Added optional section numbering in HTML output.

This involves a change to the Element data structure,
including a section number as well as an id and title
for each section.  Section numbers are lists of integers;
this should allow different numbering schemes to be used
in the future.  Currently [1,2,3] -> 1.2.3.

Resolves Issue #150.

git-svn-id: https://pandoc.googlecode.com/svn/trunk@1658 788f1e2b-df1e-0410-8736-df70ead52e1b

7 files changed, 33 insertions, 19 deletions

diff --git a/README b/README
index bc40566fc..8296d8fec 100644
--- a/README
+++ b/README
@@ -363,8 +363,8 @@ For further documentation, see the `pandoc(1)` man page.
     displayed all at once.
 
 `-N` or `--number-sections`
-:   causes sections to be numbered in LaTeX or ConTeXt output. By default,
-    sections are not numbered.
+:   causes sections to be numbered in LaTeX, ConTeXt, or HTML output.
+    By default, sections are not numbered.
 
 `--no-wrap`
 :   disables text-wrapping in output.  By default, text is wrapped
diff --git a/man/man1/pandoc.1.md b/man/man1/pandoc.1.md
index 3eeb93fb4..3caf104f4 100644
--- a/man/man1/pandoc.1.md
+++ b/man/man1/pandoc.1.md
@@ -134,8 +134,8 @@ to Pandoc.  Or use `html2markdown`(1), a wrapper around `pandoc`.
 :   Make list items in S5 display incrementally (one by one).
 
 -N, \--number-sections
-:   Number section headings in LaTeX output.  (Default is not to number
-    them.)
+:   Number section headings in LaTeX, ConTeXt, or HTML output.
+    (Default is not to number them.)
 
 \--no-wrap
 :   Disable text wrapping in output. (Default is to wrap text.)
diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index 6f11d0200..c99fa3e9e 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -882,8 +882,8 @@ isPara _        = False
 
 -- | Data structure for defining hierarchical Pandoc documents
 data Element = Blk Block 
-             | Sec Int String [Inline] [Element]
-             --    lvl  ident  label    contents
+             | Sec Int [Int] String [Inline] [Element]
+             --    lvl  num ident  label    contents
              deriving (Eq, Read, Show, Typeable, Data)
 
 -- | Convert Pandoc inline list to plain text identifier.
@@ -921,18 +921,22 @@ inlineListToIdentifier' (x:xs) =
 
 -- | Convert list of Pandoc blocks into (hierarchical) list of Elements
 hierarchicalize :: [Block] -> [Element]
-hierarchicalize blocks = S.evalState (hierarchicalizeWithIds blocks) []
+hierarchicalize blocks = S.evalState (hierarchicalizeWithIds blocks) ([],[])
 
-hierarchicalizeWithIds :: [Block] -> S.State [String] [Element]
+hierarchicalizeWithIds :: [Block] -> S.State ([Int],[String]) [Element]
 hierarchicalizeWithIds [] = return []
 hierarchicalizeWithIds ((Header level title'):xs) = do
-  usedIdents <- S.get
+  (lastnum, usedIdents) <- S.get
   let ident = uniqueIdent title' usedIdents
-  S.modify (ident :)
+  let lastnum' = take level lastnum
+  let newnum = if length lastnum' >= level
+                  then init lastnum' ++ [last lastnum' + 1] 
+                  else lastnum ++ replicate (level - length lastnum - 1) 0 ++ [1]
+  S.put (newnum, (ident : usedIdents))
   let (sectionContents, rest) = break (headerLtEq level) xs
   sectionContents' <- hierarchicalizeWithIds sectionContents
   rest' <- hierarchicalizeWithIds rest
-  return $ Sec level ident title' sectionContents' : rest'
+  return $ Sec level newnum ident title' sectionContents' : rest'
 hierarchicalizeWithIds (x:rest) = do
   rest' <- hierarchicalizeWithIds rest
   return $ (Blk x) : rest'
diff --git a/src/Text/Pandoc/Writers/Docbook.hs b/src/Text/Pandoc/Writers/Docbook.hs
index b4f760e6c..b46bb0eb4 100644
--- a/src/Text/Pandoc/Writers/Docbook.hs
+++ b/src/Text/Pandoc/Writers/Docbook.hs
@@ -82,7 +82,7 @@ writeDocbook opts (Pandoc (Meta title authors date) blocks) =
 -- | Convert an Element to Docbook.
 elementToDocbook :: WriterOptions -> Element -> Doc
 elementToDocbook opts (Blk block) = blockToDocbook opts block 
-elementToDocbook opts (Sec _ id' title elements) =
+elementToDocbook opts (Sec _ _num id' title elements) =
   -- Docbook doesn't allow sections with no content, so insert some if needed
   let elements' = if null elements
                     then [Blk (Para [])]
diff --git a/src/Text/Pandoc/Writers/HTML.hs b/src/Text/Pandoc/Writers/HTML.hs
index 9e397477e..56398b263 100644
--- a/src/Text/Pandoc/Writers/HTML.hs
+++ b/src/Text/Pandoc/Writers/HTML.hs
@@ -38,7 +38,7 @@ import Text.Pandoc.Highlighting ( highlightHtml, defaultHighlightingCss )
 import Text.Pandoc.XML (stripTags)
 import Numeric ( showHex )
 import Data.Char ( ord, toLower )
-import Data.List ( isPrefixOf )
+import Data.List ( isPrefixOf, intersperse )
 import Data.Maybe ( catMaybes )
 import qualified Data.Set as S
 import Control.Monad.State
@@ -156,12 +156,19 @@ tableOfContents opts sects = do
   contents  <- mapM (elementToListItem opts') sects
   return $ thediv ! [prefixedId opts' "TOC"] $ unordList $ catMaybes contents
 
