[英]Issues with using Custom iterators for regex_iterator
I want to do regex search on a text where I want to skip certain characters from the text. 我想对要跳过文本中某些字符的文本进行正则表达式搜索。 Original question asked here : Regular Expression library that maintains state, takes input character by character and returns true whenever match is found For this I have made a custom iterator and am trying to pass those iterators to regex_iterator. 最初的问题在这里: 维护状态的正则表达式库,一个字符一个字符地输入,并在找到匹配项时返回true 。为此,我制作了一个自定义迭代器,并试图将这些迭代器传递给regex_iterator。 But I am getting following errors: 但是我遇到以下错误:
regex(2775): error C2512: 'fixed_array::iterator' : no appropriate default constructor available
with
[
T=char
]
regex(2773) : while compiling class template member function 'std::tr1::regex_iterator::regex_iterator(void)'
with
[
_BidIt=fixed_array::iterator
]
iterator.cpp(168) : see reference to class template instantiation 'std::tr1::regex_iterator' being compiled
with
[
_BidIt=fixed_array::iterator
]
regex(2775): error C2512: 'fixed_array::iterator' : no appropriate default constructor available
with
[
T=char
]
Here's my code: 这是我的代码:
template
class fixed_array
{
public:
typedef int size_type;
class iterator
{
public:
typedef iterator self_type;
typedef T value_type;
typedef T& reference;
typedef T* pointer;
typedef std::bidirectional_iterator_tag iterator_category;
typedef int difference_type;
iterator(pointer ptr) : ptr_(ptr) { }
self_type operator++() /*skip character 'a'*/
{
self_type i = *this;
ptr_++;
if(*ptr_ == 'a')
ptr_++;
return i;
}
self_type operator++(int junk)
{
ptr_++;
if(*ptr_ == 'a')
ptr_++;
return *this;
}
reference operator*()
{
return *ptr_;
}
pointer operator->()
{
return ptr_;
}
bool operator==(const self_type& rhs)
{
return ptr_ == rhs.ptr_;
}
bool operator!=(const self_type& rhs)
{
return ptr_ != rhs.ptr_;
}
private:
pointer ptr_;
};
class const_iterator
{
public:
typedef const_iterator self_type;
typedef T value_type;
typedef T& reference;
typedef T* pointer;
typedef int difference_type;
typedef std::bidirectional_iterator_tag iterator_category;
const_iterator(pointer ptr) : ptr_(ptr) { }
self_type operator++() { self_type i = *this; ptr_++; return i; }
self_type operator++(int junk) { ptr_++; return *this; }
const reference operator*() { return *ptr_; }
const pointer operator->() { return ptr_; }
bool operator==(const self_type& rhs) { return ptr_ == rhs.ptr_; }
bool operator!=(const self_type& rhs) { return ptr_ != rhs.ptr_; }
private:
pointer ptr_;
};
fixed_array(size_type size) : size_(size) {
data_ = new T[size_];
}
size_type size() const { return size_; }
T& operator[](size_type index)
{
assert(index < size_);
return data_[index];
}
const T& operator[](size_type index) const
{
assert(index < size_);
return data_[index];
}
iterator begin()
{
return iterator(data_);
}
iterator end()
{
return iterator(data_ + size_);
}
const_iterator begin() const
{
return const_iterator(data_);
}
const_iterator end() const
{
return const_iterator(data_ + size_);
}
private:
T* data_;
size_type size_;
};
using namespace std;
int main()
{
fixed_array<char> point3d(50);
//initialize the array with some string.
regex e ("a.*ea");
fixed_array<char>::iterator beg = point3d.begin();
fixed_array<char>::iterator end = point3d.end();
regex_iterator<fixed_array<char>::iterator> rit ( beg, end, e );
regex_iterator<fixed_array<char>::iterator> rend;
while (rit!=rend) {
cout << rit->str() << std::endl;
++rit;
}
return 0;
}
Filter iterators are tricky to get right. 筛选器迭代器很难正确处理。 Also, your const and non-const iterators are inconsistent. 同样,您的const和非const迭代器也不一致。
I recommend you use a Boost filter_iterator instead of writing your own thing. 我建议您使用Boost filter_iterator而不是编写自己的东西。
Ok finally with the help of answer by Sebastian, and some research, I was able to achieve what i intended to do. 好的,最终,借助塞巴斯蒂安(Sebastian)的回答以及一些研究,我得以实现我的目标。
I used the filter iterator code given at the following page : http://blogs.msdn.com/b/vcblog/archive/2010/08/09/the-filterator.aspx 我使用了在以下页面上给出的过滤器迭代器代码: http : //blogs.msdn.com/b/vcblog/archive/2010/08/09/the-filterator.aspx
Here is what i wrote apart from the iterator above: 除了上面的迭代器,这是我写的:
struct is_current_charT {
bool operator()(char s) const {
return s != 't';
}
};
int main() {
using namespace std;
string str = "test1 ,,ktest2,, ktest3,, ktest0,,";
regex e ("kes[0-9]");
auto fit = make_filterator(str.begin(), str.end(),
is_current_charT());
filterator<string::iterator,is_current_charT> cdogs(fit);
regex_iterator<filterator<string::iterator,is_current_charT>> rit ( cdogs, cdogs.end(), e );
regex_iterator<filterator<string::iterator,is_current_charT>> rend;
while (rit!=rend) {
cout << rit->str() << std::endl;
++rit;
}
}
OutPut: 输出:
kes2
kes3
kes0
This can now easily be modified to write more meaningful filtering functions. 现在可以轻松对其进行修改,以编写更有意义的过滤功能。
Thanks Ahmed and thanks Sebastian! 谢谢艾哈迈德和塞巴斯蒂安!
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