[elpa] externals/denote 0e83bee5b7 141/355: Add denote-retrieve for internal purposes

[ELPA Syncer]

branch: externals/denote
commit 0e83bee5b75349288c68bbd83f6f2af82e1a8e0a
Author: Protesilaos Stavrou <info@protesilaos.com>
Commit: Protesilaos Stavrou <info@protesilaos.com>

    Add denote-retrieve for internal purposes
    
    Basicallly we shall use it to extract data from a file.
---
 denote-retrieve.el | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/denote-retrieve.el b/denote-retrieve.el
new file mode 100644
index 0000000000..8ee9037b75
--- /dev/null
+++ b/denote-retrieve.el
@@ -0,0 +1,74 @@
+;;; denote-retrieve.el --- Link facility for Denote -*- lexical-binding: t -*-
+
+;; Copyright (C) 2022  Free Software Foundation, Inc.
+
+;; Author: Protesilaos Stavrou <info@protesilaos.com>
+;; URL: https://git.sr.ht/~protesilaos/denote
+;; Version: 0.1.0
+;; Package-Requires: ((emacs "27.1"))
+
+;; This file is NOT part of GNU Emacs.
+
+;; This program 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.
+;;
+;; This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Used internally by commands that operate on file contents.
+
+;;; Code:
+
+(require 'denote)
+
+(defconst denote-retrieve--title-regexp
+  "^\\(?:#\\+\\)?\\(?:title:\\)[\s\t]+\\(?1:.*\\)"
+  "Regular expression for title key and value.
+
+The match that needs to be extracted is explicityly marked as
+group 1.  `denote-retrieve--find-value' uses the group 1 sting.")
+
+(defconst denote-retrieve--identifier-regexp
+  "^.?.?\\b\\(?:identifier\\|ID\\)\\s-*[:=]\\s-*\"?\\(?1:[0-9T]+\\)"
+  "Regular expression for filename key and value.
+
+The match that needs to be extracted is explicityly marked as
+group 1.  `denote-retrieve--find-value' uses the group 1 sting.")
+
+(defun denote-retrieve--search (regexp)
+  "Search for REGEXP in the current buffer."
+  (save-excursion
+    (save-restriction
+      (widen)
+      (goto-char (point-min))
+      (re-search-forward regexp nil t 1)
+      (match-string-no-properties 1))))
+
+(defun denote-retrieve--find-value (regexp)
+  "Return value from REGEXP by searching the file."
+  (or (denote-retrieve--search regexp)
+      (user-error "Cannot retrieve %s" regexp)))
+
+(defun denote-retrieve--retrieve-value (file regexp)
+  "Return REGEXP value from FILE.
+FILE is a note in the variable `denote-directory'."
+  (let ((default-directory (denote-directory)))
+    (with-temp-buffer
+      (insert-file-contents-literally file)
+      (denote-retrieve--find-value regexp))))
+
+(defun denote-retrieve--read-file-prompt ()
+  "Prompt for regular file in variable `denote-directory'."
+  (read-file-name "Select note: " (denote-directory) nil t nil 
#'file-regular-p))
+
+(provide 'denote-retrieve)
+;;; denote-retrieve.el ends here