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

@@ -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 '\ ' or '\ '.
+appear in TeX output as '`~`' and in HTML and XML as '`\ `' or
+'`\ `'.
+
+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
 ---------------------------

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

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

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"] ]
 

tests/markdown-reader-more.txt

@@ -59,3 +59,8 @@ $\$2 + \$3$
 -->
 - three
 
+## Backslash newline
+
+hi\
+there
+