Markdown and a layout-quine

The speedata Publisher has now (version 4.17.11) basic support for markdown, an easy to use markup language.

As an example of markdown formatting, this snippet creates a level 1 heading and a simple bullet list:

# A title

* one
* anotherone
* three

Using markdown with the speedata Publisher is very easy. There is a new layout function called sd:markdown()

<Layout xmlns="urn:speedata.de:2009/publisher/en"
    xmlns:sd="urn:speedata:2009/publisher/functions/en">

    <Record element="data">
        <PlaceObject>
            <Textblock>
                <Paragraph>
                    <Value select="sd:markdown(.)" />
                </Paragraph>
            </Textblock>
        </PlaceObject>
    </Record>
</Layout>

The result is, as expected, a heading and a bullet list.

Markdown comes with several flavors and extensions, for example a table extension that lets you write

| foo | bar |
| --- | --- |
| baz | bim |

to create a table. To activate these extensions, use the <Options> command:

<Options markdown-extensions="highlight,table" />

The complete list of options is available in the documentation.

A markdown-layout quine

What is a quine? The wikipedia article defines: “A quine is a computer program that takes no input and produces a copy of its own source code as its only output.”

The idea is to create a markdown file with the contents of the layout.xml file, surround it with the markdown instructions for code formatting and render this to the PDF.

Run the following code with sp --dummy to get the PDF:

<Layout xmlns="urn:speedata.de:2009/publisher/en"
    xmlns:sd="urn:speedata:2009/publisher/functions/en">
    <Options markdown-extensions="highlight,hlstyle_tango" />

    <Record element="data">
        <SetVariable
            variable="raw"
            select="unparsed-text('layout.xml')" />
        <SetVariable
            variable="fenced"
            select="concat('```xml&#x0a;', $raw ,'&#x0a;```'))"/>
        <PlaceObject>
            <Textblock>
                <Paragraph>
                    <Value select="sd:markdown($fenced)" />
                </Paragraph>
            </Textblock>
        </PlaceObject>
    </Record>
</Layout>

The markdown code that is generated looks like this:

```xml
<Layout xmlns="urn:speedata.de:2009/publisher/en"
...
</Layout>
```

the contents between the backticks is taken from the non-interpreted layout.xml file, which is read with the xpath function unparsed-text().

This is the result:

Admittedly, this quine is not perfect, since it reads the source code from storage. It would be nicer to have a “to_xml()” function for the layout XML that marshals the layout instructions back to XML.