Better support for default methods in classes

  * default methods now get rendered differently
  * default associated types get rendered
  * fix a forgotten `s/TypeSig/ClassOpSig/` refactor in LaTeX backend
  * LaTeX backend now renders default method signatures

NB: there is still no way to document default class members and the
NB: LaTeX backend still crashes on associated types

3 files changed, 99 insertions, 51 deletions

diff --git a/haddock-api/src/Haddock/Backends/LaTeX.hs b/haddock-api/src/Haddock/Backends/LaTeX.hs
index 119bbc01..d2baefac 100644
--- a/haddock-api/src/Haddock/Backends/LaTeX.hs
+++ b/haddock-api/src/Haddock/Backends/LaTeX.hs
@@ -295,7 +295,7 @@ ppDecl decl pats (doc, fnArgsDoc) instances subdocs _fxts = case unLoc decl of
 --    | Just _  <- tcdTyPats d    -> ppTyInst False loc doc d unicode
 -- Family instances happen via FamInst now
   TyClD _ d@ClassDecl{}          -> ppClassDecl instances doc subdocs d unicode
-  SigD _ (TypeSig _ lnames ty)   -> ppFunSig (doc, fnArgsDoc) (map unLoc lnames) (hsSigWcType ty) unicode
+  SigD _ (TypeSig _ lnames ty)   -> ppFunSig Nothing (doc, fnArgsDoc) (map unLoc lnames) (hsSigWcType ty) unicode
   SigD _ (PatSynSig _ lnames ty) -> ppLPatSig (doc, fnArgsDoc) (map unLoc lnames) ty unicode
   ForD _ d                       -> ppFor (doc, fnArgsDoc) d unicode
   InstD _ _                      -> empty
@@ -307,7 +307,7 @@ ppDecl decl pats (doc, fnArgsDoc) instances subdocs _fxts = case unLoc decl of
 
 ppFor :: DocForDecl DocName -> ForeignDecl DocNameI -> Bool -> LaTeX
 ppFor doc (ForeignImport _ (L _ name) typ _) unicode =
-  ppFunSig doc [name] (hsSigType typ) unicode
+  ppFunSig Nothing doc [name] (hsSigType typ) unicode
 ppFor _ _ _ = error "ppFor error in Haddock.Backends.LaTeX"
 --  error "foreign declarations are currently not supported by --latex"
 
@@ -414,17 +414,23 @@ ppTySyn _ _ _ = error "declaration not supported by ppTySyn"
 -------------------------------------------------------------------------------
 
 
-ppFunSig :: DocForDecl DocName -> [DocName] -> LHsType DocNameI
-         -> Bool -> LaTeX
-ppFunSig doc docnames (L _ typ) unicode =
+ppFunSig
+  :: Maybe LaTeX         -- ^ a prefix to put right before the signature
+  -> DocForDecl DocName  -- ^ documentation
+  -> [DocName]           -- ^ pattern names in the pattern signature
+  -> LHsType DocNameI    -- ^ type of the pattern synonym
+  -> Bool                -- ^ unicode
+  -> LaTeX
+ppFunSig leader doc docnames (L _ typ) unicode =
   ppTypeOrFunSig typ doc
-    ( ppTypeSig names typ False
-    , hsep . punctuate comma $ map ppSymName names
+    ( lead $ ppTypeSig names typ False
+    , lead $ hsep . punctuate comma $ map ppSymName names
     , dcolon unicode
     )
     unicode
  where
    names = map getName docnames
+   lead = maybe id (<+>) leader
 
