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;;; oc-csl.el --- csl citation processor for Org -*- lexical-binding: t; -*-
;; Copyright (C) 2021-2022 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 `csl' citation processor, which provides
;; the "export" capability for citations.
;; The processor relies on the external Citeproc Emacs library, which must be
;; available prior to loading this library.
;; By default, citations are rendered in Chicago author-date CSL style. You can
;; use another style file by specifying it in `org-cite-export-processors' or
;; from within the document by adding the file name to "cite_export" keyword
;;
;; #+cite_export: csl /path/to/style-file.csl
;; #+cite_export: csl "/path/to/style-file.csl"
;;
;; With the variable `org-cite-csl-styles-dir' set appropriately, the
;; above can even be shortened to
;;
;; #+cite_export: csl style-file.csl
;;
;; Styles can be downloaded, for instance, from the Zotero Style Repository
;; (<https://www.zotero.org/styles>). Dependent styles (which are not "unique"
;; in the Zotero Style Repository terminology) are not supported.
;; The processor uses the "en-US" CSL locale file shipped with Org for rendering
;; localized dates and terms in the references, independently of the language
;; settings of the Org document. Additional CSL locales can be made available
;; by setting `org-cite-csl-locales-dir' to a directory containing the locale
;; files in question (see <https://github.com/citation-style-language/locales>
;; for such files).
;; Bibliography is defined with the "bibliography" keyword. It supports files
;; with ".bib", ".bibtex", and ".json" extensions. References are exported using
;; the "print_bibliography" keyword.
;; The library supports the following citation styles:
;;
;; - author (a), including caps (c), full (f), and caps-full (cf) variants,
;; - noauthor (na), including bare (b), caps (c) and bare-caps (bc) variants,
;; - year (y), including a bare (b) variant,
;; - text (t). including caps (c), full (f), and caps-full (cf) variants,
;; - default style, including bare (b), caps (c) and bare-caps (bc) variants.
;; CSL styles recognize "locator" in citation references' suffix. For example,
;; in the citation
;;
;; [cite:see @Tarski-1965 chapter 1, for an example]
;;
;; "chapter 1" is the locator. The whole citation is rendered as
;;
;; (see Tarski 1965, chap. 1 for an example)
;;
;; in the default CSL style.
;;
;; The locator starts with a locator term, among "bk.", "bks.", "book", "chap.",
;; "chaps.", "chapter", "col.", "cols.", "column", "figure", "fig.", "figs.",
;; "folio", "fol.", "fols.", "number", "no.", "nos.", "line", "l.", "ll.",
;; "note", "n.", "nn.", "opus", "op.", "opp.", "page", "p.", "pp.", "paragraph",
;; "para.", "paras.", "¶", "¶¶", "§", "§§", "part", "pt.", "pts.", "section",
;; "sec.", "secs.", "sub verbo", "s.v.", "s.vv.", "verse", "v.", "vv.",
;; "volume", "vol.", and "vols.". It ends with the last comma or digit in the
;; suffix, whichever comes last, or runs till the end of the suffix.
;;
;; The part of the suffix before the locator is appended to reference's prefix.
;; If no locator term is used, but a number is present, then "page" is assumed.
;; This library was heavily inspired by and borrows from András Simonyi's
;; Citeproc Org (<https://github.com/andras-simonyi/citeproc-org>) library.
;; Many thanks to him!
;;; Code:
(require 'bibtex)
(require 'json)
(require 'oc)
(require 'citeproc nil t)
(declare-function citeproc-style-cite-note "ext:citeproc")
(declare-function citeproc-proc-style "ext:citeproc")
(declare-function citeproc-bt-entry-to-csl "ext:citeproc")
(declare-function citeproc-locale-getter-from-dir "ext:citeproc")
(declare-function citeproc-create "ext:citeproc")
(declare-function citeproc-citation-create "ext:citeproc")
(declare-function citeproc-append-citations "ext:citeproc")
(declare-function citeproc-render-citations "ext:citeproc")
(declare-function citeproc-render-bib "ext:citeproc")
(declare-function citeproc-hash-itemgetter-from-any "ext:citeproc")
(declare-function org-element-interpret-data "org-element" (data))
(declare-function org-element-map "org-element" (data types fun &optional info first-match no-recursion with-affiliated))
(declare-function org-element-property "org-element" (property element))
(declare-function org-element-put-property "org-element" (element property value))
(declare-function org-export-data "org-export" (data info))
(declare-function org-export-derived-backend-p "org-export" (backend &rest backends))
(declare-function org-export-get-footnote-number "org-export" (footnote info &optional data body-first))
;;; Customization
;;;; Location of CSL directories
(defcustom org-cite-csl-locales-dir nil
"Directory of CSL locale files.
