;;; oc-basic.el --- basic back-end for citations -*- 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:
;; The `basic' citation processor provides "activate", "follow", "export" and
;; "insert" capabilities.
;; "activate" capability re-uses default fontification, but provides additional
;; features on both correct and wrong keys according to the bibliography
;; defined in the document.
;; When the mouse is over a known key, it displays the corresponding
;; bibliography entry. Any wrong key, however, is highlighted with `error'
;; face. Moreover, moving the mouse onto it displays a list of suggested correct
;; keys, and pressing <mouse-1> on the faulty key will try to fix it according to
;; those suggestions.
;; On a citation key, "follow" capability moves point to the corresponding entry
;; in the current bibliography. Elsewhere on the citation, it asks the user to
;; follow any of the keys cited there, with completion.
;; "export" capability supports the following citation styles:
;;
;; - author (a), including caps (c) variant,
;; - noauthor (na) including bare (b) variant,
;; - text (t), including bare (b), caps (c), and bare-caps (bc) variants,
;; - note (ft, including bare (b), caps (c), and bare-caps (bc) variants,
;; - nocite (n)
;; - numeric (nb),
;; - default, including bare (b), caps (c), and bare-caps (bc) variants.
;;
;; It also supports the following styles for bibliography:
;; - plain
;; - numeric
;; - author-year (default)
;; "insert" capability inserts or edits (with completion) citation style or
;; citation reference keys. In an appropriate place, it offers to insert a new
;; citation. With a prefix argument, it removes the one at point.
;; It supports bibliography files in BibTeX (".bibtex"), biblatex (".bib") and
;; JSON (".json") format.
;; Disclaimer: this citation processor is meant to be a proof of concept, and
;; possibly a fall-back mechanism when nothing else is available. It is too
;; limited for any serious use case.
;;; Code:
(require 'org-macs)
(org-assert-version)
(require 'bibtex)
(require 'json)
(require 'map)
(require 'oc)
(require 'seq)
(declare-function org-open-at-point "org" (&optional arg))
(declare-function org-open-file "org" (path &optional in-emacs line search))
(declare-function org-element-interpret-data "org-element" (data))
(declare-function org-element-property "org-element" (property element))
(declare-function org-element-type "org-element" (element))
(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-raw-string "org-export" (contents))
;;; Customization
(defcustom org-cite-basic-sorting-field 'author
"Field used to sort bibliography items as a symbol, or nil."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'symbol
:safe #'symbolp)
(defcustom org-cite-basic-author-year-separator ", "
"String used to separate cites in an author-year configuration."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'string
:safe #'stringp)
(defcustom org-cite-basic-max-key-distance 2
"Maximum (Levenshtein) distance between a wrong key and its suggestions."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'integer
:safe #'integerp)
(defcustom org-cite-basic-author-column-end 25
"Column where author field ends in completion table, as an integer."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'integer
:safe #'integerp)
(defcustom org-cite-basic-column-separator " "
"Column separator in completion table, as a string."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'string
:safe #'stringp)
(defcustom org-cite-basic-mouse-over-key-face 'highlight
"Face used when mouse is over a citation key."
:group 'org-cite
:package-version '(Org . "9.5")
:type 'face
:safe #'facep)
;;; Internal variables
(defvar org-cite-basic--bibliography-cache nil
"Cache for parsed bibliography files.
This is an association list following the pattern:
(FILE-ID . ENTRIES)
FILE-ID is a cons cell (FILE . HASH), with FILE being the absolute file name of
the bibliography file, and HASH a hash of its contents.
ENTRIES is a hash table with citation references as keys and fields alist as
values.")
(defvar org-cite-basic--completion-cache (make-hash-table :test #'equal)
"Cache for key completion table.
This is an a hash-table.")
;;; Internal functions
(defun org-cite-basic--parse-json ()
"Parse JSON entries in the current buffer.
Return a hash table with citation references as keys and fields alist as values."
