[Article linked on the VisualVM frontpage.]

I used the mongo ruby driver for my experiments. A colleague recommended Mongoid for Rails mongodb usaged. It supports some pretty syntactic sugar for chaining criteria and named scopes.

No experience yet with using MongoDB on a customer project. Because it’s very young, the implementation for full text search with MongoDB is immature. As pretty much all of our customer projects require heavy use of sphinx / search this might be a reason to hold off for now. There is a MongoSphinx gem, but the use of XML to transfer data just feels dirty. ;-)

Thanks for the write-up! Looking forward to more interesting posts about Mongo :)

Also, if you prefer the first method, don’t forget to rename ‘parseline’ (the name does not actually matter) back to ‘getline’ so other programs can still be compiled with getline from glibc.

#!/bin/bash 

DIGITS=""
SCALE="2" 

function parse_args {
    while getopts  "s:" flag
    do
        SCALE="$OPTARG"
    done
    shift $(($OPTIND-1))
    DIGITS="$1"
} 

SPRITE_LINE0=".-.....-..-.....-..-..-..-..-."
SPRITE_LINE1="|.|..|..|..||.||..|....||.||.|"
SPRITE_LINE2=".......-..-..-..-..-.....-..-."
SPRITE_LINE3="|.|..||....|..|..||.|..||.|..|"
SPRITE_LINE4=".-.....-..-.....-..-.....-..-." 

NEWLINE_SUBSITUTE="L"
READ_DELIM="X" 

function digit_to_sprite {
    local DIGIT="$*"
    local SPRITE_TEMPLATE_OFFSET=$(($DIGIT*3))
    for SPRITE_LINE_NR in $(seq 0 4); do
        local VAR_SELECTOR="SPRITE_LINE$SPRITE_LINE_NR"
        echo -n ${!VAR_SELECTOR:$SPRITE_TEMPLATE_OFFSET:3}$NEWLINE_SUBSITUTE
    done
    echo
} 

function digits_to_sprites {
    local DIGITS="$*"
    DIGITS="$(echo $DIGITS | sed 's/\(.\)/\1 /g')" 

    for DIGIT in $DIGITS ; do
        digit_to_sprite $DIGIT
    done
} 

function calculate_scale {
    local SPRITES=$1
    local FIRST_SPRITE=$(echo $SPRITES | head -1) 

    local TOTAL_LINES=$(echo -n $FIRST_SPRITE | tr $NEWLINE_SUBSITUTE
\\n | wc -l)
    echo $((($TOTAL_LINES-3)/2))
} 

function render_sprites {
    local SPRITES=""
    read  -d $READ_DELIM SPRITES
    local SPRITE_SCALE=$(calculate_scale $SPRITES) 

    for LINE_NR in $(seq 1 $((($SPRITE_SCALE * 2) + 3))); do
        local TOTAL_LINE=""
        for SPRITE in $SPRITES; do
            local PIECE=$(echo -n $SPRITE | cut -d $NEWLINE_SUBSITUTE
-f $LINE_NR)
            TOTAL_LINE="$TOTAL_LINE$PIECE "
        done
        echo $TOTAL_LINE | tr '.' ' '
    done
} 

function scale_sprites {
    local SCALE=$1
    local SPRITES=""
    read -d $READ_DELIM SPRITES
    local VSCALE_AWK="
/([|][.][.])|([.][.][|])|([|][.][|])/ {
  for (i = 1; i < scale; i++)
    print \$0
}
BEGIN {
  RS=\"$NEWLINE_SUBSITUTE\"
  ORS=\"$NEWLINE_SUBSITUTE\"
}
{
  print \$0
}
"
    local HSCALE_AWK="
BEGIN {
  RS=\"$NEWLINE_SUBSITUTE\"
  ORS=\"$NEWLINE_SUBSITUTE\"
  FS=\"\"
  OFS=\"\"
}
{
  line = \$1
  for (i = 1; i <= scale; i++)
    line = line \$2
  line = line \$3
  print line
}
"
    AWK_VARIABLES="scale=$SCALE"
    for SPRITE in $SPRITES; do
        echo -n "$SPRITE" \
            | awk "$VSCALE_AWK" $AWK_VARIABLES \
            | awk "$HSCALE_AWK" $AWK_VARIABLES
        echo
    done
} 

parse_args $*
digits_to_sprites $DIGITS | scale_sprites $SCALE | render_sprites