From 72c73ec99d31587297f0c8d626b7e8a3a7faddaa Mon Sep 17 00:00:00 2001
From: Nathan McCarty <thatonelutenist@stranger.systems>
Date: Thu, 27 Feb 2025 05:28:06 -0500
Subject: [PATCH] Hard line break support

---
 src/SSG/Djot/Inline.idr                | 17 ++++++++++++++++-
 src/SSG/Djot/Render.idr                |  1 +
 test/djotToHtml/001-paragraph/expected | 17 +++++++++++++++++
 test/djotToHtml/001-paragraph/test.dj  | 11 +++++++++++
 todo.org                               |  6 +++---
 5 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/src/SSG/Djot/Inline.idr b/src/SSG/Djot/Inline.idr
index 80d11f1..d547c43 100644
--- a/src/SSG/Djot/Inline.idr
+++ b/src/SSG/Djot/Inline.idr
@@ -22,6 +22,7 @@ public export
 data Inline : Type where
   Text : (text : String) -> Inline
   SoftLineBreak : Inline
+  HardLineBreak : Inline
 
 %runElab derive "Inline" [Eq, Show, Pretty]
 
@@ -145,9 +146,18 @@ softLineBreak = do
       _ <- many horiz
       pure ()
 
+hardLineBreak : IParser Inline
+hardLineBreak = do
+  _ <- exactly "\\"
+  _ <- many horiz
+  _ <- vert
+  _ <- many horiz
+  pure HardLineBreak
+
 -- Definition of pInline
 pInline = oneOf
-  [ softLineBreak
+  [ hardLineBreak
+  , softLineBreak
   , text
   ]
 
@@ -223,3 +233,8 @@ testTrailingSoftLineBreak =
 testTrailingSoftLineBreaks : IO Bool
 testTrailingSoftLineBreaks =
   golden "Hello\n\nWorld!\n\n\n" [Text "Hello", SoftLineBreak, Text "World!"]
+
+-- @@test Hard line break smoke
+smokeHardLineBreak : IO Bool
+smokeHardLineBreak =
+  golden "Hello\\\nWorld!" [Text "Hello", HardLineBreak, Text "World!"]
diff --git a/src/SSG/Djot/Render.idr b/src/SSG/Djot/Render.idr
index a6b8b03..b610349 100644
--- a/src/SSG/Djot/Render.idr
+++ b/src/SSG/Djot/Render.idr
@@ -13,6 +13,7 @@ renderInline : Inline -> Maybe (t ** Html t)
 -- FIXME: escape text
 renderInline (Text text) = Just (_ ** Text text)
 renderInline SoftLineBreak = Nothing
+renderInline HardLineBreak = Just (_ ** Void "br" [])
 
 ||| Render a list of inline elments to html
 export
diff --git a/test/djotToHtml/001-paragraph/expected b/test/djotToHtml/001-paragraph/expected
index 6875061..612076b 100644
--- a/test/djotToHtml/001-paragraph/expected
+++ b/test/djotToHtml/001-paragraph/expected
@@ -12,5 +12,22 @@
       A multiline paragraph
       with some indentation
     </p>
+    <p>
+      This is a hard
+      <br>
+      line break
+    </p>
+    <p>
+      And again
+      <br>
+      with some spaces afterwards
+    </p>
+    <p>
+      And now we
+      mix soft
+      <br>
+      and hard
+      linebreaks
+    </p>
   </body>
 </html>
diff --git a/test/djotToHtml/001-paragraph/test.dj b/test/djotToHtml/001-paragraph/test.dj
index d4ab1bf..1525f0b 100644
--- a/test/djotToHtml/001-paragraph/test.dj
+++ b/test/djotToHtml/001-paragraph/test.dj
@@ -10,3 +10,14 @@ Two line breaks
 
 A multiline paragraph
   with some indentation
+
+This is a hard\
+line break
+
+And again\   
+with some spaces afterwards
+
+And now we
+mix soft\ 
+and hard
+linebreaks
diff --git a/todo.org b/todo.org
index ce5e9de..cce0eed 100644
--- a/todo.org
+++ b/todo.org
@@ -10,11 +10,11 @@ Decided to rename =Tag= to =Html=, and =Raw= to =Text=, which makes this make se
 ** TODO Refine =location= in =ParserLocation=
 ** TODO Error messages
 ** TODO Combinators for predictive parsing
-* Djot [2/38]
+* Djot [3/38]
 :PROPERTIES:
 :COOKIE_DATA: recursive
 :END:
-** Parsing [2/33]
+** Parsing [3/33]
 *** Block Level
 **** TODO Heading
 **** TODO Block Quote
@@ -43,12 +43,12 @@ Decided to rename =Tag= to =Html=, and =Raw= to =Text=, which makes this make se
 **** TODO Smart Puncuation
 **** TODO Math
 **** TODO Footnote Reference
-**** TODO Linebreak
 **** TODO Comment
 **** TODO Symbols
 **** TODO Raw Inline
 **** TODO Inline Attributes
 **** DONE Ordinary Text
+**** DONE Linebreak
 *** Lines effect
 **** TODO =IO= Backed implementation
 *** Known Inaccuracies