(let ((entries (make-hash-table :test #'equal)))
(let ((json-array-type 'list)
(json-key-type 'symbol))
(dolist (item (json-read))
(puthash (cdr (assq 'id item))
(mapcar (pcase-lambda (`(,field . ,value))
(pcase field
('author
;; Author is an array of objects, each
;; of them designing a person. These
;; objects may contain multiple
;; properties, but for this basic
;; processor, we'll focus on `given' and
;; `family'.
;;
;; For compatibility with BibTeX, add
;; "and" between authors.
(cons 'author
(mapconcat
(lambda (alist)
(concat (alist-get 'family alist)
" "
(alist-get 'given alist)))
value
" and ")))
('issued
;; Date are expressed as an array
;; (`date-parts') or a "string (`raw'
;; or `literal'). In both cases,
;; extract the year and associate it
;; to `year' field, for compatibility
;; with BibTeX format.
(let ((date (or (alist-get 'date-parts value)
(alist-get 'literal value)
(alist-get 'raw value))))
(cons 'year
(cond
((consp date)
(let ((year (caar date)))
(cond
((numberp year) (number-to-string year))
((stringp year) year)
(t
(error
"First element of CSL-JSON date-parts should be a number or string, got %s: %S"
(type-of year) year)))))
((stringp date)
(replace-regexp-in-string
(rx
(minimal-match (zero-or-more anything))
(group-n 1 (repeat 4 digit))
(zero-or-more anything))
(rx (backref 1))
date))
(t
(error "Unknown CSL-JSON date format: %S"
value))))))
(_
(cons field value))))
item)
entries))
entries)))
(defun org-cite-basic--parse-bibtex (dialect)
"Parse BibTeX entries in the current buffer.
DIALECT is the BibTeX dialect used. See `bibtex-dialect'.
Return a hash table with citation references as keys and fields alist as values."
(let ((entries (make-hash-table :test #'equal))
(bibtex-sort-ignore-string-entries t))
(bibtex-set-dialect dialect t)
;; Throw an error if bibliography is malformed.
(unless (bibtex-validate)
(user-error "Malformed bibliography at %S"
(or (buffer-file-name) (current-buffer))))
(bibtex-map-entries
(lambda (key &rest _)
;; Normalize entries: field names are turned into symbols
;; including special "=key=" and "=type=", and consecutive
;; white spaces are removed from values.
(puthash key
(mapcar
(pcase-lambda (`(,field . ,value))
(pcase field
("=key=" (cons 'id key))
("=type=" (cons 'type value))
(_
(cons
(intern (downcase field))
(replace-regexp-in-string "[ \t\n]+" " " value)))))
;; Parse, substituting the @string replacements.
;; See Emacs bug#56475 discussion.
(let ((bibtex-string-files `(,(buffer-file-name)))
(bibtex-expand-strings t))
(bibtex-parse-entry t)))
entries)))
entries))
(defvar org-cite-basic--file-id-cache nil
"Hash table linking files to their hash.")
(defun org-cite-basic--parse-bibliography (&optional info)
"List all entries available in the buffer.
Each association follows the pattern
(FILE . ENTRIES)
where FILE is the absolute file name of the BibTeX file, and ENTRIES is a hash
table where keys are references and values are association lists between fields,
as symbols, and values as strings or nil.
Optional argument INFO is the export state, as a property list."
(unless (hash-table-p org-cite-basic--file-id-cache)
(setq org-cite-basic--file-id-cache (make-hash-table :test #'equal)))
(if (plist-member info :cite-basic/bibliography)
(plist-get info :cite-basic/bibliography)
(let ((results nil))
(dolist (file (org-cite-list-bibliography-files))
(when (file-readable-p file)
(with-temp-buffer
(when (or (org-file-has-changed-p file)
(not (gethash file org-cite-basic--file-id-cache)))
(insert-file-contents file)
(set-visited-file-name file t)
(puthash file (org-buffer-hash) org-cite-basic--file-id-cache))
(condition-case nil
(unwind-protect
(let* ((file-id (cons file (gethash file org-cite-basic--file-id-cache)))
(entries
(or (cdr (assoc file-id org-cite-basic--bibliography-cache))
(let ((table
(pcase (file-name-extension file)
("json" (org-cite-basic--parse-json))
("bib" (org-cite-basic--parse-bibtex 'biblatex))
("bibtex" (org-cite-basic--parse-bibtex 'BibTeX))
(ext
(user-error "Unknown bibliography extension: %S"
ext)))))
(push (cons file-id table) org-cite-basic--bibliography-cache)
table))))
(push (cons file entries) results))
(set-visited-file-name nil t))
(error (setq org-cite-basic--file-id-cache nil))))))
(when info (plist-put info :cite-basic/bibliography results))
results)))
(defun org-cite-basic--key-number (key info)
"Return number associated to cited KEY.