 -- | Pretty-print a pattern synonym
 ppLPatSig :: DocForDecl DocName  -- ^ documentation
@@ -433,15 +439,7 @@ ppLPatSig :: DocForDecl DocName  -- ^ documentation
           -> Bool                -- ^ unicode
           -> LaTeX
 ppLPatSig doc docnames ty unicode
-  = ppTypeOrFunSig typ doc
-      ( keyword "pattern" <+> ppTypeSig names typ False
-      , keyword "pattern" <+> (hsep . punctuate comma $ map ppSymName names)
-      , dcolon unicode
-      )
-      unicode
-  where
-    typ = unLoc (hsSigType ty)
-    names = map getName docnames
+  = ppFunSig (Just (keyword "pattern")) doc docnames (hsSigType ty) unicode
 
 -- | Pretty-print a type, adding documentation to the whole type and its
 -- arguments as needed.
@@ -585,6 +583,7 @@ ppFds fds unicode =
                            hsep (map (ppDocName . unLoc) vars2)
 
 
+-- TODO: associated types, associated type defaults, docs on default methods
 ppClassDecl :: [DocInstance DocNameI]
             -> Documentation DocName -> [(DocName, DocForDecl DocName)]
             -> TyClDecl DocNameI -> Bool -> LaTeX
@@ -610,13 +609,15 @@ ppClassDecl instances doc subdocs
 
     methodTable =
       text "\\haddockpremethods{}" <> emph (text "Methods") $$
-      vcat  [ ppFunSig doc names (hsSigWcType typ) unicode
-            | L _ (TypeSig _ lnames typ) <- lsigs
-            , let doc = lookupAnySubdoc (head names) subdocs
-                  names = map unLoc lnames ]
-              -- FIXME: is taking just the first name ok? Is it possible that
-              -- there are different subdocs for different names in a single
-              -- type signature?
+      vcat  [ ppFunSig leader doc names (hsSigType typ) unicode
+            | L _ (ClassOpSig _ is_def lnames typ) <- lsigs
+            , let doc | is_def = noDocForDecl
+                      | otherwise = lookupAnySubdoc (head names) subdocs
+                  names = map unLoc lnames
+                  leader = if is_def then Just (keyword "default") else Nothing
+            ]
+            -- N.B. taking just the first name is ok. Signatures with multiple
+            -- names are expanded so that each name gets its own signature.
 
     instancesBit = ppDocInstances unicode instances
 
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
index f2cab635..56a79d57 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
@@ -36,6 +36,7 @@ import           Text.XHtml hiding     ( name, title, p, quote )
 
 import BasicTypes (PromotionFlag(..), isPromoted)
 import GHC hiding (LexicalFixity(..))
+import qualified GHC
 import GHC.Exts
 import Name
 import BooleanFormula
@@ -75,14 +76,14 @@ ppLFunSig :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName ->
              [Located DocName] -> LHsType DocNameI -> [(DocName, Fixity)] ->
              Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppLFunSig summary links loc doc lnames lty fixities splice unicode pkg qual =
-  ppFunSig summary links loc doc (map unLoc lnames) lty fixities
+  ppFunSig summary links loc noHtml doc (map unLoc lnames) lty fixities
            splice unicode pkg qual
 
-ppFunSig :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName ->
+ppFunSig :: Bool -> LinksInfo -> SrcSpan -> Html -> DocForDecl DocName ->
             [DocName] -> LHsType DocNameI -> [(DocName, Fixity)] ->
             Splice -> Unicode -> Maybe Package -> Qualification -> Html
-ppFunSig summary links loc doc docnames typ fixities splice unicode pkg qual =
-  ppSigLike summary links loc mempty doc docnames fixities (unLoc typ, pp_typ)
+ppFunSig summary links loc leader doc docnames typ fixities splice unicode pkg qual =
+  ppSigLike summary links loc leader doc docnames fixities (unLoc typ, pp_typ)
             splice unicode pkg qual HideEmptyContexts
   where
     pp_typ = ppLType unicode qual HideEmptyContexts typ
@@ -218,7 +219,7 @@ ppFor :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName
       -> Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppFor summary links loc doc (ForeignImport _ (L _ name) typ _) fixities
       splice unicode pkg qual
-  = ppFunSig summary links loc doc [name] (hsSigType typ) fixities splice unicode pkg qual
+  = ppFunSig summary links loc noHtml doc [name] (hsSigType typ) fixities splice unicode pkg qual
 ppFor _ _ _ _ _ _ _ _ _ _ = error "ppFor"
 
