Add the SimpleFigure bidirectional pattern synonym.

Author: argent0

src/Text/Pandoc/Builder.hs

@@ -1,6 +1,6 @@
 {-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, DeriveDataTypeable,
     GeneralizedNewtypeDeriving, CPP, StandaloneDeriving, DeriveGeneric,
-    DeriveTraversable, OverloadedStrings, PatternGuards #-}
+    DeriveTraversable, OverloadedStrings, PatternGuards, PatternSynonyms #-}
 {-
 Copyright (C) 2010-2019 John MacFarlane
 
@@ -170,6 +170,7 @@ module Text.Pandoc.Builder ( module Text.Pandoc.Definition
                            , caption
                            , simpleCaption
                            , emptyCaption
+                           , pattern SimpleFigure
                            , simpleFigureWith
                            , simpleFigure
                            , divWith
@@ -568,6 +569,21 @@ simpleCaption = caption Nothing
 emptyCaption :: Caption
 emptyCaption = simpleCaption mempty
 
+-- | Bidirectional patter synonym
+--
+-- It can pass as a Block constructor
+--
+-- λ> SimpleFigure nullAttr [] (T.pack "") (T.pack "")
+-- Para [Image ("",[],[]) [] ("","fig:")]
+--
+-- It can be used to pattern match
+-- foo :: Block -> ...
+-- foo (SimpleFigure attr figureCaption src title) -> handleFigure ...
+pattern SimpleFigure :: Attr -> [Inline] -> Text -> Text -> Block
+pattern SimpleFigure attr figureCaption src title <- Para [Image attr figureCaption (src, title)] where
+  SimpleFigure attr figureCaption src title =
+    Para [Image attr figureCaption (src, "fig:" <> title)]
+
 simpleFigureWith :: Attr -> Inlines -> Text -> Text -> Blocks
 simpleFigureWith attr figureCaption url title =
   para $ imageWith attr url ("fig:" <> title) figureCaption