Implement task lists (#5139)

Closes #3051

1 files changed, 113 insertions, 0 deletions

diff --git a/test/command/tasklist.md b/test/command/tasklist.md
new file mode 100644
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--- /dev/null
+++ b/test/command/tasklist.md
@@ -0,0 +1,113 @@
+tests adapted from <https://github.github.com/gfm/#task-list-items-extension->
+
+```
+% pandoc
+- [ ] foo
+- [x] bar
+^D
+<ul>
+<li><input type="checkbox" disabled="" />
+foo</li>
+<li><input type="checkbox" disabled="" checked="" />
+bar</li>
+</ul>
+```
+
+
+```
+% pandoc
+- [x] foo
+  - [ ] bar
+  - [x] baz
+- [ ] bim
+^D
+<ul>
+<li><input type="checkbox" disabled="" checked="" />
+foo<ul>
+<li><input type="checkbox" disabled="" />
+bar</li>
+<li><input type="checkbox" disabled="" checked="" />
+baz</li>
+</ul></li>
+<li><input type="checkbox" disabled="" />
+bim</li>
+</ul>
+```
+
+
+custom html task list test:
+
+```
+% pandoc
+- [ ]  unchecked
+- plain item
+-  [x] checked
+
+paragraph
+
+1. [ ] ordered unchecked
+2. [] plain item
+3. [x] ordered checked
+
+paragraph
+
+- [ ] list item with a
+
+    second paragraph
+
+- [x] checked
+^D
+<ul>
+<li><input type="checkbox" disabled="" />
+unchecked</li>
+<li>plain item</li>
+<li><input type="checkbox" disabled="" checked="" />
+checked</li>
+</ul>
+<p>paragraph</p>
+<ol type="1">
+<li><input type="checkbox" disabled="" />
+ordered unchecked</li>
+<li>[] plain item</li>
+<li><input type="checkbox" disabled="" checked="" />
+ordered checked</li>
+</ol>
+<p>paragraph</p>
+<ul>
+<li><p><input type="checkbox" disabled="" />
+list item with a</p><p>second paragraph</p></li>
+<li><p><input type="checkbox" disabled="" checked="" />
+checked</p></li>
+</ul>
+```
+
+latex task list test:
+
+```
+% pandoc -t latex
+- [ ] foo bar
+
+  baz
+
+- [x] ok
+^D
+\begin{itemize}
+\item[$\square$]
+  foo bar
+
+  baz
+\item[$\boxtimes$]
+  ok
+\end{itemize}
+```
+
+round trip:
+
+```
+% pandoc -f markdown -t markdown
+- [ ] foo
+- [x] bar
+^D
+-   [ ] foo
+-   [x] bar
+```