 
@@ -496,7 +497,7 @@ ppShortClassDecl summary links (ClassDecl { tcdCtxt = lctxt, tcdLName = lname, t
 
                 -- ToDo: add associated type defaults
 
-            [ ppFunSig summary links loc doc names (hsSigType typ)
+            [ ppFunSig summary links loc noHtml doc names (hsSigType typ)
                        [] splice unicode pkg qual
               | L _ (ClassOpSig _ False lnames typ) <- sigs
               , let doc = lookupAnySubdoc (head names) subdocs
@@ -517,8 +518,9 @@ ppClassDecl :: Bool -> LinksInfo -> [DocInstance DocNameI] -> [(DocName, Fixity)
             -> [(DocName, DocForDecl DocName)] -> TyClDecl DocNameI
             -> Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppClassDecl summary links instances fixities loc d subdocs
-        decl@(ClassDecl { tcdCtxt = lctxt, tcdLName = lname, tcdTyVars = ltyvars
-                        , tcdFDs = lfds, tcdSigs = lsigs, tcdATs = ats })
+        decl@(ClassDecl { tcdCtxt = lctxt, tcdLName = lname@(L _ nm)
+                        , tcdTyVars = ltyvars, tcdFDs = lfds, tcdSigs = lsigs
+                        , tcdATs = ats, tcdATDefs = atsDefs })
             splice unicode pkg qual
   | summary = ppShortClassDecl summary links decl loc subdocs splice unicode pkg qual
   | otherwise = classheader +++ docSection curname pkg qual d
@@ -535,28 +537,68 @@ ppClassDecl summary links instances fixities loc d subdocs
     -- Only the fixity relevant to the class header
     fixs = ppFixities [ f | f@(n,_) <- fixities, n == unLoc lname ] qual
 
-    nm   = tcdName decl
-
     hdr = ppClassHdr summary lctxt (unLoc lname) ltyvars lfds
 
