Support rowspans and colspans in grid tables (#8202)

* Add tests for zero-width and fullwidth chars in grid tables

* T.P.Parsing: simplify `gridTableWith'`, `gridTableWith` [API Change]
  The functions `gridTableWith` and `gridTableWith'` no longer takes a
  boolean argument that toggles whether a table head should be parsed:
  both, tables with heads and without heads, are always accepted now.

* Support colspans, rowspans, and multirow headers in grid tables.

  Grid tables in Markdown, reStructuredText, and Org can now contain cells
  spanning over multiple columns and/or multiple rows; table headers
  containing multiple rows are supported as well.

Note: the markdown writer does not yet support these more complex grid
table features.

4 files changed, 515 insertions, 3 deletions

diff --git a/test/markdown-reader-more.native b/test/markdown-reader-more.native
index 82b3577be..f200d0705 100644
--- a/test/markdown-reader-more.native
+++ b/test/markdown-reader-more.native
@@ -1022,7 +1022,7 @@ Pandoc
                       1
                       ( "col-1" , [] , [] )
                       [ Str "col" , Space , Str "1" ]
-                  , Plain [ Str "col" , Space , Str "1" ]
+                  , Para [ Str "col" , Space , Str "1" ]
                   ]
               , Cell
                   ( "" , [] , [] )
@@ -1033,7 +1033,7 @@ Pandoc
                       1
                       ( "col-2" , [] , [] )
                       [ Str "col" , Space , Str "2" ]
-                  , Plain [ Str "col" , Space , Str "2" ]
+                  , Para [ Str "col" , Space , Str "2" ]
                   ]
               , Cell
                   ( "" , [] , [] )
@@ -1044,7 +1044,7 @@ Pandoc
                       1
                       ( "col-3" , [] , [] )
                       [ Str "col" , Space , Str "3" ]
-                  , Plain [ Str "col" , Space , Str "3" ]
+                  , Para [ Str "col" , Space , Str "3" ]
                   ]
               ]
           , Row
@@ -1261,6 +1261,239 @@ Pandoc
           ]
       ]
       (TableFoot ( "" , [] , [] ) [])
+  , Para
+      [ Str "Table"
+      , Space
+      , Str "with"
+      , Space
+      , Str "cells"
+      , Space
+      , Str "spanning"
+      , Space
+      , Str "multiple"
+      , Space
+      , Str "rows"
+      , Space
+      , Str "or"
+      , Space
+      , Str "columns:"
+      ]
+  , Table
+      ( "" , [] , [] )
+      (Caption Nothing [])
+      [ ( AlignDefault , ColWidth 0.19444444444444445 )
+      , ( AlignDefault , ColWidth 0.1111111111111111 )
+      , ( AlignDefault , ColWidth 0.1527777777777778 )
+      ]
+      (TableHead
+         ( "" , [] , [] )
+         [ Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 2)
+                 [ Plain [ Str "Property" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "Earth" ] ]
+             ]
+         ])
+      [ TableBody
+          ( "" , [] , [] )
+          (RowHeadColumns 0)
+          []
+          [ Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 3)
+                  (ColSpan 1)
+                  [ Plain
+                      [ Str "Temperature"
+                      , SoftBreak
+                      , Str "1961-1990"
+                      ]
+                  ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "min" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" , Space , Str "\176C" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "mean" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "14" , Space , Str "\176C" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "min" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "56.7" , Space , Str "\176C" ] ]
+              ]
+          ]
+      ]
+      (TableFoot ( "" , [] , [] ) [])
+  , Para
+      [ Str "Table"
+      , Space
+      , Str "with"
+      , Space
+      , Str "complex"
+      , Space
+      , Str "header:"
+      ]
+  , Table
+      ( "" , [] , [] )
+      (Caption Nothing [])
+      [ ( AlignDefault , ColWidth 0.3055555555555556 )
+      , ( AlignDefault , ColWidth 0.1111111111111111 )
+      , ( AlignDefault , ColWidth 0.1111111111111111 )
+      , ( AlignDefault , ColWidth 0.1111111111111111 )
+      ]
+      (TableHead
+         ( "" , [] , [] )
+         [ Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 2)
+                 (ColSpan 1)
+                 [ Plain [ Str "Location" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 3)
+                 [ Plain
+                     [ Str "Temperature"
+                     , Space
+                     , Str "1961-1990"
+                     , SoftBreak
+                     , Str "in"
+                     , Space
+                     , Str "degree"
+                     , Space
+                     , Str "Celsius"
+                     ]
+                 ]
+             ]
+         , Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "min" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "mean" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "max" ] ]
+             ]
+         ])
+      [ TableBody
+          ( "" , [] , [] )
+          (RowHeadColumns 0)
+          []
+          [ Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "Antarctica" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "N/A" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "19.8" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "Earth" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "14" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "56.7" ] ]
+              ]
+          ]
+      ]
+      (TableFoot ( "" , [] , [] ) [])
   , Header
       2
       ( "entities-in-links-and-titles" , [] , [] )
diff --git a/test/markdown-reader-more.txt b/test/markdown-reader-more.txt
index c6f313b20..8d2bed5ef 100644
--- a/test/markdown-reader-more.txt
+++ b/test/markdown-reader-more.txt
@@ -286,6 +286,32 @@ Empty cells
 |   |   |
 +---+---+
 
