Better support for multiple packages (#1277)

* FromJSON class

Aeson style FromJSON class with Parsec based json parser.

* doc-index.json file for multiple packages

When creating haddock summary page for multiple packages render
doc-index.json file using contents of all found 'doc-index.json' files.

* Render doc-index.json

When rendering html, render doc-index.json file independently of
maybe_index_url option.  doc-index.json file is useful now even if
maybe_index_url is not `Nothing`.

* base url option

New `Flag_BaseURL` which configures from where static files are loaded
(--base-url).  If given and not equal "." static files are not coppied,
as this indicates that they are not read from the the directory where
we'd copy them.  The default value is ".".

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 ^>= 1.10.0
                , 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 ^>= 1.10.0
                , 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);
 });