-    -- ToDo: add assocatied typ defaults
-    atBit = subAssociatedTypes [ ppAssocType summary links doc at subfixs splice unicode pkg qual
-                      | at <- ats
-                      , let n = unL . fdLName $ unL at
-                            doc = lookupAnySubdoc (unL $ fdLName $ unL at) subdocs
-                            subfixs = [ f | f@(n',_) <- fixities, n == n' ] ]
-
-    methodBit = subMethods [ ppFunSig summary links loc doc [name] (hsSigType typ)
-                                      subfixs splice unicode pkg qual
-                           | L _ (ClassOpSig _ _ lnames typ) <- lsigs
-                           , name <- map unLoc lnames
-                           , let doc = lookupAnySubdoc name subdocs
-                                 subfixs = [ f | f@(n',_) <- fixities
-                                               , name == n' ]
-                           ]
-                           -- N.B. taking just the first name is ok. Signatures with multiple names
-                           -- are expanded so that each name gets its own signature.
+    -- Associated types
+    atBit = subAssociatedTypes
+      [ ppAssocType summary links doc at subfixs splice unicode pkg qual
+          <+>
+        subDefaults (maybeToList defTys)
+      | at <- ats
+      , let name = unL . fdLName $ unL at
+            doc = lookupAnySubdoc name subdocs
+            subfixs = filter ((== name) . fst) fixities
+            defTys = ppDefaultAssocTy name <$> lookupDAT name
+      ]
+
+    -- Default associated types
+    ppDefaultAssocTy n (vs,t,d') = ppTySyn summary links [] loc d' synDecl
+      splice unicode pkg qual
+      where
+        synDecl = SynDecl { tcdSExt = noExt
+                          , tcdLName = noLoc n
+                          , tcdTyVars = vs
+                          , tcdFixity = GHC.Prefix
+                          , tcdRhs = t }
+
+    lookupDAT name = Map.lookup (getName name) defaultAssocTys
+    defaultAssocTys = Map.fromList
+      [ (getName name, (vs, typ, doc))
+      | L _ (FamEqn { feqn_rhs = typ
+                    , feqn_tycon = L _ name
+                    , feqn_pats = vs }) <- atsDefs
+      , let doc = noDocForDecl -- TODO: get docs for associated type defaults
+      ]
+
+    -- Methods
+    methodBit = subMethods
+      [ ppFunSig summary links loc noHtml doc [name] (hsSigType typ)
+                 subfixs splice unicode pkg qual
+          <+>
+        subDefaults (maybeToList defSigs)
+      | ClassOpSig _ False lnames typ <- sigs
+      , name <- map unLoc lnames
+      , let doc = lookupAnySubdoc name subdocs
+            subfixs = filter ((== name)  . fst) fixities
+            defSigs = ppDefaultFunSig name <$> lookupDM name
+      ]
+      -- N.B. taking just the first name is ok. Signatures with multiple names
+      -- are expanded so that each name gets its own signature.
+
+    -- Default methods
+    ppDefaultFunSig n (t, d') = ppFunSig summary links loc (keyword "default")
+      d' [n] (hsSigType t) [] splice unicode pkg qual
+
+    lookupDM name = Map.lookup (getOccString name) defaultMethods
+    defaultMethods = Map.fromList
+      [ (nameStr, (typ, doc))
+      | ClassOpSig _ True lnames typ <- sigs
+      , name <- map unLoc lnames
+      , let doc = noDocForDecl -- TODO: get docs for method defaults
+            nameStr = getOccString name
+      ]
 
+    -- Minimal complete definition
     minimalBit = case [ s | MinimalSig _ _ (L _ s) <- sigs ] of
       -- Miminal complete definition = every shown method
       And xs : _ | sort [getName n | L _ (Var (L _ n)) <- xs] ==
@@ -565,7 +607,7 @@ ppClassDecl summary links instances fixities loc d subdocs
 
       -- Minimal complete definition = the only shown method
       Var (L _ n) : _ | [getName n] ==
-                        [getName n' | L _ (ClassOpSig _ _ ns _) <- lsigs, L _ n' <- ns]
+                        [getName n' | ClassOpSig _ _ ns _ <- sigs, L _ n' <- ns]
         -> noHtml
 
       -- Minimal complete definition = nothing
@@ -580,6 +622,7 @@ ppClassDecl summary links instances fixities loc d subdocs
       where wrap | p = parens | otherwise = id
     ppMinimal p (Parens x) = ppMinimal p (unLoc x)
 
+    -- Instances
     instancesBit = ppInstances links (OriginClass nm) instances
         splice unicode pkg qual
 
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/Layout.hs b/haddock-api/src/Haddock/Backends/Xhtml/Layout.hs
index 25d8b07a..4535b897 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/Layout.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/Layout.hs
@@ -35,6 +35,7 @@ module Haddock.Backends.Xhtml.Layout (
   subInstances, subOrphanInstances,
   subInstHead, subInstDetails, subFamInstDetails,
   subMethods,
+  subDefaults,
   subMinimal,
 
   topDeclElem, declElem,
@@ -259,6 +260,9 @@ instAnchorId iid = makeAnchorId $ "i:" ++ iid
 subMethods :: [Html] -> Html
 subMethods = divSubDecls "methods" "Methods" . subBlock
 
+subDefaults :: [Html] -> Html
+subDefaults = divSubDecls "default" "" . subBlock
+
 subMinimal :: Html -> Html
 subMinimal = divSubDecls "minimal" "Minimal complete definition" . Just . declElem