Highlight grep results in different colors, a color per match (up to 3 colors)

Question

Im using grep for searching pattern in huge log files, since it's a log file and i want to see what's going on around the matches, i usually do grep -C 3 -color ...

however, after reading a lot of logs i find a little annoying to distinguish between every 7 lines, which line belongs to which match, so i want to find a way to distinguish between each matches (and the 6 lines surround it)

the thing i think would be helpful and easier for my eyes to read is to make each match in a different color - of course not really a new color for each match but just pick a few colors, let's say 3 colors such that matches will be colored in that sequence of colors, for example if I got 4 matches they will be colored as the following:

prefix1 match1 // purple color: start
prefix2 match1
prefix3 match1
match1:   
suffix1 match1
suffix2 match1
suffix3 match1  // purple color: end   

prefix1 match2 // blue color: start
prefix2 match2
prefix3 match2
match2:   
suffix1 match2
suffix2 match2
suffix3 match2  // blue color: end  

prefix1 match3 // green color: start
prefix2 match3
prefix3 match3
match3:   
suffix1 match3
suffix2 match3
suffix3 match3  // green color: end 

prefix1 match4 // purple color: start
prefix2 match4
prefix3 match4
match4:   
suffix1 match4
suffix2 match4
suffix3 match4  // purple color: end  

7 lines each color

So what essentially im looking for is a way to tell grep to do that, or a command to redirect grep to so that it will be colored as above

Answer 1

Like this using Perl and core Term::ANSIColor (installed by default):

<COMMAND> | perl -MTerm::ANSIColor=:constants -pe '
    BEGIN{
       our @colors = (MAGENTA, BLUE, GREEN);
       our @cols;
    }
    @cols = @colors if not scalar @cols;
    my $color = shift @cols if /^$/ or $. == 1;
    print $color;
    END{ print RESET }
'

Or even shorter, Thanks @Terdon:

<COMMAND> | perl -MTerm::ANSIColor=:constants -00 -pe '
       BEGIN{ @colors = (GREEN, MAGENTA, BLUE) }
       print $colors[$.%($#colors+1)];
       END{ print RESET }
'

Check color capabilities:

perldoc Term::ANSIColor