use Math::Matrix ;

my $key-width     = 0;
my $value-width   = 0;
my $comment-width = 0;
my $padding       = 5;
my @sep           = ('=', '//')   ;
my @lengths;

# sub MAIN() {

# }
# 找到每一列的最大长度

for $=finish.lines -> $line {
    my @items = $line.split(/ @sep /);
    my @l;
    for @items -> $item {
        @l.append($item.trim.chars);
    }
    @lengths.push(@l);
}

my $m = Math::Matrix.new( [@lengths] );
my @maximal-width;
my @b = $m.transposed.list-rows;
@maximal-width.append(.max) for @b;
@maximal-width »+=» $padding;
my @f = @maximal-width».&sformat;
my $cformat = j(@f, @sep);

for $=finish.lines -> $l {
    my @items = $l.split(/@sep/);
    say sprintf("{$cformat}", @items);
}

sub sformat($l) {
    return '%-' ~ $l ~ 's'
}

# 如果不使用 is copy , 会修改 @sep 的值, 影响结果, 坑！
sub j(@columns, @separators is copy) {
    return (@columns »~» (@separators.append(""))).join("");
} 

=finish
  val GAS = "gas"  //天然气
  val HYDROGEN = "hydrogen"  //氢气
  val GASOLINE = "gasoline"  //汽油
  val LOWEST_VOLTAGE_CELL_MONOMER = "lowest_voltage_cell_monomer"  //电池单体电压最低值