INFO is the export state, as a property list."
(let ((predicate
(org-cite-basic--field-less-p org-cite-basic-sorting-field info)))
(org-cite-key-number key info predicate)))
(defun org-cite-basic--all-keys ()
"List all keys available in current bibliography."
(seq-mapcat (pcase-lambda (`(,_ . ,entries))
(map-keys entries))
(org-cite-basic--parse-bibliography)))
(defun org-cite-basic--get-entry (key &optional info)
"Return BibTeX entry for KEY, as an association list.
When non-nil, INFO is the export state, as a property list."
(catch :found
(pcase-dolist (`(,_ . ,entries) (org-cite-basic--parse-bibliography info))
(let ((entry (gethash key entries)))
(when entry (throw :found entry))))
nil))
(defun org-cite-basic--get-field (field entry-or-key &optional info raw)
"Return FIELD value for ENTRY-OR-KEY, or nil.
FIELD is a symbol. ENTRY-OR-KEY is either an association list, as returned by
`org-cite-basic--get-entry', or a string representing a citation key.
Optional argument INFO is the export state, as a property list.
Return value may be nil or a string. If current export back-end is derived
from `latex', return a raw string instead, unless optional argument RAW is
non-nil."
(let ((value
(cdr
(assq field
(pcase entry-or-key
((pred stringp)
(org-cite-basic--get-entry entry-or-key info))
((pred consp)
entry-or-key)
(_
(error "Wrong value for ENTRY-OR-KEY: %S" entry-or-key)))))))
(if (and value
(not raw)
(org-export-derived-backend-p (plist-get info :back-end) 'latex))
(org-export-raw-string value)
value)))
(defun org-cite-basic--shorten-names (names)
"Return a list of family names from a list of full NAMES.
To better accomomodate corporate names, this will only shorten
personal names of the form \"family, given\"."
(when (stringp names)
(mapconcat
(lambda (name)
(if (eq 1 (length name))
(cdr (split-string name))
(car (split-string name ", "))))
(split-string names " and ")
", ")))
(defun org-cite-basic--number-to-suffix (n)
"Compute suffix associated to number N.
This is used for disambiguation."
(let ((result nil))
(apply #'string
(mapcar (lambda (n) (+ 97 n))
(catch :complete
(while t
(push (% n 26) result)
(setq n (/ n 26))
(cond
((= n 0) (throw :complete result))
((< n 27) (throw :complete (cons (1- n) result)))
((= n 27) (throw :complete (cons 0 (cons 0 result))))
(t nil))))))))
(defun org-cite-basic--get-author (entry-or-key &optional info raw)
"Return author associated to ENTRY-OR-KEY.
ENTRY-OR-KEY, INFO and RAW arguments are the same arguments as
used in `org-cite-basic--get-field', which see.
Author is obtained from the \"author\" field, if available, or
from the \"editor\" field otherwise."
(or (org-cite-basic--get-field 'author entry-or-key info raw)
(org-cite-basic--get-field 'editor entry-or-key info raw)))
(defun org-cite-basic--get-year (entry-or-key info &optional no-suffix)
"Return year associated to ENTRY-OR-KEY.
ENTRY-OR-KEY is either an association list, as returned by
`org-cite-basic--get-entry', or a string representing a citation
key. INFO is the export state, as a property list.
