en/kitchen/color-wdiff

   1 #!/bin/bash
   2
   3 # NAME
   4 #    color-wdiff - visualize differences between text files
   5
   6 # SYNOPSIS
   7 #    color-wdiff FILE0 FILE1
   8
   9 # DEPENDENCIES
  10 #    wdiff, reformat-html in $HOME/bin.
  11
  12 # DESCRIPTION
  13 #    1. If the input files are HTML, they are reformatted, to remove
  14 #       indentation among other things.
  15 #    2. The markup is inactivated by replacing angle brackets with the
  16 #       corresponding entities.
  17 #    3. The files are compared with wdiff, using options which label
  18 #       insertions and deletions. The labels are HTML tags with specific
  19 #       classes.
  20 #    4. The diff is turned into a valid HTML page by adding the required
  21 #       markup, plus CSS style for the insertion and deletion classes.
  22 #
  23 #    The diff file is created in the directory where FILE0 resides.
  24
  25 # ORIGIN OF THE SCRIPT
  26 #    This script was extracted from GNUN's GNUmakefile (function
  27 #    "mark-outdated"), and adapted.
  28 #    GNUN (http://www.gnu.org/software/gnun/) is under GPLv3.
  29
  30 # =============================================================================
  31
  32 # Command-line arguments
  33 arg=($1 $2)
  34
  35 set -e
  36
  37 close_term () {
  38   printf '\n%s' '*** Close the terminal window or press Return.'; read OK
  39   test -z "$OK" && exit $1
  40 }
  41
  42 f[0]=$(mktemp -t cdif.XXXXXX) || close_or_exit 1
  43 f[1]=$(mktemp -t cdif.XXXXXX) || close_or_exit 1
  44 trap 'rm -f "${f[0]}" "${f[1]}"' EXIT
  45
  46 ## Prepare the pages to be compared.
  47
  48 for n in 0 1; do
  49   # Input a valid file.
  50   input=${arg[$n]}
  51   if test ! -f "$input" -o ! -s "$input"; then
  52     echo "*** color-wdiff - Please enter file $n."; read input
  53     input=${input%\'}; input=${input#\'}
  54     test -f "$input" -a -s "$input" \
  55     || (echo 1>&2 "!!! This file doesn't exist or is empty."; close_term 1)
  56   fi
  57
  58   # Name the diff after file 0.
  59   test "$n" == "0" && diff_file=${input%.html}-diff.html
  60
  61   # If the file is an HTML but not a diff, process it:
  62   if test "${input%.html}" != "$input" -a "${input%-diff.html}" == "$input";
  63   then
  64     # - Standardize the format for easier reading of the diff.
  65     if test -f "$HOME/bin/reformat-html"; then
  66       $HOME/bin/reformat-html $input ${f[$n]}
  67     else
  68       cp $input ${f[$n]}
  69     fi
  70     # - Replace chevrons with HTML entities. The page becomes simple text.
  71     sed -i "s/</\&lt;/g;s/>/\&gt;/g" ${f[$n]}
  72   fi
  73 done
  74
  75 ## Build the diff page.
  76
  77 # Add an HTML header to the wdiff output, with style for visualizing the
  78 # insertions and deletions, and write the title of the page.
  79 cat > $diff_file << EOF
  80 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
  81     "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
  82 <!-- Generated by GNUN -->
  83 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  84 <head>
  85 <meta http-equiv="content-type" content="text/html; charset=utf-8" />
  86 <title>${diff_file##*\/}</title>
  87 <style type="text/css">
  88 span.removed { background-color: #f22; color: #000; }
  89 span.inserted { background-color: #2f2; color: #000; }
  90 </style></head>
  91 <body><pre>
  92 EOF
  93
  94 # Run wdiff with options to add the proper markup at the beginning and end of
  95 # deletions and insertions.
  96 wdiff --start-delete '<span class="removed"><del><strong>' \
  97       --end-delete '</strong></del></span>' \
  98       --start-insert '<span class="inserted"><ins><em>' \
  99       --end-insert '</em></ins></span>' \
 100       ${f[0]} ${f[1]} >> $diff_file || true
 101
 102 # Add the closing tags.
 103 echo '</pre></body></html>' >> ${diff_file}
 104
 105 echo -e "\n    The diff file is $diff_file."
 106 close_term 0