mirror of https://github.com/texmacs/doc.git
150 lines
4.7 KiB
Tcl
150 lines
4.7 KiB
Tcl
<TeXmacs|1.0.4.1>
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<style|tmdoc>
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<\body>
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<tmdoc-title|Background evaluations>
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Until now, we have always considered interfaces between <TeXmacs> and
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applications which are intended to be used interactively in shell sessions.
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But there also exists a <value|scheme> command
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<\scheme-fragment>
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(plugin-eval <em|plugin> <em|session> <em|expression>)
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</scheme-fragment>
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for evaluating an expression using the application. Here
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<verbatim|<em|plugin>> is the name of the plug-in, <verbatim|<em|session>>
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the name of the session and <verbatim|<em|expression>> a <value|scheme>
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expression which represents a <TeXmacs> tree.
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<paragraph*|The <verbatim|substitute> plug-in>
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Background evaluations may for instance be used in order to provide a
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feature which allows the user to select an expression and replace it by its
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evaluation. For instance, the <verbatim|substitute> plug-in converts
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mathematical <LaTeX> expressions into <TeXmacs>, and it provides the
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<shortcut|(substitute-substitute)> keyboard shortcut for replacing a selected text by its
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conversion. The plug-in consists of the following files
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<\verbatim>
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\ \ \ \ <example-plugin-link|substitute/Makefile>
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\ \ \ \ <example-plugin-link|substitute/progs/init-substitute.scm>
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\ \ \ \ <example-plugin-link|substitute/src/substitute.cpp>
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</verbatim>
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The main evaluation loop of <verbatim|substitute.cpp> simply consists of
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<\cpp-fragment>
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char buffer[100];
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cin.getline (buffer, 100, '\\n');
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cout \<less\>\<less\> DATA_BEGIN;
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cout \<less\>\<less\> "latex:$" \<less\>\<less\> buffer \<less\>\<less\>
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"$";
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cout \<less\>\<less\> DATA_END;
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fflush (stdout);
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</cpp-fragment>
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Moreover, the configuration file <verbatim|init-substitute.scm> contains
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the following code for replacing a selected region by its evaluation
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<\scheme-fragment>
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(define (substitute-substitute)
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\ \ (import-from (texmacs plugin plugin-cmd))
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\ \ (if (selection-active-any?)
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\ \ \ \ \ \ (let* ((t (tree-\<gtr\>stree (the-selection)))
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\ \ \ \ \ \ \ \ \ \ \ \ \ (u (plugin-eval "substitute" "default" t)))
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\ \ \ \ \ \ \ \ (clipboard-cut "primary")
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\ \ \ \ \ \ \ \ (insert (stree-\<gtr\>tree u)))))
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</scheme-fragment>
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as well as the keyboard shortcut for <shortcut|(substitute-substitute)>:
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<\scheme-fragment>
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(kbd-map
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\ \ ("C-F12" (substitute-substitute)))
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</scheme-fragment>
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Notice that these routines should really be defined in a separate module
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for larger plug-ins.
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<paragraph*|The <verbatim|secure> plug-in>
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Another example of using an interface in the background is the
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<verbatim|secure> plug-in which consists of the files
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<\verbatim>
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\ \ \ \ <example-plugin-link|secure/Makefile>
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\ \ \ \ <example-plugin-link|secure/packages/secure.ts>
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\ \ \ \ <example-plugin-link|secure/progs/init-secure.scm>
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\ \ \ \ <example-plugin-link|secure/progs/secure-secure.scm>
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\ \ \ \ <example-plugin-link|secure/src/secure.cpp>
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</verbatim>
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Just as <verbatim|substitute.cpp> above, the main program
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<verbatim|secure.cpp> just converts mathematical <LaTeX> expressions to
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<TeXmacs>. The <verbatim|secure-secure.scm> module contains the <em|secure>
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<value|scheme> routine <verbatim|latexer>:
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<\scheme-fragment>
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(tm-define (latexer s)
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\ \ (:type (tree -\<gtr\> object))
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\ \ (:synopsis "convert LaTeX string to TeXmacs tree using plugin")
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\ \ (:secure #t)
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\ \ (plugin-eval "secure" "default" (tree-\<gtr\>string s)))
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</scheme-fragment>
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It is important to define <verbatim|latexer> as being secure, so that it
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can be used in order to define additional markup using the <markup|extern>
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primitive. This is done in the style file <verbatim|secure.ts>:
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<\tm-fragment>
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<\inactive*>
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See a LaTeX math command as a TeXmacs expression via plug-in
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<assign|latexer|<macro|x|<extern|latexer|<arg|x>>>>
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</inactive*>
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</tm-fragment>
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After compilation, installation, relaunching <TeXmacs> and selecting
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<menu|Document|Use package|secure>, you will now be able to use
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<markup|latexer> as a new primitive. The primitive takes a mathematical
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<LaTeX> expression as its argument and displays its <TeXmacs> conversion.
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<tmdoc-copyright|1998--2002|Joris van der Hoeven>
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<tmdoc-license|Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation; with no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled "GNU Free
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Documentation License".>
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</body>
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<\initial>
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<\collection>
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<associate|language|english>
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</collection>
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</initial> |