regex_token_iterator Class

Iterator class for submatches.

Syntax

template<class BidIt,
   class Elem = typename std::iterator_traits<BidIt>::value_type,
   class RxTraits = regex_traits<Elem> >
class regex_token_iterator

Parameters

BidIt
The iterator type for submatches.

Elem
The type of elements to match.

RXtraits
Traits class for elements.

Remarks

The template class describes a constant forward iterator object. Conceptually, it holds a regex_iterator object that it uses to search for regular expression matches in a character sequence. It extracts objects of type sub_match<BidIt> representing the submatches identified by the index values in the stored vector subs for each regular expression match.

An index value of -1 designates the character sequence beginning immediately after the end of the previous regular expression match, or beginning at the start of the character sequence if there was no previous regular expression match, and extending to but not including the first character of the current regular expression match, or to the end of the character sequence if there is no current match. Any other index value idx designates the contents of the capture group held in it.match[idx].

Members

Member Default Value
private regex_iterator<BidIt, Elem, RXtraits> it
private vector<int> subs
private int pos

Constructors

Constructor Description
regex_token_iterator Constructs the iterator.

Typedefs

Type name Description
difference_type The type of an iterator difference.
iterator_category The type of the iterator category.
pointer The type of a pointer to a match.
reference The type of a reference to a submatch.
regex_type The type of the regular expression to match.
value_type The type of a submatch.

Operators

Operator Description
operator!= Compares iterators for inequality.
operator* Accesses the designated submatch.
operator++ Increments the iterator.
operator== Compares iterators for equality.
operator-> Accesses the designated submatch.

Requirements

Header: <regex>

Namespace: std

Example

#include <regex>
#include <iostream>

typedef std::regex_token_iterator<const char *> Myiter;
int main()
    {
    const char *pat = "aaxaayaaz";
    Myiter::regex_type rx("(a)a");
    Myiter next(pat, pat + strlen(pat), rx);
    Myiter end;

// show whole match
    for (; next != end; ++next)
        std::cout << "match == " << next->str() << std::endl;
    std::cout << std::endl;

// show prefix before match
    next = Myiter(pat, pat + strlen(pat), rx, -1);
    for (; next != end; ++next)
        std::cout << "match == " << next->str() << std::endl;
    std::cout << std::endl;

// show (a) submatch only
    next = Myiter(pat, pat + strlen(pat), rx, 1);
    for (; next != end; ++next)
        std::cout << "match == " << next->str() << std::endl;
    std::cout << std::endl;

// show prefixes and submatches
    std::vector<int> vec;
    vec.push_back(-1);
    vec.push_back(1);
    next = Myiter(pat, pat + strlen(pat), rx, vec);
    for (; next != end; ++next)
        std::cout << "match == " << next->str() << std::endl;
    std::cout << std::endl;

// show prefixes and whole matches
    int arr[] = {-1, 0};
    next = Myiter(pat, pat + strlen(pat), rx, arr);
    for (; next != end; ++next)
        std::cout << "match == " << next->str() << std::endl;
    std::cout << std::endl;

// other members
    Myiter it1(pat, pat + strlen(pat), rx);
    Myiter it2(it1);
    next = it1;

    Myiter::iterator_category cat = std::forward_iterator_tag();
    Myiter::difference_type dif = -3;
    Myiter::value_type mr = *it1;
    Myiter::reference ref = mr;
    Myiter::pointer ptr = &ref;

    dif = dif; // to quiet "unused" warnings
    ptr = ptr;

    return (0);
    }
match == aa
match == aa
match == aa

match ==
match == x
match == y
match == z

match == a
match == a
match == a

match ==
match == a
match == x
match == a
match == y
match == a
match == z

match ==
match == aa
match == x
match == aa
match == y
match == aa
match == z

regex_token_iterator::difference_type

The type of an iterator difference.

typedef std::ptrdiff_t difference_type;

Remarks

The type is a synonym for std::ptrdiff_t.

regex_token_iterator::iterator_category

The type of the iterator category.

typedef std::forward_iterator_tag iterator_category;

Remarks

The type is a synonym for std::forward_iterator_tag.

regex_token_iterator::operator!=

Compares iterators for inequality.

bool operator!=(const regex_token_iterator& right);

Parameters

right
The iterator to compare to.