Year is obtained from the \"year\" field, if available, or from
the \"date\" field if it starts with a year pattern.
Unlike `org-cite-basic--get-field', this function disambiguates
author-year patterns by adding a letter suffix to the year when
necessary, unless optional argument NO-SUFFIX is non-nil."
;; The cache is an association list with the following structure:
;;
;; (AUTHOR-YEAR . KEY-SUFFIX-ALIST).
;;
;; AUTHOR-YEAR is the author year pair associated to current entry
;; or key.
;;
;; KEY-SUFFIX-ALIST is an association (KEY . SUFFIX), where KEY is
;; the cite key, as a string, and SUFFIX is the generated suffix
;; string, or the empty string.
(let* ((author (org-cite-basic--get-author entry-or-key info 'raw))
(year
(or (org-cite-basic--get-field 'year entry-or-key info 'raw)
(let ((date
(org-cite-basic--get-field 'date entry-or-key info t)))
(and (stringp date)
(string-match (rx string-start
(group (= 4 digit))
(or string-end (not digit)))
date)
(match-string 1 date)))))
(cache-key (cons author year))
(key
(pcase entry-or-key
((pred stringp) entry-or-key)
((pred consp) (cdr (assq 'id entry-or-key)))
(_ (error "Wrong value for ENTRY-OR-KEY: %S" entry-or-key))))
(cache (plist-get info :cite-basic/author-date-cache)))
(pcase (assoc cache-key cache)
('nil
(let ((value (cons cache-key (list (cons key "")))))
(plist-put info :cite-basic/author-date-cache (cons value cache))
year))
(`(,_ . ,alist)
(let ((suffix
(or (cdr (assoc key alist))
(let ((new (org-cite-basic--number-to-suffix
(1- (length alist)))))
(push (cons key new) alist)
new))))
(if no-suffix year (concat year suffix)))))))
(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'.
Optional argument INFO is the export state, as a property list."
(let ((author (org-cite-basic--get-author entry info))
(title (org-cite-basic--get-field 'title entry info))
(from
(or (org-cite-basic--get-field 'publisher entry info)
(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)) "."))))))
;;; "Activate" capability
(defun org-cite-basic--close-keys (key keys)
"List cite keys close to KEY in terms of string distance."
(seq-filter (lambda (k)
(>= org-cite-basic-max-key-distance
(org-string-distance k key)))
keys))
(defun org-cite-basic--set-keymap (beg end suggestions)
"Set keymap on citation key between BEG and END positions.
When the key is know, SUGGESTIONS is nil. Otherwise, it may be
a list of replacement keys, as strings, which will be offered as
substitutes for the unknown key. Finally, it may be the symbol
`all'."
(let ((km (make-sparse-keymap)))
(define-key km (kbd "<mouse-1>")
(pcase suggestions
('nil #'org-open-at-point)
('all #'org-cite-insert)
(_
(lambda ()
(interactive)
(save-excursion
(goto-char beg)
(delete-region beg end)
(insert
"@"
(if (= 1 (length suggestions))
(car suggestions)
(completing-read "Did you mean: "
suggestions nil t))))))))
(put-text-property beg end 'keymap km)))
(defun org-cite-basic-activate (citation)
"Set various text properties on CITATION object.
Fontify whole citation with `org-cite' face. Fontify key with `error' face
when it does not belong to known keys. Otherwise, use `org-cite-key' face.
Moreover, when mouse is on a known key, display the corresponding bibliography.
On a wrong key, suggest a list of possible keys, and offer to substitute one of
them with a mouse click."
(pcase-let ((`(,beg . ,end) (org-cite-boundaries citation))
(keys (org-cite-basic--all-keys)))
(put-text-property beg end 'font-lock-multiline t)
(add-face-text-property beg end 'org-cite)
(dolist (reference (org-cite-get-references citation))
(pcase-let* ((`(,beg . ,end) (org-cite-key-boundaries reference))
(key (org-element-property :key reference)))
;; Highlight key on mouse over.
