ox-bibtex: Small refactoring

* contrib/lisp/ox-bibtex.el (org-bibtex-process-bib-files): Execute
  function only when back-end is HTML.

contrib/lisp/ox-bibtex.el

@@ -138,6 +138,74 @@ to `org-bibtex-citation-p' predicate."
 	   (substring value (match-end 0) -1)))))
 
 
+
+;;; Filters
+
+(defun org-bibtex-process-bib-files (tree backend info)
+  "Send each bibliography in parse tree to \"bibtex2html\" process.
+Return new parse tree."
+  (when (org-export-derived-backend-p backend 'html)
+    ;; Initialize dynamically scoped variables.  The first one
+    ;; contain an alist between keyword objects and their HTML
+    ;; translation.  The second one will contain an alist between
+    ;; citation keys and names in the output (according to style).
+    (setq org-bibtex-html-entries-alist nil
+	  org-bibtex-html-keywords-alist nil)
+    (org-element-map tree 'keyword
+      (lambda (keyword)
+	(when (equal (org-element-property :key keyword) "BIBLIOGRAPHY")
+	  (let ((arguments (org-bibtex-get-arguments keyword))
+		(file (org-bibtex-get-file keyword))
+		temp-file)
+	    ;; limit is set: collect citations throughout the document
+	    ;; in TEMP-FILE and pass it to "bibtex2html" as "-citefile"
+	    ;; argument.
+	    (when (plist-get arguments :limit)
+	      (let ((citations
+		     (org-element-map tree '(latex-fragment link)
+		       (lambda (object)
+			 (and (org-bibtex-citation-p object)
+			      (org-bibtex-get-citation-key object))))))
+		(with-temp-file (setq temp-file (make-temp-file "ox-bibtex"))
+		  (insert (mapconcat 'identity citations "\n")))
+		(setq arguments
+		      (plist-put arguments
+				 :options
+				 (append (plist-get arguments :options)
+					 (list "-citefile" temp-file))))))
+	    ;; Call "bibtex2html" on specified file.
+	    (unless (eq 0 (apply 'call-process
+				 (append '("bibtex2html" nil nil nil)
+					 '("-a" "-nodoc" "-noheader" "-nofooter")
+					 (list "--style"
+					       (org-bibtex-get-style keyword))
+					 (plist-get arguments :options)
+					 (list (concat file ".bib")))))
+	      (error "Executing bibtex2html failed"))
+	    (and temp-file (delete-file temp-file))
+	    ;; Open produced HTML file, wrap references within a block and
+	    ;; return it.
+	    (with-temp-buffer
+	      (insert "<div id=\"bibliography\">\n<h2>References</h2>\n")
+	      (insert-file-contents (concat file ".html"))
+	      (insert "\n</div>")
+	      ;; Update `org-bibtex-html-keywords-alist'.
+	      (push (cons keyword (buffer-string))
+		    org-bibtex-html-keywords-alist)
+	      ;; Update `org-bibtex-html-entries-alist'.
+	      (goto-char (point-min))
+	      (while (re-search-forward
+		      "a name=\"\\([-_a-zA-Z0-9:]+\\)\">\\(\\w+\\)" nil t)
+		(push (cons (match-string 1) (match-string 2))
+		      org-bibtex-html-entries-alist))))))))
+  ;; Return parse tree unchanged.
+  tree)
+
+(eval-after-load 'ox
+  '(add-to-list 'org-export-filter-parse-tree-functions
+                'org-bibtex-process-bib-files))
+
+
 
 ;;; LaTeX Part
 
@@ -221,74 +289,6 @@ Fallback to `html' back-end for other types."
 (ad-activate 'org-html-link)
 
 
-;;;; Filter
-
-(defun org-bibtex-process-bib-files (tree backend info)
-  "Send each bibliography in parse tree to \"bibtex2html\" process.
-Return new parse tree.  This function assumes current back-end is HTML."
-  ;; Initialize dynamically scoped variables.  The first one
-  ;; contain an alist between keyword objects and their HTML
-  ;; translation.  The second one will contain an alist between
-  ;; citation keys and names in the output (according to style).
-  (setq org-bibtex-html-entries-alist nil
-        org-bibtex-html-keywords-alist nil)
-  (org-element-map tree 'keyword
-    (lambda (keyword)
-      (when (equal (org-element-property :key keyword) "BIBLIOGRAPHY")
-        (let ((arguments (org-bibtex-get-arguments keyword))
-              (file (org-bibtex-get-file keyword))
-              temp-file)
-          ;; limit is set: collect citations throughout the document
-          ;; in TEMP-FILE and pass it to "bibtex2html" as "-citefile"
-          ;; argument.
-          (when (plist-get arguments :limit)
-            (let ((citations
-                   (org-element-map tree '(latex-fragment link)
-                     (lambda (object)
-                       (and (org-bibtex-citation-p object)
-			    (org-bibtex-get-citation-key object))))))
-              (with-temp-file (setq temp-file (make-temp-file "ox-bibtex"))
-                (insert (mapconcat 'identity citations "\n")))
-              (setq arguments
-                    (plist-put arguments
-                               :options
-                               (append (plist-get arguments :options)
-                                       (list "-citefile" temp-file))))))
-          ;; Call "bibtex2html" on specified file.
-          (unless (eq 0 (apply 'call-process
-                               (append '("bibtex2html" nil nil nil)
-                                       '("-a" "-nodoc" "-noheader" "-nofooter")
-                                       (list "--style"
-                                             (org-bibtex-get-style keyword))
-                                       (plist-get arguments :options)
-                                       (list (concat file ".bib")))))
-            (error "Executing bibtex2html failed"))
-          (and temp-file (delete-file temp-file))
-          ;; Open produced HTML file, wrap references within a block and
-          ;; return it.
-          (with-temp-buffer
-            (insert "<div id=\"bibliography\">\n<h2>References</h2>\n")
-            (insert-file-contents (concat file ".html"))
-            (insert "\n</div>")
-            ;; Update `org-bibtex-html-keywords-alist'.
-            (push (cons keyword (buffer-string))
-                  org-bibtex-html-keywords-alist)
-            ;; Update `org-bibtex-html-entries-alist'.
-            (goto-char (point-min))
-            (while (re-search-forward
-                    "a name=\"\\([-_a-zA-Z0-9:]+\\)\">\\(\\w+\\)" nil t)
-              (push (cons (match-string 1) (match-string 2))
-                    org-bibtex-html-entries-alist)))))))
-  ;; Return parse tree unchanged.
-  tree)
-
-(eval-after-load 'ox
-  '(add-to-list 'org-export-filter-parse-tree-functions
-                (lambda (e b i) (when (eql b 'html)
-			     (org-bibtex-process-bib-files e b i)))))
-
-
-
 (provide 'ox-bibtex)
 
 ;;; ox-bibtex.el ends here