Grid Tables (#718)

* Add table examples

* Add table types and adopt simple parser

Simple parser is done by Giovanni Cappellotto (@potomak)
in https://github.com/haskell/haddock/pull/577
It seems to support single fine full tables, so far from full
RST-grid tables, but it's good start.

Table type support row- and colspans, but obviously parser is lacking.

Still TODO:
- Latex backend. Should we use multirow package
  https://ctan.org/pkg/multirow?lang=en?
- Hoogle backend: ?

* Implement grid-tables

* Refactor table parser

* Add two ill-examples

* Update CHANGES.md

* Basic documentation for tables

* Fix documentation example

6 files changed, 66 insertions, 3 deletions

diff --git a/haddock-api/src/Haddock/Backends/Hoogle.hs b/haddock-api/src/Haddock/Backends/Hoogle.hs
index f1d8ddb2..fc71d4b5 100644
--- a/haddock-api/src/Haddock/Backends/Hoogle.hs
+++ b/haddock-api/src/Haddock/Backends/Hoogle.hs
@@ -328,7 +328,8 @@ markupTag dflags = Markup {
   markupAName                = const $ str "",
   markupProperty             = box TagPre . str,
   markupExample              = box TagPre . str . unlines . map exampleToString,
-  markupHeader               = \(Header l h) -> box (TagInline $ "h" ++ show l) h
+  markupHeader               = \(Header l h) -> box (TagInline $ "h" ++ show l) h,
+  markupTable                = \(Table _ _) -> str "TODO: table"
   }
 
 
diff --git a/haddock-api/src/Haddock/Backends/LaTeX.hs b/haddock-api/src/Haddock/Backends/LaTeX.hs
index d79e0e6c..3ac3b405 100644
--- a/haddock-api/src/Haddock/Backends/LaTeX.hs
+++ b/haddock-api/src/Haddock/Backends/LaTeX.hs
@@ -1140,7 +1140,8 @@ parLatexMarkup ppId = Markup {
   markupAName                = \_ _ -> empty,
   markupProperty             = \p _ -> quote $ verb $ text p,
   markupExample              = \e _ -> quote $ verb $ text $ unlines $ map exampleToString e,
-  markupHeader               = \(Header l h) p -> header l (h p)
+  markupHeader               = \(Header l h) p -> header l (h p),
+  markupTable                = \(Table h b) p -> table h b p
   }
   where
     header 1 d = text "\\section*" <> braces d
@@ -1149,6 +1150,8 @@ parLatexMarkup ppId = Markup {
       | l > 0 && l <= 6 = text "\\subsubsection*" <> braces d
     header l _ = error $ "impossible header level in LaTeX generation: " ++ show l
 
+    table _ _ _ = text "{TODO: Table}"
+
     fixString Plain s = latexFilter s
     fixString Verb  s = s
     fixString Mono  s = latexMonoFilter s
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs b/haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs
index e63667b0..2990e1e4 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs
@@ -73,7 +73,8 @@ parHtmlMarkup qual insertAnchors ppId = Markup {
   markupMathDisplay          = \mathjax -> toHtml ("\\[" ++ mathjax ++ "\\]"),
   markupProperty             = pre . toHtml,
   markupExample              = examplesToHtml,
-  markupHeader               = \(Header l t) -> makeHeader l t
+  markupHeader               = \(Header l t) -> makeHeader l t,
+  markupTable                = \(Table h r) -> makeTable h r
   }
   where
     makeHeader :: Int -> Html -> Html
@@ -85,6 +86,22 @@ parHtmlMarkup qual insertAnchors ppId = Markup {
     makeHeader 6 mkup = h6 mkup
     makeHeader l _ = error $ "Somehow got a header level `" ++ show l ++ "' in DocMarkup!"
 
+    makeTable :: [TableRow Html] -> [TableRow Html] -> Html
+    makeTable hs bs = table (concatHtml (hs' ++ bs'))
+      where
+        hs' | null hs   = []
+            | otherwise = [thead (concatHtml (map (makeTableRow th) hs))]
+
+        bs' = [tbody (concatHtml (map (makeTableRow td) bs))]
+
+    makeTableRow :: (Html -> Html) -> TableRow Html -> Html
+    makeTableRow thr (TableRow cs) = tr (concatHtml (map (makeTableCell thr) cs))
+
+    makeTableCell :: (Html -> Html) -> TableCell Html -> Html
+    makeTableCell thr (TableCell i j c) = thr c ! (i' ++ j')
+      where
+        i' = if i == 1 then [] else [ colspan i ]
+        j' = if j == 1 then [] else [ rowspan j ]
 
