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doc/devel/interface/interface-input.en.tm

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<TeXmacs|1.0.1.20>
<style|tmdoc>
<\body>
<expand|tmdoc-title|Mathematical and customized input>
The <TeXmacs> meta-format allows application output to contain structured
text like mathematical formulas. In a similar way, you may use general
<TeXmacs> content as the input for your application. By default, only the
text part of such content is kept and sent to the application as a string.
Moreover, all characters in the range 0--31 are ignored, except for
<verbatim|'\\t'> and <verbatim|'\\n'> which are transformed into spaces.
There are two methods to customize the way input is sent to your
application. First of all, the configuration option
<\expand|scheme-fragment>
(:serializer ,<em|routine>)
</expand>
specifies a scheme function for converting <TeXmacs> trees to string input
for your application, thereby overriding the default method. This method
allows you for instance to treat multi-line input in a particular way or
the perform transformations on the <TeXmacs> tree.
The <verbatim|:serialize> option is a very powerful, but also a very
abstract way to customize input: it forces you to write a complete input
transformation function. In many circumstances, the user really wants to
rewrite two dimensional mathematical input to a more standard form, like
rewriting <format|no line break><with|mode|math|<frac|a|b>> to
<verbatim|((a)/(b))>. Therefore, a second way for customizing the input is
to use the command
<\expand|scheme-fragment>
\ (plugin-input-converters <em|myplugin>
\ \ \ <em|rules>)
</expand>
This command specifies input conversion rules for <verbatim|<em|myplugin>>
for ``mathematical input'' and reasonable defaults are provided by
<TeXmacs>. Each rule is of one of the following two forms:
<\description>
<expand|item*|Leaf transformation rules>
Given two strings <verbatim|<em|symbol>> and <verbatim|<em|conversion>>,
the rule
<\expand|scheme-fragment>
(<verbatim|<em|symbol>> <verbatim|<em|conversion>>)
</expand>
specifies that the <TeXmacs> symbol <verbatim|<em|symbol>> should be
converted to <verbatim|<em|conversion>>.
<expand|item*|Tag transformation rules>
Given a symbol <verbatim|<em|tag>> and a <value|scheme> function
<verbatim|<em|routine>>, the rule
<\expand|scheme-fragment>
(<em|tag> <em|routine>)
</expand>
specifies that <verbatim|<em|routine>> will be used as the conversion
routine for <verbatim|<em|tag>>. This routine should just write a string
to the standard output. The <value|scheme> function
<expand|scheme-code|plugin-input> may be used for the recursive
transformation of the arguments of the tag.
</description>
<paragraph|The <verbatim|input> plugin>
The <verbatim|input> plugin demonstrates the use of customized mathematical
input. It consists of the files
<\verbatim>
\ \ \ \ <expand|example-plugin-link|input/Makefile>
\ \ \ \ <expand|example-plugin-link|input/packages/session/input.ts>
\ \ \ \ <expand|example-plugin-link|input/progs/init-input.scm>
\ \ \ \ <expand|example-plugin-link|input/progs/input-input.scm>
\ \ \ \ <expand|example-plugin-link|input/src/input.cpp>
</verbatim>
The <value|scheme> configuration code in <verbatim|init-input.scm> is given
by
<\expand|scheme-fragment>
(plugin-configure input
\ \ (:require (url-exists-in-path? "input.bin"))
\ \ (:initialize (input-initialize))
\ \ (:launch "input.bin")
\ \ (:session "Input"))
</expand>
Here <verbatim|input-initialize> is an initialization routine which adds
the new input conversion rules in a lazy way:
