
  \fi
}%
%
\def\f@search@gobble#1\relax{}%
%
%
%
% Font feature manipulations.
%
\newdimen\f@cur@size \f@cur@size=10pt
% \setfont{ATTRS}
\def\setfont{%
  % Empty \ff0, \ff1, ..., \ff<ffeature_count - 1>.
  \ff@reset
  \addfontattrs % Substitutes and sets the font.
}%
%
% \modfont{REM-FEATURES}{ADD-OR-MOD-ATTRS}
\def\modfont#1{%
  \unsetfontfeatures{#1}%
  \addfontattrs % Substitutes and sets the font.
}%
%
% \addfontattrs{ADD-OR-MOD-ATTRS}
\def\addfontattrs#1{%
  % For each feature with attribute in #1, set \ff<f> to `<a> ', where
  % <f> is the feature index and <a> is the attribute index.  For a
  % number or a dimen in #1, set \f@cur@size.  Dimen specs starting
  % with '.' (e.g., '.1pt') are not supported.
  \for\f@i:=#1\do{%
    \expandafter\gobble@to@finish % Gobbles 'pt' when \f@i is '10pt'.
      \ifnum9<1\f@i\relax
    \finish
        % A number or a dimen.
        \get@dimen{\f@i}%
        \f@cur@size=\dimen@
      \else
    \finish
        % Not a number.
        \f@get@af\f@i
        \expandafter\edef\csname ff\tempb\endcsname {\tempa\space}%
      \fi
  }%
  % Try to set the font; if it's not defined, do substitution and try
  % to set the resulting font.  Do font substitution inside a group so
  % that the current set of font attributes is not clobbered.
  \f@setfont{{\f@subst \f@setfont{\f@err@nofont}\expandafter}\the\font}%
}%
%
% Take a dimension or a number, and save it in \dimen@.  In case of a
% number, assume `pt' units.
\def\get@dimen#1{%
  \afterassignment\gobble@to@finish
  \dimen@#1pt \finish
}%
\def\gobble@to@finish#1\finish{}%
%
\def\f@err@nofont{%
  \dumpfontfeatures
  \errmessage{^^JFound no font def for the selected feature set}%
}%
%
% \remfontfeatures{REM-FEATURES}
\def\remfontfeatures#1{%
  \unsetfontfeatures{#1}%
  % Try to set the font; if it's not defined, do substitution and try
  % to set the resulting font.  Do font substitution inside a group so
  % that the current set of font attributes is not clobbered.
  \f@setfont{{\f@subst \f@setfont{\f@err@nofont}\expandafter}\the\font}%
}%
%
\def\unsetfontfeatures#1{%
  % Unset \ff<f> for each feature <f> in #1.
  \for\f@i:=#1\do{%
    \expandafter\let\expandafter\temp\csname ff:\f@i\endcsname
    \ifx\temp\relax
      \errmessage{Undefined font feature "\f@i"}%
    \fi
    \expandafter\let \csname ff\temp\endcsname \empty
  }%
}%
%
% Pretty-print the current settings of font features.
\def\dumpfontfeatures{%
  \message{^^J\the\inputlineno: font size \the\f@cur@size, features (}%
  \@dumpfontfeatures\message
  \message{).}%
}%
%
\def\@dumpfontfeatures#1{%
  \fori0\ffeatcount{%
    \edef\temp{\csname ff\the\count@\endcsname}%
    #1{%
      \csname ff@\the\count@\endcsname=%
      \ifx\temp\empty
        <unset>%
      \else
        \expandafter\dump@ff\temp
      \fi
    }%
  }%
}%
%
\def\dump@ff#1 {\csname fa@#1\endcsname}%
%
%
%
% Construction of font filter strings.
%
% \fontsubstpre =MATCH-ATTR -REM-FEATURES +ADD-OR-MOD-ATTRS
%
% Install a new font substitution to be applied before other font
% substitutions.
\def\fontsubstpre{%
  \let\fontsubst@mklist\fontsubst@pre
  \@fontsubst
}%
%
% \fontsubstpost =MATCH-ATTR -REM-FEATURES +ADD-OR-MOD-ATTRS
%
% Install a new font substitution to be applied after other font
% substitutions.
\def\fontsubstpost{%
  \let\fontsubst@mklist\fontsubst@post
  \@fontsubst
}%
%
% \@fontsubst =MATCH-ATTR -REM-FEATURES +ADD-OR-MOD-ATTRS
\def\@fontsubst{%
  % Construct the match string in \fontsubst@match@list.
  \f@mk@falist\fontsubst@\fontsubst@match@list % =MATCH-ATTR
}%
%
% \fontsubst@ -REM-FEATURES +ADD-OR-MOD-ATTRS
\def\fontsubst@{%
