--- /dev/null
+;;; vlf-search.el --- Search functionality for VLF -*- lexical-binding: t -*-
+
+;; Copyright (C) 2014 Free Software Foundation, Inc.
+
+;; Keywords: large files, search
+;; Author: Andrey Kotlarski <m00naticus@gmail.com>
+;; URL: https://github.com/m00natic/vlfi
+
+;; This file 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, or (at your option)
+;; any later version.
+
+;; This file 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; see the file COPYING. If not, write to
+;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+;; This package provides search utilities for dealing with large files
+;; in constant memory.
+
+;;; Code:
+
+(defun vlf-re-search (regexp count backward batch-step)
+ "Search for REGEXP COUNT number of times forward or BACKWARD.
+BATCH-STEP is amount of overlap between successive chunks."
+ (if (<= count 0)
+ (error "Count must be positive"))
+ (let* ((case-fold-search t)
+ (match-chunk-start vlf-start-pos)
+ (match-chunk-end vlf-end-pos)
+ (match-start-pos (+ vlf-start-pos (position-bytes (point))))
+ (match-end-pos match-start-pos)
+ (to-find count)
+ (reporter (make-progress-reporter
+ (concat "Searching for " regexp "...")
+ (if backward
+ (- vlf-file-size vlf-end-pos)
+ vlf-start-pos)
+ vlf-file-size)))
+ (vlf-with-undo-disabled
+ (unwind-protect
+ (catch 'end-of-file
+ (if backward
+ (while (not (zerop to-find))
+ (cond ((re-search-backward regexp nil t)
+ (setq to-find (1- to-find)
+ match-chunk-start vlf-start-pos
+ match-chunk-end vlf-end-pos
+ match-start-pos (+ vlf-start-pos
+ (position-bytes
+ (match-beginning 0)))
+ match-end-pos (+ vlf-start-pos
+ (position-bytes
+ (match-end 0)))))
+ ((zerop vlf-start-pos)
+ (throw 'end-of-file nil))
+ (t (let ((batch-move (- vlf-start-pos
+ (- vlf-batch-size
+ batch-step))))
+ (vlf-move-to-batch
+ (if (< match-start-pos batch-move)
+ (- match-start-pos vlf-batch-size)
+ batch-move) t))
+ (goto-char (if (< match-start-pos
+ vlf-end-pos)
+ (or (byte-to-position
+ (- match-start-pos
+ vlf-start-pos))
+ (point-max))
+ (point-max)))
+ (progress-reporter-update
+ reporter (- vlf-file-size
+ vlf-start-pos)))))
+ (while (not (zerop to-find))
+ (cond ((re-search-forward regexp nil t)
+ (setq to-find (1- to-find)
+ match-chunk-start vlf-start-pos
+ match-chunk-end vlf-end-pos
+ match-start-pos (+ vlf-start-pos
+ (position-bytes
+ (match-beginning 0)))
+ match-end-pos (+ vlf-start-pos
+ (position-bytes
+ (match-end 0)))))
+ ((= vlf-end-pos vlf-file-size)
+ (throw 'end-of-file nil))
+ (t (let ((batch-move (- vlf-end-pos batch-step)))
+ (vlf-move-to-batch
+ (if (< batch-move match-end-pos)
+ match-end-pos
+ batch-move) t))
+ (goto-char (if (< vlf-start-pos match-end-pos)
+ (or (byte-to-position
+ (- match-end-pos
+ vlf-start-pos))
+ (point-min))
+ (point-min)))
+ (progress-reporter-update reporter
+ vlf-end-pos)))))
+ (progress-reporter-done reporter))
+ (set-buffer-modified-p nil)
+ (if backward
+ (vlf-goto-match match-chunk-start match-chunk-end
+ match-end-pos match-start-pos
+ count to-find)
+ (vlf-goto-match match-chunk-start match-chunk-end
+ match-start-pos match-end-pos
+ count to-find))))))
+
+(defun vlf-goto-match (match-chunk-start match-chunk-end
+ match-pos-start
+ match-pos-end
+ count to-find)
+ "Move to MATCH-CHUNK-START MATCH-CHUNK-END surrounding \
+MATCH-POS-START and MATCH-POS-END.
+According to COUNT and left TO-FIND, show if search has been
+successful. Return nil if nothing found."
+ (if (= count to-find)
+ (progn (vlf-move-to-chunk match-chunk-start match-chunk-end)
+ (goto-char (or (byte-to-position (- match-pos-start
+ vlf-start-pos))
+ (point-max)))
+ (message "Not found")
+ nil)
+ (let ((success (zerop to-find)))
+ (if success
+ (vlf-update-buffer-name)
+ (vlf-move-to-chunk match-chunk-start match-chunk-end))
+ (let* ((match-end (or (byte-to-position (- match-pos-end
+ vlf-start-pos))
+ (point-max)))
+ (overlay (make-overlay (byte-to-position
+ (- match-pos-start
+ vlf-start-pos))
+ match-end)))
+ (overlay-put overlay 'face 'match)
+ (unless success
+ (goto-char match-end)
+ (message "Moved to the %d match which is last"
+ (- count to-find)))
+ (unwind-protect (sit-for 3)
+ (delete-overlay overlay))
+ t))))
+
+(defun vlf-re-search-forward (regexp count)
+ "Search forward for REGEXP prefix COUNT number of times.
+Search is performed chunk by chunk in `vlf-batch-size' memory."
+ (interactive (if (vlf-no-modifications)
+ (list (read-regexp "Search whole file"
+ (if regexp-history
+ (car regexp-history)))
+ (or current-prefix-arg 1))))
+ (vlf-re-search regexp count nil (/ vlf-batch-size 8)))
+
+(defun vlf-re-search-backward (regexp count)
+ "Search backward for REGEXP prefix COUNT number of times.
+Search is performed chunk by chunk in `vlf-batch-size' memory."
+ (interactive (if (vlf-no-modifications)
+ (list (read-regexp "Search whole file backward"
+ (if regexp-history
+ (car regexp-history)))
+ (or current-prefix-arg 1))))
+ (vlf-re-search regexp count t (/ vlf-batch-size 8)))
+
+(defun vlf-goto-line (n)
+ "Go to line N. If N is negative, count from the end of file."
+ (interactive (if (vlf-no-modifications)
+ (list (read-number "Go to line: "))))
+ (let ((start-pos vlf-start-pos)
+ (end-pos vlf-end-pos)
+ (pos (point))
+ (success nil))
+ (unwind-protect
+ (if (< 0 n)
+ (progn (vlf-beginning-of-file)
+ (goto-char (point-min))
+ (setq success (vlf-re-search "[\n\C-m]" (1- n)
+ nil 0)))
+ (vlf-end-of-file)
+ (goto-char (point-max))
+ (setq success (vlf-re-search "[\n\C-m]" (- n) t 0)))
+ (if success
+ (message "Onto line %s" n)
+ (vlf-move-to-chunk start-pos end-pos)
+ (goto-char pos)))))
+
+(provide 'vlf-search)
+
+;;; vlf-search.el ends here