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%% This is part of OpTeX project, see http://petr.olsak.net/optex
\_codedecl \newif {Special if-macros, is-macros and loops <2020-05-22>} % preloaded in format
\_doc ----------------------------
\secc Classical \code{\\newif}
The \`\newif` macro implements boolean value.
It works as in plain \TeX. It means that
after `\newif\ifxxx` you can use `\xxxtrue` or
`\xxxfalse` to set the boolean value and use `\ifxxx true\else false\fi`
to test this value. The default value is false.
The macro \`\_newifi` enables to declare `\_ifxxx` and to use `\_xxxtrue` and
`\_xxxfalse`. This means that it is usable for internal name space
(`_`prefixed macros).
\_cod ----------------------------
\_def\_newif #1{\_ea\_newifA \_string #1\_relax#1}
\_ea\_def \_ea\_newifA \_string\if #1\_relax#2{%
\_sdef{#1true}{\_let#2=\_iftrue}%
\_sdef{#1false}{\_let#2=\_iffalse}%
\_let#2=\_iffalse
}
\_def\_newifi #1{\_ea\_newifiA \string#1\_relax#1}
\_ea\_def \_ea\_newifiA \_string\_if #1\_relax#2{%
\_sdef{_#1true}{\_let#2=\_iftrue}%
\_sdef{_#1false}{\_let#2=\_iffalse}%
\_let#2=\_iffalse
}
\_public \newif ;
\_doc ----------------------------
\secc Loops
The \`\loop` `<codeA> \ifsomething <codeB>` \`\repeat` loops `<codeA><codeB>`
until `\ifsomething` is false. Then `<codeB>` is not executed and loop is
finished. This works like in plain \TeX, but implementation is somewhat
better (you can use `\else` clause after the `\ifsomething`).
There are public version `\loop...\repeat` and private version
\`\_loop` ...\`\_repeat`. You cannot mix both versions in one loop.
The `\loop` macro keeps its original plain TeX meaning. It is not
expandable and nested `\loop`s are possible only in a \TeX/ group.
\_cod ----------------------------
\_long\_def \_loop #1\_repeat{\_def\_body{#1}\_iterate}
\_def \loop #1\repeat{\_def\_body{#1}\_iterate}
\_let \_repeat=\_fi % this makes \loop...\if...\repeat skippable
\_let \repeat=\_fi
\_def \_iterate {\_body \_ea \_iterate \_fi}
\_doc -----------------------------
\`\foreach` `<list>` \`\do` `{<what>}`
repeats `<what>` for each element of the
`<list>`. The `<what>` can include `#1` which is substituted by each
element of the `<list>`. The macro is expandable.
\`\fornum` `<from>..<to>` \`\do` `{<what>}` or
\`\fornumstep` `<num>: <from>..<to>` \`\do` `{<what>}`
repeats `<what>` for each number from `<from>` to `<to>` (with step `<num>`
or with step one). The `<what>` can include `#1` which is substituted by
current number. The sequence `<from>..<to>` can be decreasing too.
The macro is expandable.
Recommendation: it is better to
use private variants of \`\_foreach` and \`\_fornum`.
When the user writes `\input tikz` then `\foreach` macro is redefined! The
private variants use \`\_do` separator instead `\do` separator.
\_cod -----------------------------
\_newcount\_frnum % the numeric variable used in \fornum
\_def\_do{\_doundefined} % we need to ask \_ifx#1\_do ...
