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462 lines
14 KiB
EmacsLisp
462 lines
14 KiB
EmacsLisp
;;; html2text.el --- a simple html to plain text converter -*- coding: utf-8 -*-
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;; Copyright (C) 2002-2016 Free Software Foundation, Inc.
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;; Author: Joakim Hove <hove@phys.ntnu.no>
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; These functions provide a simple way to wash/clean html infected
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;; mails. Definitely do not work in all cases, but some improvement
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;; in readability is generally obtained. Formatting is only done in
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;; the buffer, so the next time you enter the article it will be
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;; "re-htmlized".
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;;
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;; The main function is `html2text'.
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;;; Code:
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;;
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;; <Global variables>
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;;
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(eval-when-compile
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(require 'cl))
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(defvar html2text-format-single-element-list '(("hr" . html2text-clean-hr)))
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(defvar html2text-replace-list
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'(("´" . "`")
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("&" . "&")
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("'" . "'")
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("¦" . "|")
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("¢" . "c")
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("ˆ" . "^")
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("©" . "(C)")
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("¤" . "(#)")
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("°" . "degree")
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("÷" . "/")
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("€" . "e")
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("½" . "1/2")
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(">" . ">")
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("¿" . "?")
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("«" . "<<")
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("&ldquo" . "\"")
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("‹" . "(")
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("‘" . "`")
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("<" . "<")
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("—" . "--")
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(" " . " ")
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("–" . "-")
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("‰" . "%%")
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("±" . "+-")
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("£" . "£")
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(""" . "\"")
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("»" . ">>")
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("&rdquo" . "\"")
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("®" . "(R)")
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("›" . ")")
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("’" . "'")
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("§" . "§")
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("¹" . "^1")
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("²" . "^2")
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("³" . "^3")
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("˜" . "~"))
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"The map of entity to text.
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This is an alist were each element is a dotted pair consisting of an
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old string, and a replacement string. This replacement is done by the
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function `html2text-substitute' which basically performs a
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`replace-string' operation for every element in the list. This is
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completely verbatim - without any use of REGEXP.")
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(defvar html2text-remove-tag-list
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'("html" "body" "p" "img" "dir" "head" "div" "br" "font" "title" "meta")
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"A list of removable tags.
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This is a list of tags which should be removed, without any
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formatting. Note that tags in the list are presented *without*
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any \"<\" or \">\". All occurrences of a tag appearing in this
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list are removed, irrespective of whether it is a closing or
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opening tag, or if the tag has additional attributes. The
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deletion is done by the function `html2text-remove-tags'.
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For instance the text:
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\"Here comes something <font size\"+3\" face=\"Helvetica\"> big </font>.\"
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will be reduced to:
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\"Here comes something big.\"
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If this list contains the element \"font\".")
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(defvar html2text-format-tag-list
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'(("b" . html2text-clean-bold)
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("strong" . html2text-clean-bold)
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("u" . html2text-clean-underline)
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("i" . html2text-clean-italic)
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("em" . html2text-clean-italic)
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("blockquote" . html2text-clean-blockquote)
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("a" . html2text-clean-anchor)
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("ul" . html2text-clean-ul)
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("ol" . html2text-clean-ol)
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("dl" . html2text-clean-dl)
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("center" . html2text-clean-center))
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"An alist of tags and processing functions.
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This is an alist where each dotted pair consists of a tag, and then
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the name of a function to be called when this tag is found. The
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function is called with the arguments p1, p2, p3 and p4. These are
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demonstrated below:
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\"<b> This is bold text </b>\"
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^ ^ ^ ^
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p1 p2 p3 p4
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Then the called function will typically format the text somewhat and
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remove the tags.")
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(defvar html2text-remove-tag-list2 '("li" "dt" "dd" "meta")
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"Another list of removable tags.
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This is a list of tags which are removed similarly to the list
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`html2text-remove-tag-list' - but these tags are retained for the
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formatting, and then moved afterward.")
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;;
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;; </Global variables>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;; <Utility functions>
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;;
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(defun html2text-replace-string (from-string to-string min max)
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"Replace FROM-STRING with TO-STRING in region from MIN to MAX."
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(goto-char min)
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(let ((delta (- (string-width to-string) (string-width from-string)))
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(change 0))
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(while (search-forward from-string max t)
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(replace-match to-string)
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(setq change (+ change delta)))
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change))
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;;
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;; </Utility functions>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;; <Functions related to attributes> i.e. <font size=+3>
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;;
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(defun html2text-attr-value (list attribute)
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"Get value of ATTRIBUTE from LIST."
