Use dev version of gridtables

This allows to specify a table foot by enclosing it with part separator
lines, i.e., row separator lines consisting only of `+` and `=`
characters. E.g.:

    +------+-------+
    | Item | Price |
    +======+=======+
    | Eggs | 5£    |
    +------+-------+
    | Spam | 3£    |
    +======+=======+
    | Sum  | 8£    |
    +======+=======+

The last row, containing "Sum" and "8£", is the table foot.

Closes: #8257

3 files changed, 53 insertions, 4 deletions

diff --git a/cabal.project b/cabal.project
index 8d9bb4062..b2effd0e0 100644
--- a/cabal.project
+++ b/cabal.project
@@ -15,3 +15,7 @@ source-repository-package
   tag: 6079d8b0fb6e45c6a03b05501900be1c151701e6
   subdir: skylighting-format-blaze-html
 
+source-repository-package
+  type: git
+  location: https://github.com/quarto-dev/gridtables
+  tag: 1dbf2ad311fc7b2d9aded51eb263067b6ff3ae28
diff --git a/src/Text/Pandoc/Parsing/GridTable.hs b/src/Text/Pandoc/Parsing/GridTable.hs
index 58ab1494b..d579939b5 100644
--- a/src/Text/Pandoc/Parsing/GridTable.hs
+++ b/src/Text/Pandoc/Parsing/GridTable.hs
@@ -135,9 +135,13 @@ gridTableWith' normalization blocks = do
   let caption = B.emptyCaption
   return $ do
     rows'' <- mapM sequence rows'
-    let (hRows, bRows) =
-          splitAt (maybe 0 GT.fromRowIndex $ GT.arrayTableHead tbl)
-                  (map (B.Row B.nullAttr) rows'')
+    let headLen = maybe 0 GT.fromRowIndex $ GT.arrayTableHead tbl
+    let (hRows, bRows') =
+          splitAt headLen (map (B.Row B.nullAttr) rows'')
+    let (bRows, fRows) =
+          case GT.arrayTableFoot tbl of
+            Just fIdx -> splitAt (GT.fromRowIndex fIdx - headLen - 1) bRows'
+            Nothing   -> (bRows', [])
     let thead = B.TableHead B.nullAttr $ case (hRows, normalization) of
           -- normalize header if necessary: remove header if it contains
           -- only a single row in which all cells are empty.
@@ -151,7 +155,7 @@ gridTableWith' normalization blocks = do
             in [B.Row nullAttr cells | not (null cells) &&
                                        not (all simple cells)]
           _ -> hRows
-    let tfoot = B.TableFoot B.nullAttr []
+    let tfoot = B.TableFoot B.nullAttr $ fRows
     let tbody = B.TableBody B.nullAttr 0 [] bRows
     return $ TableComponents nullAttr caption colspecs thead [tbody] tfoot
 
diff --git a/test/command/8257.md b/test/command/8257.md
new file mode 100644
index 000000000..a284fd38a
--- /dev/null
+++ b/test/command/8257.md
@@ -0,0 +1,41 @@
+```
+% pandoc -f markdown -t html5
++------+-------+
+| Item | Price |
++======+=======+
+| Eggs | 5£    |
++------+-------+
+| Spam | 3£    |
++======+=======+
+| Sum  | 8£    |
++======+=======+
+^D
+<table style="width:21%;">
+<colgroup>
+<col style="width: 9%" />
+<col style="width: 11%" />
+</colgroup>
+<thead>
+<tr class="header">
+<th>Item</th>
+<th>Price</th>
+</tr>
+</thead>
+<tbody>
+<tr class="odd">
+<td>Eggs</td>
+<td>5£</td>
+</tr>
+<tr class="even">
+<td>Spam</td>
+<td>3£</td>
+</tr>
+</tbody><tfoot>
+<tr class="odd">
+<td>Sum</td>
+<td>8£</td>
+</tr>
+</tfoot>
+
+</table>
+```