(put-text-property beg end
'mouse-face
org-cite-basic-mouse-over-key-face)
(if (member key keys)
;; Activate a correct key. Face is `org-cite-key' and
;; `help-echo' displays bibliography entry, for reference.
;; <mouse-1> calls `org-open-at-point'.
(let* ((entry (org-cite-basic--get-entry key))
(bibliography-entry
(org-element-interpret-data
(org-cite-basic--print-entry entry "plain"))))
(add-face-text-property beg end 'org-cite-key)
(put-text-property beg end 'help-echo bibliography-entry)
(org-cite-basic--set-keymap beg end nil))
;; Activate a wrong key. Face is `error', `help-echo'
;; displays possible suggestions.
(add-face-text-property beg end 'error)
(let ((close-keys (org-cite-basic--close-keys key keys)))
(when close-keys
(put-text-property beg end 'help-echo
(concat "Suggestions (mouse-1 to substitute): "
(mapconcat #'identity close-keys " "))))
;; When the are close know keys, <mouse-1> provides
;; completion to fix the current one. Otherwise, call
;; `org-cite-insert'.
(org-cite-basic--set-keymap beg end (or close-keys 'all))))))))
;;; "Export" capability
(defun org-cite-basic--format-author-year (citation format-cite format-ref info)
"Format CITATION object according to author-year format.
FORMAT-CITE is a function of three arguments: the global prefix, the contents,
and the global suffix. All arguments can be strings or secondary strings.
FORMAT-REF is a function of four arguments: the reference prefix, as a string or
secondary string, the author, the year, and the reference suffix, as a string or
secondary string.
INFO is the export state, as a property list."
(org-export-data
(funcall format-cite
(org-element-property :prefix citation)
(org-cite-mapconcat
(lambda (ref)
(let ((k (org-element-property :key ref))
(prefix (org-element-property :prefix ref))
(suffix (org-element-property :suffix ref)))
(funcall format-ref
prefix
(org-cite-basic--get-author k info)
(org-cite-basic--get-year k info)
suffix)))
(org-cite-get-references citation)
org-cite-basic-author-year-separator)
(org-element-property :suffix citation))
info))
(defun org-cite-basic--citation-numbers (citation info)
"Return numbers associated to references in CITATION object.
INFO is the export state as a property list."
(let* ((numbers
(sort (mapcar (lambda (k) (org-cite-basic--key-number k info))
(org-cite-get-references citation t))
#'<))
(last (car numbers))
(result (list (number-to-string (pop numbers)))))
;; Use compact number references, i.e., "1, 2, 3" becomes "1-3".
(while numbers
(let ((current (pop numbers))
(next (car numbers)))
(cond
((and next
(= current (1+ last))
(= current (1- next)))
(unless (equal "-" (car result))
(push "-" result)))
((equal "-" (car result))
(push (number-to-string current) result))
(t
(push (format ", %d" current) result)))
(setq last current)))
(apply #'concat (nreverse result))))
(defun org-cite-basic--field-less-p (field info)
"Return a sort predicate comparing FIELD values for two citation keys.
INFO is the export state, as a property list."
(and field
(lambda (a b)
(string-collate-lessp
(org-cite-basic--get-field field a info 'raw)
(org-cite-basic--get-field field b info 'raw)
nil t))))
(defun org-cite-basic--sort-keys (keys info)
"Sort KEYS by author name.
INFO is the export communication channel, as a property list."
(let ((predicate (org-cite-basic--field-less-p org-cite-basic-sorting-field info)))
(if predicate
(sort keys predicate)
keys)))
(defun org-cite-basic-export-citation (citation style _ info)
"Export CITATION object.
STYLE is the expected citation style, as a pair of strings or nil. INFO is the
export communication channel, as a property list."
(let ((has-variant-p
(lambda (variant type)
;; Non-nil when style VARIANT has TYPE. TYPE is either
;; `bare' or `caps'.
(member variant
(pcase type
('bare '("bare" "bare-caps" "b" "bc"))
('caps '("caps" "bare-caps" "c" "bc"))
(_ (error "Invalid variant type: %S" type)))))))
(pcase style
;; "author" style.
