oc-basic.el: Drop {...} when rendering Bibtex entries

* lisp/oc-basic.el (org-cite-basic--print-bibtex-string): New function
approximately parsing Bibtex strings and dropping {...}.
(org-cite-basic--print-entry): Use the new function.
* testing/examples/Basic.bib:
*
testing/lisp/test-oc-basic.el (test-org-cite-basic/export-bibliography):
Add test.

Reported-by: Dominik Schrempf <dominik.schrempf@gmail.com>
Link: https://orgmode.org/list/CAF+0kSg8O3RQBG1wXoHjMEHwnGFz0gaDkTTSGv+ZaOt4d4myCA@mail.gmail.com

lisp/oc-basic.el

@@ -463,6 +463,38 @@ necessary, unless optional argument NO-SUFFIX is non-nil."
                     new))))
          (if no-suffix year (concat year suffix)))))))
 
+(defun org-cite-basic--print-bibtex-string (element &optional info)
+  "Print Bibtex formatted string ELEMENT, according to Bibtex syntax.
+Remove all the {...} that are not a part of LaTeX macros and parse the
+LaTeX fragments.  Do nothing when current backend is derived from
+LaTeX, according to INFO.
+
+Return updated ELEMENT."
+  (if (org-export-derived-backend-p (plist-get info :back-end) 'latex)
+      ;; Derived from LaTeX, no need to use manual ad-hoc LaTeX
+      ;; parser.
+      element
+    ;; Convert ELEMENT to anonymous when ELEMENT is string.
+    ;; Otherwise, we cannot modify ELEMENT by side effect.
+    (when (org-element-type-p element 'plain-text)
+      (setq element (org-element-create 'anonymous nil element)))
+    ;; Approximately parse LaTeX fragments, assuming Org mode syntax
+    ;; (it is close to original LaTeX, and we do not want to
+    ;; re-implement complete LaTeX parser here))
+    (org-element-map element t
+      (lambda (str)
+        (when (stringp str)
+          (org-element-set
+           str
+           (org-element-parse-secondary-string
+            str '(latex-fragment entity))))))
+    ;; Strip the remaining { and }.
+    (org-element-map element t
+      (lambda (str)
+        (when (stringp str)
+          (org-element-set str (replace-regexp-in-string "[{}]" "" str)))))
+    element))
+
 (defun org-cite-basic--print-entry (entry style &optional info)
   "Format ENTRY according to STYLE string.
 ENTRY is an alist, as returned by `org-cite-basic--get-entry'.
@@ -474,27 +506,29 @@ Optional argument INFO is the export state, as a property list."
              (org-cite-basic--get-field 'journal entry info)
              (org-cite-basic--get-field 'institution entry info)
              (org-cite-basic--get-field 'school entry info))))
-    (pcase style
-      ("plain"
-       (let ((year (org-cite-basic--get-year entry info 'no-suffix)))
-         (org-cite-concat
-          (org-cite-basic--shorten-names author) ". "
-          title (and from (list ", " from)) ", " year ".")))
-      ("numeric"
-       (let ((n (org-cite-basic--key-number (cdr (assq 'id entry)) info))
-             (year (org-cite-basic--get-year entry info 'no-suffix)))
-         (org-cite-concat
-          (format "[%d] " n) author ", "
-          (org-cite-emphasize 'italic title)
-          (and from (list ", " from)) ", "
-          year ".")))
-      ;; Default to author-year.  Use year disambiguation there.
-      (_
-       (let ((year (org-cite-basic--get-year entry info)))
-         (org-cite-concat
-          author " (" year "). "
-          (org-cite-emphasize 'italic title)
-          (and from (list ", " from)) "."))))))
+    (org-cite-basic--print-bibtex-string
+     (pcase style
+       ("plain"
+        (let ((year (org-cite-basic--get-year entry info 'no-suffix)))
+          (org-cite-concat
+           (org-cite-basic--shorten-names author) ". "
+           title (and from (list ", " from)) ", " year ".")))
+       ("numeric"
+        (let ((n (org-cite-basic--key-number (cdr (assq 'id entry)) info))
+              (year (org-cite-basic--get-year entry info 'no-suffix)))
+          (org-cite-concat
+           (format "[%d] " n) author ", "
+           (org-cite-emphasize 'italic title)
+           (and from (list ", " from)) ", "
+           year ".")))
+       ;; Default to author-year.  Use year disambiguation there.
+       (_
+        (let ((year (org-cite-basic--get-year entry info)))
+          (org-cite-concat
+           author " (" year "). "
+           (org-cite-emphasize 'italic title)
+           (and from (list ", " from)) "."))))
+     info)))
 
 
 ;;; "Activate" capability

testing/examples/Basic.bib

@@ -7,3 +7,14 @@
   doi = {10.1007/978-3-642-23816-1},
   isbn = {9783642238161}
 }
+
+@InCollection{Geyer2011,
+  author          = {Geyer, Charles J},
+  title           = {{Introduction to Markov\plus Chain Monte Carlo}},
+  year            = 2011,
+  booktitle       = {{Handbook of Markov Chain Monte Carlo}},
+  editor          = {Brooks, Steve and Gelman, Andrew and Jones, Galin and Meng,
+		  Xiao-Li},
+  publisher       = {CRC press},
+  pages           = 45,
+}

testing/lisp/test-oc-basic.el

@@ -156,5 +156,24 @@ Text: [cite/t: Citing ; @friends; and @friends also; is duplication.]"
            (search-forward "Text: Citing van Dongen, M.R.C. (2012), and van Dongen, M.R.C. (2012)
 also is duplication." nil t)))))))
 
+(ert-deftest test-org-cite-basic/export-bibliography ()
+  "Test `org-cite-basic-export-bibliography'."
+  ;; Drop {...} Bibtex brackets and render entities.
+  (org-test-with-temp-text
+      (format
+       "#+bibliography: %s
+#+cite_export: basic
+Foo [cite/plain:@Geyer2011]
+#+print_bibliography:"
+       (expand-file-name "examples/Basic.bib" org-test-dir))
+    (let ((export-buffer "*Test ASCII Export*")
+          (org-export-show-temporary-export-buffer nil))
+      (org-export-to-buffer 'ascii export-buffer)
+      (with-current-buffer export-buffer
+        (let ((case-fold-search t))
+          (should
+           ;; Rendered from {Introduction to Markov\plus Chain Monte Carlo}
+           (search-forward "Introduction to Markov+ Chain Monte Carlo" nil t)))))))
+
 (provide 'test-oc-basic)
 ;;; test-oc-basic.el ends here