Moved tabFilter to Shared.

Removed optPreserveTabs; instead, tabstop of 0 means preserve tabs.


git-svn-id: https://pandoc.googlecode.com/svn/trunk@1532 788f1e2b-df1e-0410-8736-df70ead52e1b

1 files changed, 21 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Shared.hs b/src/Text/Pandoc/Shared.hs
index 6854e5ae6..13eab9bdb 100644
--- a/src/Text/Pandoc/Shared.hs
+++ b/src/Text/Pandoc/Shared.hs
@@ -49,6 +49,7 @@ module Text.Pandoc.Shared (
                      wrapTeXIfNeeded,
                      BlockWrapper (..),
                      wrappedBlocksToDoc,
+                     tabFilter,
                      -- * Parsing
                      (>>~),
                      anyLine,
@@ -285,6 +286,26 @@ wrappedBlocksToDoc = foldr addBlock empty
            addBlock (Pad d) accum = d $$ text "" $$ accum
            addBlock (Reg d) accum = d $$ accum
 
+-- | Convert tabs to spaces and filter out DOS line endings.
+-- Tabs will be preserved if tab stop is set to 0.
+tabFilter :: Int       -- ^ Tab stop
+          -> String    -- ^ Input
+          -> String
+tabFilter tabStop =
+  let go _ [] = ""
+      go _ ('\n':xs) = '\n' : go tabStop xs
+      go _ ('\r':'\n':xs) = '\n' : go tabStop xs
+      go _ ('\r':xs) = '\n' : go tabStop xs
+      go spsToNextStop ('\t':xs) =
+        if tabStop == 0
+           then '\t' : go tabStop xs
+           else replicate spsToNextStop ' ' ++ go tabStop xs
+      go 1 (x:xs) =
+        x : go tabStop xs
+      go spsToNextStop (x:xs) =
+        x : go (spsToNextStop - 1) xs
+  in  go tabStop
+
 --
 -- Parsing
 --