Comments on instances

Implementing this was a little trickier than I thought, since we need to match
up instances from the renamed syntax with instances represented by
InstEnv.Instance. This is due to the current design of Haddock, which matches
comments with declarations from the renamed syntax, while getting the list of
instances of a class/family directly using the GHC API.

- Works for class instances only (Haddock has no support for type family
  instances yet)
- The comments are rendered to the right of the instance head in the HTML output
- No change to the .haddock file format
- Works for normal user-written instances only. No comments are added on
  derived or TH-generated instances

1 files changed, 26 insertions, 21 deletions

diff --git a/src/Haddock/Backends/Html.hs b/src/Haddock/Backends/Html.hs
index fead8470..93c2a491 100644
--- a/src/Haddock/Backends/Html.hs
+++ b/src/Haddock/Backends/Html.hs
@@ -809,7 +809,7 @@ declWithDoc False links loc nm (Just doc) html_decl =
 
 -- TODO: use DeclInfo DocName or something
 ppDecl :: Bool -> LinksInfo -> LHsDecl DocName -> 
-          DocForDecl DocName -> [InstHead DocName] -> [(DocName, DocForDecl DocName)] -> Bool -> HtmlTable
+          DocForDecl DocName -> [DocInstance DocName] -> [(DocName, DocForDecl DocName)] -> Bool -> HtmlTable
 ppDecl summ links (L loc decl) (mbDoc, fnArgsDoc) instances subdocs unicode = case decl of
   TyClD d@(TyFamily {})          -> ppTyFam summ False links loc mbDoc d unicode
   TyClD d@(TyData {})
@@ -955,7 +955,7 @@ ppTyFam summary associated links loc mbDoc decl unicode
   	  tda [theclass "body"] << 
             collapsed thediv instId (
               spacedTable1 << (
-                aboves (map (declBox . ppInstHead unicode) instances)
+                aboves (map (ppDocInstance unicode) instances)
               )
             )
 
@@ -1150,7 +1150,7 @@ ppShortClassDecl _ _ _ _ _ _ = error "declaration type not supported by ppShortC
     
 
 
-ppClassDecl :: Bool -> LinksInfo -> [InstHead DocName] -> SrcSpan
+ppClassDecl :: Bool -> LinksInfo -> [DocInstance DocName] -> SrcSpan
             -> Maybe (HsDoc DocName) -> [(DocName, DocForDecl DocName)]
             -> TyClDecl DocName -> Bool -> HtmlTable
 ppClassDecl summary links instances loc mbDoc subdocs
@@ -1191,12 +1191,19 @@ ppClassDecl summary links instances loc mbDoc subdocs
         =  s8 </> instHdr instId </>
            tda [theclass "body"] << 
              collapsed thediv instId (
-             spacedTable1 << (
-               aboves (map (declBox . ppInstHead unicode) instances)
-             ))
+               spacedTable1 << aboves (map (ppDocInstance unicode) instances)
+             )
 ppClassDecl _ _ _ _ _ _ _ _ = error "declaration type not supported by ppShortClassDecl"
 
 
+-- | Print a possibly commented instance. The instance header is printed inside
+-- an 'argBox'. The comment is printed to the right of the box in normal comment
+-- style.
+ppDocInstance :: Bool -> DocInstance DocName -> HtmlTable
+ppDocInstance unicode (_, instHead, maybeDoc) =
+  argBox (ppInstHead unicode instHead) <-> maybeRDocBox maybeDoc
+
+
 ppInstHead :: Bool -> InstHead DocName -> Html
 ppInstHead unicode ([],   n, ts) = ppAppNameTypes n ts unicode
 ppInstHead unicode (ctxt, n, ts) = ppContextNoLocs ctxt unicode <+> ppAppNameTypes n ts unicode
@@ -1249,7 +1256,7 @@ ppShortDataDecl summary links loc dataDecl unicode
     cons      = tcdCons dataDecl
     resTy     = (con_res . unLoc . head) cons 
 
-ppDataDecl :: Bool -> LinksInfo -> [InstHead DocName] ->
+ppDataDecl :: Bool -> LinksInfo -> [DocInstance DocName] ->
               [(DocName, DocForDecl DocName)] ->
               SrcSpan -> Maybe (HsDoc DocName) -> TyClDecl DocName -> Bool -> HtmlTable
 ppDataDecl summary links instances subdocs loc mbDoc dataDecl unicode
@@ -1303,8 +1310,7 @@ ppDataDecl summary links instances subdocs loc mbDoc dataDecl unicode
         = instHdr instId </>
 	  tda [theclass "body"] << 
           collapsed thediv instId (
-            spacedTable1 << (
-              aboves (map (declBox . ppInstHead unicode) instances)
+            spacedTable1 << aboves (map (ppDocInstance unicode) instances
             )
           )
 
