doctoc_lang_intro(n) 1.0 tcllib "Documentation tools"

Fundamentals

While the doctoc markup language is quite similar to the doctools markup language, in the broadest terms possible, there is one key difference. A table of contents consists essentially only of markup commands, with no plain text interspersed between them, except for whitespace.

Each markup command is a Tcl command surrounded by a matching pair of [ and ]. Inside of these delimiters the usual rules for a Tcl command apply with regard to word quotation, nested commands, continuation lines, etc. I.e.

    ... [division_start {Appendix 1}] ...

  ... [item thefile \\
          label {file description}] ...

Basic structure

The most simple document which can be written in doctoc is

    [toc_begin GROUPTITLE TITLE]
    [toc_end]

This also shows us that all doctoc documents consist of only one part where we will list items and divisions.

The user is free to mix these as she sees fit. This is a change from version 1 of the language, which did not allow this mixing, but only the use of either a series of items or a series of divisions.

We will discuss the commands for each of these two possibilities in the next sections.

Items

Use the command item to put an item into a table of contents. This is essentially a reference to a section, subsection, etc. in the document, or set of documents, the table of contents is for. The command takes three arguments, a symbolic name for the file the item is for and two text to label the item and describe the referenced section.

Symbolic names are used to preserve the convertibility of this format to any output format. The actual name of any file will be inserted by the chosen formatting engine when converting the input, based on a mapping from symbolic to actual names given to the engine.

Here a made up example for a table of contents of this document:

[toc_begin Doctoc {Language Introduction}]
[item 1 DESCRIPTION]
[item 1.1 {Basic structure}]
[item 1.2 Items]
[item 1.3 Divisions]
[item 2 {FURTHER READING}]
[toc_end]

Divisions

One thing of notice in the last example in the previous section is that the referenced sections actually had a nested structure, something which was expressed in the item labels, by using a common prefix for all the sections nested under section 1.

This kind of structure can be made more explicit in the doctoc language by using divisions. Instead of using a series of plain items we use a series of divisions for the major references, and then place the nested items inside of these.

Of course, instead of the nested items we can again use divisions and thus nest arbitrarily deep.

A division is marked by two commands instead of one, one to start it, the other to close the last opened division. They are:

division_start

This command opens a new division. It takes one or two arguments, the title of the division, and the symbolic name of the file it refers to. The latter is optional. If the symbolic filename is present then the section title should link to the referenced document, if links are supported by the output format.

division_end

This command closes the last opened and not yet closed division.

Using this we can recast the last example like this

[toc_begin Doctoc {Language Introduction}]
[division_start DESCRIPTION]
[item 1 {Basic structure}]
[item 2 Items]
[item 3 Divisions]
[division_end]
[division_start {FURTHER READING}]
[division_end]
[toc_end]

Or, to demonstrate deeper nesting

[toc_begin Doctoc {Language Introduction}]
[division_start DESCRIPTION]
[division_start {Basic structure}]
[item 1 Do]
[item 2 Re]
[division_end]
[division_start Items]
[item a Fi]
[item b Fo]
[item c Fa]
[division_end]
[division_start Divisions]
[item 1 Sub]
[item 1 Zero]
[division_end]
[division_end]
[division_start {FURTHER READING}]
[division_end]
[toc_end]

And do not forget, it is possible to freely mix items and divisions, and to have empty divisions.

[toc_begin Doctoc {Language Introduction}]
[item 1 Do]
[division_start DESCRIPTION]
[division_start {Basic structure}]
[item 2 Re]
[division_end]
[item a Fi]
[division_start Items]
[item b Fo]
[item c Fa]
[division_end]
[division_start Divisions]
[division_end]
[division_end]
[division_start {FURTHER READING}]
[division_end]
[toc_end]

Advanced structure

In all previous examples we fudged a bit regarding the markup actually allowed to be used before the toc_begin command opening the document.

Instead of only whitespace the two templating commands include and vset are also allowed, to enable the writer to either set and/or import configuration settings relevant to the table of contents. I.e. it is possible to write

[include FILE]
[vset VAR VALUE]
[toc_begin GROUPTITLE TITLE]
...
[toc_end]

Even more important, these two commands are allowed anywhere where a markup command is allowed, without regard for any other structure.

[toc_begin GROUPTITLE TITLE]
[include FILE]
[vset VAR VALUE]
...
[toc_end]

The only restriction include has to obey is that the contents of the included file must be valid at the place of the inclusion. I.e. a file included before toc_begin may contain only the templating commands vset and include, a file included in a division may contain only items or divisions commands, etc.

Escapes

Beyond the 6 commands shown so far we have two more available. However their function is not the marking up of toc structure, but the insertion of characters, namely [ and ]. These commands, lb and rb respectively, are required because our use of [ and ] to bracket markup commands makes it impossible to directly use [ and ] within the text.

Our example of their use are the sources of the last sentence in the previous paragraph, with some highlighting added.

  ...
  These commands, [cmd lb] and [cmd lb] respectively, are required
  because our use of [lb] and [rb] to bracket markup commands makes it
  impossible to directly use [lb] and [rb] within the text.
  ...