org-mode/lisp/oc-biblatex.el

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;;; oc-biblatex.el --- biblatex citation processor for Org -*- lexical-binding: t; -*-
;; Copyright (C) 2021-2024 Free Software Foundation, Inc.
;; Author: Nicolas Goaziou <mail@nicolasgoaziou.fr>
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; This library registers the `biblatex' citation processor, which provides
;; the "export" capability for citations.
;; The processor relies on "biblatex" LaTeX package. As such it ensures that
;; the package is properly required in the document's preamble. More
;; accurately, it will reuse any "\usepackage{biblatex}" already present in
;; the document (e.g., through `org-latex-packages-alist'), or insert one using
;; options defined in `org-cite-biblatex-options'.
;; In any case, the library will override style-related options with those
;; specified with the citation processor, in `org-cite-export-processors' or
;; "cite_export" keyword. If you need to use different styles for bibliography
;; and citations, you can separate them with "bibstyle/citestyle" syntax. E.g.,
;;
;; #+cite_export: biblatex authortitle/authortitle-ibid
;; The library supports the following citation styles:
;;
;; - author (a), including caps (c), full (f) and caps-full (cf) variants,
;; - locators (l), including bare (b), caps (c) and bare-caps (bc) variants,
;; - noauthor (na), including bare (b) variant,
;; - nocite (n),
;; - text (t), including caps (c) variant,
;; - default style, including bare (b), caps (c) and bare-caps (bc) variants.
;; When citation and style permit, the library automatically generates
;; "multicite" versions of the commands above.
;; Bibliography is printed using "\printbibliography" command. Additional
;; options may be passed to it through a property list attached to the
;; "print_bibliography" keyword. E.g.,
;;
;; #+print_bibliography: :section 2 :heading subbibliography
;;
;; Values including spaces must be surrounded with double quotes. If you need
;; to use a key multiple times, you can separate its values with commas, but
;; without any space in-between:
;;
;; #+print_bibliography: :keyword abc,xyz :title "Primary Sources"
;;; Code:
(require 'org-macs)
(org-assert-version)
(require 'map)
(require 'org-macs)
(require 'oc)
(declare-function org-element-property "org-element-ast" (property node))
(declare-function org-element-parent "org-element-ast" (node))
(declare-function org-export-data "org-export" (data info))
;;; Customization
(defcustom org-cite-biblatex-options nil
"Options added to \"biblatex\" package.
If \"biblatex\" package is already required in the document, e.g., through
`org-latex-packages-alist' variable, these options are ignored."
:group 'org-cite
:package-version '(Org . "9.5")
:type '(choice
(string :tag "Options (key=value,key2=value2...)")
(const :tag "No option" nil))
:safe #'string-or-null-p)
(defcustom org-cite-biblatex-styles
'(("author" "caps" "Citeauthor*" nil nil)
("author" "full" "citeauthor" nil nil)
("author" "caps-full" "Citeauthor" nil nil)
("author" nil "citeauthor*" nil nil)
("locators" "bare" "notecite" nil nil)
("locators" "caps" "Pnotecite" nil nil)
("locators" "bare-caps" "Notecite" nil nil)
("locators" nil "pnotecite" nil nil)
("noauthor" "bare" "cite*" nil nil)
("noauthor" nil "autocite*" nil nil)
("nocite" nil "nocite" nil t)
("text" "caps" "Textcite" "Textcites" nil)
("text" nil "textcite" "textcites" nil)
(nil "bare" "cite" "cites" nil)
(nil "caps" "Autocite" "Autocites" nil)
(nil "bare-caps" "Cite" "Cites" nil)
(nil nil "autocite" "autocites" nil))
"List of styles and variants, with associated BibLaTeX commands.
Each style follows the pattern
(NAME VARIANT COMMAND MULTI-COMMAND NO-OPTION)
where:
NAME is the name of the style, as a string, or nil. The nil
style is the default style. As such, it must have an entry in
the list.
VARIANT is the name of the style variant, as a string or nil.
The nil variant is the default variant for the current style.
As such, each style name must be associated to a nil variant.
COMMAND is the LaTeX command to use, as a string. It should
not contain the leading backslash character.
MULTI-COMMAND is the LaTeX command to use when a multi-cite
command is appropriate. When nil, the style is deemed
inappropriate for multi-cites. The command should not contain
the leading backslash character.
NO-OPTION is a boolean. When non-nil, no optional argument
should be added to the LaTeX command.
Each NAME-VARIANT pair should be unique in the list.
It is also possible to provide shortcuts for style and variant
names. See `org-cite-biblatex-style-shortcuts'."
:group 'org-cite
:package-version '(Org . "9.6")
:type '(repeat
(list :tag "Style/variant combination"
;; Name part.
(choice :tag "Style"
(string :tag "Name")
(const :tag "Default style" nil))
;; Variant part.