Remarks

The member function returns !(*this == right).

regex_token_iterator::operator*

Accesses the designated submatch.

const sub_match<BidIt>& operator*();

Remarks

The member function returns a sub_match<BidIt> object representing the capture group identified by the index value subs[pos].

regex_token_iterator::operator++

Increments the iterator.

regex_token_iterator& operator++();

regex_token_iterator& operator++(int);

Remarks

If the stored iterator it is an end-of-sequence iterator the first operator sets the stored value pos to the value of subs.size() (thus making an end-of-sequence iterator). Otherwise the operator increments the stored value pos; if the result is equal to the value subs.size() it sets the stored value pos to zero and increments the stored iterator it. If incrementing the stored iterator leaves it unequal to an end-of-sequence iterator the operator does nothing further. Otherwise, if the end of the preceding match was at the end of the character sequence the operator sets the stored value of pos to subs.size(). Otherwise, the operator repeatedly increments the stored value pos until pos == subs.size() or subs[pos] == -1 (thus ensuring that the next dereference of the iterator will return the tail of the character sequence if one of the index values is -1). In all cases the operator returns the object.

The second operator makes a copy of the object, increments the object, then returns the copy.

regex_token_iterator::operator==

Compares iterators for equality.

bool operator==(const regex_token_iterator& right);

Parameters

right
The iterator to compare to.

Remarks

The member function returns it == right.it && subs == right.subs && pos == right.pos.

regex_token_iterator::operator->

Accesses the designated submatch.

const sub_match<BidIt> * operator->();

Remarks

The member function returns a pointer to a sub_match<BidIt> object representing the capture group identified by the index value subs[pos].

regex_token_iterator::pointer

The type of a pointer to a match.

typedef sub_match<BidIt> *pointer;

Remarks

The type is a synonym for sub_match<BidIt>*, where BidIt is the template parameter.

regex_token_iterator::reference

The type of a reference to a submatch.

typedef sub_match<BidIt>& reference;

Remarks

The type is a synonym for sub_match<BidIt>&, where BidIt is the template parameter.

regex_token_iterator::regex_token_iterator

Constructs the iterator.

regex_token_iterator();

regex_token_iterator(BidIt first, BidIt last,
    const regex_type& re, int submatch = 0,
    regex_constants::match_flag_type f = regex_constants::match_default);

regex_token_iterator(BidIt first, BidIt last,
    const regex_type& re, const vector<int> submatches,
    regex_constants::match_flag_type f = regex_constants::match_default);

template <std::size_t N>
regex_token_iterator(BidIt first, BidIt last,
    const regex_type& re, const int (&submatches)[N],
    regex_constants::match_flag_type f = regex_constants::match_default);

Parameters

first
Beginning of sequence to match.

last
End of sequence to match.

re
Regular expression for matches.

f
Flags for matches.

Remarks

The first constructor constructs an end-of-sequence iterator.

The second constructor constructs an object whose stored iterator it is initialized to regex_iterator<BidIt, Elem, RXtraits>(first, last, re, f), whose stored vector subs holds exactly one integer, with value submatch, and whose stored value pos is zero. Note: the resulting object extracts the submatch identified by the index value submatch for each successful regular expression match.

The third constructor constructs an object whose stored iterator it is initialized to regex_iterator<BidIt, Elem, RXtraits>(first, last, re, f), whose stored vector subs holds a copy of the constructor argument submatches, and whose stored value pos is zero.

The fourth constructor constructs an object whose stored iterator it is initialized to regex_iterator<BidIt, Elem, RXtraits>(first, last, re, f), whose stored vector subs holds the N values pointed to by the constructor argument submatches, and whose stored value pos is zero.

regex_token_iterator::regex_type

The type of the regular expression to match.

typedef basic_regex<Elem, RXtraits> regex_type;

Remarks

The typedef is a synonym for basic_regex<Elem, RXtraits>.

regex_token_iterator::value_type

The type of a submatch.

typedef sub_match<BidIt> value_type;

Remarks

The type is a synonym for sub_match<BidIt>, where BidIt is the template parameter.

See also

<regex>
regex_constants Class
regex_error Class
<regex> functions
regex_iterator Class
<regex> operators
regex_traits Class
<regex> typedefs