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(nth 1 (assoc attribute list)))
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(defun html2text-get-attr (p1 p2)
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(goto-char p1)
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(re-search-forward "\\s-+" p2 t)
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(let (attr-list)
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(while (re-search-forward "[-a-z0-9._]+" p2 t)
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(setq attr-list
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(cons
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(list (match-string 0)
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(when (looking-at "\\s-*=")
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(goto-char (match-end 0))
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(skip-chars-forward "[:space:]")
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(when (or (looking-at "\"[^\"]*\"\\|'[^']*'")
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(looking-at "[-a-z0-9._:]+"))
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(goto-char (match-end 0))
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(match-string 0))))
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attr-list)))
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attr-list))
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;;
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;; </Functions related to attributes>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;; <Functions to be called to format a tag-pair>
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;;
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(defun html2text-clean-list-items (p1 p2 list-type)
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(goto-char p1)
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(let ((item-nr 0)
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(items 0))
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(while (search-forward "<li>" p2 t)
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(setq items (1+ items)))
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(goto-char p1)
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(while (< item-nr items)
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(setq item-nr (1+ item-nr))
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(search-forward "<li>" (point-max) t)
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(cond
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((string= list-type "ul") (insert " o "))
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((string= list-type "ol") (insert (format " %s: " item-nr)))
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(t (insert " x "))))))
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(defun html2text-clean-dtdd (p1 p2)
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(goto-char p1)
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(let ((items 0)
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(item-nr 0))
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(while (search-forward "<dt>" p2 t)
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(setq items (1+ items)))
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(goto-char p1)
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(while (< item-nr items)
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(setq item-nr (1+ item-nr))
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(re-search-forward "<dt>\\([ ]*\\)" (point-max) t)
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(when (match-string 1)
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(delete-region (point) (- (point) (string-width (match-string 1)))))
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(let ((def-p1 (point))
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(def-p2 0))
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(re-search-forward "\\([ ]*\\)\\(</dt>\\|<dd>\\)" (point-max) t)
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(if (match-string 1)
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(progn
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(let* ((mw1 (string-width (match-string 1)))
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(mw2 (string-width (match-string 2)))
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(mw (+ mw1 mw2)))
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(goto-char (- (point) mw))
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(delete-region (point) (+ (point) mw1))
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(setq def-p2 (point))))
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(setq def-p2 (- (point) (string-width (match-string 2)))))
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(put-text-property def-p1 def-p2 'face 'bold)))))
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(defun html2text-delete-tags (p1 p2 p3 p4)
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(delete-region p1 p2)
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(delete-region (- p3 (- p2 p1)) (- p4 (- p2 p1))))
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(defun html2text-delete-single-tag (p1 p2)
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(delete-region p1 p2))
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(defun html2text-clean-hr (p1 p2)
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(html2text-delete-single-tag p1 p2)
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(goto-char p1)
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(newline 1)
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(insert (make-string fill-column ?-)))
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(defun html2text-clean-ul (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4)
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(html2text-clean-list-items p1 (- p3 (- p1 p2)) "ul"))
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(defun html2text-clean-ol (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4)
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(html2text-clean-list-items p1 (- p3 (- p1 p2)) "ol"))
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(defun html2text-clean-dl (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4)
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(html2text-clean-dtdd p1 (- p3 (- p1 p2))))
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(defun html2text-clean-center (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4)
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(center-region p1 (- p3 (- p2 p1))))
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(defun html2text-clean-bold (p1 p2 p3 p4)
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(put-text-property p2 p3 'face 'bold)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-title (p1 p2 p3 p4)
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(put-text-property p2 p3 'face 'bold)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-underline (p1 p2 p3 p4)
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(put-text-property p2 p3 'face 'underline)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-italic (p1 p2 p3 p4)
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(put-text-property p2 p3 'face 'italic)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-font (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-blockquote (p1 p2 p3 p4)
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(html2text-delete-tags p1 p2 p3 p4))
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(defun html2text-clean-anchor (p1 p2 p3 p4)
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;; If someone can explain how to make the URL clickable I will surely
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;; improve upon this.
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;; Maybe `goto-addr.el' can be used here.
