Using pcre2 in a c++ project

Question

I am looking at using pcre2 in my simple c++ app, (I am using vs2015). (I am looking at various regex libraries and the general feeling is that pcre/pcre2 are the most flexible)

First I downloaded pcre2 from the official location, (http://sourceforge.net/projects/pcre/files/pcre2/10.20/) and created a very simple example.

#define PCRE2_CODE_UNIT_WIDTH 8
#include <pcre2.h>
...
PCRE2_SPTR subject = (PCRE2_SPTR)std::string("this is it").c_str();
PCRE2_SPTR pattern = (PCRE2_SPTR)std::string("([a-z]+)|\\s").c_str();

...
int errorcode;
PCRE2_SIZE erroroffset;
pcre2_code *re = pcre2_compile(pattern, PCRE2_ZERO_TERMINATED, 
                                PCRE2_ANCHORED | PCRE2_UTF, &errorcode,  
                                &erroroffset, NULL);
...

First of all the file "pcre2.h" does not exist, so I renamed pcre2.h.generic to pcre2.h

But then I get linker errors with unresolved externals.

I am guessing I need to include one or more files from the source to project. But I am reluctant to just randomly add files without knowing what it all does.

Can someone give some simple steps to follow to successfully build a project using pcre2?

UPDATE
This is not an import library issue, pcre2.h does not come with a librar, (not one that I can see in their release location).

Answer 1

If you don't mind using a wrapper, here's mine: JPCRE2

You need to select the basic character type (char, wchar_t, char16_t, char32_t) according to the string classes you will use (respectively std::string, std::wstring, std::u16string, std::u32string):

typedef jpcre2::select<char> jp;
//Selecting char as the basic character type will require
//8 bit PCRE2 library where char is 8 bit,
//or 16 bit PCRE2 library where char is 16 bit,
//or 32 bit PCRE2 library where char is 32 bit.
//If char is not 8, 16 or 32 bit, it's a compile error.

Match Examples:

Check if a string matches a pattern:

if(jp::Regex("(\\d)|(\\w)").match("I am the subject")) 
    std::cout<<"\nmatched";
else
    std::cout<<"\nno match";

Match all and get the match count:

size_t count = 
jp::Regex("(\\d)|(\\w)","mi").match("I am the subject", "g");
// 'm' modifier enables multi-line mode for the regex
// 'i' modifier makes the regex case insensitive
// 'g' modifier enables global matching

Get numbered substrings/captured groups:

jp::VecNum vec_num;
count = 
jp::Regex("(\\w+)\\s*(\\d+)","im").initMatch()
                                  .setSubject("I am 23, I am digits 10")
                                  .setModifier("g")
                                  .setNumberedSubstringVector(&vec_num)
                                  .match();
std::cout<<"\nTotal match of first match: "<<vec_num[0][0];      
std::cout<<"\nCaptrued group 1 of first match: "<<vec_num[0][1]; 
std::cout<<"\nCaptrued group 2 of first match: "<<vec_num[0][2]; 

std::cout<<"\nTotal match of second match: "<<vec_num[1][0];
std::cout<<"\nCaptrued group 1 of second match: "<<vec_num[1][1];
std::cout<<"\nCaptrued group 2 of second match: "<<vec_num[1][2]; 

Get named substrings/captured groups:

jp::VecNas vec_nas;
count = 
jp::Regex("(?<word>\\w+)\\s*(?<digit>\\d+)","m")
                         .initMatch()
                         .setSubject("I am 23, I am digits 10")
                         .setModifier("g")
                         .setNamedSubstringVector(&vec_nas)
                         .match();
std::cout<<"\nCaptured group (word) of first match: "<<vec_nas[0]["word"];
std::cout<<"\nCaptured group (digit) of first match: "<<vec_nas[0]["digit"];

std::cout<<"\nCaptured group (word) of second match: "<<vec_nas[1]["word"];
std::cout<<"\nCaptured group (digit) of second match: "<<vec_nas[1]["digit"];

Iterate through all matches and substrings:

//Iterating through numbered substring
for(size_t i=0;i<vec_num.size();++i){
    //i=0 is the first match found, i=1 is the second and so forth
    for(size_t j=0;j<vec_num[i].size();++j){
        //j=0 is the capture group 0 i.e the total match
        //j=1 is the capture group 1 and so forth.
        std::cout<<"\n\t("<<j<<"): "<<vec_num[i][j]<<"\n";
    }
}

Replace/Substitute Examples:

std::cout<<"\n"<<
///replace all occurrences of a digit with @
jp::Regex("\\d").replace("I am the subject string 44", "@", "g");

///swap two parts of a string
std::cout<<"\n"<<
jp::Regex("^([^\t]+)\t([^\t]+)$")
             .initReplace()
             .setSubject("I am the subject\tTo be swapped according to tab")
             .setReplaceWith("$2 $1")
             .replace();

Replace with Match Evaluator:

jp::String callback1(const jp::NumSub& m, void*, void*){
    return "("+m[0]+")"; //m[0] is capture group 0, i.e total match (in each match)
}
int main(){
    jp::Regex re("(?<total>\\w+)", "n");
    jp::RegexReplace rr(&re);
    String s3 = "I am ঋ আা a string 879879 fdsjkll ১ ২ ৩ ৪ অ আ ক খ গ ঘ আমার সোনার বাংলা";
    rr.setSubject(s3)
      .setPcre2Option(PCRE2_SUBSTITUTE_GLOBAL);
    std::cout<<"\n\n### 1\n"<<
            rr.nreplace(jp::MatchEvaluator(callback1));
            //nreplace() treats the returned string from the callback as literal,
            //while replace() will process the returned string
            //with pcre2_substitute()

    #if __cplusplus >= 201103L
    //example with lambda
    std::cout<<"\n\n### Lambda\n"<<
            rr.nreplace(
                jp::MatchEvaluator(
                    [](const jp::NumSub& m1, const jp::MapNas& m2, void*){
                        return "("+m1[0]+"/"+m2.at("total")+")";
                    }
                ));
    #endif
    return 0;
}

You can read the complete documentation here.