If nil then only the fallback en-US locale will be available."
:group 'org-cite
:package-version '(Org . "9.5")
:type '(choice
(directory :tag "Locales directory")
(const :tag "Use en-US locale only" nil))
;; It's not obvious to me that arbitrary locations are safe.
;;; :safe #'string-or-null-p
)
(defcustom org-cite-csl-styles-dir nil
"Directory of CSL style files.
When non-nil, relative style file names are expanded relatively to this
directory. This variable is ignored when style file is absolute."
:group 'org-cite
:package-version '(Org . "9.5")
:type '(choice
(directory :tag "Styles directory")
(const :tag "Use absolute file names" nil))
;; It's not obvious to me that arbitrary locations are safe.
;;; :safe #'string-or-null-p
)
;;;; Citelinks
(defcustom org-cite-csl-link-cites t
"When non-nil, link cites to references."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'boolean
:safe #'booleanp)
(defcustom org-cite-csl-no-citelinks-backends '(ascii)
"List of export back-ends for which cite linking is disabled.
Cite linking for export back-ends derived from any of the back-ends listed here,
is also disabled."
:group 'org-cite
:package-version '(Org . "9.5")
:type '(repeat symbol))
;;;; Output-specific variables
(defcustom org-cite-csl-html-hanging-indent "1.5em"
"Size of hanging-indent for HTML output in valid CSS units."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'string
:safe #'stringp)
(defcustom org-cite-csl-html-label-width-per-char "0.6em"
"Character width in CSS units for calculating entry label widths.
Used only when `second-field-align' is activated by the used CSL style."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'string
:safe #'stringp)
(defcustom org-cite-csl-latex-hanging-indent "1.5em"
"Size of hanging-indent for LaTeX output in valid LaTeX units."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'string
:safe #'stringp)
;;; Internal variables
(defconst org-cite-csl--etc-dir
(let ((oc-root (file-name-directory (locate-library "oc"))))
(cond
;; First check whether it looks like we're running from the main
;; Org repository.
((let ((csl-org (expand-file-name "../etc/csl/" oc-root)))
(and (file-directory-p csl-org) csl-org)))
;; Next look for the directory alongside oc.el because package.el
;; and straight will put all of org-mode/lisp/ in org-mode/.
((let ((csl-pkg (expand-file-name "etc/csl/" oc-root)))
(and (file-directory-p csl-pkg) csl-pkg)))
;; Finally fall back the location used by shared system installs
;; and when running directly from Emacs repository.
(t
(expand-file-name "org/csl/" data-directory))))
"Directory containing CSL-related data files.")
(defconst org-cite-csl--fallback-locales-dir org-cite-csl--etc-dir
"Fallback CSL locale files directory.")
(defconst org-cite-csl--fallback-style-file
(expand-file-name "chicago-author-date.csl"
org-cite-csl--etc-dir)
"Default CSL style file, or nil.
If nil then the Chicago author-date style is used as a fallback.")
(defconst org-cite-csl--label-alist
'(("bk." . "book")
("bks." . "book")
("book" . "book")
("chap." . "chapter")
("chaps." . "chapter")
("chapter" . "chapter")
("col." . "column")
("cols." . "column")
("column" . "column")
("figure" . "figure")
("fig." . "figure")
("figs." . "figure")
("folio" . "folio")
("fol." . "folio")
("fols." . "folio")
("number" . "number")
("no." . "number")
("nos." . "number")
("line" . "line")
("l." . "line")
("ll." . "line")
("note" . "note")
("n." . "note")
("nn." . "note")
("opus" . "opus")
("op." . "opus")
("opp." . "opus")
("page" . "page")
("p" . "page")
("p." . "page")
("pp." . "page")
("paragraph" . "paragraph")
("para." . "paragraph")
("paras." . "paragraph")
("" . "paragraph")
("¶¶" . "paragraph")
("part" . "part")
("pt." . "part")
("pts." . "part")
("§" . "section")
("§§" . "section")
("section" . "section")
("sec." . "section")
("secs." . "section")
("sub verbo" . "sub verbo")
("s.v." . "sub verbo")
("s.vv." . "sub verbo")
("verse" . "verse")
("v." . "verse")
("vv." . "verse")
("volume" . "volume")
("vol." . "volume")
("vols." . "volume"))
"Alist mapping locator names to locators.")
(defconst org-cite-csl--label-regexp
;; Prior to Emacs-27.1 argument of `regexp' form must be a string literal.
;; It is the reason why `rx' is avoided here.