\_long\_def\_foreach #1\_do#2{\_putforstack
\_immediateassignment\_gdef\_fbody##1{#2}%
\_foreachA #1\_do}
\_long\_def\_foreachA #1{\_ifx\_do#1\_getforstack\_else\_fbody{#1}\_ea\_foreachA\_fi}
\_def\_fornum#1..#2\_do{\_fornumstep 1:#1..#2\_do}
\_long\_def\_fornumstep#1:#2..#3\_do#4{\_putforstack
\_immediateassigned{%
\_gdef\_fbody##1{#4}%
\_gdef\_fornumsgn{}%
\_gdef\_fornumrel{<}%
\_global\_frnum=\_numexpr#2\_relax
\_ifnum\_numexpr#3<\_frnum \_gdef\_fornumrel{>}\_fi %decreasing sequence
\_ifnum\_numexpr#1\_fornumrel0 \_gdef\_fornumsgn{-}\_fi % correction
}%
\_fornumB{#3}{#1}%
}
\_def\_fornumB #1#2{\_ifnum\_numexpr#1\_fornumrel\_frnum \_getforstack \_else
\_ea\_fbody\_ea{\_the\_frnum}%
\_immediateassignment\_global\_advance\_frnum by\_numexpr\_fornumsgn#2\_relax
\_afterfi{\_fornumB{#1}{#2}}\_fi
}
\_def\_afterfi#1#2\_fi{\_fi#1}
\_def\foreach #1\do{\_foreach #1\_do}
\_def\fornum#1..#2\do{\_fornumstep 1:#1..#2\_do}
\_def\fornumstep#1:#2..#3\do{\_fornumstep #1:#2..#3\_do}
\_doc ----------------------------
The `\foreach` and `\fornum` macros can be nested and arbitrary combined.
When they are nested then use `##1` for the variable of nested level,
`####1` for the variable of second nested level etc. Example:
\begtt
\foreach ABC \do {\fornum 1..5 \do {letter:#1, number: ##1. }}
\endtt
Implementation note:
we cannot use \TeX/-groups for nesting levels because we want to do the
macros expandable. We must implement a special for-stack which saves the
data needed by `\foreach` and `\fornum`. The \`\_putforstack` is used
when `\for*` is initialized and \`\_getforstack` is used when the
`\for*` macro ends. The \`\_forlevel` variable keeps the current nesting
level. If it is zero, then we need not save nor restore any data.
\_cod ----------------------------
\_newcount\_forlevel
\_def\_putforstack{\_immediateassigned{%
\_ifnum\_forlevel>0
\_sxdef{_frnum:\_the\_forlevel\_ea}{\_the\_frnum}%
\_global\_slet{_fbody:\_the\_forlevel}{_fbody}%
\_fi
\_global\_advance\_forlevel by1
}}
\_def\_getforstack{\_immediateassigned{%
\_global\_advance\_forlevel by-1
\_ifnum\_forlevel>0
\_global\_slet{_fbody}{_fbody:\_the\_forlevel}%
\_global\_frnum=\_cs{_frnum:\_the\_forlevel}\_space
\_fi
}}
\_doc ----------------------------
\secc Is-macros
There are a collection of macros
`\isempty`, `\istoksempty`, `\isequal`, `\ismacro`, `\isdefined`, `\isinlist` and `\isfile`
with common syntax:
\begtt \catcode`\<=13
\issomething <params> \iftrue <codeA> \else <codeB> \fi
or
\issomething <params> \iffalse <codeB> \else <codeA> \fi
\endtt
The `\else` part is optional. The `<codeA>` is processed if
`\issomething<params>` generates true condition. The `<codeB>`
is processed if `\issomething<params>` generates false condition.
The `\iftrue` or `\iffalse` is an integral part of this syntax
because we need to keep skippable nested `\if` conditions.
Implementation note:
we read this `\iftrue` or `\iffalse` into unseparated parameter and repeat
it because we need to remove an optional space before this command.
\medskip\noindent
\`\isempty` `{<text>}\iftrue`
is true if the `<text>` is empty. This macro is expandable.\nl
\`\istoksempty` `<tokens variable>\iftrue`
is true if the `<tokens variable>` is empty. It is expandable.