  % Construct the rem string in \fontsubst@rem@list.
  \f@mk@flist\fontsubst@@\fontsubst@rem@list % -REM-FEATURES
}%
%
% \fontsubst@ +ADD-OR-MOD-ATTRS
\def\fontsubst@@{%
  % Construct the add string in \fontsubst@add@list.
  \f@mk@falist\fontsubst@fin\fontsubst@add@list% +ADD-OR-MOD-ATTRS
}%
%
\def\fontsubst@fin{%
  % Add the new substitution to either head or tail of the current
  % substitution list.
  \let\@end\relax
  \edef\f@subst@list{\fontsubst@mklist}%
}%
%
\def\fontsubst@pre{%
  \fontsubst@match@list \@end
  \fontsubst@rem@list   \@end
  \fontsubst@add@list   \@end
  \f@subst@list
}%
%
\def\fontsubst@post{%
  \f@subst@list
  \fontsubst@match@list \@end
  \fontsubst@rem@list   \@end
  \fontsubst@add@list   \@end
}%
%
% Initialize the font substitution list to empty.
\let\f@subst@list\empty
%
% Given the name of an attribute, return index of the attribute
% in \tempa and index of the attribute's feature in \tempb.
\def\f@get@af#1{%
  % Get attribute's index.
  \expandafter\let\expandafter\tempa\csname fa:#1\endcsname
  \ifx\tempa\relax
    \errmessage{Undefined font attribute "#1"}%
  \fi
  % Get feature index for the attribute.
  \expandafter\let\expandafter\tempb\csname faf:#1\endcsname
  \ifx\tempb\relax
    \errmessage{Undefined font attribute "#1"}%
  \fi
}%
%
% Given a comma-separated list of attributes #4, construct a string
% (saving it in macro #2) as a sequence of `F.A,' specs, where F is
% the index of the feature to which attribute belongs, and A is the
% index of the attribute.  After that, call #1.  #3 is an ignored
% syntax sugar ("=" or "+") from the user-visible command.
\def\f@mk@falist#1#2#3#4 {%
  \let#2\empty % Start with a clean slate.
  \let\do\relax
  \for\f@i:=#4\do{%
    \f@get@af\f@i
    \edef#2{#2\do\tempb.\tempa,}% Append the spec to the list.
  }%
  #1%
}%
%
% Given a comma-separated list of features #4, construct a string
% (saving it in macro #2) as a sequence of `F,' specs, where F is the
% feature index.  After that, call #1.  After that, call #1.  #3 is an
% ignored syntax sugar ("-") from the user-visible command.
\def\f@mk@flist#1#2#3#4 {%
  \let#2\empty
  \let\do\relax
  \for\f@i:=#4\do{%
    \expandafter\let\expandafter\temp\csname ff:\f@i\endcsname
    \ifx\temp\relax
      \errmessage{Undefined font feature "\f@i"}%
    \fi
    \edef#2{#2\do\temp,}%
  }%
  #1%
}%
%
% \fori{FROM-INCL}{TO-EXCL}{EXEC}
\def\fori#1#2#3{%
  \count@=#1\relax
  \loop
    #3\relax
    \advance\count@ by1
  \ifnum\count@<#2\repeat
}%
%
%
%
% Generic filter parsing macros.  Configure by defining these
% callbacks (before running \f@run@filter on the filter string):
%
%   \f@do@filter@match#1.#2,  - match the pair filter/attribute.
%   \f@do@filter@rem          - unset feature `F,'.
%   \f@do@filter@add          - add the pair `F.A,'.
%   \f@hook@filter@end        - action at the end of the filter (upon
%                               successful match).
%   \f@hook@filter@skip       - action for \f@filter@gobble@this
%                               and \f@filter@gobble@all.
%
% To skip one filter, \f@do@filter@match can
% call \f@filter@gobble@this.  To skip all remaining filters,
% call \f@filter@gobble@all.
%
% Note:  Theoretically, we can use a construct like
%
%   \csname ff@\csname faf:A\endcsname\endcsname
%
% to get the feature corresponding to attribute A.  But this would
% fail with an incomprehensible error message (`missing \endcsname')
% if \csname faf:A\endcsname is undefined, so we'd have to test this
% before each use.  To avoid the overhead, we just add the font
% feature index to the font filter.
%
%
