We don't bite newbies here... much PerlMonks

### Comment on

 Need Help??
Hi monks, I am working in a project in helping colleges to do logic check from batch of Excel files. Staffs will write a sort of simple syntax (still designing) within a INI file; basically the so called syntax(expression) are some and or eq etc. operators with {[()]}. , which will return a true or false.

The first problem come to me is how do I resolve those brackets, so I can determine the logic's precedence. Now I have this :

```\$expr = '(A&(B&C)|((C&D)|\((A EQ 1)))';
#       01234567890123456789012345678

my (@open, @close);
my @charArr = split //, \$expr;
foreach my \$pos ( 0..\$#charArr ) {
push @open, \$pos if ( \$charArr[\$pos] =~ /\(/ && \$charArr[\$pos-1] n
+e "\\" ) ;
push @close, \$pos if ( \$charArr[\$pos] =~ /\)/ && \$charArr[\$pos-1]
+ne "\\" ) ;
}

die "Imbalance Pair" unless @open == @close;
print "@open\$/@close\$/\$/";

my @preced;
foreach my \$firstClose ( @close ) {
my @temp = ();
while ( @open ) {
my \$lastOpen = pop @open;
if ( \$lastOpen < \$firstClose ) {
push @preced, "\$lastOpen - \$firstClose";
@open = (@open, @temp);
last
}
else {
unshift @temp, \$lastOpen;
}
}
}
print \$_.\$/ foreach @preced;
__END__

prints:
0 3 9 10 18
7 14 25 26 27

3 - 7
10 - 14
18 - 25
9 - 26
0 - 27

The @preced carries the string positions of each open-end brackets, and their precedence order. However, it looks like a stupid algorithm, which sound unsafe and not efficient.

My questions :

1. What is the terminology of this sort of issues ? I like to look up more, but I don't know what is it called

2. Is there any module actually suits for this kind of case? What I have only a start up, implementing each block is another issue, if more operators are needed later, like >= == != boolean, string compare etc. situations. I can't foresee what's gonna happen.

Any clues for me ? Thanks in advance.

In reply to Need a start point for resolving {[()]} by exilepanda

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

• Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
• Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
• Read Where should I post X? if you're not absolutely sure you're posting in the right place.
• Posts may use any of the Perl Monks Approved HTML tags:
a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
• You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
 For: Use: & & < < > > [ [ ] ]
• Link using PerlMonks shortcuts! What shortcuts can I use for linking?

Create A New User
Chatterbox?
and all is quiet...

How do I use this? | Other CB clients
Other Users?
Others rifling through the Monastery: (5)
As of 2018-06-18 12:28 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
Should cpanminus be part of the standard Perl release?

Results (109 votes). Check out past polls.

Notices?