Fix 1st Line Indentation in Code Blocks

[tajmone]

Problem

In documents that use Highlight, after an Alan code block starting with an indentation is processed by Highlight, the indentation on the first line is lost.

• [x] ALAN Beginner's Guide:
  • [x] Fix all occurrences in current sources using the {wj} workaround.
  • [x] Before committing, check that it doesn't interfere with:
    • [x] PDF builds (via Asciidoc-fopub).
  • [x] Found a real fix to the problem by editing the Haml template.

EDIT — The problem was fixed at it's root by editing the Haml template and using the :preserve filter to ensure that indentation of 1st line is always preserved correctly:

      %pre{:class=>pre_class, :lang=>pre_lang}
        %code{:class=>code_class, 'data-lang'=>code_lang}
          :preserve
            #{content}

---

For more info on this problem, see: tajmone/hugo-book#15

For an example, see:

• The Hugo Book: 5.4. Init And Main (a106ed8).

The {wj} Workaround

EDIT: No longer required, problem fixed!

Right now, the only workaround solution is to add a word joiner character (⁠) at the beginning of the first indented line using its predefined attribute for character replacement ({wj}):

[source,alan, subs="+attributes"]
---------------------------------
{wj}  Add To Every object

This works fine, although it's far from being an ideal solution (but, at least, it shouldn't create any problems for other Asciidoctor backends and output formats).

[tajmone]

This problem seems to affect only documents using Highlight, not those using Highlight.js.

Highlight.js Note

Currently the ALAN Manual still uses Highlight.js, due to the presence of some callouts (See #36, #50).

So this problem doesn't affect the ALAN Manual — I've checked every single code block in the book, and there's no trace of this indentation problem.

Highlight Note

This problem affects The Beginner's Guide, I just need to check if I've already applied the {wj} fix to all occurences of the problem.

Note, if/when we switch also the ALAN Manual to use Highlight (see #50) there might be a Lua filter to handle this problem, among those that ship with Highlight (if I remember correctly).