Solution to task 1

1 files changed, 155 insertions, 0 deletions

diff --git a/challenge-140/jo-37/perl/ch-1.pl b/challenge-140/jo-37/perl/ch-1.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use experimental 'signatures';
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [M N]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+M N
+    interpret numbers M and N as decimals holding binaries and add these.
+
+EOS
+
+
+### Input and Output
+
+say PWC::BitNumber->new($ARGV[0]) + PWC::BitNumber->new($ARGV[1]);
+
+
+### Implementation
+
+# Overload addition? Let's have some more fun and overload a wider set
+# of integer operators including integer constants (enabled by
+# calling import()).
+#
+# Use scalar references as BitNumber objects.
+# - The constructor will interpret its argument as a binary number by
+#   taking the digits of the decimal representation as binary "digits".
+# - The overloaded numification operator does the reverse by exchanging
+#   the bases.
+# - Negative BitNumbers are not 2's complement but have a sign instead.
+# - Operations between a (scalar) number and a BitNumber are allowed.
+# - Dereferencing a BitNumber object reveals its integer value.
+# - !!! When integer constant overloading is enabled, decimal numbers
+#   need to be specified as strings or floating point numbers !!!
+#
+#   See tests.
+
+package PWC::BitNumber;
+
+use Math::Prime::Util qw(fromdigits todigits);
+
+### Some helper subs (not methods):
+
+# Retrieve the value of a BitNumber or anything else.
+sub _val ($num) {
+    ref($num) eq __PACKAGE__ ? $$num : $num;
+}
+
+# Get the sign of anything.
+sub _sign ($num) {
+    _val($num) < 0 ? -1 : 1;
+}
+
+# Swap factor: false -> 1, true -> -1
+sub _swap ($swap) {
+    1 - 2 * !!$swap;
+}
+
+###
+
+# Constructor: take decimal digits as binary and retain the sign.
+sub new ($, $bn) {
+    bless \(_sign($bn) * fromdigits [todigits($bn, 10)], 2);
+}
+
+# Enable integer constant overloading in the caller's package.
+sub import {
+    overload::constant integer => sub ($bn, @) {__PACKAGE__->new($bn)};
+}
+
+# Provide some principal integer operators.
+use overload
+    '+' => sub ($self, $other, $) {
+        bless \($$self + _val($other));
+    },
+    '-' => sub ($self, $other, $swap) {
+        bless \(_swap($swap) * ($$self - _val($other)));
+    },
+    '*' => sub ($self, $other, $) {
+        bless \($$self * _val($other));
+    },
+    '/' => sub ($self, $other, $swap) {
+        bless \(int +($$self / _val($other)) ** _swap($swap));
+    },
+    # returns float
+    '**' => sub ($self, $other, $swap) {
+        $swap = !!$swap;
+        exp log($$self) ** (1 - $swap) * $$self ** $swap *
+            log(_val($other)) ** $swap * _val($other) ** (1 - $swap);
+    },
+    '0+' => sub ($self, $, $) {
+        _sign($self) * fromdigits [todigits $$self, 2], 10;
+    },
+    '<=>' => sub ($self, $other, $swap) {
+        _swap($swap) * ($$self <=> _val($other));
+    };
+
+
+### Examples and tests
+
+package main;
+
+# Enable integer constant overloading
+BEGIN {
+    PWC::BitNumber->import;
+}
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is 11 + 1, 100, 'example 1';
+        is 101 + 1, 110, 'example 2';
+        is 100 + 11, 111, 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is ${1111},     15.,    'get integer value';
+        is ${-1111},    -15.,   'negative value';
+        is 0,           0.,     'zero';
+        is 1111 + 1,    10000,  'carry';
+        is 1111 + 16.,  11111,  'add scalar';
+        is 100 - 1,     11,     '4 - 1 = 3';
+        is 111 * 11,    10101,  '7 * 3 = 21';
+        is 10101 / 11,  111,    '21 / 3 = 7';
+        is 21. / 11,    111,    '21 / 3 = 7';
+        is -10. <=> -10, -1.,   '-10 < -2';
+        is '123',       123.,   'strings and floats';
+        is 101 ** 11,   125.,   '5 ** 3 = 125';
+
+        # The binary digits' range is not limited to 0 and 1.  They are
+        # taken as the factor at their corresponding position, e.g.:
+        # 123(10) = 1 * 10**2 + 2 * 10**1 + 3 * 10**0
+        # ->
+        # 1 * 2**2 + 2 * 2**1 + 3 * 2**0 = 11(10) = 1011(2)
+        is 123,         1011,   'pseudo binary number';
+	}
+
+    done_testing;
+    exit;
+}