% \f@run@filter
%   [MATCH-ATTR\@end REM-FEATURES\@end ADD-OR-MOD-ATTRS\@end [...]]\relax
\def\f@run@filter{%
  \let\do\f@do@filter@match
  \let\@end\f@run@filter@rem
}%
%
% \f@run@filter@rem REM-FEATURES\@end ADD-OR-MOD-ATTRS\@end ... \relax
\def\f@run@filter@rem{%
  \let\do\f@do@filter@rem
  \let\@end\f@run@filter@add
}%
%
% \f@run@filter@add ADD-OR-MOD-ATTRS\@end ... \relax
\def\f@run@filter@add{%
  \let\do\f@do@filter@add
  \let\@end\f@hook@filter@end
}%
%
\def\f@filter@gobble@this#1\@end#2\@end#3\@end{\f@hook@filter@skip \f@run@filter}%
\def\f@filter@gobble@all#1\relax{\f@hook@filter@skip}%
%
%
%
% Filter parsing callbacks for font substitution.
%
% Apply only the first font substitution matching the current font.
\def\f@subst@once{%
  \let\f@do@filter@match\f@subst@match@init
  \let\f@do@filter@rem\f@subst@rem
  \let\f@do@filter@add\f@subst@add
  \let\f@hook@filter@end\f@subst@nomore
  \let\f@hook@filter@skip\f@subst@skip
  \expandafter\f@run@filter \f@subst@list \relax
}%
%
% Apply all font substitutions in order, allowing substitutions to be
% chained.
\def\f@subst{%
  \let\f@do@filter@match\f@subst@match@init
  \let\f@do@filter@rem\f@subst@rem
  \let\f@do@filter@add\f@subst@add
  \let\f@hook@filter@end\f@subst@again
  \let\f@hook@filter@skip\f@subst@skip
  \f@verbose{^^J\the\inputlineno: (Running font substitution filter:}%
  \expandafter\f@run@filter \f@subst@list \relax
  \f@verbose{^^J)}%
}%
%
% Match one feature.
\def\f@subst@match@init{%
  \f@verbose{^^J(}%
  \let\do\f@subst@match
  \do
}%
%
\def\f@subst@match#1.#2,{%
  \f@verbose{^^Jmatching \csname ff@#1\endcsname.\csname fa@#2\endcsname}%
  % This funky way to compare the two numbers takes care of \ff#1
  % being \empty.  However, keep in mind that if \ff#1 is undefined,
  % the following will make it a \relax.  Space at the end of \ff#1
  % will be gobbled by TeX, because it's a space following a number.
  \ifnum 1#2=1\csname ff#1\endcsname \else
    \f@verbose{^^J  skipping, unmatched
      \csname ff@#1\endcsname.\csname fa@#2\endcsname}%
    \expandafter\f@filter@gobble@this % Skip to the next filter.
  \fi
}%
%
% Remove one feature.
\def\f@subst@rem#1,{%
  \f@verbose{^^Junsetting \csname ff@#1\endcsname}%
  \expandafter\let\csname ff#1\endcsname \empty
}%
%
% Add attribute #2 (which must belong to feature #1).
\def\f@subst@add#1.#2,{%
  \f@verbose{^^Jadding \csname ff@#1\endcsname.\csname fa@#2\endcsname}%
  \expandafter\def\csname ff#1\endcsname{#2 }%
}%
%
\def\f@subst@nomore{\f@verbose{^^J)}\f@filter@gobble@all}%
\def\f@subst@again{\f@verbose{^^J)}\f@run@filter}%
\def\f@subst@skip{\f@verbose{^^J)}}%
%
%
%
% Filter parsing callbacks for pretty-printing the current font filter
% string.
%
% Pretty-print the current font filter string.
\def\dumpfontfilter{\f@dump@filter\f@subst@list}%
%
% Pretty-print the given font filter string.
\def\f@dump@filter#1{%
  \let\f@do@filter@match\f@dump@match@init
  \let\f@do@filter@rem\f@dump@rem@init
  \let\f@do@filter@add\f@dump@add@init
  \let\f@hook@filter@end\f@dump@again
  \let\f@hook@filter@skip\relax
  \message{\the\inputlineno: (Dumping font substitution filter:}%
  \expandafter\f@run@filter #1\relax
  \message{^^J)}%
}%
\def\f@dump@match@init{%
  \message{^^J(^^J=}%
  \def\do##1.##2,{\message{\csname ff@##1\endcsname.\csname fa@##2\endcsname}}%
  \do
}%
\def\f@dump@rem@init{%
  \message{^^J-}%
  \def\do##1,{\message{\csname ff@##1\endcsname}}%
  \do
}%
\def\f@dump@add@init{%
  \message{^^J+}%
  \def\do##1.##2,{\message{\csname ff@##1\endcsname.\csname fa@##2\endcsname}}%
  \do
}%
\def\f@dump@again{\message{^^J)}\f@run@filter}%