+-- | Convert section number to inline
+showSecNum :: [Int] -> Inline
+showSecNum = Str . concat . intersperse "." . map show
+
 -- | Converts an Element to a list item for a table of contents,
 -- retrieving the appropriate identifier from state.
 elementToListItem :: WriterOptions -> Element -> State WriterState (Maybe Html)
 elementToListItem _ (Blk _) = return Nothing
-elementToListItem opts (Sec _ id' headerText subsecs) = do
-  txt <- inlineListToHtml opts headerText
+elementToListItem opts (Sec _ num id' headerText subsecs) = do
+  let headerText' = if writerNumberSections opts
+                       then showSecNum num : Space : headerText
+                       else headerText
+  txt <- inlineListToHtml opts headerText'
   subHeads <- mapM (elementToListItem opts) subsecs >>= return . catMaybes
   let subList = if null subHeads
                    then noHtml
@@ -171,9 +178,12 @@ elementToListItem opts (Sec _ id' headerText subsecs) = do
 -- | Convert an Element to Html.
 elementToHtml :: WriterOptions -> Element -> State WriterState Html
 elementToHtml opts (Blk block) = blockToHtml opts block 
-elementToHtml opts (Sec level id' title' elements) = do
+elementToHtml opts (Sec level num id' title' elements) = do
   innerContents <- mapM (elementToHtml opts) elements
-  header' <- blockToHtml opts (Header level title')
+  let title'' = if writerNumberSections opts
+                   then showSecNum num : Space : title'
+                   else title'
+  header' <- blockToHtml opts (Header level title'')
   return $ if writerS5 opts || (writerStrictMarkdown opts && not (writerTableOfContents opts))
               -- S5 gets confused by the extra divs around sections
               then toHtmlFromList (header' : innerContents)
diff --git a/src/Text/Pandoc/Writers/Markdown.hs b/src/Text/Pandoc/Writers/Markdown.hs
index 31b12976d..0e1231b62 100644
--- a/src/Text/Pandoc/Writers/Markdown.hs
+++ b/src/Text/Pandoc/Writers/Markdown.hs
@@ -138,7 +138,7 @@ tableOfContents opts headers =
 -- | Converts an Element to a list item for a table of contents,
 elementToListItem :: Element -> [Block]
 elementToListItem (Blk _) = []
-elementToListItem (Sec _ _ headerText subsecs) = [Plain headerText] ++ 
+elementToListItem (Sec _ _ _ headerText subsecs) = [Plain headerText] ++ 
   if null subsecs
      then []
      else [BulletList $ map elementToListItem subsecs]
diff --git a/src/Text/Pandoc/Writers/RTF.hs b/src/Text/Pandoc/Writers/RTF.hs
index 2376557a8..15bac115d 100644
--- a/src/Text/Pandoc/Writers/RTF.hs
+++ b/src/Text/Pandoc/Writers/RTF.hs
@@ -59,7 +59,7 @@ tableOfContents headers =
 
 elementToListItem :: Element -> [Block]
 elementToListItem (Blk _) = []
-elementToListItem (Sec _ _ sectext subsecs) = [Plain sectext] ++
+elementToListItem (Sec _ _ _ sectext subsecs) = [Plain sectext] ++
   if null subsecs
      then []
      else [BulletList (map elementToListItem subsecs)]