[Boost-bugs] [Boost C++ Libraries] #4103: erase_all_regex does not work well with possibly empty strings.

Subject: [Boost-bugs] [Boost C++ Libraries] #4103: erase_all_regex does not work well with possibly empty strings.
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2010-04-15 14:32:42

#4103: erase_all_regex does not work well with possibly empty strings.
-------------------------------------------------+--------------------------
 Reporter:  Paolo Bolzoni <bolzoni@…>            |       Owner:         
     Type:  Bugs                                 |      Status:  new    
Milestone:  Boost 1.43.0                         |   Component:  None   
  Version:  Boost Development Trunk              |    Severity:  Problem
 Keywords:                                       |  
-------------------------------------------------+--------------------------
 Here is a test case, I want to remove all the substrings that matches the
 regular expression '`\s*`': all spaces, tabs and similars.

 {{{
  $ cat test_case.cc

  #include <boost/algorithm/string/regex.hpp>
  #include <iostream>
  #include <string>

  boost::regex const& spaces() {
      static boost::regex rv("\\s*");
      return rv;
  }

  int main() {
      std::string e1("  Leading spaces!   Remove them   all!   ");
      std::string c1(e1);
      std::string e2("No  trailing  or leading... Remove     them all!");
      std::string c2(e2);

      boost::erase_all_regex(e1, spaces());
      std::cout << "Erased:   -" << e1 << "-" << std::endl;
      std::cout << "Original: -" << c1 << "-" << std::endl;

      std::cout << std::endl;

      boost::erase_all_regex(e2, spaces());
      std::cout << "Erased:   -" << e2 << "-" << std::endl;
      std::cout << "Original: -" << c2 << "-" << std::endl;
  }

  $ g++ -lboost_regex -W -Wall -pedantic -o test_case test_case.cc
  $ ./test_case
  Erased:   -Leading spaces!   Remove them   all!   -
  Original: -  Leading spaces!   Remove them   all!   -

  Erased:   -No  trailing  or leading... Remove     them all!-
  Original: -No  trailing  or leading... Remove     them all!-
  $
 }}}


 I think the expected output should not have spaces in the output
 string. Instead only the leading spaces are removed.

 While the problem still persist with '`\s*`' the bug apparead also
 with regex '`\s+`' in the version 1.41, but using the svn trunk
 downloaded yesterday it disappeared. It is worth to note because the bug
 is not very grave anymore. It is enough to use a regex that does
 not allow empty strings.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/4103>
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