Weekly Programming Challenge - making our own data format

Unfortunately I don't quite have the time to approach this one this week, but it looks amazing fun...

So instead, as a little inspiration for others, what about a minimal INI parser... For sh?

It's been published before here (about 7 weeks ago?), and well... I created it for a device that could only run busybox with no room for anything else.

It's kinda awful, but translates INI into variables with a standard name mangling:

#!/bin/sh

VER='0.1'
DEBUG=1

hr() {
  # Echo a whole-width line

  # Get terminal width
  hr_width=$(tput cols)

  # Print a character, multiple times to make our horizontal line
  # We need to declare c, but it is unused.
  #shellcheck disable=SC2034
  for c in $(seq 1 "$hr_width")
  do
    printf '-'
  done
}

help() {
  # Our helpfile!
  echo "minini v$VER"
  hr
  echo
  echo 'Usage:'
  hr
  echo
  echo 'minini FILE - Read an INI file, and output the generated variables.'
}

# Choose what to do
if [ -z "$1" ] || [ "$1" = '-h' ] || [ "$1" = '--help' ]; then
  help
  exit
fi

# Confirm file is accessible
if [ ! -f "$1" ]; then
  # True if file cannot be found

  echo 'Cannot find file. Does it exist?' >&2
  echo "File: $1" >&2
  exit 1

elif [ ! -r "$1" ]; then
  # True if the user doesn't have the 'read' bit on the file in question

  echo 'File is not readable. Do you have permission?' >&2
  echo "File: $1" >&2
  exit 1

fi

# Default section
# define before loop, so it doesn't get reset
section='__main__'

# Buffer for final output
buffer=' '

# Read data line by line
cat "$1" | while read -r line
do
  if [ ! -z "$line" ]; then
  # Skip blank lines

  # Strip whitespace
  data=$(echo "$line" | sed -e 's/^[[:space:]]*//')

  # Get first non-whitespace character
  c=$(echo "$data" | cut -c1)

  if [ "$c" = '[' ]; then
    # Parse section title

    # grep grabs between brackets, sed strips leading and trailing whitespace
    section=$(echo "$data" | grep -Po '\[\K[^]]*' | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')

    # make section shellsafe
    section=$(echo "ini_$section" | sed 's/[^a-zA-Z0-9]/_/g')

    if [ "$DEBUG" -eq 0 ]; then
      echo "Section: <$section>"
    fi

  elif echo "$data" | grep -q '='; then
    # Parse assignment

    # get varname and strip whitespace
    varname=$(echo "$data" | sed -e 's/=.*//' -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')

    # get value to be assigned and strip whitespace
    value=$(echo "$data" | sed -e 's/.*=//' -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')

    if [ "$DEBUG" -eq 0 ]; then
      echo "Variable: <$section::$varname> set to <$value>"
    fi
    buffer="${section}__$varname='$value'"
  fi

  # Echo built shell var, stripping blank lines
  echo "$buffer" | sed '/^\s*$/d'
  fi
done

This will translate an INI file like:

[ Main ]
x = 34
y = 3

[Hello]
z=3
x=Hello world

[ Hello World!]
y=Boo!

[ This has numbers 62 ]
12=twelve

Into this:

ini_Main__x='34'
ini_Main__y='3'
ini_Main__y='3'
ini_Hello__z='3'
ini_Hello__x='Hello world'
ini_Hello__x='Hello world'
ini_Hello_World___y='Boo!'
ini_Hello_World___y='Boo!'
ini_This_has_numbers_62__12='twelve'

Which your script can then eval, and you can check that the appropriate values exist.

It's slightly insane, but rather fun.

I'm sure they will beat at least csv. Good luck!

Challenge accepted.

At uni after a lecture extolling the virtue of the water language we came up with an xml image schema.

It was a long time ago so I can only give you the gist of it but something like:

<row number="1">
    <pixel number="1">
        <red value="255"/>
        <green value="30"/>
        <blue value="46"/>
        <hue value="356"/>
        <saturation value="88.2"/>
        <value value="100.0"/>
    </pixel>
    <pixel number="2">
        <red value="1"/>
        <green value="18"/>
        <blue value="46"/>
        <hue value="217"/>
        <saturation value="97.8"/>
        <value value="18.0"/>
    </pixel>
</row>

Ahh good times.