<\expand|scheme-fragment>
(define (input-initialize)
\ \ (import-from (texmacs plugin plugin-convert))
\ \ (lazy-input-converter (input-input) input))
</expand>
In other words, the module <verbatim|input-input.scm> will only be loaded
when we explicitely request to make a conversion. The conversion rules in
<verbatim|input-input.scm> are given by
<\expand|scheme-fragment>
(plugin-input-converters input
\ \ (frac input-input-frac)
\ \ (special input-input-special)
\ \ ("\<less\>vee\<gtr\>" "\|\|")
\ \ ("\<less\>wedge\<gtr\>" "&&"))
</expand>
This will cause <with|mode|math|\<vee\>> and <with|mode|math|\<wedge\>> to
be rewritten as <verbatim|\|\|> and <verbatim|&&> respectively. Fractions
<with|mode|math|<frac|a|b>> are rewritten as <verbatim|((a):(b))> using the
routine
<\expand|scheme-fragment>
(define (input-input-frac t)
\ \ (display "((")
\ \ (plugin-input (car t))
\ \ (display "):(")
\ \ (plugin-input (cadr t))
\ \ (display "))"))
</expand>
In the additional style file <verbatim|input.ts> we also defined some
additional markup <markup|special>:
<\expand|tm-fragment>
<with|preamble|true|<assign|special|<macro|body|<block|<tformat|<cwith|1|1|1|1|cell
background|pastel green>|<table|<row|<cell|<arg|body>>>>>>>>>
</expand>
This tag is rewritten using the special conversion rule
<\expand|scheme-fragment>
(define (input-input-special t)
\ \ (display "[[[SPECIAL:")
\ \ (plugin-input (car t))
\ \ (display "]]]"))
</expand>
As to the <value|cpp> code in <verbatim|input.cpp>, the startup banner
automatically puts the shell session in mathematical input mode:
<\expand|cpp-fragment>
cout \<less\>\<less\> DATA_BEGIN \<less\>\<less\> "verbatim:";
cout \<less\>\<less\> DATA_BEGIN \<less\>\<less\>
"command:(session-use-math-input #t)"
\ \ \ \ \ \<less\>\<less\> DATA_END;
cout \<less\>\<less\> "Convert mathematical input into plain text";
cout \<less\>\<less\> DATA_END;
fflush (stdout);
</expand>
In the main loop, we content ourselves the reproduce the input as output:
<\expand|cpp-fragment>
char buffer[100];
cin.getline (buffer, 100, '\\n');
cout \<less\>\<less\> DATA_BEGIN \<less\>\<less\> "verbatim:";
cout \<less\>\<less\> buffer;
cout \<less\>\<less\> DATA_END;
fflush (stdout);
</expand>
<apply|tmdoc-copyright|1998--2002|Joris van der Hoeven>
<expand|tmdoc-license|Permission is granted to copy, distribute and/or
modify this document under the terms of the GNU Free Documentation License,
Version 1.1 or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts. A copy of the license is included in the section entitled
"GNU Free Documentation License".>
</body>
<\initial>
<\collection>
<associate|paragraph width|150mm>
<associate|odd page margin|30mm>
<associate|shrinking factor|4>
<associate|page right margin|30mm>
<associate|page top margin|30mm>
<associate|reduction page right margin|25mm>
<associate|page type|a4>
<associate|reduction page bottom margin|15mm>
<associate|even page margin|30mm>
<associate|reduction page left margin|25mm>
<associate|page bottom margin|30mm>
<associate|reduction page top margin|15mm>
<associate|language|english>
</collection>
</initial>
<\references>
<\collection>
<associate|idx-1|<tuple|<uninit>|?>>
<associate|toc-1|<tuple|<uninit>|?>>
<associate|toc-2|<tuple|<uninit>|?>>
<associate|idx-2|<tuple|<uninit>|?>>
</collection>
</references>
<\auxiliary>
<\collection>
<\associate|toc>
<with|left margin|<quote|6fn>|font size|<quote|0.84>|The <with|font
family|<quote|tt>|language|<quote|verbatim>|input>
plugin<value|toc-dots><pageref|toc-1>>
</associate>
</collection>
</auxiliary>