From 8671bc5a1be38f6555e34d7ccc542ebbe91f69fd Mon Sep 17 00:00:00 2001
From: fiddlosopher <fiddlosopher@788f1e2b-df1e-0410-8736-df70ead52e1b>
Date: Sat, 5 Dec 2009 05:33:24 +0000
Subject: [PATCH] Markdown reader: Treat a backslash followed by a newline as
 hard linebreak.

Resolves Issue #154.

git-svn-id: https://pandoc.googlecode.com/svn/trunk@1646 788f1e2b-df1e-0410-8736-df70ead52e1b
---
 README                              | 9 ++++++++-
 changelog                           | 5 +++++
 src/Text/Pandoc/Readers/Markdown.hs | 8 ++++----
 tests/markdown-reader-more.native   | 4 +++-
 tests/markdown-reader-more.txt      | 5 +++++
 5 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/README b/README
index 10dc66cc5..c1fd7cbde 100644
--- a/README
+++ b/README
@@ -463,7 +463,14 @@ which allows only the following characters to be backslash-escaped:
     \`*_{}[]()>#+-.!
 
 A backslash-escaped space is parsed as a nonbreaking space.  It will
-appear in TeX output as '~' and in HTML and XML as '\&#160;' or '\&nbsp;'.
+appear in TeX output as '`~`' and in HTML and XML as '`\&#160;`' or
+'`\&nbsp;`'.
+
+A backslash-escaped newline (i.e. a backslash occurring at the end of
+a line) is parsed as a hard line break.  It will appear in TeX output as
+'`\\`' and in HTML as '`<br />`'.  This is a nice alternative to
+markdown's "invisible" way of indicating hard line breaks using
+two trailing spaces on a line.
 
 Subscripts and superscripts
 ---------------------------
diff --git a/changelog b/changelog
index c3d46f782..2f726f90c 100644
--- a/changelog
+++ b/changelog
@@ -15,6 +15,11 @@ pandoc (1.3)
     to use for indented code blocks.  (Thanks to buttock for the
 	patch; resolves Issue #87.)
 
+  * Treat a backslash followed by a newline as a hard line break
+    in markdown.  Resolves Issue #154.  This is a nice alternative
+	to markdown's "invisible" way of indicating hardline breaks
+	using lines that end with two spaces.
+
   * Improved performance of markdown reader by ~10% by
     eliminating the need for a separate parsing pass for notes.
     Raw notes are now stored on the first pass (which parses
diff --git a/src/Text/Pandoc/Readers/Markdown.hs b/src/Text/Pandoc/Readers/Markdown.hs
index 4f0d1b6ad..c6926e3c1 100644
--- a/src/Text/Pandoc/Readers/Markdown.hs
+++ b/src/Text/Pandoc/Readers/Markdown.hs
@@ -863,10 +863,10 @@ escapedChar = do
   result <- option '\\' $ if stateStrict state 
                              then oneOf "\\`*_{}[]()>#+-.!~"
                              else satisfy (not . isAlphaNum)
-  let result' = if result == ' '
-                   then '\160'  -- '\ ' is a nonbreaking space
-                   else result
-  return $ Str [result']
+  return $ case result of
+                ' '   -> Str "\160" -- "\ " is a nonbreaking space
+                '\n'  -> LineBreak  -- "\[newline]" is a linebreak
+                _     -> Str [result]
 
 ltSign :: GenParser Char ParserState Inline
 ltSign = do
diff --git a/tests/markdown-reader-more.native b/tests/markdown-reader-more.native
index 0e76ace86..e6665591a 100644
--- a/tests/markdown-reader-more.native
+++ b/tests/markdown-reader-more.native
@@ -19,5 +19,7 @@ Pandoc (Meta [] [] "")
 , Header 2 [Str "Commented",Str "-",Str "out",Space,Str "list",Space,Str "item"]
 , BulletList
   [ [ Plain [Str "one"]
-    , RawHtml "<!--\n- two\n-->" ], [ Plain [Str "three"] ] ] ]
+    , RawHtml "<!--\n- two\n-->" ], [ Plain [Str "three"] ] ]
+, Header 2 [Str "Backslash",Space,Str "newline"]
+, Para [Str "hi",LineBreak,Str "there"] ]
 
diff --git a/tests/markdown-reader-more.txt b/tests/markdown-reader-more.txt
index 02b425e11..4689ee84a 100644
--- a/tests/markdown-reader-more.txt
+++ b/tests/markdown-reader-more.txt
@@ -59,3 +59,8 @@ $\$2 + \$3$
 -->
 - three
 
+## Backslash newline
+
+hi\
+there
+