Why boost locale didn't provide character leve

问题:

Env: boost1.53.0 c++11;

New to c++.

In boost locale boundary analysis, the rule type is specified for word(eg.boundary::word_letter, boundary::word_number) and sentence , but there is no boundary rule type for character. All I want is something like isUpperCase(), isLowerCase(), isDigit(), isPunctuation().

Tried boost string algorithm which didn't work.

boost::locale::generator gen;
std::locale loc = gen("ru_RU.UTF-8");
std::string context = "ДВ";
std::cout << boost::algorithm::all(context, boost::algorithm::is_upper(loc));

Why these features can be accessed easily in Java or python but so so confusing in C++? Any consist way to achieve these?

回答1:

This works for me under VS 2013.

locale::global(locale("ru-RU")); 
std::string context = "ДВ"; 
std::cout << any_of(context.begin(), context.end(), boost::algorithm::is_upper());

Prints 1

It is important how you initialize the locale.

UPDATE:

Here's solution which will work under Ubuntu.

#include <iostream>

#include <boost/algorithm/string/classification.hpp>
#include <boost/algorithm/string/predicate.hpp>
#include <boost/locale.hpp>

using namespace std;

int main()
{
    locale::global(locale("ru_RU"));

    wstring context = L"ДВ";
    wcout << boolalpha << any_of(context.begin(), context.end(), boost::algorithm::is_upper());

    wcout<<endl;

    wstring context1 = L"ПРИВЕТ, МИР"; //HELLO WORLD in russian
    wcout << boolalpha << any_of(context1.begin(), context1.end(), boost::algorithm::is_upper());

    wcout<<endl;

    wstring context2 = L"привет мир"; //hello world in russian
    wcout << boolalpha << any_of(context2.begin(), context2.end(), boost::algorithm::is_upper());

    return 0;
}

Prints

true
true
false

This will work with boost::algorithm::all as well.

wstring context = L"ДВ";
wcout << boolalpha << boost::algorithm::all(context, boost::algorithm::is_upper());

回答2:

Boost.locale is based on ICU and ICU itself did provide character level classification, which seems pretty consist and readable(more of Java-style).

Here is a simple example.

#include <unicode/brkiter.h>
#include <unicode/utypes.h>
#include <unicode/uchar.h>

int main()
{
UnicodeString s("А аБ Д д2 -");
UErrorCode status = U_ERROR_WARNING_LIMIT;
Locale ru("ru", "RU");
BreakIterator* bi = BreakIterator::createCharacterInstance(ru, status);
bi->setText(s);
int32_t p = bi->first();
while(p != BreakIterator::DONE) {
    std::string type;
    if(u_isUUppercase(s.charAt(p)))
        type = "upper" ;
    if(u_isULowercase(s.charAt(p)))
        type = "lower" ;
    if(u_isUWhiteSpace(s.charAt(p)))
        type = "whitespace" ;
    if(u_isdigit(s.charAt(p)))
        type = "digit" ;
    if(u_ispunct(s.charAt(p)))
        type = "punc" ;
    printf("Boundary at position %d is %s\n", p, type.c_str());
    p= bi->next();
}
delete bi;
return 0;

}