HW 4: Regex with Perl Solution

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Overview: This is an optional assignment designed to give you some experience with Perl’s regular expres-sion capabilities, I/O, and external command execution.

Objective: Write a program that

locates the provided ASCII image pattern in an arbitrarily-sized rectangular ASCII image, colorizes the located pattern (and only the pattern) using ANSI escape codes,

loops through 7 colors forever

for each color, writes the colorized image to an output le

The ASCII image pattern of interest is:



/m m\

The pattern above has a width of 5 characters and a height of 3 characters. It may appear at any location in a provided ASCII image. The input ASCII image can be any width or any height, lled with any characters. The given pattern will never be clipped on any sides, and will only appear once in an image.

Sample input:





o.o/o.a/m m\o.o/o.o/o.o/o.



Guidelines and Restrictions:

You must read the input image from the STDIN lehandle.

You must write the output to a le named output_colorized.asciimg (in the same directory) using your own lehandle.


The output ASCII image must be the same dimensions as the input image.

You cannot use heuristics or looping to locate the pattern of interest; you must use regular expressions.

Helpful hints:

Newlines are a single character, but ordinarily won’t be matched by . in a regexp.

Consider how in C/C++ a 1D array can represent a 2D array and vice versa. This might help you write your regular expression. (Don’t actually try to make a multidimensional array).

To observe updates to your output le, you can run the watch command at a speci ed interval in another terminal.

watch -n.1 -c “cat output_colorized.asciiimg”

The -c ag retains the output’s color, and the -n.1 runs the command every .1 seconds. You should see the pattern strobe:

lu66049ceo7 tmp b080214f71e6a735

If you read the le output every .1 seconds, you should write to the le roughly every .2 seconds. One way to do this is to sleep for this amount of time.

Your whole script should be roughly 30 lines without comments. Please add comments. For reference, the ANSI color codes are:

# Regular Colors

Black= \033[0;30m # Black

Red= \033[0;31m # Red

Green= \033[0;32m # Green

Yellow= \033[0;33m # Yellow

Blue= \033[0;34m # Blue

Purple= \033[0;35m # Purple

Cyan= \033[0;36m # Cyan

White= \033[0;37m # White



Upload a single text le containing the script to Canvas by the due date.