Support exporting table column alignment markers

The Org table alignment markers "<l>", "<r>", "<c>" translate to the markers in Markdown tables for left, right, center column alignment as recognized by Blackfriday. Fixes https://github.com/kaushalmodi/ox-hugo/issues/95
8 years ago · 40e65192d5
parent 553c5108bf
commit 40e65192d5
3 changed files with 139 additions and 6 deletions
--- a/ox-blackfriday.el
+++ b/ox-blackfriday.el
@ -35,6 +35,7 @@
 This check is specifically track if that horizontal rule was
 inserted after the first row of the table.")

+

 ;;; User-Configurable Variables

@ -43,6 +44,7 @@ inserted after the first row of the table.")
  :tag "Org Export Blackfriday"
  :group 'org-export)

+

 ;;; Define Back-End

@ -130,10 +132,8 @@ INFO is a plist used as a communication channel."
  "Return width of TABLE at given COLUMN using INFO.

 INFO is a plist used as communication channel.  Width of a column
-is determined either by inquiring
-`org-blackfriday-width-cookies' in the column, or by the maximum
-cell with in the column."
-  ;; (message "[ox-bf-table-col-width DBG] table: %S" table)
+is determined either by inquiring `org-blackfriday-width-cookies'
+in the column, or by the maximum cell with in the column."
  (let ((cookie (when (hash-table-p org-blackfriday-width-cookies)
                  (gethash column org-blackfriday-width-cookies))))
    (if (and (eq table org-blackfriday-width-cookies-table)
@ -192,6 +192,61 @@ Returns nil immediately if PLAIN-LIST is not an ordered list."
    ;; (message "has custom counter: %S" has-custom-counter)
    has-custom-counter))

+;;;; Table Cell Alignment
+;; Below function is heavily adapted from
+;; `org-export-table-cell-alignment' from ox.el.  The main difference
+;; is that the below variation can return a `default' value too.
+(defun org-blackfriday-table-cell-alignment (table-cell info)
+  "Return TABLE-CELL contents alignment.
+
+INFO is a plist used as the communication channel.
+
+Return alignment as specified by the last alignment cookie in the
+same column as TABLE-CELL.  If no such cookie is found, return
+`default'.  Possible values are `default', `left', `right' and
+`center'."
+  (let* ((row (org-export-get-parent table-cell))
+         (table (org-export-get-parent row))
+         (cells (org-element-contents row))
+         (columns (length cells))
+         (column (- columns (length (memq table-cell cells))))
+         (cache (or (plist-get info :table-cell-alignment-cache)
+                    (let ((table (make-hash-table :test #'eq)))
+                      (plist-put info :table-cell-alignment-cache table)
+                      table)))
+         (align-vector (or (gethash table cache)
+                           (puthash table (make-vector columns nil) cache))))
+    (or (aref align-vector column)
+        (let (cookie-align)
+          (dolist (row (org-element-contents (org-export-get-parent row)))
+            (cond
+             ;; In a special row, try to find an alignment cookie at
+             ;; COLUMN.
+             ((org-export-table-row-is-special-p row info)
+              (let ((value (org-element-contents
+                            (elt (org-element-contents row) column))))
+                ;; Since VALUE is a secondary string, the following
+                ;; checks avoid useless expansion through
+                ;; `org-export-data'.
+                (when (and value
+                           (not (cdr value))
+                           (stringp (car value))
+                           (string-match "\\`<\\([lrc]\\)?\\([0-9]+\\)?>\\'"
+                                         (car value))
+                           (match-string 1 (car value)))
+                  (setq cookie-align (match-string 1 (car value))))))
+             ;; Ignore table rules.
+             ((eq (org-element-property :type row) 'rule))))
+          ;; Return value.  Alignment specified by cookies has
+          ;; precedence over alignment deduced from cell's contents.
+          (aset align-vector
+                column
+                (cond ((equal cookie-align "l") 'left)
+                      ((equal cookie-align "r") 'right)
+                      ((equal cookie-align "c") 'center)
+                      (t 'default)))))))
+
+

 ;;; Transcode Functions

@ -363,6 +418,7 @@ CONTENTS contains the text with strike-through markup."

 CONTENTS is content of the cell.  INFO is a plist used as a
 communication channel."
+  ;; (message "[ox-bf-table-cell DBG]")
  ;; (message "[ox-bf-table-cell DBG] In contents: %s" contents)
  (let* ((table (org-export-get-parent-table table-cell))
         (column (cdr (org-export-table-cell-address table-cell info)))
@ -375,6 +431,10 @@ communication channel."
                       (make-string (max 0 (- width (string-width data))) ?\s)
                       right-border))
         (cell-width (length cell)))
+    ;; Just calling `org-blackfriday-table-cell-alignment' will save
+    ;; the alignment info for the current cell/column to the INFO
+    ;; channel.. magic!
+    (org-blackfriday-table-cell-alignment table-cell info)
    ;; Each cell needs to be at least 3 characters wide (4 chars,
    ;; including the table border char "|"); otherwise the export
    ;; is not rendered as a table
@ -389,6 +449,7 @@ communication channel."