     examplesToHtml l = pre (concatHtml $ map exampleToHtml l) ! [theclass "screen"]
 
diff --git a/haddock-api/src/Haddock/Interface/LexParseRn.hs b/haddock-api/src/Haddock/Interface/LexParseRn.hs
index 75b2f223..311301ee 100644
--- a/haddock-api/src/Haddock/Interface/LexParseRn.hs
+++ b/haddock-api/src/Haddock/Interface/LexParseRn.hs
@@ -144,6 +144,7 @@ rename dflags gre = rn
       DocEmpty -> pure (DocEmpty)
       DocString str -> pure (DocString str)
       DocHeader (Header l t) -> DocHeader . Header l <$> rn t
+      DocTable t -> DocTable <$> traverse rn t
 
 -- | Wrap an identifier that's out of scope (i.e. wasn't found in
 -- 'GlobalReaderEnv' during 'rename') in an appropriate doc. Currently
diff --git a/haddock-api/src/Haddock/InterfaceFile.hs b/haddock-api/src/Haddock/InterfaceFile.hs
index 76bcb4ae..bbd8d04e 100644
--- a/haddock-api/src/Haddock/InterfaceFile.hs
+++ b/haddock-api/src/Haddock/InterfaceFile.hs
@@ -459,6 +459,32 @@ instance Binary a => Binary (Header a) where
         t <- get bh
         return (Header l t)
 
+instance Binary a => Binary (Table a) where
+    put_ bh (Table h b) = do
+        put_ bh h
+        put_ bh b
+    get bh = do
+        h <- get bh
+        b <- get bh
+        return (Table h b)
+
+instance Binary a => Binary (TableRow a) where
+    put_ bh (TableRow cs) = put_ bh cs
+    get bh = do
+        cs <- get bh
+        return (TableRow cs)
+
+instance Binary a => Binary (TableCell a) where
+    put_ bh (TableCell i j c) = do
+        put_ bh i
+        put_ bh j
+        put_ bh c
+    get bh = do
+        i <- get bh
+        j <- get bh
+        c <- get bh
+        return (TableCell i j c)
+
 instance Binary Meta where
   put_ bh Meta { _version = v } = put_ bh v
   get bh = (\v -> Meta { _version = v }) <$> get bh
@@ -542,6 +568,9 @@ instance (Binary mod, Binary id) => Binary (DocH mod id) where
     put_ bh (DocMathDisplay x) = do
             putByte bh 22
             put_ bh x
+    put_ bh (DocTable x) = do
+            putByte bh 23
+            put_ bh x
 
     get bh = do
             h <- getByte bh
@@ -615,6 +644,9 @@ instance (Binary mod, Binary id) => Binary (DocH mod id) where
               22 -> do
                     x <- get bh
                     return (DocMathDisplay x)
+              23 -> do
+                    x <- get bh
+                    return (DocTable x)
               _ -> error "invalid binary data found in the interface file"
 
 
diff --git a/haddock-api/src/Haddock/Types.hs b/haddock-api/src/Haddock/Types.hs
index b4cdc343..725606b2 100644
--- a/haddock-api/src/Haddock/Types.hs
+++ b/haddock-api/src/Haddock/Types.hs
@@ -454,6 +454,7 @@ instance (NFData a, NFData mod)
     DocProperty a             -> a `deepseq` ()
     DocExamples a             -> a `deepseq` ()
     DocHeader a               -> a `deepseq` ()
+    DocTable a                -> a `deepseq` ()
 
 #if !MIN_VERSION_ghc(8,0,2)
 -- These were added to GHC itself in 8.0.2
@@ -474,6 +475,14 @@ instance NFData Picture where
 instance NFData Example where
   rnf (Example a b) = a `deepseq` b `deepseq` ()
 
+instance NFData id => NFData (Table id) where
+    rnf (Table h b) = h `deepseq` b `deepseq` ()
+
+instance NFData id => NFData (TableRow id) where
+    rnf (TableRow cs) = cs `deepseq` ()
+
+instance NFData id => NFData (TableCell id) where
+    rnf (TableCell i j c) = i `deepseq` j `deepseq` c `deepseq` ()
 
 exampleToString :: Example -> String
 exampleToString (Example expression result) =