因此,除了我8小时前发表的评论之外:
可能相关:使用Boost.Spirit编译简单解析器, 替换字符串的部分内容, 如何使用Boost在.ini文件中扩展环境变量,也许最有趣的是快速将多个替换映射到字符串中
我看到还有另一种方法。如果...您需要基于相同的文本模板进行许多替换,但使用不同的替换映射怎么办?
最近我发现Boost ICL可以用于映射输入字符串的区域, 所以我想在这里做同样的事情。
我将事情变得非常通用,并使用Spirit进行分析(study
):
template <
typename InputRange,
typename It = typename boost::range_iterator<InputRange const>::type,
typename IntervalSet = boost::icl::interval_set<It> >
IntervalSet study(InputRange const& input) {
using std::begin;
using std::end;
It first(begin(input)), last(end(input));
using namespace boost::spirit::qi;
using boost::spirit::repository::qi::seek;
IntervalSet variables;
parse(first, last, *seek [ raw [ "{$" >> +alnum >> "}" ] ], variables);
return variables;
}
正如您所看到的,我们没有进行任何替换,而是返回一个
interval_set<It>
,以便我们知道变量的位置。这现在是可以用来执行替换的“智慧”,从替换字符串的映射中进行替换:
template <
typename InputRange,
typename Replacements,
typename OutputIterator,
typename StudyMap,
typename It = typename boost::range_iterator<InputRange const>::type
>
OutputIterator perform_replacements(InputRange const& input, Replacements const& m, StudyMap const& wisdom, OutputIterator out)
{
using std::begin;
using std::end;
It current(begin(input));
for (auto& replace : wisdom)
{
It l(lower(replace)),
u(upper(replace));
if (current < l)
out = std::copy(current, l, out);
auto match = m.find({l+2, u-1});
if (match == m.end())
out = std::copy(l, u, out);
else
out = std::copy(begin(match->second), end(match->second), out);
current = u;
}
if (current!=end(input))
out = std::copy(current, end(input), out);
return out;
}
现在,一个简单的测试程序可能是这样的:
现在,一个简单的测试程序可能是这样的:
int main()
{
using namespace std;
string const input = "This {$oops} is an {$severity} {$experience}!\n";
auto const wisdom = study(input);
cout << "Wisdom: ";
for(auto& entry : wisdom)
cout << entry;
auto m = map<string, string> {
{ "severity", "absolute" },
{ "OOPS", "REALLY" },
{ "experience", "nightmare" },
};
ostreambuf_iterator<char> out(cout);
out = '\n';
perform_replacements(input, m, wisdom, out);
map<string, string, ci_less> im { m.begin(), m.end() };
im["eXperience"] = "joy";
perform_replacements(input, im, wisdom, out);
}
打印
Wisdom: {$oops}{$severity}{$experience}
This {$oops} is an absolute nightmare!
This REALLY is an absolute joy!
您可以将其称为输入字符串字面量,使用
unordered_map
进行替换等操作。您可以省略
wisdom
,在这种情况下,实现将会动态学习它。
完整程序
在Coliru上实时运行
#include <iostream>
#include <map>
#include <boost/regex.hpp>
#include <boost/icl/interval_set.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/repository/include/qi_seek.hpp>
namespace boost { namespace spirit { namespace traits {
template <typename It>
struct assign_to_attribute_from_iterators<icl::discrete_interval<It>, It, void> {
template <typename ... T> static void call(It b, It e, icl::discrete_interval<It>& out) {
out = icl::discrete_interval<It>::right_open(b, e);
}
};
} } }
template <
typename InputRange,
typename It = typename boost::range_iterator<InputRange const>::type,
typename IntervalSet = boost::icl::interval_set<It> >
IntervalSet study(InputRange const& input) {
using std::begin;
using std::end;
It first(begin(input)), last(end(input));
using namespace boost::spirit::qi;
using boost::spirit::repository::qi::seek;
IntervalSet variables;
parse(first, last, *seek [ raw [ "{$" >> +alnum >> "}" ] ], variables);
return variables;
}
template <
typename InputRange,
typename Replacements,
typename OutputIterator,
typename StudyMap,
typename It = typename boost::range_iterator<InputRange const>::type
>
OutputIterator perform_replacements(InputRange const& input, Replacements const& m, StudyMap const& wisdom, OutputIterator out)
{
using std::begin;
using std::end;
It current(begin(input));
for (auto& replace : wisdom)
{
It l(lower(replace)),
u(upper(replace));
if (current < l)
out = std::copy(current, l, out);
auto match = m.find({l+2, u-1});
if (match == m.end())
out = std::copy(l, u, out);
else
out = std::copy(begin(match->second), end(match->second), out);
current = u;
}
if (current!=end(input))
out = std::copy(current, end(input), out);
return out;
}
template <
typename InputRange,
typename Replacements,
typename OutputIterator,
typename It = typename boost::range_iterator<InputRange const>::type
>
OutputIterator perform_replacements(InputRange const& input, Replacements const& m, OutputIterator out) {
return perform_replacements(input, m, study(input), out);
}
#include <boost/algorithm/string.hpp>
struct ci_less {
template <typename S>
bool operator() (S const& a, S const& b) const {
return boost::lexicographical_compare(a, b, boost::is_iless());
}
};
namespace boost { namespace icl {
template <typename It>
static inline std::ostream& operator<<(std::ostream& os, discrete_interval<It> const& i) {
return os << make_iterator_range(lower(i), upper(i));
}
} }
int main()
{
using namespace std;
string const input = "This {$oops} is an {$severity} {$experience}!\n";
auto const wisdom = study(input);
cout << "Wisdom: ";
for(auto& entry : wisdom)
cout << entry;
auto m = map<string, string> {
{ "severity", "absolute" },
{ "OOPS", "REALLY" },
{ "experience", "nightmare" },
};
ostreambuf_iterator<char> out(cout);
out = '\n';
perform_replacements(input, m, wisdom, out);
map<string, string, ci_less> im { m.begin(), m.end() };
im["eXperience"] = "joy";
perform_replacements(input, im, wisdom, out);
}
原地操作
只要确保替换字符串始终比{$pattern}
字符串短(或长度相等),就可以将此函数与input.begin()
作为输出迭代器一起调用。
在 Coliru 上实时运行
string input1 = "This {$803525c8-3ce4-423a-ad25-cc19bbe8422a} is an {$efa72abf-fe96-4983-b373-a35f70551e06} {$8a10abaa-cc0d-47bd-a8e1-34a8aa0ec1ef}!\n",
input2 = input1;
auto m = map<string, string> {
{ "efa72abf-fe96-4983-b373-a35f70551e06", "absolute" },
{ "803525C8-3CE4-423A-AD25-CC19BBE8422A", "REALLY" },
{ "8a10abaa-cc0d-47bd-a8e1-34a8aa0ec1ef", "nightmare" },
};
input1.erase(perform_replacements(input1, m, input1.begin()), input1.end());
map<string, string, ci_less> im { m.begin(), m.end() };
im["8a10abaa-cc0d-47bd-a8e1-34a8aa0ec1ef"] = "joy";
input2.erase(perform_replacements(input2, im, input2.begin()), input2.end());
std::cout << input1
<< input2;
打印
This {$803525c8-3ce4-423a-ad25-cc19bbe8422a} is an absolute nightmare!
This REALLY is an absolute joy!
请注意,您显然不能在相同的输入模板上再次重复使用相同的“智慧”,因为它已被修改。