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NAME

       doctools::idx::export - Exporting keyword indices

SYNOPSIS

       package require doctools::idx::export  ?0.2?

       package require Tcl  8.4

       package require doctools::config

       package require doctools::idx::structure

       package require snit

       package require pluginmgr

       ::doctools::idx::export objectName

       objectName method ?arg arg ...?

       objectName destroy

       objectName export serial serial ?format?

       objectName export object object ?format?

       objectName config names

       objectName config get

       objectName config set name ?value?

       objectName config unset pattern...

       export serial configuration

_________________________________________________________________________________________________

DESCRIPTION

       This  package  provides a class to manage the plugins for the export of keyword indices to
       other formats, i.e. their conversion to, for example docidx, HTML, etc.

       This is one of the three public pillars the management of keyword indices resides on.  The
       other two pillars are

       [1]    Importing keyword indices, and

       [2]    Holding keyword indices

       For information about the Concepts of keyword indices, and their parts, see the same-named
       section.  For information about the data structure which is the major input to the manager
       objects provided by this package see the section Keyword index serialization format.

       The  plugin  system of our class is based on the package pluginmgr, and configured to look
       for plugins using

       [1]    the environment variable DOCTOOLS_IDX_EXPORT_PLUGINS,

       [2]    the environment variable DOCTOOLS_IDX_PLUGINS,

       [3]    the environment variable DOCTOOLS_PLUGINS,

       [4]    the path "~/.doctools/idx/export/plugin"

       [5]    the path "~/.doctools/idx/plugin"

       [6]    the path "~/.doctools/plugin"

       [7]    the path "~/.doctools/idx/export/plugins"

       [8]    the path "~/.doctools/idx/plugins"

       [9]    the path "~/.doctools/plugins"

       [10]   the registry entry "HKEY_CURRENT_USER\SOFTWARE\DOCTOOLS\IDX\EXPORT\PLUGINS"

       [11]   the registry entry "HKEY_CURRENT_USER\SOFTWARE\DOCTOOLS\IDX\PLUGINS"

       [12]   the registry entry "HKEY_CURRENT_USER\SOFTWARE\DOCTOOLS\PLUGINS"

       The last three are used only when the package  is  run  on  a  machine  using  Windows(tm)
       operating system.

       The whole system is delivered with six predefined export plugins, namely

       docidx See docidx export plugin for details.

       html   See html export plugin for details.

       json   See json export plugin for details.

       nroff  See nroff export plugin for details.

       text   See text export plugin for details.

       wiki   See wiki export plugin for details.

       Readers  wishing  to  write  their own export plugin for some format, i.e.  plugin writers
       reading and understanding the section containing the Export plugin API v2 reference is  an
       absolute  necessity,  as it specifies the interaction between this package and its plugins
       in detail.

CONCEPTS

       [1]    A keyword index consists of a (possibly empty) set of keywords.

       [2]    Each keyword in the set is identified by its name.

       [3]    Each keyword has a (possibly empty) set of references.

       [4]    A reference can be associated with more than one keyword.

       [5]    A reference not associated with at least one keyword is not possible however.

       [6]    Each reference is identified by its target, specified as either an url or  symbolic
              filename, depending on the type of reference (url, or manpage).

       [7]    The type of a reference (url, or manpage) depends only on the reference itself, and
              not the keywords it is associated with.

       [8]    In addition to a type each reference has a descriptive label as  well.  This  label
              depends only on the reference itself, and not the keywords it is associated with.

       A few notes

       [1]    Manpage  references  are  intended  to  be used for references to the documents the
              index is made for. Their target is a symbolic file name identifying  the  document,
              and export plugins may replace symbolic with actual file names, if specified.

       [2]    Url  references  are intended on the othre hand are inteded to be used for links to
              anything else, like websites. Their target is an url.

       [3]    While url and manpage references share a  namespace  for  their  identifiers,  this
              should  be no problem, given that manpage identifiers are symbolic filenames and as
              such they should never look like urls, the identifiers for url references.

