Robert Krimen


String::Comments::Extract - Extract comments from C/C++/JavaScript/Java source


version 0.023


    use String::Comments::Extract;

    my $source = <<_END_
    /* A Hello World program
        Copyright Ty Coon
        // ...and Buckaroo Banzai

    void main() {
        printf("Hello, World.\n");
        printf("/* This is not a real comment */");
        printf("// Neither is this */");
        // But this is

    // Last comment

    my $comments = String::Comments::Extract::C->extract($source)
    # ... returns the following result:

        /* A Hello World program
            Copyright Ty Coon
            // ...and Buckaroo Banzai

            // But this is

        // Last comment

    my @comments = String::Comments::Extract::C->collect($source)
    # ... returns the following list:
' A Hello World program
        Copyright Ty Coon
        // ...and Buckaroo Banzai
            ' But this is',
            ' Last comment',


String::Comments::Extract is a tool for extracting comments from C/C++/JavaScript/Java source. The extractor is implemented using an actual tokenizer (written in C via XS [adapted from JavaScript::Minifier::XS]). By using a tokenizer, it can correctly deal with notoriously problematic cases, such as comment-like structures embedded in strings:

    std::cout << "This is not a // real C++ comment " << std::endl
    printf("/* This is not a real C comment */\n");
    # The extractor will ignore both of the above

String::Comments::Extract considers C/C++/JavaScript/Java comment structures the same, so, for now, it doesn't really matter which method you use (this means it will not complain about C++ style comments in C source).

The language agnostic interface to C/C++/JavaScript/Java comment extractor is accessible via String::Comments::Extract::SlashStar

    # Can handle slash-star (/* */) and slash-slash (//) comments


String::Comments::Extract::JavaScript->extract( <source> )

String::Comments::Extract::CPP->extract( <source> )

String::Comments::Extract::C->extract( <source> )

String::Comments::Extract::SlashStar->extract( <source> )

Returns a string representing the comments in <source>

Comment delimeters ( /* */ // ) are left in as-is

Whitespace of <source> is otherwise preserved, so you'll probably have to do some post-processing to get rid of some cruft.

String::Comments::Extract::JavaScript->collect( <source> )

String::Comments::Extract::CPP->collect( <source> )

String::Comments::Extract::C->collect( <source> )

String::Comments::Extract::SlashStar->collect( <source> )

Returns a list containing an item for each block- or line-comment in <source>

Comment delimeters ( /* */ // ) around the comment are removed

Whitespace outside of comments may not be preserved exactly




Robert Krimen <>


This software is copyright (c) 2010 by Robert Krimen.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.