@@ -1374,17 +1380,17 @@ ppSideBySideConstr subdocs unicode (L _ con) = case con_res con of
 
     PrefixCon args -> 
       argBox (hsep ((header_ unicode +++ ppBinder False occ) : map (ppLParendType unicode) args)) 
-      <-> maybeRDocBox mbLDoc  
+      <-> maybeRDocBox mbDoc  
 
     RecCon fields -> 
       argBox (header_ unicode +++ ppBinder False occ) <->
-      maybeRDocBox mbLDoc
+      maybeRDocBox mbDoc
       </>
       doRecordFields fields
 
     InfixCon arg1 arg2 -> 
       argBox (hsep [header_ unicode+++ppLParendType unicode arg1, ppBinder False occ, ppLParendType unicode arg2])
-      <-> maybeRDocBox mbLDoc
+      <-> maybeRDocBox mbDoc
  
   ResTyGADT resTy -> case con_details con of
     -- prefix & infix could also use hsConDeclArgTys if it seemed to
@@ -1401,7 +1407,7 @@ ppSideBySideConstr subdocs unicode (L _ con) = case con_res con of
     doGADTCon args resTy = argBox (ppBinder False occ <+> dcolon unicode <+> hsep [
                                ppForAll forall ltvs (con_cxt con) unicode,
                                ppLType unicode (foldr mkFunTy resTy args) ]
-                            ) <-> maybeRDocBox mbLDoc
+                            ) <-> maybeRDocBox mbDoc
 
 
     header_ = ppConstrHdr forall tyVars context
@@ -1412,19 +1418,17 @@ ppSideBySideConstr subdocs unicode (L _ con) = case con_res con of
     forall  = con_explicit con
     -- don't use "con_doc con", in case it's reconstructed from a .hi file,
     -- or also because we want Haddock to do the doc-parsing, not GHC.
-    -- The 'fmap' and 'join' are in Maybe
-    mbLDoc  = fmap noLoc $ join $ fmap fst $
-                lookup (unLoc $ con_name con) subdocs
+    -- 'join' is in Maybe.
+    mbDoc = join $ fmap fst $ lookup (unLoc $ con_name con) subdocs
     mkFunTy a b = noLoc (HsFunTy a b)
 
 ppSideBySideField :: [(DocName, DocForDecl DocName)] -> Bool -> ConDeclField DocName ->  HtmlTable
 ppSideBySideField subdocs unicode (ConDeclField (L _ name) ltype _) =
   argBox (ppBinder False (docNameOcc name)
-    <+> dcolon unicode <+> ppLType unicode ltype) <->
-  maybeRDocBox mbLDoc
+    <+> dcolon unicode <+> ppLType unicode ltype) <-> maybeRDocBox mbDoc
   where
     -- don't use cd_fld_doc for same reason we don't use con_doc above
-    mbLDoc = fmap noLoc $ join $ fmap fst $ lookup name subdocs
+    mbDoc = join $ fmap fst $ lookup name subdocs
 
 {-
 ppHsFullConstr :: HsConDecl -> Html
@@ -1764,6 +1768,7 @@ htmlCleanup = idMarkup {
 -- -----------------------------------------------------------------------------
 -- * Misc
 
+
 hsep :: [Html] -> Html
 hsep [] = noHtml
 hsep htmls = foldr1 (\a b -> a+++" "+++b) htmls
@@ -1890,9 +1895,9 @@ ndocBox html = tda [theclass "ndoc"] << html
 rdocBox :: Html -> HtmlTable
 rdocBox html = tda [theclass "rdoc"] << html
 
-maybeRDocBox :: Maybe (LHsDoc DocName) -> HtmlTable
+maybeRDocBox :: Maybe (HsDoc DocName) -> HtmlTable
 maybeRDocBox Nothing = rdocBox (noHtml)
-maybeRDocBox (Just ldoc) = rdocBox (docToHtml (unLoc ldoc))
+maybeRDocBox (Just doc) = rdocBox (docToHtml doc)
 
 -- a box for the buttons at the top of the page
 topButBox :: Html -> HtmlTable