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(let* ((attr-list (html2text-get-attr p1 p2))
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(href (html2text-attr-value attr-list "href")))
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(delete-region p1 p4)
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(when href
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(goto-char p1)
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(insert (if (string-match "\\`['\"].*['\"]\\'" href)
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(substring href 1 -1) href))
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(put-text-property p1 (point) 'face 'bold))))
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;;
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;; </Functions to be called to format a tag-pair>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;; <Functions to be called to fix up paragraphs>
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;;
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(defun html2text-fix-paragraph (p1 p2)
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(goto-char p1)
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(let ((refill-start)
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(refill-stop))
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(when (re-search-forward "<br>$" p2 t)
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(goto-char p1)
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(when (re-search-forward ".+[^<][^b][^r][^>]$" p2 t)
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(beginning-of-line)
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(setq refill-start (point))
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(goto-char p2)
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(re-search-backward ".+[^<][^b][^r][^>]$" refill-start t)
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(forward-line 1)
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(end-of-line)
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;; refill-stop should ideally be adjusted to
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;; accommodate the "<br>" strings which are removed
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;; between refill-start and refill-stop. Can simply
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;; be returned from my-replace-string
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(setq refill-stop (+ (point)
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(html2text-replace-string
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"<br>" ""
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refill-start (point))))
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;; (message "Point = %s refill-stop = %s" (point) refill-stop)
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;; (sleep-for 4)
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(fill-region refill-start refill-stop))))
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(html2text-replace-string "<br>" "" p1 p2))
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;;
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;; This one is interactive ...
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;;
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(defun html2text-fix-paragraphs ()
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"This _tries_ to fix up the paragraphs - this is done in quite a ad-hook
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fashion, quite close to pure guess-work. It does work in some cases though."
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(interactive)
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(goto-char (point-min))
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(while (re-search-forward "^<br>$" nil t)
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(delete-region (match-beginning 0) (match-end 0)))
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;; Removing lonely <br> on a single line, if they are left intact we
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;; don't have any paragraphs at all.
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(goto-char (point-min))
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(while (not (eobp))
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(let ((p1 (point)))
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(forward-paragraph 1)
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;;(message "Kaller fix med p1=%s p2=%s " p1 (1- (point))) (sleep-for 5)
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(html2text-fix-paragraph p1 (1- (point)))
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(goto-char p1)
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(when (not (eobp))
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(forward-paragraph 1)))))
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;;
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;; </Functions to be called to fix up paragraphs>
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;
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;; <Interactive functions>
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;;
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(defun html2text-remove-tags (tag-list)
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"Removes the tags listed in the list `html2text-remove-tag-list'.
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See the documentation for that variable."
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(interactive)
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(dolist (tag tag-list)
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(goto-char (point-min))
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(while (re-search-forward (format "\\(</?%s[^>]*>\\)" tag) (point-max) t)
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(delete-region (match-beginning 0) (match-end 0)))))
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(defun html2text-format-tags ()
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"See the variable `html2text-format-tag-list' for documentation."
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(interactive)
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(dolist (tag-and-function html2text-format-tag-list)
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(let ((tag (car tag-and-function))
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(function (cdr tag-and-function)))
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(goto-char (point-min))
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(while (re-search-forward (format "\\(<%s\\( [^>]*\\)?>\\)" tag)
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(point-max) t)
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(let ((p1)
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(p2 (point))
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(p3) (p4))
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(search-backward "<" (point-min) t)
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(setq p1 (point))
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(unless (search-forward (format "</%s>" tag) (point-max) t)
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(goto-char p2)
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(insert (format "</%s>" tag)))
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(setq p4 (point))
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(search-backward "</" (point-min) t)
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(setq p3 (point))
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(funcall function p1 p2 p3 p4)
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(goto-char p1))))))
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(defun html2text-substitute ()
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"See the variable `html2text-replace-list' for documentation."
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(interactive)
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(dolist (e html2text-replace-list)
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(goto-char (point-min))
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(let ((old-string (car e))
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(new-string (cdr e)))
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(html2text-replace-string old-string new-string (point-min) (point-max)))))
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(defun html2text-format-single-elements ()
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(interactive)
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(dolist (tag-and-function html2text-format-single-element-list)
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(let ((tag (car tag-and-function))
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(function (cdr tag-and-function)))
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(goto-char (point-min))
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(while (re-search-forward (format "\\(<%s\\( [^>]*\\)?>\\)" tag)
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(point-max) t)
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(let ((p1)
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(p2 (point)))
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(search-backward "<" (point-min) t)
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(setq p1 (point))
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(funcall function p1 p2))))))
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;;
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;; Main function
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;;
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;;;###autoload
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(defun html2text ()
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"Convert HTML to plain text in the current buffer."
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(interactive)
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(save-excursion
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(let ((case-fold-search t)
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(buffer-read-only))
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(html2text-remove-tags html2text-remove-tag-list)
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(html2text-format-tags)
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(html2text-remove-tags html2text-remove-tag-list2)
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(html2text-substitute)
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(html2text-format-single-elements)
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(html2text-fix-paragraphs))))
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;;
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;; </Interactive functions>
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;;
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(provide 'html2text)
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;;; html2text.el ends here
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