[Rcpp-devel] Bug: replace_last()

[津田真樹]

I find a bug in String::replace_last().

I can reproduce the bug with the following code.
(I also showed output of replace_first and replace_all for comparison.)


=============
// [[Rcpp::export]]
void rcpp_string(){
    
    String s("abcdabcd");
    Rcout << "replace_first()\n";
    Rcout << s.replace_first("ab", "AB").get_cstring() << "\n";
    Rcout << "\n";
    
    s="abcdabcd";
    Rcout << "replace_last()\n";
    Rcout << s.replace_last("ab", "AB").get_cstring()  << "\n";
    Rcout << "\n";
    
    s="abcdabcd";
    Rcout << "replace_all()\n";
    Rcout << s.replace_all("ab", "AB").get_cstring()  << "\n";
    Rcout << "\n";
}
=============

output
=============
replace_first()
ABcdabcd

replace_last()
abcdaABd

replace_all()
ABcdABcd
=============


I also tried to fix the bug with following code. And the bug seems to be fixed.

=============
inline String& replace_last(const char* s, const char* news) {
    RCPP_STRING_DEBUG_2("String::replace_last(const char* = '%s' , const char* = '%s')", s, news);
    if (is_na()) return *this;
    setBuffer();
    //size_t index = buffer.find_last_of(s);
    size_t index = buffer.find_last_of(s) - (strlen(s)-1);
    Rcout << "A" << index << "\n";
    if (index != std::string::npos) buffer.replace(index, strlen(s), news);
    valid = false;
    return *this;
}
=============

output
=============
replace_first()
ABcdabcd

replace_last()
abcdABcd

replace_all()
ABcdABcd
=============


Mac OS 10.10.5
R version 3.2.3
Rcpp 0.12.4