\endinput


\ftracelevel=3

\newfontattr family   CMRoman
\newfontattr family   CMTypewriter
\newfontattr family   CMSansSerif
\newfontattr encoding OT1
\newfontattr encoding OML
\newfontattr encoding OMS
\newfontattr encoding OMX
\newfontattr slant    up
\newfontattr slant    sl
\newfontattr slant    it
\newfontattr slant    ui

\fontsubstpre =CMRoman -slant +OT1
%\dumpfontfilter

\fontsubstpre =up - +CMRoman,OML
%\dumpfontfilter

\fontsubstpost =CMTypewriter -encoding +
%\dumpfontfilter

\fontsubstpost =CMRoman,up,OML -slant +OMX
%\dumpfontfilter

\fontsubstpre =it,CMTypewriter,OMX -family,encoding +OT1
%\dumpfontfilter

\fontsubstpost =CMSansSerif,ui -encoding +CMTypewriter,OMX,it
%\dumpfontfilter

\fontsubstpost =it,CMTypewriter,OMX -encoding,family +ui,OMS

\dumpfontfilter
\dumpfontfeatures

%\newfont 10 cmbx10 {}
%\message{^^J***\f@name}
\newfont 10 1000 cmti10 CMRoman,it,OT1
\message{^^J***\f@name}
\newfont 10 1000 cmt10 CMRoman,OT1
\message{^^J***\f@name}
\newfont 12pt 1000 cmti12 CMRoman,it,OT1
\message{^^J***\f@name}
\newfont 10 1000 cmmi10 ui,OMS
\message{^^J***\f@name}
\newfont 8 1000 cmti8 CMRoman,it,OT1
\message{^^J***\f@name}
\newfont 11 1000 cmti11 CMRoman,it,OT1
\message{^^J***\f@name}
\newfont 8 1000 cmt8 CMRoman,OT1
\message{^^J***\f@name}
\newfont 9 1000 cmt9 CMRoman,OT1
\message{^^J***\f@name}
\newfont 0.2cm 1000 cmti1cm CMRoman,it,OT1
\message{^^J***\f@name}
\newfont 1.in 1000 cmin it,OT1
\message{^^J***\f@name}
\newfont 5. 1000 cmot1 OT1
\message{^^J***\f@name}

\setfont        {CMRoman,it,0.3cm,OMS}% -> family=CMRoman encoding=OT1 slant=<unset>
\dumpfontfeatures
\setfont        {CMTypewriter,it,OMX}%  -> family=<unset> encoding=OT1 slant=it
\dumpfontfeatures
\addfontattrs   {7,up}%                 -> family=CMRoman encoding=OT1 slant=<unset>
\dumpfontfeatures
\remfontfeatures{family}%               -> family=<unset> encoding=OT1 slant=<unset>
\dumpfontfeatures
\modfont        {}{CMSansSerif,ui}%     -> family=<unset> encoding=OMS slant=ui
\dumpfontfeatures
\remfontfeatures{}%                     -> family=<unset> encoding=OMS slant=ui
\dumpfontfeatures
\addfontattrs   {}%                     -> family=<unset> encoding=OMS slant=ui
\dumpfontfeatures
\modfont        {}{}%                   -> family=<unset> encoding=OMS slant=ui
\dumpfontfeatures

\message{^^J*********************************************************}

\newfontattr family   TestFamily
\newfont 5. 1000 sz5-1.0-1 TestFamily
\message{^^J***\f@name}
\newfont 5. 1000 sz5-1.0-2 TestFamily
\message{^^J***\f@name}
\newfont 5. 1400 sz5-1.4-1 TestFamily
\message{^^J***\f@name}
\newfont 5. 900 sz5-0.9-1 TestFamily
\message{^^J***\f@name}
\newfont 5. 900 sz5-0.9-2 TestFamily
\message{^^J***\f@name}
\newfont 5. 1400 sz5-1.4-2 TestFamily
\message{^^J***\f@name}
\setfont        {CMRoman,9pt}%          ->


\newfont 10 1000 cmr10 CMRoman,rm,OT1
\message{^^J***\f@name}

\bye