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# doctools::idx(n) 2 tcllib "Documentation tools"

## Name

doctools::idx - Holding keyword indices

## Synopsis

- package require doctools::idx ?2?
- package require Tcl 8.4
- package require doctools::idx::structure
- package require snit

- ::doctools::idx objectName
- objectName method ?arg arg ...?
- objectName destroy
- objectName key add name
- objectName key remove name
- objectName key references name
- objectName keys
- objectName reference add type key name label
- objectName reference remove name
- objectName reference label name
- objectName reference keys name
- objectName reference type name
- objectName references
- objectName title
- objectName title text
- objectName label
- objectName label text
- objectName importer
- objectName importer object
- objectName exporter
- objectName exporter object
- objectName deserialize = data ?format?
- objectName deserialize += data ?format?
- objectName serialize ?format?

## Description

This package provides a class to contain and programmatically manipulate keyword indices

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

1. Exporting keyword indices, and

2. Importing 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 used to encode keyword indices as values see the section Keyword index serialization format. This is the only format directly known to this class. Conversions from and to any other format are handled by export and import manager objects. These may be attached to a container, but do not have to be, it is merely a convenience.

## 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 objectName

  This command creates a new container 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 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 key add name

  This method adds the keyword name to the index. If the keyword is already known nothing is done. The result of the method is the empty string.

objectName key remove name

  This method removes the keyword name from the index. If the keyword is already gone nothing is done. Any references for whom this keyword was the last association are removed as well. The result of the method is the empty string.

objectName key references name

  This method returns a list containing the names of all references associated with the keyword name. An error is thrown in the keyword is not known to the index. The order of the references in the list is undefined.

objectName keys

  This method returns a list containing the names of all keywords known to the index. The order of the keywords in the list is undefined.

objectName reference add type key name label

  This method adds the reference name to the index and associates it with the keyword key. The other two arguments hold the type and label of the reference, respectively. The type has to match the stored information, should the reference exist already, i.e. this information is immutable after the reference is known. The only way to change it is delete and recreate the reference. The label on the other hand is automatically updated to the value of the argument, overwriting any previously stored information. Should the reference exists already it is simply associated with the key. If that is true already as well nothing is done, but the label updated to the new value. The result of the method is the empty string.

  The type argument has be to one of manpage or url.

objectName reference remove name

  The reference name is removed from the index. All associations with keywords are released and the relevant reference labels removed. The result of the method is the empty string.

objectName reference label name

  This method returns the label associated with the reference name. An error is thrown if the reference is not known.

objectName reference keys name

  This method returns a list containing the names of all keywords associated with the reference name. An error is thrown in the reference is not known to the index. The order of the keywords in the list is undefined.

objectName reference type name

  This method returns the type of the reference name. An error is thrown in the reference is not known to the index.

objectName references

  This method returns a list containing the names of all references known to the index. The order of the references in the list is undefined.

objectName title

  Returns the currently defined title of the keyword index.

objectName title text

  Sets the title of the keyword index to text, and returns it as the result of the command.

objectName label

  Returns the currently defined label of the keyword index.

objectName label text

  Sets the label of the keyword index to text, and returns it as the result of the command.

objectName importer

  Returns the import manager object currently attached to the container, if any.

objectName importer object

  Attaches the object as import manager to the container, and returns it as the result of the command. Note that the object is not put into ownership of the container. I.e., destruction of the container will not destroy the object.

  It is expected that object provides a method named import text which takes a text and a format name, and returns the canonical serialization of the keyword index contained in the text, assuming the given format.

objectName exporter

  Returns the export manager object currently attached to the container, if any.

objectName exporter object

  Attaches the object as export manager to the container, and returns it as the result of the command. Note that the object is not put into ownership of the container. I.e., destruction of the container will not destroy the object.

  It is expected that object provides a method named export object which takes the container and a format name, and returns a text encoding keyword index stored in the container, in the given format. It is further expected that the object will use the container's method serialize to obtain the serialization of the keyword index from which to generate the text.

objectName deserialize = data ?format?

  This method replaces the contents of the index object with the index contained in the data. If no format was specified it is assumed to be the regular serialization of a keyword index.

  Otherwise the object will use the attached import manager to convert the data from the specified format to a serialization it can handle. In that case an error will be thrown if the container has no import manager attached to it.

  The result of the method is the empty string.

objectName deserialize += data ?format?

  This method behaves like deserialize = in its essentials, except that it merges the keyword index in the data to its contents instead of replacing it. The method will throw an error if merging is not possible, i.e. would produce an invalid index. The existing content is left unchanged in that case.

  The result of the method is the empty string.

objectName serialize ?format?

  This method returns the keyword index contained in the object. If no format is not specified the returned result is the canonical serialization of its contents.

  Otherwise the object will use the attached export manager to convert the data to the specified format. In that case an error will be thrown if the container has no export manager attached to it.

## 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, refering to one of the documents the index was made for.

     url

       The identifier of the reference is interpreted as an url, refering 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. Please also report any ideas for enhancements you may have for either package and/or documentation.

## Keywords

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

## Category

Documentation tools

## Copyright

Copyright © 2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>