(choice :tag "Variant"
(string :tag "Name")
(const :tag "Default variant" nil))
;; Command part.
(string :tag "Command name")
(choice :tag "Multicite command"
(string :tag "Command name")
(const :tag "No multicite support" nil))
(choice :tag "Skip optional arguments"
(const :tag "Yes" t)
(const :tag "No" nil)))))
(defcustom org-cite-biblatex-style-shortcuts
'(("a" . "author")
("b" . "bare")
("bc" . "bare-caps")
("c" . "caps")
("cf" . "caps-full")
("f" . "full")
("l" . "locators")
("n" . "nocite")
("na" . "noauthor")
("t" . "text"))
"List of shortcuts associated to style or variant names.
Each entry is a pair (NAME . STYLE-NAME) where NAME is the name
of the shortcut, as a string, and STYLE-NAME is the name of
a style in `org-cite-biblatex-styles'."
:group 'org-cite
:package-version '(Org . "9.6")
:type '(repeat
(cons :tag "Shortcut"
(string :tag "Name")
(string :tag "Full name")))
:safe t)
;;; Internal functions
(defun org-cite-biblatex--package-options (initial style)
"Return options string for \"biblatex\" package.
INITIAL is an initial style of comma-separated options, as a string or nil.
STYLE is the style definition as a string or nil.
Return a string."
(let ((options-no-style
(and initial
(let ((re (rx string-start (or "bibstyle" "citestyle" "style"))))
(seq-filter
(lambda (option) (not (string-match re option)))
(split-string (org-unbracket-string "[" "]" initial)
"," t " \t")))))
(style-options
(cond
((null style) nil)
((not (string-match "/" style)) (list (concat "style=" style)))
(t
(list (concat "bibstyle=" (substring style nil (match-beginning 0)))
(concat "citestyle=" (substring style (match-end 0))))))))
(if (or options-no-style style-options)
(format "[%s]"
(mapconcat #'identity
(append options-no-style style-options)
","))
"")))
(defun org-cite-biblatex--multicite-p (citation)
"Non-nil when citation could make use of a \"multicite\" command."
(let ((references (org-cite-get-references citation)))
(and (< 1 (length references))
(seq-some (lambda (r)
(or (org-element-property :prefix r)
(org-element-property :suffix r)))
references))))
(defun org-cite-biblatex--atomic-arguments (references info &optional no-opt)
"Build argument for the list of citation REFERENCES.
When NO-OPT argument is non-nil, only provide mandatory arguments."
(let ((mandatory
(format "{%s}"
(mapconcat (lambda (r) (org-element-property :key r))
references
","))))
(if no-opt mandatory
(let* ((origin (pcase references
(`(,reference) reference)
(`(,reference . ,_)
(org-element-parent reference))))
(suffix (org-element-property :suffix origin))
(prefix (org-element-property :prefix origin)))
(concat (and prefix
(format "[%s]" (org-trim (org-export-data prefix info))))
(cond
(suffix (format "[%s]"
(org-trim (org-export-data suffix info))))
(prefix "[]")
(t nil))
mandatory)))))
(defun org-cite-biblatex--multi-arguments (citation info)
"Build \"multicite\" command arguments for CITATION object.
INFO is the export state, as a property list."
(let ((global-prefix (org-element-property :prefix citation))
(global-suffix (org-element-property :suffix citation)))
(concat (and global-prefix
(format "(%s)"
(org-trim (org-export-data global-prefix info))))
(cond
;; Global pre/post-notes.
(global-suffix
(format "(%s)"
(org-trim (org-export-data global-suffix info))))
(global-prefix "()")
(t nil))
;; All arguments.
(mapconcat (lambda (r)
(org-cite-biblatex--atomic-arguments (list r) info))
(org-cite-get-references citation)
""))))
(defun org-cite-biblatex--command (citation info name &optional multi no-opt)
"Return BibLaTeX command NAME for CITATION object.
INFO is the export state, as a property list.
When optional argument MULTI is non-nil, use it as a multicite
command name when appropriate. When optional argument NO-OPT is
non-nil, do not add optional arguments to the command."
(if (and multi (org-cite-biblatex--multicite-p citation))
(format "\\%s%s" multi (org-cite-biblatex--multi-arguments citation info))
(format "\\%s%s"
name
(org-cite-biblatex--atomic-arguments
(org-cite-get-references citation) info no-opt))))
(defun org-cite-biblatex--expand-shortcuts (style)
"Return STYLE pair with shortcuts expanded."
(pcase style
(`(,style . ,variant)
(cons (or (alist-get style org-cite-biblatex-style-shortcuts
nil nil #'equal)
style)
(or (alist-get variant org-cite-biblatex-style-shortcuts
nil nil #'equal)
variant)))
(_ (error "This should not happen"))))
(defun org-cite-biblatex-list-styles ()
"List styles and variants supported in `biblatex' citation processor.
