Advent Calendar - December 19, 2019

Thursday, Dec 19, 2019| Tags: Raku

Advent Calendar 2019


The gift is presented by Khalid. Today he is talking about his solutions to Task #1: Strip leading zeros of “The Weekly Challenge - 002”.

Write a script or one-liner to remove leading zeros from positive numbers.


This solution uses Raku Grammer

At first here is the code :

grammar Grammer {
    token TOP {<sign>? <int> <decimal>?}
    token decimal {<dot><digit>?}
    token int {<zeros>? <digit>?}
    token digit { \d+ }
    token dot { '.' }
    token zeros {0+}
    token sign {'+'}
}
my $match = Grammer.parse(@*ARGS[0]);
my $number =  ($match<int><digit> // '')  ~ ($match<decimal> // '');
say $number;

at the first line we simply creat a Grammer with name ‘Grammer’ which is a Class that have methods (rules, tokens and regexes) as documented here.

Let’s get the zeros token first:

0+ matches any number of Zeros in the input

dot token : matches only .

digit token : matches any number of digit characters

int token : uses zeros token and digit token to match the first part of the number incase it is decimal.

and I made it’s parts optional using ? as the first part may not contain zeros or digits input ex: .53, 1.52

decimal token : matches a dot . followed by any number of digit characters

and putting them together in the main TOP token gives us the full number.


If you have any suggestion then please do share with us perlweeklychallenge@yahoo.com.

Advent Calendar 2019

SO WHAT DO YOU THINK ?

If you have any suggestions or ideas then please do share with us.

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