API

   PACKAGE COMMANDS
       ::doctools::idx::export objectName
              This command creates a new export manager object with  an  associated  Tcl  command
              whose  name  is  objectName. This object command is explained in full detail in the
              sections Object command and Object methods. The  object  command  will  be  created
              under  the  current  namespace if the objectName is not fully qualified, and in the
              specified namespace otherwise.

   OBJECT COMMAND
       All objects created by the ::doctools::idx::export  command  have  the  following  general
       form:

       objectName method ?arg arg ...?
              The  method  method and its arg'uments determine the exact behavior of the command.
              See section Object methods for the detailed specifications.

   OBJECT METHODS
       objectName destroy
              This method destroys the object it is invoked for.

       objectName export serial serial ?format?
              This method takes the canonical serialization of a keyword index stored  in  serial
              and converts it to the specified format, using the export plugin for the format. An
              error is thrown if no plugin could be found for the format.  The  string  generated
              by the conversion process is returned as the result of this method.

              If no format is specified the method defaults to docidx.

              The  specification of what a canonical serialization is can be found in the section
              Keyword index serialization format.

              The plugin has to conform to the interface specified in section Export  plugin  API
              v2 reference.

       objectName export object object ?format?
              This  method  is  a convenient wrapper around the export serial method described by
              the previous item.  It expects that  object  is  an  object  command  supporting  a
              serialize  method  returning  the  canonical  serialization  of a keyword index. It
              invokes that method, feeds the result into export serial and returns the  resulting
              string as its own result.

       objectName config names
              This  method  returns  a  list  containing the names of all configuration variables
              currently known to the object.

       objectName config get
              This  method  returns  a  dictionary  containing  the  names  and  values  of   all
              configuration variables currently known to the object.

       objectName config set name ?value?
              This method sets the configuration variable name to the specified value and returns
              the new value of the variable.

              If no value is specified it simply returns the current value, without changing it.

              Note that while the user can set the predefined configuration  variables  user  and
              format  doing  so  will  have no effect, these values will be internally overridden
              when invoking an import plugin.

       objectName config unset pattern...
              This  method  unsets  all  configuration  variables  matching  the  specified  glob
              patterns.  If  no  pattern  is  specified  it  will  unset  all  currently  defined
              configuration variables.

EXPORT PLUGIN API V2 REFERENCE

       Plugins are what this package uses to manage the support for any output format beyond  the
       Keyword  index  serialization  format. Here we specify the API the objects created by this
       package use to interact with their plugins.

       A plugin for this package has to follow the rules listed below:

       [1]    A plugin is a package.

       [2]    The name of a plugin package has the form doctools::idx::export::FOO, where FOO  is
              the  name  of the format the plugin will generate output for. This name is also the
              argument to provide to the various export methods of export manager objects to  get
              a string encoding a keyword index in that format.

       [3]    The plugin can expect that the package doctools::idx::export::plugin is present, as
              indicator that it was invoked from a genuine plugin manager.

       [4]    A plugin has to provide one command, with the signature shown below.

              export serial configuration
                     Whenever an export manager of doctools::idx has to generate  output  for  an
                     index it will invoke this command.

                     string serial
                            This  argument  will contain the canonical serialization of the index
                            for which to generate  the  output.   The  specification  of  what  a
                            canonical  serialization is can be found in the section Keyword index
                            serialization format.

                     dictionary configuration
                            This argument will contain the current configuration to apply to  the
                            generation, as a dictionary mapping from variable names to values.

                            The  following  configuration variables have a predefined meaning all
                            plugins have to obey, although they can ignore  this  information  at
                            their  discretion. Any other other configuration variables recognized
                            by a plugin will be described in the manpage for that plugin.

                            user   This variable is expected to contain  the  name  of  the  user
                                   owning the process invoking the plugin.