(rx-to-string
`(seq (or line-start space)
(regexp ,(regexp-opt (mapcar #'car org-cite-csl--label-alist) t))
(0+ digit)
(or word-end line-end space " "))
t)
"Regexp matching a label in a citation reference suffix.
Label is in match group 1.")
;;; Internal functions
(defun org-cite-csl--barf-without-citeproc ()
"Raise an error if Citeproc library is not loaded."
(unless (featurep 'citeproc)
(error "Citeproc library is not loaded")))
(defun org-cite-csl--note-style-p (info)
"Non-nil when bibliography style implies wrapping citations in footnotes.
INFO is the export state, as a property list."
(citeproc-style-cite-note
(citeproc-proc-style
(org-cite-csl--processor info))))
(defun org-cite-csl--create-structure-params (citation info)
"Return citeproc structure creation params for CITATION object.
STYLE is the citation style, as a string or nil. INFO is the export state, as
a property list."
(let ((style (org-cite-citation-style citation info)))
(pcase style
;; "author" style.
(`(,(or "author" "a") . ,variant)
(pcase variant
((or "caps" "c") '(:mode author-only :capitalize-first t))
((or "full" "f") '(:mode author-only :ignore-et-al t))
((or "caps-full" "cf") '(:mode author-only :capitalize-first t :ignore-et-al t))
(_ '(:mode author-only))))
;; "noauthor" style.
(`(,(or "noauthor" "na") . ,variant)
(pcase variant
((or "bare" "b") '(:mode suppress-author :suppress-affixes t))
((or "caps" "c") '(:mode suppress-author :capitalize-first t))
((or "bare-caps" "bc")
'(:mode suppress-author :suppress-affixes t :capitalize-first t))
(_ '(:mode suppress-author))))
;; "year" style.
(`(,(or "year" "y") . ,variant)
(pcase variant
((or "bare" "b") '(:mode year-only :suppress-affixes t))
(_ '(:mode year-only))))
;; "text" style.
(`(,(or "text" "t") . ,variant)
(pcase variant
((or "caps" "c") '(:mode textual :capitalize-first t))
((or "full" "f") '(:mode textual :ignore-et-al t))
((or "caps-full" "cf") '(:mode textual :ignore-et-al t :capitalize-first t))
(_ '(:mode textual))))
;; Default "nil" style.
(`(,_ . ,variant)
(pcase variant
((or "caps" "c") '(:capitalize-first t))
((or "bare" "b") '(:suppress-affixes t))
((or "bare-caps" "bc") '(:suppress-affixes t :capitalize-first t))
(_ nil)))
;; This should not happen.
(_ (error "Invalid style: %S" style)))))
(defun org-cite-csl--no-citelinks-p (info)
"Non-nil when export BACKEND should not create cite-reference links."
(or (not org-cite-csl-link-cites)
(and org-cite-csl-no-citelinks-backends
(apply #'org-export-derived-backend-p
(plist-get info :back-end)
org-cite-csl-no-citelinks-backends))
;; No references are being exported anyway.
(not (org-element-map (plist-get info :parse-tree) 'keyword
(lambda (k)
(equal "PRINT_BIBLIOGRAPHY" (org-element-property :key k)))
info t))))
(defun org-cite-csl--output-format (info)
"Return expected Citeproc's output format.
INFO is the export state, as a property list. The return value is a symbol
corresponding to one of the output formats supported by Citeproc: `html',
`latex', or `org'."
(let ((backend (plist-get info :back-end)))
(cond
((org-export-derived-backend-p backend 'html) 'html)
((org-export-derived-backend-p backend 'latex) 'latex)
(t 'org))))
(defun org-cite-csl--style-file (info)
"Return style file associated to current export process.
INFO is the export state, as a property list.
When file name is relative, expand it according to `org-cite-csl-styles-dir',
or raise an error if the variable is unset."
(pcase (org-cite-bibliography-style info)
('nil org-cite-csl--fallback-style-file)
((and (pred file-name-absolute-p) file) file)
((and (guard org-cite-csl-styles-dir) file)
(expand-file-name file org-cite-csl-styles-dir))
(other
(user-error "Cannot handle relative style file name: %S" other))))
(defun org-cite-csl--locale-getter ()
"Return a locale getter.
The getter looks for locales in `org-cite-csl-locales-dir' directory. If it
cannot find them, it retrieves the default \"en_US\" from
`org-cite-csl--fallback-locales-dir'."