(`(,(or "author" "a") . ,variant)
(let ((caps (member variant '("caps" "c"))))
(org-export-data
(mapconcat
(lambda (key)
(let ((author (org-cite-basic--get-author key info)))
(if caps (capitalize author) author)))
(org-cite-get-references citation t)
org-cite-basic-author-year-separator)
info)))
;; "noauthor" style.
(`(,(or "noauthor" "na") . ,variant)
(format (if (funcall has-variant-p variant 'bare) "%s" "(%s)")
(mapconcat (lambda (key) (org-cite-basic--get-year key info))
(org-cite-get-references citation t)
org-cite-basic-author-year-separator)))
;; "nocite" style.
(`(,(or "nocite" "n") . ,_) nil)
;; "text" and "note" styles.
(`(,(and (or "text" "note" "t" "ft") style) . ,variant)
(when (and (member style '("note" "ft"))
(not (org-cite-inside-footnote-p citation)))
(org-cite-adjust-note citation info)
(org-cite-wrap-citation citation info))
(let ((bare (funcall has-variant-p variant 'bare))
(caps (funcall has-variant-p variant 'caps)))
(org-cite-basic--format-author-year
citation
(lambda (p c s) (org-cite-concat p c s))
(lambda (p a y s)
(org-cite-concat p
(if caps (capitalize a) a)
(if bare " " " (")
y s
(and (not bare) ")")))
info)))
;; "numeric" style.
;;
;; When using this style on citations with multiple references,
;; use global affixes and ignore local ones.
(`(,(or "numeric" "nb") . ,_)
(pcase-let ((`(,prefix . ,suffix) (org-cite-main-affixes citation)))
(org-export-data
(org-cite-concat
"(" prefix (org-cite-basic--citation-numbers citation info) suffix ")")
info)))
;; Default ("nil") style.
(`(,_ . ,variant)
(let ((bare (funcall has-variant-p variant 'bare))
(caps (funcall has-variant-p variant 'caps)))
(org-cite-basic--format-author-year
citation
(lambda (p c s)
(org-cite-concat (and (not bare) "(") p c s (and (not bare) ")")))
(lambda (p a y s)
(org-cite-concat p (if caps (capitalize a) a) ", " y s))
info)))
;; This should not happen.
(_ (error "Invalid style: %S" style)))))
(defun org-cite-basic-export-bibliography (keys _files style _props backend info)
"Generate bibliography.
KEYS is the list of cited keys, as strings. STYLE is the expected bibliography
style, as a string. BACKEND is the export back-end, as a symbol. INFO is the
export state, as a property list."
(mapconcat
(lambda (entry)
(org-export-data
(org-cite-make-paragraph
(and (org-export-derived-backend-p backend 'latex)
(org-export-raw-string "\\noindent\n"))
(org-cite-basic--print-entry entry style info))
info))
(delq nil
(mapcar
(lambda (k) (org-cite-basic--get-entry k info))
(org-cite-basic--sort-keys keys info)))
"\n"))
;;; "Follow" capability
(defun org-cite-basic-goto (datum _)
"Follow citation or citation reference DATUM.
When DATUM is a citation reference, open bibliography entry referencing
the citation key. Otherwise, select which key to follow among all keys
present in the citation."
(let* ((key
(if (eq 'citation-reference (org-element-type datum))
(org-element-property :key datum)
(pcase (org-cite-get-references datum t)
(`(,key) key)
(keys
(or (completing-read "Select citation key: " keys nil t)
(user-error "Aborted"))))))
(file
(pcase (seq-find (pcase-lambda (`(,_ . ,entries))
(gethash key entries))
(org-cite-basic--parse-bibliography))
(`(,f . ,_) f)
(_ (user-error "Cannot find citation key: %S" key)))))
(org-open-file file '(4))
(pcase (file-name-extension file)
("json"
;; `rx' can not be used with Emacs <27.1 since `literal' form
;; is not supported.
