CodeMagic: serialize - an approach to serializing and de-serializing arbitrary data entirely within bash

#!/bin/bash
#
# serialize demonstrates an approach to serializing and de-serializing
# arbitrary data entirely within the native facilities of bash.
# Performance, however, is sufficiently slow that this approach is
# infeasible for anything but small datasets.
#
# A simple way to run the script is by invoking:
#
#     ./serialize.sh 
#
# serialize then runs a small self-test harness. The test includes a
# timing cycle of deflating and re-inflating the contents of the file
# holding the script itself as well as serializing the entire ASCII
# sequence except for x'00'. Although performance is painfully slow,
# the demonstration exposes scripting techniques for sophisticated data
# handling including advanced array manipulation, as well as binary
# and hex string processing. Cache effects are explored in a second,
# related script named serialize_with_cache.
# 
# Copyright (c) 2008 Technetra Corp
# 
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#
PASSED=0
TOTAL=0
find_char() {
  local hex_result=$1
  local in_char=$2
  local hex_digits1 hex_digits2=(0 1 2 3 4 5 6 7 8 9 A B C D E F)
  if [[ "$in_char" > $'\x6f' ]]; then
    hex_digits1=(7 8 9 A B C D E F)
  elif [[ "$in_char" > $'\x5f' ]]; then
    hex_digits1=(6)
  elif [[ "$in_char" > $'\x4f' ]]; then
    hex_digits1=(5)
  elif [[ "$in_char" > $'\x3f' ]]; then
    hex_digits1=(4)
  elif [[ "$in_char" > $'\x2f' ]]; then
    hex_digits1=(3)
  elif [[ "$in_char" > $'\x1f' ]]; then
    hex_digits1=(2)
  else
    hex_digits1=(0 1)
  fi
  local finished=0
  local c t targ hxi hxj
  for hxi in ${hex_digits1[@]}; do
    for hxj in ${hex_digits2[@]}; do
      c=$hxi$hxj
      #t="`eval echo z\$\'\\\x$c\'z`"
      t="`echo -e "z\x${c}z"`"
      targ=${t:1:1}
      if [[ "$in_char" == "$targ" ]]; then
        finished=1
        break
      fi
    done
    [[ $finished -eq 1 ]] && break
  done
  eval $hex_result=$c
}
deflate() {
  local result=$1
  local s="$2"
  local i=0 deflated out_hex
  local c="${s:i++:1}"
  while [[ "$c" ]]; do
    find_char out_hex "$c"
    deflated=$deflated$out_hex
    c="${s:i++:1}"
  done 
  eval $result=$deflated
}
inflate() {
  local result=$1
  local hex_string=$2 
  local i=0 inflated t targ
  local h=${hex_string:i:2}
  i=$((i+2))
  while [[ "$h" ]]; do
    #t="`eval echo z\$\'\\\x$h\'z`"
    t="`echo -e "z\x${h}z"`"
    targ=${t:1:1}
    [[ "$targ" == '"' ]] && targ='\"'
    inflated="$inflated$targ"
    h=${hex_string:i:2}
    i=$((i+2))
  done
  eval "$result=\"$inflated\""
}
test_full_hex_table() {
  local hex_string=$1 
  local i=0 inflated t hex stat=failed
  local h=${hex_string:i:2}
  i=$((i+2))
  while [[ "$h" ]]; do
    t="`echo -e "z\x${h}z"`"
    inflated="$inflated${t:1:1}"
    h=${hex_string:i:2}
    i=$((i+2))
  done
  deflate hex "$inflated"
  if [[ "$hex_string" == "$hex" ]]; then
    stat=passed
    ((PASSED++))
  fi
  ((TOTAL++))
  echo -n "$stat test $TOTAL, hex=$hex, original=\"$(echo $inflated | cat -v)\"\n"
}
test_file_content() {
  local s="$1"
  local i=0 deflated out_hex inflated t hex stat=failed
  local c="${s:i++:1}"
  while [[ "$c" ]]; do
    find_char out_hex "$c"
    deflated=$deflated$out_hex
    c="${s:i++:1}"
  done 
  i=0
  local h=${deflated:i:2}
  i=$((i+2))
  while [[ "$h" ]]; do
    t="`echo -e "z\x${h}z"`"
    inflated="$inflated${t:1:1}"
    h=${deflated:i:2}
    i=$((i+2))
  done
  deflate hex "$inflated"
  if [[ "$deflated" == "$hex" ]]; then
    stat=passed
    ((PASSED++))
  fi
  ((TOTAL++))
  echo "$stat test $TOTAL, hex=$hex, original=\"$s\""
}
test_serialize () {
  local in_orig="$1"
  local stat hex copy
  deflate hex "$in_orig"
  inflate copy $hex
  if [[ "$in_orig" == "$copy" ]]; then
    stat=passed
    ((PASSED++))
  else
    stat=failed
  fi
  ((TOTAL++))
  echo "$stat test $TOTAL, hex=$hex, original=\"$in_orig\""
}
time_file () {
  local file=$1
  echo "timing serialization on file $file, may take several minutes..."
  time test_file_content "$(cat $file)"
}
time_full_hex_range () {
  local hex_digits=(0 1 2 3 4 5 6 7 8 9 A B C D E F)
  local copy hstr
  for hxi in ${hex_digits[@]}; do
    for hxj in ${hex_digits[@]}; do
      [[ $hxi == "0" && $hxj == "0" ]] || hstr=$hstr$hxi$hxj
    done
  done
  echo "timing serialization of fully populated (except NULL) ASCII table..."
  time test_full_hex_table $hstr
}
###
### MAIN
###
test_serialize "a\"c"
test_serialize "a\'c"
test_serialize "$(echo -e " a\n\tb")"
test_serialize "'%' in a prerequisite of a pattern rule stands for the same stem that was matched by the"
time_file $0
time_file /etc/passwd
time_full_hex_range
echo "TEST SUMMARY: passed $PASSED of $TOTAL tests"
# end serialize