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 Need Help??

As I had some fun with drawing binary trees recently, I thought, parsing equations into such a tree would be interesting as well. I was also able to simplify the tree for operations on numbers (in contrast to variables) and expand based on distributivity. But now I am stuck. I was thinking that some re-ordering would lead to a definite form for each equation but I have no idea how to go about it. In any case, the code produces the following output which might be of interest (or at least entertaining). (Numbers are written vertically, and I have used ^ instead of **.)

```
Equation: 1+x^2*((1+y)*3)+5*(4+(4+3))

+
/ \__________________
1                     +
__________/ \
*             5
__/ \__          5
^       +
/ \     / \__
x   2   3     *
/ \
y   3

Equation: ((4+c)*y)^(4+2)/5-s^200

-
__/ \__
/       ^
__/ \     / \
^     5   s   2
______/ \            0
+         6           0
__/ \__
*       *
/ \     / \
4   y   c   y

Equation: 2+2

4
```use strict;
use warnings;
use Data::Dumper;

my %ops = (
'+' => sub { \$_[0] + \$_[1] },
'-' => sub { \$_[0] - \$_[1] },
'*' => sub { \$_[0] * \$_[1] },
'/' => sub { \$_[1] or die "Division by zero.\n"; \$_[0] / \$_[1]
+},
'^' => sub { \$_[0] ** \$_[1] },
);

my @ops      = ( '^', '*', '/', '+', '-' );
my @parens   = ( '(', ')' );
my @operands = ( '\d+', '\w+' );

my \$tokre = join "|", @operands, map { "\Q\$_\E" } @ops, @parens ;

sub reduce_parens {
my \$tokens = shift;
my @temp;
while( @\$tokens ) {
my \$tok = shift @\$tokens;
if( \$tok eq '(' ) {
push @temp, [ reduce_parens( \$tokens ) ];
next;
}
return @temp if \$tok eq ')';
push @temp, \$tok;
}
return @temp;
}

sub reduce_ops {
my( \$tokens, \$op ) = @_;
my @temp;
while( @\$tokens ) {
my \$tok = shift @\$tokens;
if( ref( \$tok ) ) {
push @temp, [ reduce_ops( \$tok, \$op ) ];
next;
}
if ( \$tok eq \$op ) {
my \$left  = [ @temp ];
my \$right = [ reduce_ops( \$tokens, \$op) ];
return ( 1==@\$left?\$\$left[0]:\$left, \$op, 1==@\$right?\$\$right[0]:\$
+right );
}
push @temp, \$tok;
}
return @temp;
}

sub distributivity {
my \$tokens = shift;
if( ref(\$tokens) && \$\$tokens[1] =~ /^(\*|\/)\$/ ) {
if( ref( \$\$tokens[0] ) && \$\$tokens[0]->[1] =~ /^(\-|\+)\$/ ) {
my \$mult    = \$\$tokens[1];
\$\$tokens[1] = \$\$tokens[0]->[1];
my \$left    = \$\$tokens[0]->[0];
my \$right   = \$\$tokens[0]->[2];
\$\$tokens[0] = [ \$left,  \$mult, \$\$tokens[2] ];
\$\$tokens[2] = [ \$right, \$mult, \$\$tokens[2] ];
} elsif( ref( \$\$tokens[2] ) && \$\$tokens[2]->[1] =~ /^(\-|\+)\$/ ) {
+
my \$mult    = \$\$tokens[1];
\$\$tokens[1] = \$\$tokens[2]->[1];
my \$left    = \$\$tokens[2]->[0];
my \$right   = \$\$tokens[2]->[2];
\$\$tokens[2] = [ \$\$tokens[0], \$mult, \$right ];
\$\$tokens[0] = [ \$\$tokens[0], \$mult, \$left ];
}
}
ref( \$\$tokens[\$_] ) and distributivity( \$\$tokens[\$_] ) for 0,2;
}

sub reduce_literals {
my \$tokens = shift;
ref \$\$tokens[\$_] and \$\$tokens[\$_] = reduce_literals( \$\$tokens[\$_] )
+for 0, 2;
if( !ref(\$\$tokens[0]) && !ref(\$\$tokens[1]) &&
(\$\$tokens[0] !~ /\D/) && (\$\$tokens[2] !~ /\D/) ) {
return \$ops{\$\$tokens[1]}->( \$\$tokens[0], \$\$tokens[2] );
}
return \$tokens;
}

sub parse_equation {
my \$eq = shift;
my \$tokens = [ \$eq =~ /(\$tokre)/g ];
@\$tokens = reduce_parens \$tokens;
@\$tokens = reduce_ops \$tokens, \$_ for reverse @ops;
distributivity \$tokens;
\$tokens = reduce_literals \$tokens;
#                print Dumper \@tokens;
return \$tokens;
}

sub prepare {
my( \$subtree, \$level, \$col, \$graph ) = @_;
my \$lcol = 0;
if( ref(\$subtree) ) {
\$lcol = prepare( \$subtree->[0], \$level+2, \$col, \$graph );    # par
+se left side of tree, keep top position
\$lcol and \$graph->[\$level]->[\$_] = '_' for \$lcol..\$\$col-1;   # dra
+w horizontal line
\$graph->[\$level]->[\$\$col++] = '/';
\$graph->[\$level-1]->[\$\$col++] = \$subtree->[1];
\$lcol = \$\$col;                                               # new
+ root of the tree
\$graph->[\$level]->[\$\$col++] = '\\';
my \$rcol = prepare( \$subtree->[2], \$level+2, \$col, \$graph ); # par
+se right side of the tree, keep its top position
\$rcol and \$graph->[\$level]->[\$_] = '_' for \$lcol+1..\$rcol-2; # dra
+w horizontal line
} else {
\$graph->[\$level++ -1]->[\$\$col] = \$_ for split //, \$subtree;
+           # leaf
\$\$col++;
}
return \$lcol;                                                  # ret
+urn column of root
}

sub printTree {
my \$root = shift;
my @graph;
my \$col = 1;
prepare( \$root, 1, \\$col, \@graph );
for my \$row ( @graph ) {
print \$_ // ' ' for @\$row;
print "\n";
}
}

for( <DATA> ){
print "\nEquation: \$_\n";
printTree parse_equation( \$_ );
}

__DATA__
1+x^2*((1+y)*3)+5*(4+(4+3))
((4+c)*y)^(4+2)/5-s^200
2+2

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 [stevieb]: I found that win10 broke a C# library I was using for one project while enhancing tests for a Perl dist, which breaks other Perl dists, and I'm about to throw my hands up on berrybrew. win2k12 broke one thing, win10 breaks something... [stevieb]: ...unrelated which requires replacing a lot of code and a whole lib. I'm about to go nix only ffs [shmem]: stevieb: what you're doing sounds afwully complex. Too much for me this evening to provide brighter insight ;-) [stevieb]: I don't even own a Windows computer. Both my girl and I have a laptop each with Linux. I'm supporting Windows in some of my projects and I can't even guage whether it's worth it or not. [stevieb]: shmem It's something I desired to have years ago, which is why I took over berrybrew. Cross-platform build/test automation locally, or over the network Test::BrewBuild [shmem]: sounds good. [shmem]: but I'm crumbling smaller stones. remember... [stevieb]: I'm working on it to fatten it up and make it more reliant so I can finalize my Raspberry Pi automated build system for that software :) It's all well and fun, until I try to make it work with Windows lol [shmem]: "debugging a program is more difficult than to write it in the first place. If you code your program as smart as you are, you are, by definition, too dumb to debug it."

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