hello, all
I want to get the Class name of .java file with perl ,
How can I do it ? I think it is difficult to result the java comment .
For Example
a java file named AAA.java
/* author : John Smith */
// comment
public class ClassA {
/* */
//comment
public static void main(String[] args) {
}
}
class ClassB {
}
I want to get like this
>perl ClassChecker.pl AAA.java
>ClassA
>ClassB
thank u.

I'm sure there's a better way to do this, but it really isn't too hard.

#!/usr/bin/perl
use warnings;
use strict;

my $file = shift || die "Please provide a java file to check.\n";
my @lines = `cat $file`;

foreach (@lines) {
/class (\w+)/ && print "$1\n";
}
end

10/26/06, bou, hou (GE Money, consultant) <hou.bou (AT) ge (DOT) comwrote:
hello, all
I want to get the Class name of .java file with perl ,
How can I do it ? I think it is difficult to result the java comment .
For Example
a java file named AAA.java

/* author : John Smith */
// comment
public class ClassA {
/* */
//comment
public static void main(String[] args) {
}

}
class ClassB {

}

I want to get like this
>perl ClassChecker.pl AAA.java
>ClassA
>ClassB
>
thank u.

hello, all
I want to get the Class name of .java file with perl ,
How can I do it ? I think it is difficult to result the java comment .
For Example

What have you tried, and how has it failed to meet your expectations?

You may want to try http://search.cpan.org/ to see if something is
already written to get you started.

The problem with any task of this nature is: To reliably parse a
language in all (even pathological) cases requires a program equal in
complexity to that of the compiler itself[1].

That being said, a simple heuristic approach can be quite successful
for non-pathological cases, or a code-base that follows some set of
rules more stringent than those required by the standard.

For example, if you can be 100% certain that class definitions will
always begin with "\npublic class Classname {", then your job has
gotten much simpler, but your program will fail (possibly
spectacularly) on a java file that does not follow that rule.

[1] More accurately, to the lexer and parser components of the
compiler -- you can safely skip code generation.

-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Lawrence Statton - lawrenabae (AT) abaluon (DOT) abaom s/aba/c/g
Computer software consists of only two components: ones and
zeros, in roughly equal proportions. All that is required is to
sort them into the correct order.

10/26/06, bou, hou (GE Money, consultant) <hou.bou (AT) ge (DOT) comwrote:
hello, all
I want to get the Class name of .java file with perl ,

I want to get like this
>perl ClassChecker.pl AAA.java
>ClassA
>ClassB

Quick and dirty:

$ perl -n -e 'print "$1\n" if /class\s+(\w+)/' AAA.java
ClassA
ClassB

This does not know anything about Java syntax and just looks for a
word after 'class' and some space. If it is in comments or you have
something like

public class
Foo {
}

it won't understand it.

More robust solutions are feasible. For example, after improving the
recent CPAN module Parse::Java, you can do a lot better. To quote
Randal, "Learn or hire".

From: "Andy Greenwood" <greenwood.andy (AT) gmail (DOT) com>
I'm sure there's a better way to do this, but it really isn't too
hard.

#!/usr/bin/perl use warnings; use strict;

my $file = shift || die "Please provide a java file to check.\n"; my
@lines = `cat $file`;

AUUUUUUUU!!!

open my $IN, '<', $file or die "Can't open $file: $^E\n";
@lines = <$IN>;
close $IN;

is much much more efficient and unlike the cat it's actually
portable!

foreach (@lines) {
/class (\w+)/ && print "$1\n";
}

You do not actually need to load the whole file into an array and
then loop through the array, this would be better:

open my $IN, '<', $file or die "Can't open $file: $^E\n";
while (<$IN>) {
/class (\w+)/ && print "$1\n";
}
close $IN;

course the problem with this is that it ignores comments and
string literals and it assumes that there will always be a single
space between the "class" and the classname.

Jenda
Jenda (AT) Krynicky (DOT) cz http://Jenda.Krynicky.cz
When it comes to wine, women and song, wizards are allowed
to get drunk and croon as much as they like.
-- Terry Pratchett in Sourcery

schreef:
my $text = do { local $/; <$fh};
There is a problem with this idiom: it uses about twice the memory of
this variant:
my $text ; { local $/ ; $text = <$fh}
So if your files can be big (related to the amount of memory available),
use the latter.