The output format is appropriate as a value for `:cite-styles' keyword
in `org-cite-register-processor', which see."
(let ((shortcuts (make-hash-table :test #'equal))
(variants (make-hash-table :test #'equal)))
(pcase-dolist (`(,name . ,full-name) org-cite-biblatex-style-shortcuts)
(push name (gethash full-name shortcuts)))
(pcase-dolist (`(,name ,variant . ,_) org-cite-biblatex-styles)
(unless (null variant) (push variant (gethash name variants))))
(map-apply (lambda (style-name variants)
(cons (cons (or style-name "nil")
(gethash style-name shortcuts))
(mapcar (lambda (v)
(cons v (gethash v shortcuts)))
variants)))
variants)))
;;; Export capability
(defun org-cite-biblatex-export-bibliography (_keys _files _style props &rest _)
"Print references from bibliography.
PROPS is the local properties of the bibliography, as a property list."
(concat "\\printbibliography"
(and props
(let ((key nil)
(results nil))
(dolist (datum props)
(cond
((keywordp datum)
(when key (push key results))
(setq key (substring (symbol-name datum) 1)))
(t
;; Comma-separated values are associated to the
;; same keyword.
(push (mapconcat (lambda (v) (concat key "=" v))
(split-string datum "," t)
",")
results)
(setq key nil))))
(format "[%s]"
(mapconcat #'identity (nreverse results) ","))))))
(defun org-cite-biblatex-export-citation (citation style _ info)
"Export CITATION object.
STYLE is the citation style, as a pair of either strings or nil.
INFO is the export state, as a property list."
(pcase-let* ((`(,name . ,variant) (org-cite-biblatex--expand-shortcuts style))
(candidates nil)
(style-match-flag nil))
(catch :match
;; Walk `org-cite-biblatex-styles' and prioritize matching
;; candidates. At the end of the process, the optimal candidate
;; should appear in front of CANDIDATES.
(dolist (style org-cite-biblatex-styles)
(pcase style
;; A matching style-variant pair trumps anything else.
;; Return it.
(`(,(pred (equal name)) ,(pred (equal variant)) . ,_)
(throw :match (setq candidates (list style))))
;; nil-nil style-variant is the fallback value. Consider it
;; only if nothing else matches.
(`(nil nil . ,_)
(unless candidates (push style candidates)))
;; A matching style with default variant trumps a matching
;; variant without the adequate style. Ensure the former
;; appears first in the list.
(`(,(pred (equal name)) nil . ,_)
(push style candidates)
(setq style-match-flag t))
(`(nil ,(pred (equal variant)) . ,_)
(unless style-match-flag (push style candidates)))
;; Discard anything else.
(_ nil))))
(apply
#'org-cite-biblatex--command citation info
(pcase (seq-elt candidates 0) ;; `seq-first' is not available in Emacs 26.
(`(,_ ,_ . ,command-parameters) command-parameters)
('nil
(user-error
"Missing default style or variant in `org-cite-biblatex-styles'"))
(other
(user-error "Invalid entry %S in `org-cite-biblatex-styles'" other))))))
(defun org-cite-biblatex--generate-latex-usepackage (info)
"Ensure that the biblatex package is loaded.
This is performed by extracting relevant information from the
INFO export plist, and modifying any existing
\\usepackage{biblatex} statement in the LaTeX header."
(let ((style (org-cite-bibliography-style info))
(usepackage-rx (rx "\\usepackage"
(opt (group "[" (*? anything) "]"))
"{biblatex}")))
(concat
(if (string-match usepackage-rx (plist-get info :latex-full-header))
;; "biblatex" package loaded, but with none (or different) options.
;; Replace with style-including command.
(plist-put info :latex-full-header
(replace-match
(format "\\usepackage%s{biblatex}"
(save-match-data
(org-cite-biblatex--package-options nil style)))
t t
(plist-get info :latex-full-header)))
;; No "biblatex" package loaded. Insert "usepackage" command
;; with appropriate options, including style.
(format "\\usepackage%s{biblatex}\n"
(org-cite-biblatex--package-options
org-cite-biblatex-options style))))))
(defun org-cite-biblatex--generate-latex-bibresources (info)
"From INFO generate LaTeX that loads the relevant bibliography resource files."
(let ((files (plist-get info :bibliography)))
(mapconcat (lambda (f)
(format "\\addbibresource%s{%s}"
(if (org-url-p f) "[location=remote]" "")
f))
files
"\n")))
;;; Register `biblatex' processor
(org-cite-register-processor 'biblatex
:export-bibliography #'org-cite-biblatex-export-bibliography
:export-citation #'org-cite-biblatex-export-citation
:cite-styles #'org-cite-biblatex-list-styles)
(provide 'oc-biblatex)
;;; oc-biblatex.el ends here