tajmone
commented
6 years ago Ciao @thoni56,
I've finally managed to work my way trhough the misteries of XSL stylesheets, and succeeded in creating different styles for Alan code examples, BNF rules and other verbatim blocks. I've also managed to add colored background and border with radius (it wasn't enabled in the original templates).
Alan Examples Theme
For testing purposes, I've used the Monokai color scheme — both because I like it and because I had a reusable ready-made template for it.
I've actually implemented in the XSL stylesheet a ful color scheme, based on Base16 variables, so changing the colors is now very easy (otherwise, the attributes that control styling of sourcecode are scattered all over the place, but now they are centralized in a block of variables):
<!-- =============================================== -->
<!-- Monokai Base16 Color Scheme, by Wimer Hazenberg -->
<!-- =============================================== -->
<xsl:param name="Monokai.base00">#272822</xsl:param><!-- Rangoon Green ( almost black ) -->
<xsl:param name="Monokai.base01">#383830</xsl:param><!-- Armadillo ( almost black ) -->
<!-- [...] -->
<!-- ================================== -->
<!-- Syntax Highlighting Theme for Alan -->
<!-- ================================== -->
<xsl:param name="AlanHL.background" select="$Monokai.base00"></xsl:param>
<xsl:param name="AlanHL.normal" select="$Monokai.base05"></xsl:param>
<xsl:param name="AlanHL.quotedId" select="$AlanHL.normal"></xsl:param><!-- TEST WITH base12 -->
<xsl:param name="AlanHL.keyword" select="$Monokai.base08"></xsl:param>
<xsl:param name="AlanHL.comment" select="$Monokai.base04"></xsl:param>
<!-- [...] -->Chossing A Color Scheme
Personally, I love the Monokai scheme, but I now that not everyone likes dark schemes. Anyhow, changing the scheme is not a problem at all, and we can test various schemes easily with the new base16 system.
I think that if it has to be a light scheme it shouldn't be a strong yellow like the current one, because of syntax highlighting colors needing contrast with the backgroun and among themselves (dark schemes provide the best contrast IMO).
Now it's a matter of choosing the final color scheme to adopt.
The ideal way would be to actually test the color schems on Alan syntax using Hihglight tool, which now ships with the Alan syntax and all the Base16 schemes:
Alternatively, here is a link to live previewes of color schemes on Highlight.js (no Alan syntax though):
We could refer to the names of those schemes to communicate and discuss choices.
About the New Alan Highlighter
I had to create a new syntax for Alan in XSLHL. It works pretty well, and have done some stress testing against edge cases and works good (eg., no false positive for keywords inside quoted identifiers).
I'm going to add to the project some test files for syntax highlighting (now PDF, later on HTML too), for both previewing and testing.
The new syntax is almost identical to the Highlight syntax, except that it doesn't capture special dollar symbols in strings (XSLHL doesn't support styling escape sequences or interpolation inside strings).
Also, I didn't add highlighting of predefined classes this time, because I realized that there is a conflict between the actor, container and location classes and their keywords counterparts (ie, actor and location pseudo-attirbutes, as in Curent Actor/Location, and the container property). The highlighter would be unable to distinguish between when these are classes or not; in fact I should remove them from the Highlight syntax too!
I've now understand why the keywords list in the Manual doesn't include some predefined classes — it doesn't actually contain ANY classes, for these are there in virtue of being either pseudo-attributes or properties.
Is it correct? or am I misunderstanding the above point?
thoni56
Task list and progress status of customization of syntax highlighting in PDF documents.
alan-hl.xml").BNF(moved to #38).Define styling for all syntax elements of BNF (terminal, non terminal).