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|
use v6d;
###############################################################################
##
## Perl Weekly Challenge 093, Task #1: Max Points
##
###############################################################################
#--------------------------------------#
# Copyright © 2021 PerlMonk Athanasius #
#--------------------------------------#
my Real constant $EPSILON = 1.11e-16; # ~ 2^(-53) for 64-bit double precision
###############################################################################
unit class Line;
###############################################################################
has Bool $.is-horizontal = False;
has Bool $.is-vertical = False;
has Real $.gradient;
has Real $.x-intercept;
has Real $.y-intercept;
has Pair @!points;
##=============================================================================
## Interface
##=============================================================================
#------------------------------------------------------------------------------
method collinear( Line:D $rhs --> Bool:D )
#------------------------------------------------------------------------------
{
my Bool $collinear;
if $!is-horizontal
{
$collinear = $rhs.is-horizontal &&
equals( $!y-intercept, $rhs.y-intercept );
}
elsif $!is-vertical
{
$collinear = $rhs.is-vertical &&
equals( $!x-intercept, $rhs.x-intercept );
}
else
{
$collinear = !$rhs.is-horizontal && !$rhs.is-vertical &&
equals( $!gradient, $rhs.gradient ) &&
equals( $!x-intercept, $rhs.x-intercept );
}
return $collinear;
}
#------------------------------------------------------------------------------
method add-point( Pair:D $new-point )
#------------------------------------------------------------------------------
{
my Bool $found = False;
for @!points -> Pair $existing-point
{
if equals( $existing-point.key, $new-point.key ) &&
equals( $existing-point.value, $new-point.value )
{
$found = True;
last;
}
}
@!points.push: $new-point unless $found;
}
#------------------------------------------------------------------------------
method count-points( --> UInt:D )
#------------------------------------------------------------------------------
{
return @!points.elems;
}
=begin comment
#------------------------------------------------------------------------------
method show() # For debugging
#------------------------------------------------------------------------------
{
"----\nLine:".put;
"Gradient: %s\n".printf: $!is-horizontal ?? '0 (horizontal)' !!
$!is-vertical ?? 'Inf (vertical)' !!
$!gradient;
"X-intercept: %s\n".printf: $!x-intercept if $!x-intercept.defined;
"Y-intercept: %s\n".printf: $!y-intercept if $!y-intercept.defined;
"Points: %s\n".\ printf: @!points.map( { sprintf "(%d,%d)", .kv } ).\
join: ', ';
'===='.put;
}
=end comment
#------------------------------------------------------------------------------
method show-points( --> Str:D ) # For verbose output
#------------------------------------------------------------------------------
{
return @!points.map( { "({ .key },{ .value })" } ).join: ', ';
}
##=============================================================================
## Implementation
##=============================================================================
#------------------------------------------------------------------------------
submethod BUILD( Real:D :$x1, Real:D :$y1, Real:D :$x2, Real:D :$y2 )
#------------------------------------------------------------------------------
{
my Real $delta-x = $x2 - $x1;
my Real $delta-y = $y2 - $y1;
if equals( $delta-x, 0 ) &&
equals( $delta-y, 0 )
{
die "ERROR: Identical points ($x1, $y1), ($x2, $y2) do not define a " ~
'line';
}
elsif equals( $delta-x, 0 )
{
$!is-vertical = True;
$!gradient = ∞;
$!x-intercept = $x1;
}
elsif equals( $delta-y, 0 )
{
$!is-horizontal = True;
$!gradient = 0;
$!y-intercept = $y1;
}
else
{
$!gradient = $delta-y / $delta-x;
$!x-intercept = $x1 - ($y1 / $!gradient);
$!y-intercept = $y1 - ($x1 * $!gradient);
}
@!points.push: $x1 => $y1, $x2 => $y2;
}
#------------------------------------------------------------------------------
sub equals( Real:D $lhs, Real:D $rhs --> Bool:D )
#------------------------------------------------------------------------------
{
return abs($lhs - $rhs) < $EPSILON;
}
###############################################################################
|
