From 79e4b9f695d1a25c960eb2f6a86aabe169f78a8e Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Sun, 31 Jul 2022 11:14:16 +0300
Subject: feat: check for definition lists, and fail if found

Sponsored-by: author
---
 riki.md      | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 src/error.rs |  3 +++
 src/html.rs  | 15 ++++++++++++---
 3 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/riki.md b/riki.md
index 6fc0d53..e208baa 100644
--- a/riki.md
+++ b/riki.md
@@ -334,6 +334,52 @@ then AST of site/page.mdwn matches that of output/page.html
 * [x] done
 ~~~
 
+## Definition list
+
+_Requirement: Markup indicating use of a definition list should be
+flagged as an error._
+
+Justification: Neither the CommonMark specification, nor GitHub
+Flavored Markdown, supports definition lists, even though some
+Markdown variants do. The Markdown parser Riki uses doesn't support
+it.
+
+~~~scenario
+given an installed riki
+
+given file site/page.mdwn from dl-1
+when I try to run riki build --plain-body site output
+then command fails
+then stderr contains "definition list"
+
+given file site/page.mdwn from dl-2
+when I try to run riki build --plain-body site output
+then command fails
+then stderr contains "definition list"
+
+given file site/page.mdwn from dl-3
+when I run riki build --plain-body site output
+then file output/page.html contains ": bar"
+~~~
+
+~~~{#dl-1 .file}
+foo
+: bar
+~~~
+
+~~~{#dl-2 .file}
+foo
+
+: bar
+~~~
+
+~~~{#dl-3 .file}
+foo
+
+<!-- no colon at beginning of line here -->: bar
+~~~
+
+
 ## Input files other than Markdown
 
 _Requirement: Input files that aren't Markdown files must be copied
diff --git a/src/error.rs b/src/error.rs
index a5e65e1..756d7f0 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -49,4 +49,7 @@ pub enum SiteError {
 
     #[error("link to missing page {1} on {0}")]
     PageMissing(PathBuf, PathBuf),
+
+    #[error("attempt to use definition lists in Markdown: {0:?}")]
+    DefinitionList(String),
 }
diff --git a/src/html.rs b/src/html.rs
index 90bf9d5..9d048a5 100644
--- a/src/html.rs
+++ b/src/html.rs
@@ -134,8 +134,17 @@ pub fn parse(markdown: &str) -> Result<Element, SiteError> {
                 }
             },
             Event::End(tag) => match &tag {
-                Tag::Paragraph
-                | Tag::Heading(_, _, _)
+                Tag::Paragraph => {
+                    trace!("at end of paragraph, looking for definition list use");
+                    let e = stack.pop();
+                    let s = as_plain_text(e.children());
+                    trace!("paragraph text: {:?}", s);
+                    if s.starts_with(": ") || s.contains("\n: ") {
+                        return Err(SiteError::DefinitionList(s));
+                    }
+                    stack.append_child(Content::Elt(e));
+                }
+                Tag::Heading(_, _, _)
                 | Tag::List(_)
                 | Tag::Item
                 | Tag::Link(_, _, _)
@@ -162,7 +171,7 @@ pub fn parse(markdown: &str) -> Result<Element, SiteError> {
             }
             Event::Html(s) => stack.append_child(Content::Html(s.to_string())),
             Event::FootnoteReference(s) => trace!("footnote ref {:?}", s),
-            Event::SoftBreak => stack.append_str(" "),
+            Event::SoftBreak => stack.append_str("\n"),
             Event::HardBreak => stack.append_element(Element::new(ElementTag::Br)),
             Event::Rule => stack.append_element(Element::new(ElementTag::Hr)),
             Event::TaskListMarker(done) => {
-- 
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