code.delx.au - gnu-emacs-elpa/blob - packages/vlf/vlf-write.el

   1 ;;; vlf-write.el --- Saving functionality for VLF  -*- lexical-binding: t -*-
   2
   3 ;; Copyright (C) 2014 Free Software Foundation, Inc.
   4
   5 ;; Keywords: large files, saving
   6 ;; Author: Andrey Kotlarski <m00naticus@gmail.com>
   7 ;; URL: https://github.com/m00natic/vlfi
   8
   9 ;; This file is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 3, or (at your option)
  12 ;; any later version.
  13
  14 ;; This file is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  21 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Commentary:
  25 ;; This package provides the `vlf-write' command which takes care of
  26 ;; saving changes where only part of file is viewed and updated.
  27
  28 ;;; Code:
  29
  30 (require 'vlf-base)
  31
  32 (defun vlf-write ()
  33   "Write current chunk to file.  Always return true to disable save.
  34 If changing size of chunk, shift remaining file content."
  35   (interactive)
  36   (when (and (buffer-modified-p)
  37              (or (verify-visited-file-modtime (current-buffer))
  38                  (y-or-n-p "File has changed since visited or saved.\
  39   Save anyway? ")))
  40     (widen)
  41     (run-hook-with-args 'vlf-before-batch-functions 'write)
  42     (let ((hexl (derived-mode-p 'hexl-mode)))
  43       (when hexl
  44         (if (consp buffer-undo-list)
  45             (setq buffer-undo-list nil))
  46         (hexl-mode-exit))
  47       (if (zerop vlf-file-size)           ;new file
  48           (progn (write-region nil nil buffer-file-name vlf-start-pos t)
  49                  (setq vlf-file-size (vlf-get-file-size
  50                                       buffer-file-truename)
  51                        vlf-end-pos vlf-file-size)
  52                  (vlf-update-buffer-name))
  53         (let* ((region-length (length (encode-coding-region
  54                                        (point-min) (point-max)
  55                                        buffer-file-coding-system t)))
  56                (size-change (- vlf-end-pos vlf-start-pos
  57                                region-length)))
  58           (if (zerop size-change)
  59               (write-region nil nil buffer-file-name vlf-start-pos t)
  60             (let ((tramp-verbose (if (boundp 'tramp-verbose)
  61                                      (min tramp-verbose 2)))
  62                   (pos (point))
  63                   (font-lock font-lock-mode))
  64               (font-lock-mode 0)
  65               (if (< 0 size-change)
  66                   (vlf-file-shift-back size-change)
  67                 (vlf-file-shift-forward (- size-change)))
  68               (if font-lock (font-lock-mode 1))
  69               (vlf-move-to-chunk-2 vlf-start-pos
  70                                    (if (< (- vlf-end-pos vlf-start-pos)
  71                                           vlf-batch-size)
  72                                        (+ vlf-start-pos vlf-batch-size)
  73                                      vlf-end-pos))
  74               (vlf-update-buffer-name)
  75               (goto-char pos)))))
  76       (if hexl (hexl-mode)))
  77     (run-hook-with-args 'vlf-after-batch-functions 'write))
  78   t)
  79
  80 (defun vlf-file-shift-back (size-change)
  81   "Shift file contents SIZE-CHANGE bytes back."
  82   (write-region nil nil buffer-file-name vlf-start-pos t)
  83   (let ((read-start-pos vlf-end-pos)
  84         (coding-system-for-write 'no-conversion)
  85         (reporter (make-progress-reporter "Adjusting file content..."
  86                                           vlf-end-pos
  87                                           vlf-file-size)))
  88     (vlf-with-undo-disabled
  89      (while (vlf-shift-batch read-start-pos (- read-start-pos
  90                                                size-change))
  91        (setq read-start-pos (+ read-start-pos vlf-batch-size))
  92        (progress-reporter-update reporter read-start-pos))
  93      ;; pad end with space
  94      (erase-buffer)
  95      (vlf-verify-size t)
  96      (insert-char 32 size-change))
  97     (write-region nil nil buffer-file-name (- vlf-file-size
  98                                               size-change) t)
  99     (progress-reporter-done reporter)))
 100
 101 (defun vlf-shift-batch (read-pos write-pos)
 102   "Read `vlf-batch-size' bytes from READ-POS and write them \
 103 back at WRITE-POS.  Return nil if EOF is reached, t otherwise."
 104   (erase-buffer)
 105   (vlf-verify-size t)
 106   (let ((read-end (+ read-pos vlf-batch-size)))
 107     (insert-file-contents-literally buffer-file-name nil
 108                                     read-pos
 109                                     (min vlf-file-size read-end))
 110     (write-region nil nil buffer-file-name write-pos 0)
 111     (< read-end vlf-file-size)))
 112
 113 (defun vlf-file-shift-forward (size-change)
 114   "Shift file contents SIZE-CHANGE bytes forward.
 115 Done by saving content up front and then writing previous batch."
 116   (let ((read-size (max (/ vlf-batch-size 2) size-change))
 117         (read-pos vlf-end-pos)
 118         (write-pos vlf-start-pos)
 119         (reporter (make-progress-reporter "Adjusting file content..."
 120                                           vlf-start-pos
 121                                           vlf-file-size)))
 122     (vlf-with-undo-disabled
 123      (when (vlf-shift-batches read-size read-pos write-pos t)
 124        (setq write-pos (+ read-pos size-change)
 125              read-pos (+ read-pos read-size))
 126        (progress-reporter-update reporter write-pos)
 127        (let ((coding-system-for-write 'no-conversion))
 128          (while (vlf-shift-batches read-size read-pos write-pos nil)
 129            (setq write-pos (+ read-pos size-change)
 130                  read-pos (+ read-pos read-size))
 131            (progress-reporter-update reporter write-pos)))))
 132     (progress-reporter-done reporter)))
 133
 134 (defun vlf-shift-batches (read-size read-pos write-pos hide-read)
 135   "Append READ-SIZE bytes of file starting at READ-POS.
 136 Then write initial buffer content to file at WRITE-POS.
 137 If HIDE-READ is non nil, temporarily hide literal read content.
 138 Return nil if EOF is reached, t otherwise."
 139   (vlf-verify-size t)
 140   (let ((read-more (< read-pos vlf-file-size))
 141         (start-write-pos (point-min))
 142         (end-write-pos (point-max)))
 143     (when read-more
 144       (goto-char end-write-pos)
 145       (insert-file-contents-literally buffer-file-name nil read-pos
 146                                       (min vlf-file-size
 147                                            (+ read-pos read-size))))
 148     ;; write
 149     (if hide-read ; hide literal region if user has to choose encoding
 150         (narrow-to-region start-write-pos end-write-pos))
 151     (write-region start-write-pos end-write-pos
 152                   buffer-file-name write-pos 0)
 153     (delete-region start-write-pos end-write-pos)
 154     (if hide-read (widen))
 155     read-more))
 156
 157 (provide 'vlf-write)
 158
 159 ;;; vlf-write.el ends here