(let ((regexp (rx-to-string `(seq "\"id\":" (0+ (any "[ \t]")) "\"" ,key "\"") t)))
(goto-char (point-min))
(re-search-forward regexp)
(search-backward "{")))
(_
(bibtex-set-dialect)
(bibtex-search-entry key)))))
;;; "Insert" capability
(defun org-cite-basic--complete-style (_)
"Offer completion for style.
Return chosen style as a string."
(let* ((styles
(mapcar (pcase-lambda (`((,style . ,_) . ,_))
style)
(org-cite-supported-styles))))
(pcase styles
(`(,style) style)
(_ (completing-read "Style (\"\" for default): " styles nil t)))))
(defun org-cite-basic--key-completion-table ()
"Return completion table for cite keys, as a hash table.
In this hash table, keys are a strings with author, date, and
title of the reference. Values are the cite keys.
Return nil if there are no bibliography files or no entries."
;; Populate bibliography cache.
(let ((entries (org-cite-basic--parse-bibliography)))
(cond
((null entries) nil) ;no bibliography files
((gethash entries org-cite-basic--completion-cache)
org-cite-basic--completion-cache)
(t
(clrhash org-cite-basic--completion-cache)
(dolist (key (org-cite-basic--all-keys))
(let* ((entry (org-cite-basic--get-entry
key
;; Supply pre-calculated bibliography to avoid
;; performance degradation.
(list :cite-basic/bibliography entries)))
(completion
(concat
(let ((author (org-cite-basic--get-author entry nil 'raw)))
(if author
(truncate-string-to-width
(replace-regexp-in-string " and " "; " author)
org-cite-basic-author-column-end nil ?\s)
(make-string org-cite-basic-author-column-end ?\s)))
org-cite-basic-column-separator
(let ((date (org-cite-basic--get-year entry nil 'no-suffix)))
(format "%4s" (or date "")))
org-cite-basic-column-separator
(org-cite-basic--get-field 'title entry nil t))))
(puthash completion key org-cite-basic--completion-cache)))
(unless (map-empty-p org-cite-basic--completion-cache) ;no key
(puthash entries t org-cite-basic--completion-cache)
org-cite-basic--completion-cache)))))
(defun org-cite-basic--complete-key (&optional multiple)
"Prompt for a reference key and return a citation reference string.
When optional argument MULTIPLE is non-nil, prompt for multiple
keys, until one of them is nil. Then return the list of
reference strings selected.
Raise an error when no bibliography is set in the buffer."
(let* ((table
(or (org-cite-basic--key-completion-table)
(user-error "No bibliography set")))
(prompt
(lambda (text)
(completing-read text table nil t))))
(if (null multiple)
(let ((key (gethash (funcall prompt "Key: ") table)))
(org-string-nw-p key))
(let* ((keys nil)
(build-prompt
(lambda ()
(if keys
(format "Key (empty input exits) %s: "
(mapconcat #'identity (reverse keys) ";"))
"Key (empty input exits): "))))
(let ((key (funcall prompt (funcall build-prompt))))
(while (org-string-nw-p key)
(push (gethash key table) keys)
(setq key (funcall prompt (funcall build-prompt)))))
keys))))
;;; Register processor
(org-cite-register-processor 'basic
:activate #'org-cite-basic-activate
:export-citation #'org-cite-basic-export-citation
:export-bibliography #'org-cite-basic-export-bibliography
:follow #'org-cite-basic-goto
:insert (org-cite-make-insert-processor #'org-cite-basic--complete-key
#'org-cite-basic--complete-style)
:cite-styles
'((("author" "a") ("caps" "c"))
(("noauthor" "na") ("bare" "b"))
(("nocite" "n"))
(("note" "ft") ("bare-caps" "bc") ("caps" "c"))
(("numeric" "nb"))
(("text" "t") ("bare-caps" "bc") ("caps" "c"))
(("nil") ("bare" "b") ("bare-caps" "bc") ("caps" "c"))))
(provide 'oc-basic)
;;; oc-basic.el ends here