Better support for multiple packages

doc/invoking.rst

@@ -223,6 +223,13 @@ The following options are available:
     Reserved for future use (output documentation in DocBook XML
     format).
 
+.. option:: --base-url=<url>
+
+    Base url for static assets (eg. css, javascript, json files etc.).
+    When present, static assets are not copied.  This option is useful
+    when creating documentation for multiple packages, it allows to have
+    a single copy of static assets served from the given url.
+
 .. option:: --source-base=<url>
             --source-module=<url>
             --source-entity=<url>

haddock-api/haddock-api.cabal

@@ -48,6 +48,7 @@ library
                , ghc-paths       ^>= 0.1.0.9
                , haddock-library ^>= 1.9.0
                , xhtml           ^>= 3000.2.2
+               , parsec          ^>= 3.1.13.0
 
   -- Versions for the dependencies below are transitively pinned by
   -- the non-reinstallable `ghc` package and hence need no version
@@ -93,6 +94,8 @@ library
     Haddock.Parser
     Haddock.Utils
     Haddock.Utils.Json
+    Haddock.Utils.Json.Types
+    Haddock.Utils.Json.Parser
     Haddock.Backends.Xhtml
     Haddock.Backends.Xhtml.Decl
     Haddock.Backends.Xhtml.DocMarkup
@@ -169,6 +172,8 @@ test-suite spec
     Haddock.Types
     Haddock.Utils
     Haddock.Utils.Json
+    Haddock.Utils.Json.Types
+    Haddock.Utils.Json.Parser
     Haddock.Version
     Paths_haddock_api
     Haddock.Backends.Hyperlinker.ParserSpec
@@ -180,6 +185,7 @@ test-suite spec
                , haddock-library ^>= 1.9.0
                , xhtml           ^>= 3000.2.2
                , hspec           >= 2.4.4 && < 2.8
+               , parsec       ^>= 3.1.13.0
                , QuickCheck      >= 2.11  && ^>= 2.14
 
   -- Versions for the dependencies below are transitively pinned by

haddock-api/resources/html/js-src/init.ts

@@ -17,6 +17,11 @@ function onDomReady(callback: () => void) {
 onDomReady(() => {
   document.body.classList.add('js-enabled');
   styleMenu.init();
-  quickJump.init();
   detailsHelper.init();
+  let head = document.getElementById('head');
+  let baseURL = ".";
+  if (head !== null) {
+    baseURL = head.getAttribute('data-base-url') || '.';
+  }
+  quickJump.init(baseURL);
 });