我在字符串中实现子字符串的搜索,我想使这个搜索“重音 - 中性”或者它可能被称为粗糙 - 如果我开始在“rábano”中搜索“aba”我应该成功。
在Find substring in string using locale中有一个有效的答案:
#include <locale>
#include <string>
#include <boost/locale.hpp>
std::string NormalizeString(const std::string & input)
{
std::locale loc = boost::locale::generator()("");
const boost::locale::collator<char>& collator = std::use_facet<boost::locale::collator<char> >(loc);
std::string result = collator.transform(boost::locale::collator_base::primary, input);
return result;
}
此解决方案的唯一问题 - 转换会在字符串末尾添加几个字节。在我的情况下,它是“\ x1 \ x1 \ x1 \ x1 \ x0 \ x0 \ x0”。四个字节,带有1个和几个零字节。 当然,删除这些字节很容易,但我不想依赖这些微妙的实现细节。 (代码应该是跨平台的)
有更可靠的方法吗?
答案 0 :(得分:0)
作为@R。 Martinho Fernandes表示,用boost来实现这样的搜索是不可能的。 我在铬源中找到了解决方案。它使用ICU。
// This class is for speeding up multiple StringSearchIgnoringCaseAndAccents()
// with the same |find_this| argument. |find_this| is passed as the constructor
// argument, and precomputation for searching is done only at that timing.
class CStringSearchIgnoringCaseAndAccents
{
public:
explicit CStringSearchIgnoringCaseAndAccents(std::u16string find_this);
~CStringSearchIgnoringCaseAndAccents();
// Returns true if |in_this| contains |find_this|. If |match_index| or
// |match_length| are non-NULL, they are assigned the start position and total
// length of the match.
bool SearchIn(const std::u16string& in_this, size_t* match_index = nullptr, size_t* match_length = nullptr);
private:
std::u16string _find_this;
UStringSearch* _search_handle;
};
CStringSearchIgnoringCaseAndAccents::CStringSearchIgnoringCaseAndAccents(std::u16string find_this) :
_find_this(std::move(find_this)),
_search_handle(nullptr)
{
// usearch_open requires a valid string argument to be searched, even if we
// want to set it by usearch_setText afterwards. So, supplying a dummy text.
const std::u16string& dummy = _find_this;
UErrorCode status = U_ZERO_ERROR;
_search_handle = usearch_open((const UChar*)_find_this.data(), _find_this.size(),
(const UChar*)dummy.data(), dummy.size(), uloc_getDefault(), NULL, &status);
if (U_SUCCESS(status)) {
UCollator* collator = usearch_getCollator(_search_handle);
ucol_setStrength(collator, UCOL_PRIMARY);
usearch_reset(_search_handle);
}
}
CStringSearchIgnoringCaseAndAccents::~CStringSearchIgnoringCaseAndAccents()
{
if (_search_handle) usearch_close(_search_handle);
}
bool CStringSearchIgnoringCaseAndAccents::SearchIn(const std::u16string& in_this, size_t* match_index, size_t* match_length)
{
UErrorCode status = U_ZERO_ERROR;
usearch_setText(_search_handle, (const UChar*) in_this.data(), in_this.size(), &status);
// Default to basic substring search if usearch fails. According to
// http://icu-project.org/apiref/icu4c/usearch_8h.html, usearch_open will fail
// if either |find_this| or |in_this| are empty. In either case basic
// substring search will give the correct return value.
if (!U_SUCCESS(status)) {
size_t index = in_this.find(_find_this);
if (index == std::u16string::npos) {
return false;
}
else {
if (match_index)
*match_index = index;
if (match_length)
*match_length = _find_this.size();
return true;
}
}
int32_t index = usearch_first(_search_handle, &status);
if (!U_SUCCESS(status) || index == USEARCH_DONE) return false;
if (match_index)
{
*match_index = static_cast<size_t>(index);
}
if (match_length)
{
*match_length = static_cast<size_t>(usearch_getMatchedLength(_search_handle));
}
return true;
}
用法:
CStringSearchIgnoringCaseAndAccents searcher(a_utf16_string_what.c_str()));
searcher.SearchIn(a_utf16_string_where)
答案 1 :(得分:0)
即使这是一个老问题,我决定发布我的解决方案,因为它可能会帮助某人(或有人可以告诉我,如果我错了)。我使用了boost text conversion methods。首先我应用normalization form decomposition (NFD),它给了我分开的字符。然后我只是过滤了那些代码低于255的那些。然后是一个简单的小写转换。它适用于您的问题(以及我的问题),但我不确定它是否适用于所有情况。这是解决方案:
#include <iostream>
#include <algorithm>
#include <string>
#include <locale>
#include <boost/locale.hpp>
static std::locale loc = boost::locale::generator()("en_US.UTF-8");
std::string NormalizeString(const std::string & input)
{
std::string s_norm = boost::locale::normalize(input, boost::locale::norm_nfd, loc);
std::string s;
std::copy_if(s_norm.begin(), s_norm.end(), std::back_inserter(s), [](unsigned int ch){return ch<256;} );
return boost::locale::to_lower(s, loc);
}
void find_norm(const std::string& input, const std::string& query) {
if (NormalizeString(input).find(NormalizeString(query)) != std::string::npos)
std::cout << query << " found in " << input << std::endl;
else
std::cout << query << " not found in " << input << std::endl;
}
int main(int argc, char *argv[])
{
find_norm("rábano", "aba");
find_norm("rábano", "aaa");
return EXIT_SUCCESS;
}