QTextMarkdownWriter: write fenced code blocks with language declaration

MD4C now makes it possible to detect indented and fenced code blocks:
https://github.com/mity/md4c/issues/81
Fenced code blocks have the advantages of being easier to write by hand,
and having an "info string" following the opening fence, which is commonly
used to declare the language.

Also, the HTML parser now recognizes tags of the form
<pre class="language-foo">
which is one convention for declaring the programming language
(as opposed to human language, for which the lang attribute would be used):
https://stackoverflow.com/questions/5134242/semantics-standards-and-using-the-lang-attribute-for-source-code-in-markup
So it's possible to read HTML and write markdown without losing this information.

It's also possible to read markdown with any type of code block:
fenced with ``` or ~~~, or indented, and rewrite it the same way.

Change-Id: I33c2bf7d7b66c8f3ba5bdd41ab32572f09349c47
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

2 files changed, 40 insertions, 15 deletions

diff --git a/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md b/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
index 44c198fdc5..6336d0219f 100644
--- a/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
+++ b/tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md
@@ -20,21 +20,43 @@ MacFarlane writes:
 > equivalent sample of Markdown. Here is a sample of AsciiDoc from the AsciiDoc
 > manual:
 
->     1. List item one.
->     +
->     List item one continued with a second paragraph followed by an
->     Indented block.
->     +
->     .................
->     $ ls *.sh
->     $ mv *.sh ~/tmp
->     .................
->     +
->     List item continued with a third paragraph.
->     
->     2. List item two continued with an open block.
->     ...
->     
+> ``` AsciiDoc
+> 1. List item one.
+> +
+> List item one continued with a second paragraph followed by an
+> Indented block.
+> +
+> .................
+> $ ls *.sh
+> $ mv *.sh ~/tmp
+> .................
+> +
+> List item continued with a third paragraph.
+> 
+> 2. List item two continued with an open block.
+> ...
+> ```
 The quotation includes an embedded quotation and a code quotation and ends with
 an ellipsis due to being incomplete.
 
+Now let's have an indented code block:
+
+    #include <stdio.h>
+    
+    int main(void)
+    {
+        printf("# hello markdown\n");
+        return 0;
+    }
+
+and end with a fenced code block:
+~~~ pseudocode
+#include <something.h>
+#include <else.h>
+
+a block {
+    a statement;
+    another statement;
+}
+~~~
+
diff --git a/tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp b/tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp
index 1935e58dec..8d38cbb18a 100644
--- a/tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp
+++ b/tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp
@@ -419,6 +419,9 @@ void tst_QTextMarkdownWriter::fromHtml_data()
     QTest::newRow("image") <<
         "<img src=\"/url\" alt=\"foo\" title=\"title\"/>" <<
         "![foo](/url \"title\")\n\n";
+    QTest::newRow("code") <<
+        "<pre class=\"language-pseudocode\">\n#include \"foo.h\"\n\nblock {\n    statement();\n}\n\n</pre>" <<
+        "``` pseudocode\n#include \"foo.h\"\n\nblock {\n    statement();\n}\n```\n\n";
     // TODO
 //    QTest::newRow("escaped number and paren after double newline") <<
 //        "<p>(The first sentence of this paragraph is a line, the next paragraph has a number</p>13) but that's not part of an ordered list" <<