+
+Table with cells spanning multiple rows or columns:
+
++---------------------+----------+
+| Property            | Earth    |
++=============+=======+==========+
+|             | min   | -89.2 °C |
+| Temperature +-------+----------+
+| 1961-1990   | mean  | 14 °C    |
+|             +-------+----------+
+|             | min   | 56.7 °C  |
++-------------+-------+----------+
+
+Table with complex header:
+
++---------------------+-----------------------+
+| Location            | Temperature 1961-1990 |
+|                     | in degree Celsius     |
+|                     +-------+-------+-------+
+|                     | min   | mean  | max   |
++=====================+=======+=======+=======+
+| Antarctica          | -89.2 | N/A   | 19.8  |
++---------------------+-------+-------+-------+
+| Earth               | -89.2 | 14    | 56.7  |
++---------------------+-------+-------+-------+
+
 ## Entities in links and titles
 
 [link](/ürl "öö!")
diff --git a/test/rst-reader.native b/test/rst-reader.native
index 51bb940bf..eb81633ff 100644
--- a/test/rst-reader.native
+++ b/test/rst-reader.native
@@ -1474,6 +1474,234 @@ Pandoc
           ]
       ]
       (TableFoot ( "" , [] , [] ) [])
+  , Para
+      [ Str "Table"
+      , Space
+      , Str "with"
+      , Space
+      , Str "cells"
+      , Space
+      , Str "spanning"
+      , Space
+      , Str "multiple"
+      , Space
+      , Str "rows"
+      , Space
+      , Str "or"
+      , Space
+      , Str "columns:"
+      ]
+  , Table
+      ( "" , [] , [] )
+      (Caption Nothing [])
+      [ ( AlignDefault , ColWidth 0.175 )
+      , ( AlignDefault , ColWidth 0.1 )
+      , ( AlignDefault , ColWidth 0.1375 )
+      ]
+      (TableHead
+         ( "" , [] , [] )
+         [ Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 2)
+                 [ Plain [ Str "Property" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "Earth" ] ]
+             ]
+         ])
+      [ TableBody
+          ( "" , [] , [] )
+          (RowHeadColumns 0)
+          []
+          [ Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 3)
+                  (ColSpan 1)
+                  [ Plain [ Str "Temperature" , SoftBreak , Str "1961-1990" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "min" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" , Space , Str "\176C" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "mean" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "14" , Space , Str "\176C" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "min" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "56.7" , Space , Str "\176C" ] ]
+              ]
+          ]
+      ]
+      (TableFoot ( "" , [] , [] ) [])
+  , Para
+      [ Str "Table"
+      , Space
+      , Str "with"
+      , Space
+      , Str "complex"
+      , Space
+      , Str "header:"
+      ]
+  , Table
+      ( "" , [] , [] )
+      (Caption Nothing [])
+      [ ( AlignDefault , ColWidth 0.275 )
+      , ( AlignDefault , ColWidth 0.1 )
+      , ( AlignDefault , ColWidth 0.1 )
+      , ( AlignDefault , ColWidth 0.1 )
+      ]
+      (TableHead
+         ( "" , [] , [] )
+         [ Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 2)
+                 (ColSpan 1)
+                 [ Plain [ Str "Location" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 3)
+                 [ Plain
+                     [ Str "Temperature"
+                     , Space
+                     , Str "1961-1990"
+                     , SoftBreak
+                     , Str "in"
+                     , Space
+                     , Str "degree"
+                     , Space
+                     , Str "Celsius"
+                     ]
+                 ]
+             ]
+         , Row
+             ( "" , [] , [] )
+             [ Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "min" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "mean" ] ]
+             , Cell
+                 ( "" , [] , [] )
+                 AlignDefault
+                 (RowSpan 1)
+                 (ColSpan 1)
+                 [ Plain [ Str "max" ] ]
+             ]
+         ])
+      [ TableBody
+          ( "" , [] , [] )
+          (RowHeadColumns 0)
+          []
+          [ Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "Antarctica" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "N/A" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "19.8" ] ]
+              ]
+          , Row
+              ( "" , [] , [] )
+              [ Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "Earth" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "-89.2" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "14" ] ]
+              , Cell
+                  ( "" , [] , [] )
+                  AlignDefault
+                  (RowSpan 1)
+                  (ColSpan 1)
+                  [ Plain [ Str "56.7" ] ]
+              ]
+          ]
+      ]
+      (TableFoot ( "" , [] , [] ) [])
   , Header 1 ( "footnotes" , [] , [] ) [ Str "Footnotes" ]
   , Para
       [ Note
diff --git a/test/rst-reader.rst b/test/rst-reader.rst
index d2d82d435..0a2ad6999 100644
--- a/test/rst-reader.rst
+++ b/test/rst-reader.rst
@@ -543,6 +543,31 @@ Multiple blocks in a cell
 | r1 bis           | - b 2     | c 2        | 
 +------------------+-----------+------------+
 
+Table with cells spanning multiple rows or columns:
+
++---------------------+----------+
+| Property            | Earth    |
++=============+=======+==========+
+|             | min   | -89.2 °C |
+| Temperature +-------+----------+
+| 1961-1990   | mean  | 14 °C    |
+|             +-------+----------+
+|             | min   | 56.7 °C  |
++-------------+-------+----------+
+
+Table with complex header:
+
++---------------------+-----------------------+
+| Location            | Temperature 1961-1990 |
+|                     | in degree Celsius     |
+|                     +-------+-------+-------+
+|                     | min   | mean  | max   |
++=====================+=======+=======+=======+
+| Antarctica          | -89.2 | N/A   | 19.8  |
++---------------------+-------+-------+-------+
+| Earth               | -89.2 | 14    | 56.7  |
++---------------------+-------+-------+-------+
+
 Footnotes
 =========