(lambda (loc)
(or (and org-cite-csl-locales-dir
(ignore-errors
(funcall (citeproc-locale-getter-from-dir org-cite-csl-locales-dir)
loc)))
(funcall (citeproc-locale-getter-from-dir
org-cite-csl--fallback-locales-dir)
loc))))
(defun org-cite-csl--processor (info)
"Return Citeproc processor reading items from current bibliography.
INFO is the export state, as a property list.
Newly created processor is stored as the value of the `:cite-citeproc-processor'
property in INFO."
(or (plist-get info :cite-citeproc-processor)
(let* ((bibliography (plist-get info :bibliography))
(locale (or (plist-get info :language) "en_US"))
(processor
(citeproc-create
(org-cite-csl--style-file info)
(citeproc-hash-itemgetter-from-any bibliography)
(org-cite-csl--locale-getter)
locale)))
(plist-put info :cite-citeproc-processor processor)
processor)))
(defun org-cite-csl--parse-reference (reference info)
"Return Citeproc's structure associated to citation REFERENCE.
INFO is the export state, as a property list.
The result is a association list. Keys are: `id', `prefix',`suffix',
`location', `locator' and `label'."
(let (label location-start locator-start location locator prefix suffix)
;; Parse suffix. Insert it in a temporary buffer to find
;; different parts: pre-label, label, locator, location (label +
;; locator), and suffix.
(with-temp-buffer
(save-excursion
(insert (org-element-interpret-data
(org-element-property :suffix reference))))
(cond
((re-search-forward org-cite-csl--label-regexp nil t)
(setq location-start (match-beginning 0))
(setq label (cdr (assoc (match-string 1) org-cite-csl--label-alist)))
(goto-char (match-end 1))
(skip-chars-forward "[:space:] ")
(setq locator-start (point)))
((re-search-forward (rx digit) nil t)
(setq location-start (match-beginning 0))
(setq label "page")
(setq locator-start location-start))
(t
(setq suffix (org-element-property :suffix reference))))
;; Find locator's end, and suffix, if any. To that effect, look
;; for the last comma or digit after label, whichever comes
;; last.
(unless suffix
(goto-char (point-max))
(let ((re (rx (or "," (group digit)))))
(when (re-search-backward re location-start t)
(goto-char (or (match-end 1) (match-beginning 0)))
(setq location (buffer-substring location-start (point)))
(setq locator (org-trim (buffer-substring locator-start (point))))
;; Skip comma in suffix.
(setq suffix
(org-cite-parse-objects
(buffer-substring (match-end 0) (point-max))
t)))))
(setq prefix
(org-cite-concat
(org-element-property :prefix reference)
(and location-start
(org-cite-parse-objects
(buffer-substring 1 location-start)
t)))))
;; Return value.
(let ((export
(lambda (data)
(org-string-nw-p
(org-trim
;; When Citeproc exports to Org syntax, avoid mix and
;; matching output formats by also generating Org
;; syntax for prefix and suffix.
(if (eq 'org (org-cite-csl--output-format info))
(org-element-interpret-data data)
(org-export-data data info)))))))
`((id . ,(org-element-property :key reference))
(prefix . ,(funcall export prefix))
(suffix . ,(funcall export suffix))
(locator . ,locator)
(label . ,label)
(location . ,location)))))
(defun org-cite-csl--create-structure (citation info)
"Create Citeproc structure for CITATION object.
INFO is the export state, as a property list."
(let* ((cites (mapcar (lambda (r)
(org-cite-csl--parse-reference r info))
(org-cite-get-references citation)))
(footnote (org-cite-inside-footnote-p citation)))
;; Global prefix is inserted in front of the prefix of the first
;; reference.
(let ((global-prefix (org-element-property :prefix citation)))
(when global-prefix
(let* ((first (car cites))
(prefix-item (assq 'prefix first)))
(setcdr prefix-item
(concat (org-element-interpret-data global-prefix)
" "
(cdr prefix-item))))))
;; Global suffix is appended to the suffix of the last reference.
(let ((global-suffix (org-element-property :suffix citation)))
(when global-suffix
(let* ((last (org-last cites))
(suffix-item (assq 'suffix last)))
(setcdr suffix-item
(concat (cdr suffix-item)
" "
(org-element-interpret-data global-suffix))))))
;; Check if CITATION needs wrapping, i.e., it should be wrapped in
;; a footnote, but isn't yet.
(when (and (not footnote) (org-cite-csl--note-style-p info))
(org-cite-adjust-note citation info)
(setq footnote (org-cite-wrap-citation citation info)))
;; Return structure.
(apply #'citeproc-citation-create
`(:note-index
,(and footnote (org-export-get-footnote-number footnote info))
:cites ,cites
,@(org-cite-csl--create-structure-params citation info)))))
(defun org-cite-csl--rendered-citations (info)
"Return the rendered citations as an association list.