                            format This  variable  is  expected to contain the name of the format
                                   whose plugin is invoked.

                            file   This variable, if defined by the user of the index  object  is
                                   expected  to  contain the name of the input file for which the
                                   plugin is generating its output for.

                            map    This variable, if defined by the user of the index  object  is
                                   expected  to  contain  a dictionary mapping from symbolic file
                                   names used in the references of type manpage to  actual  paths
                                   (or  urls).  A plugin has to be able to handle the possibility
                                   that a symbolic name is without entry in this mapping.

       [5]    A single usage cycle of a plugin consists of the invokations of the command export.
              This  call  has to leave the plugin in a state where another usage cycle can be run
              without problems.

KEYWORD INDEX SERIALIZATION FORMAT

       Here we specify the format used by the doctools v2 packages to serialize  keyword  indices
       as immutable values for transport, comparison, etc.

       We  distinguish  between  regular  and canonical serializations. While a keyword index may
       have more than one regular serialization only exactly one of them will be canonical.

       regular serialization

              [1]    An index serialization is a nested Tcl dictionary.

              [2]    This dictionary holds a single key, doctools::idx, and its value. This value
                     holds the contents of the index.

              [3]    The  contents  of  the  index  are a Tcl dictionary holding the title of the
                     index, a label, and the keywords and references. The relevant keys and their
                     values are

                     title  The value is a string containing the title of the index.

                     label  The value is a string containing a label for the index.

                     keywords
                            The  value is a Tcl dictionary, using the keywords known to the index
                            as keys. The associated values are lists containing  the  identifiers
                            of the references associated with that particular keyword.

                            Any reference identifier used in these lists has to exist as a key in
                            the references dictionary, see the next item for its definition.

                     references
                            The value  is  a  Tcl  dictionary,  using  the  identifiers  for  the
                            references  known  to  the  index  as keys. The associated values are
                            2-element lists containing the type and label of  the  reference,  in
                            this order.

                            Any  key  here  has  to be associated with at least one keyword, i.e.
                            occur in at least one of the reference lists which are the values  in
                            the keywords dictionary, see previous item for its definition.

              [4]    The type of a reference can be one of two values,

                     manpage
                            The identifier of the reference is interpreted as symbolic file name,
                            referring to one of the documents the index was made for.

                     url    The identifier of the reference is interpreted as an  url,  referring
                            to some external location, like a website, etc.

       canonical serialization
              The  canonical  serialization of a keyword index has the format as specified in the
              previous item, and then additionally satisfies the constraints below, which make it
              unique among all the possible serializations of the keyword index.

              [1]    The  keys  found  in all the nested Tcl dictionaries are sorted in ascending
                     dictionary order, as generated by Tcl's builtin  command  lsort  -increasing
                     -dict.

              [2]    The  references  listed for each keyword of the index, if any, are listed in
                     ascending dictionary order of their labels, as generated  by  Tcl's  builtin
                     command lsort -increasing -dict.

BUGS, IDEAS, FEEDBACK

       This  document,  and  the  package  it  describes, will undoubtedly contain bugs and other
       problems.   Please  report  such  in  the  category  doctools  of  the   Tcllib   Trackers
       [http://core.tcl.tk/tcllib/reportlist].  Please also report any ideas for enhancements you
       may have for either package and/or documentation.

       When proposing code changes, please provide unified diffs, i.e the output of diff -u.

       Note further that attachments are strongly preferred over inlined patches. Attachments can
       be  made  by going to the Edit form of the ticket immediately after its creation, and then
       using the left-most button in the secondary navigation bar.

KEYWORDS

       HTML, conversion, docidx, documentation,  export,  formatting,  generation,  index,  json,
       keyword index, manpage, markup, nroff, plugin, reference, tcler's wiki, text, url, wiki

CATEGORY

       Documentation tools

COPYRIGHT

       Copyright (c) 2009-2018 Andreas Kupries <andreas_kupries@users.sourceforge.net>