esv.el: add a package for integrating into Emacs

esv.el

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+;;; esv.el --- read the Bible from Emacs  -*- lexical-binding:t -*-
+
+(defgroup esv nil
+  "Read the Bible."
+  :prefix "esv-"
+  :group 'applications)
+
+(defcustom esv-columns 72
+  "Length of each line output by `esv'."
+  :type 'natnum
+  :group 'esv)
+(defcustom esv-mode-hook nil
+  "Hook run after entering `esv-mode'."
+  :type 'hook
+  :group 'esv)
+(defcustom esv-process "esv"
+  "Name of the process created by `esv'."
+  :type 'string
+  :group 'esv)
+(defcustom esv-program "esv"
+  "Path to or name of the program started by `esv'."
+  :type 'string
+  :group 'esv)
+
+(define-derived-mode esv-mode text-mode "ESV-Bible"
+  "Major mode used for reading the Bible with `esv'."
+  :group 'esv
+
+  (read-only-mode))
+
+(defun esv (book verses)
+  "Fetch the Bible passage identified by BOOK and VERSES.
+The result will be redirected to a buffer specified by `esv-buffer'."
+  (interactive "MBook: \nMVerses: ")
+  (let ((buffer (concat book " " verses)))
+    (catch 'buffer-exists
+      (when (get-buffer buffer)
+        (message "Buffer `%s' already exists" buffer)
+        (throw 'buffer-exists nil))
+      ;; execute esv
+      (call-process esv-program nil buffer t
+        ;; arguments
+        (format "-l%d" esv-columns) book verses)
+      ;; display buffer in another window
+      (display-buffer buffer)
+      ;; move point to the beginning of the buffer
+      (with-current-buffer buffer
+        (esv-mode)
+        (goto-char (point-min)))
+      (set-window-start (get-buffer-window buffer) (point-min))
+      t)))
+
+(provide 'esv)