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Math-Inequalities-Parser-0.002
River stage zero No dependents
/ Math::Inequalities::Parser

NAME

Math::Inequalities::Parser - Minimum and maximum values allowed by an inequality.

SYNOPSIS

use Math::Inequalities::Parser;

my ($min, $max) = parse_inequality( ' 10 < n < 20 ' );
# $min = 11
# $max = 19

DESCRIPTION

Tiny library for parsing integer maximum and minimum out when given an arbitrary inequality.

Because getting this simple thing right was far harder than it looked, and I never want to have to think about it again.

FUNCTIONS

parse_inequality

Parses an inequality string and returns a list of two values, the minimum and the maxium value that string will allow.

TYPES OF INEQUALITY

VALUE

The simplest type, a single value, e.g. 42 = Min 42, Max 42.

n < VALUE

Maximum is VALUE - 1, Minimum is undefined, e.g. n < 42 = Min undef, Max 41.

n > VALUE

Minimum is VALUE +1, Maximum is undefined, e.g. n > 42 = Min 43, Max undef.

n <= VALUE

Maximum is VALUE, Minimum is undefined, e.g. n < 42 = Min undef, Max 42.

n >= VALUE

Minimum is VALUE, Maximum is undefined, e.g. n > 42 = Min 42, Max undef.

Cases with VALUE, followed by N.

Handled as above, but with minimum and maximum reversed as expected.

VALUE1 < n < VALUE2

Minimum is VALUE1 + 1, maximum is VALUE2 - 1, e.g 42 < n < 200 = Min 43, Max 199.

BUGS

Does not handle VALUE1 <= n <= VALUE2 or similar. Patches welcome.
Does not complain at impossible <VALUE1 < n < VALUE 2 > combinations (e.g. 5 < n < 4) which result in a higher minumum than the maxiumum. Patches welcome.
Does not work with negative numbers. Patches welcome.
Always uses n as the number identifier, this should be configureable at import time.
Uses Exporter (should use Sub::Exporter)
DOES NOT work with floating point numbers. I consider this a feature.

AUTHORS

Tomas Doran (t0m) <bobtfish@bobtfish.net>

Dave Lambley

COPYRIGHT & LICENSE

Copyright 2011 the above author(s).

This sofware is free software, and is licensed under the same terms as perl itself.