INFO is the export state, as a property list.
Return an alist (CITATION . OUTPUT) where CITATION object has been rendered as
OUTPUT using Citeproc."
(or (plist-get info :cite-citeproc-rendered-citations)
(let* ((citations (org-cite-list-citations info))
(processor (org-cite-csl--processor info))
(structures
(mapcar (lambda (c) (org-cite-csl--create-structure c info))
citations)))
(citeproc-append-citations structures processor)
(let* ((rendered
(citeproc-render-citations
processor
(org-cite-csl--output-format info)
(org-cite-csl--no-citelinks-p info)))
(result (seq-mapn #'cons citations rendered)))
(plist-put info :cite-citeproc-rendered-citations result)
result))))
;;; Export capability
(defun org-cite-csl-render-citation (citation _style _backend info)
"Export CITATION object.
INFO is the export state, as a property list."
(org-cite-csl--barf-without-citeproc)
(let ((output (cdr (assq citation (org-cite-csl--rendered-citations info)))))
(if (not (eq 'org (org-cite-csl--output-format info)))
output
;; Parse Org output to re-export it during the regular export
;; process.
(org-cite-parse-objects output))))
(defun org-cite-csl-render-bibliography (_keys _files _style _props _backend info)
"Export bibliography.
INFO is the export state, as a property list."
(org-cite-csl--barf-without-citeproc)
(pcase-let* ((format (org-cite-csl--output-format info))
(`(,output . ,parameters)
(citeproc-render-bib
(org-cite-csl--processor info)
format
(org-cite-csl--no-citelinks-p info))))
(pcase format
('html
(concat
(and (cdr (assq 'second-field-align parameters))
(let* ((max-offset (cdr (assq 'max-offset parameters)))
(char-width
(string-to-number org-cite-csl-html-label-width-per-char))
(char-width-unit
(progn
(string-match (number-to-string char-width)
org-cite-csl-html-label-width-per-char)
(substring org-cite-csl-html-label-width-per-char
(match-end 0)))))
(format
"<style>.csl-left-margin{float: left; padding-right: 0em;}
.csl-right-inline{margin: 0 0 0 %d%s;}</style>"
(* max-offset char-width)
char-width-unit)))
(and (cdr (assq 'hanging-indent parameters))
(format
"<style>.csl-entry{text-indent: -%s; margin-left: %s;}</style>"
org-cite-csl-html-hanging-indent
org-cite-csl-html-hanging-indent))
output))
('latex
(if (cdr (assq 'hanging-indent parameters))
(format "\\begin{hangparas}{%s}{1}\n%s\n\\end{hangparas}"
org-cite-csl-latex-hanging-indent
output)
output))
(_
;; Parse Org output to re-export it during the regular export
;; process.
(org-cite-parse-elements output)))))
(defun org-cite-csl-finalizer (output _keys _files _style _backend info)
"Add \"hanging\" package if missing from LaTeX output.
OUTPUT is the export document, as a string. INFO is the export state, as a
property list."
(org-cite-csl--barf-without-citeproc)
(if (not (eq 'latex (org-cite-csl--output-format info)))
output
(with-temp-buffer
(save-excursion (insert output))
(when (search-forward "\\begin{document}" nil t)
(goto-char (match-beginning 0))
;; Ensure that \citeprocitem is defined for citeproc-el.
(insert "\\makeatletter\n\\newcommand{\\citeprocitem}[2]{\\hyper@linkstart{cite}{citeproc_bib_item_#1}#2\\hyper@linkend}\n\\makeatother\n\n")
;; Ensure there is a \usepackage{hanging} somewhere or add one.
(let ((re (rx "\\usepackage" (opt "[" (*? nonl) "]") "{hanging}")))
(unless (re-search-backward re nil t)
(insert "\\usepackage[notquote]{hanging}\n"))))
(buffer-string))))
;;; Register `csl' processor
(org-cite-register-processor 'csl
:export-citation #'org-cite-csl-render-citation
:export-bibliography #'org-cite-csl-render-bibliography
:export-finalizer #'org-cite-csl-finalizer
:cite-styles
'((("author" "a") ("full" "f") ("caps" "c") ("caps-full" "cf"))
(("noauthor" "na") ("bare" "b") ("caps" "c") ("bare-caps" "bc"))
(("year" "y") ("bare" "b"))
(("text" "t") ("caps" "c") ("full" "f") ("caps-full" "cf"))
(("nil") ("bare" "b") ("caps" "c") ("bare-caps" "bc"))))
(provide 'oc-csl)
;;; oc-csl.el ends here