\_cod ----------------------------
\_long\_def \_isempty #1#2{\_if\_relax\_detokenize{#1}\_relax \_else \_ea\_unless \_fi#2}
\_def \_istoksempty #1#2{\_ea\_isempty\_ea{\_the#1}#2}
\_public \isempty \istoksempty ;
\_doc ----------------------------
\`\isequal` `{<textA>}{<textB>}\iftrue`
is true if the <textA> and <textB> are
equal, only from strings point of view, category codes are ignored.
The macro is expandable.
\_cod ----------------------------
\_def\_isequal#1#2#3{\_directlua{%
if "\_luaescapestring{\_detokenize{#1}}"=="\_luaescapestring{\_detokenize{#2}}"
then else tex.print("\_nbb unless") end}#3}
\_public \isequal ;
\_doc ----------------------------
\`\ismacro` `\macro{text}\iftrue` is true if macro is defined as {<text>}.
Category codes are ignored in this testing. The macro is expandable.
\_cod ----------------------------
\_def\_ismacro#1{\_ea\_isequal\_ea{#1}}
\_public \ismacro ;
\_doc ----------------------------
\`\isdefined` `{<csname>}\iftrue` is true if `\<csname>` is defined.
The macro is expandable.
\_cod ----------------------------
\_def\_isdefined #1#2{\_ifcsname #1\_endcsname \_else \_ea\_unless \_fi #2}
\_public \isdefined ;
\_doc ----------------------------
\`\isinlist` `\list{<text>}\iftrue` is true if the
`<text>` is included the macro body of the `\list`.
The category code are relevant here. The macro is not expandable.
\_cod ----------------------------
\_long\_def\_isinlist#1#2{\_begingroup
\_long\_def\_tmp##1#2##2\_end/_%
{\_endgroup\_if\_relax\_detokenize{##2}\_relax \_ea\_unless\_fi}%
\_ea\_tmp#1\_endlistsep#2\_end/_%
}
\_public \isinlist ;
\_doc -----------------------------
\`\isfile` `{<filename>}\iftrue` is true if the file <filename> exists and are
readable by \TeX.
\_cod -----------------------------
\_newread \_testin
\_def\_isfile #1{%
\_openin\_testin ={#1}\_relax
\_ifeof\_testin \_ea\_unless
\_else \_closein\_testin
\_fi
}
\_public \isfile ;
\_doc -----------------------------
\`\isfont` `{<fontname or [fontfile]>}\iftrue`
is true if given font exists. The result of this testing
is saved to the \`\_ifexistfam`.
\_cod -----------------------------
\_newifi \_ifexistfam
\_def\_isfont#1#2{%
\_begingroup
\_suppressfontnotfounderror=1
\_font\_testfont={#1}\_relax
\_ifx\_testfont\_nullfont \_def\_tmp{\_existfamfalse \_unless}
\_else \_def\_tmp{\_existfamtrue}\_fi
\_ea \_endgroup \_tmp #2%
}
\_public \isfont ;
\_doc ----------------------------
The last macro \`\isnextchar` `<char>{<codeA>}{<codeB>}`
has different syntax than all others is-macros.
It executes `<codeA>` if next character is equal to <char>.
Else the `<codeB>` is executed. The macro is not expandable.
\_cod ----------------------------
\_long\_def\_isnextchar#1#2#3{\_begingroup\_toks0={\_endgroup#2}\_toks1={\_endgroup#3}%
\_let\_tmp= #1\_futurelet\_next\_isnextcharA
}
\_def\_isnextcharA{\_the\_toks\_ifx\_tmp\_next0\_else1\_fi\_space}
\_public \isnextchar ;
\_endcode
2020-05-22 \foreach, \fornum: all settings are global, independent on TeX group
2020-05-06 \isnextchar: \let\tmp=#1 -> \let\tmp= #1 (bug fix, #1 should be space)
2020-05-02 \newif bug fix
2020-04-15 \fornumstep 3: 1..12 instead \fornum 1..12\step 3
2020-04-15 \fornum, \foreach can be nested without groups
2020-04-01 implemented
|