 CONTENTS is cell contents of TABLE-ROW.  INFO is a plist used as a
 communication channel."
+  ;; (message "[ox-bf-table-row DBG]")
  (let* ((table (org-export-get-parent-table table-row))
         (row-num (cl-position          ;Begins with 0
                   table-row
@ -417,8 +478,34 @@ communication channel."
    ;; under it for Blackfriday to detect the whole object as a table.
    (when (and (stringp row)
               (null org-blackfriday--hrule-inserted))
-      (let ((rule (replace-regexp-in-string "[^|]" "-" row)))
-        (setq row (concat row "\n" rule))
+      ;; (message "[ox-bf-table-row DBG] row: %s" row)
+      (let ((rule (replace-regexp-in-string "[^|]" "-" row))
+            (pos 0)
+            (new-rule "")
+            matches)
+        ;; (message "[ox-bf-table-row DBG] rule: %s" rule)
+        ;; https://emacs.stackexchange.com/a/7150/115
+        (while (string-match "|-+" rule pos)
+          (push (match-string 0 rule) matches)
+          (setq pos (match-end 0)))
+        (setq matches (nreverse matches))
+        ;; Get the align-vector that was saved in the INFO channel in
+        ;; `org-blackfriday-table-cell-alignment'.
+        (let* ((alignment-cache (plist-get info :table-cell-alignment-cache))
+               (align-vector (gethash table alignment-cache))
+               (col 0))
+          ;; (message "[ox-bf-table-row DBG] align-vector: %S" align-vector)
+          (dolist (match matches)
+            (let ((align (aref align-vector col)))
+              (when (member align '(left center))
+                (setq match (replace-regexp-in-string "\\`|-" "|:" match)))
+              (when (member align '(right center))
+                (setq match (replace-regexp-in-string "-\\'" ":" match))))
+            (setq new-rule (concat new-rule match))
+            (setq col (1+ col))))
+        (setq new-rule (concat new-rule "|"))
+        ;; (message "[ox-bf-table-row DBG] new-rule: %s" new-rule)
+        (setq row (concat row "\n" new-rule))
        (setq org-blackfriday--hrule-inserted t)))
    ;; (message "[ox-bf-table-row DBG] Row:\n%s" row)
    row))
--- a/test/site/content-org/all-posts.org
+++ b/test/site/content-org/all-posts.org
@ -439,6 +439,24 @@ Here is the second post on Emacs.
 :EXPORT_FILE_NAME: table-with-single-row
 :END:
 | a | b |
+** Table column alignment
+:PROPERTIES:
+:EXPORT_FILE_NAME: table-column-alignment
+:END:
+*** Table with 3 rows
+|             <r> | <l>                  |           |              <c>              |
+|           Right | Left                 | No        |            Center             |
+| Long Content To | Spread Out the Width | Alignment | Of the Table To See Alignment |
+|           Right | Left                 | Marker    |            Center             |
+*** Table with 2 rows
+| <l>  |         |  <c>   |   <r> |
+| Left | Default | Center | Right |
+| 1    |       2 |   3    |     4 |
+*** Table with 1 row
+/A table with just one row, with alignment markers doesn't make
+sense. But hey, a test is a test./
+| <l>  |         |  <c>   |   <r> |
+| Left | Default | Center | Right |
 * Source blocks                                                   :src_block:
 ** Example text with code blocks                                    :ARCHIVE:
 :PROPERTIES:
--- a/test/site/content/posts/table-column-alignment.md
+++ b/test/site/content/posts/table-column-alignment.md
@ -0,0 +1,28 @@
+++
+title = "Table column alignment"
+tags = ["table"]
+draft = false
+++
+
+## Table with 3 rows {#table-with-3-rows}
+
+| Right           | Left                 | No        | Center                        |
+|----------------:|:---------------------|-----------|:-----------------------------:|
+| Long Content To | Spread Out the Width | Alignment | Of the Table To See Alignment |
+| Right           | Left                 | Marker    | Center                        |
+
+
+## Table with 2 rows {#table-with-2-rows}
+
+| Left | Default | Center | Right |
+|:-----|---------|:------:|------:|
+| 1    | 2       | 3      | 4     |
+
+
+## Table with 1 row {#table-with-1-row}
+
+_A table with just one row, with alignment markers doesn't make
+sense. But hey, a test is a test._
+
+| Left | Default | Center | Right |
+|:-----|---------|:------:|------:|