> On Jun 3, 2018, at 7:41 PM, Xin Cheng <[email protected]> wrote:
>
> I am trying to make a program to do grep with perl6 regular expression, and I
> would like to colorize the matched part to the terminal.
—snip--
> if $temp ~~ s/ (<$pattern>) /\\x1b\[31m$0\\x1b\[0m/ {say $temp}
—snip—
Change this: s/ (<$pattern>) /\\x1b\[31m$0\\x1b\[0m/
to this: s/ (<$pattern>) /\x1b[31m$0\x1b[0m/
and your example code will correctly highlight the pattern in the (terminal)
output.
The doubled backslash in your original code becomes a literal backslash;
“\\x1b” is 4 characters long, “\x1b” is 1 character long (the escape
character). Also, you would need to back-whack the `[` only on the left-hand
side of `s///` (the pattern, which uses Regex syntax), not on the right-hand
side (the replacement, which uses double-quoted string syntax).
If you do not want to use Terminal::ANSIColor, I recommend that you save
yourself some future confusion by isolating your escape sequences, like so:
constant $color_red = "\e[31m";
constant $color_off = "\e[0m";
sub MAIN ( Str $pattern, Str $filename ) {
for $filename.IO.lines -> $line {
my Str $temp = $line;
# if no <> surrounding $pattern it becomes literal.
if $temp ~~ s/ (<$pattern>) /$color_red$0$color_off/ {
say $temp;
}
}
}
—
Hope this helps,
Bruce Gray (Util of PerlMonks)
