mirror of https://github.com/texmacs/doc.git
94 lines
4.4 KiB
Tcl
94 lines
4.4 KiB
Tcl
<TeXmacs|1.99.8>
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<style|<tuple|tmdoc|english|old-spacing>>
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<\body>
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<tmdoc-title|Converters to other data formats>
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Currently, we have implemented imperfect converters between <TeXmacs> and
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<LaTeX> and from html to <TeXmacs>. We hope that someone else will be
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willing to write better converters from scratch. This chapter has been
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included in order to give some recommendations in that direction based on
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our experience from the implementation of the actual conversion programs.
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We also recommend to take a look at the current implementations in the
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directory <verbatim|Convert>.
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<section|Parsing extern data formats>
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In order to write a converter from <LaTeX> html, xml, etc. to <TeXmacs>, a
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good first step is to write a parser for the extern data format. For html,
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xml, etc. this should be rather easy, but for <LaTeX>, you will probably
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need to be a real <LaTeX> guru (which I am not). We recommend the result of
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the parsing step to be a <scheme> expression (something which is
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regrettable not the case for our actual converters), because this language
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is very well adapted for the implementation of the actual converter.
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This first step should be able to process any correct file having the
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extern data format; possible incompatibilities should only come into play
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during the actual conversion. In the case of <LaTeX>, one should not expand
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the macros and keep all macro definitions, because <TeXmacs> will be able
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to take advantage out of this.
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<section|The actual converter>
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We recommend the actual converter to proceed in several steps. Often it is
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convenient to start with a rough, structural, conversion step, which is
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\Ppolished\Q by a certain number of additional steps. These additional
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steps may take care of some very particular layout issues which can not be
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treated conveniently at the main step.
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Actually, the main difficulties usually come from exceptional text, like
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verbatim, and layout issues which are handled differently in the extern
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data format and <TeXmacs>. A good example of such a difference between
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<LaTeX> and <TeXmacs> is the way equations or lists are handled. Consider
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for instance the following paragraph:
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Text before.
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<\equation*>
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a<rsup|2>+b<rsup|2>=c<rsup|2>.
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</equation*>
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Text after.
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In <LaTeX>, the equation is really seen as a part of the paragraph. Indeed,
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there will not be any blank line between \PText before\Q and the equation.
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However, for efficiency reasons, it is better to see the paragraph as three
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paragraphs in <TeXmacs>, because the lines can be typeset independently.
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Nevertheless, the equation environment will disable the indentation of
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\PText after\Q.
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As a result of this anomaly, converted texts have to be postprocessed, so
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as to insert paragraph breaks at strategic places. It should be noticed
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that this step may be independent from the format which is actually being
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converted and that a similar reverse step may be implemented for backward
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conversions. We also notice that one needs an exhaustive list of all
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similar exceptional environments for this postprocessing step. Actually, a
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future version of <TeXmacs> might come with an additional feature, which
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permits the automatic detection of such environments. This is also
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important from a semantical point of view, because one should be able to
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detect that the above example logically forms only one and not three
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paragraphs.
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<section|Backward conversions>
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Conversions from <TeXmacs> to an extern data format are usually easier to
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implement, because the <TeXmacs> data format is semantically rich. However,
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conversions to an extern data format without a <TeX>-like macro facility
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give rise to the problem of macro expansion of non supported <TeXmacs>
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functions or environments. We plan to write a facility for this, which you
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will be able to use when writing a converter from <TeXmacs> to something
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else.
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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|<\collection>
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</collection>> |