[/ Copyright 2006-2007 John Maddock. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt). ] [section:match_results match_results] [h4 Synopsis] #include Regular expressions are different from many simple pattern-matching algorithms in that as well as finding an overall match they can also produce sub-expression matches: each sub-expression being delimited in the pattern by a pair of parenthesis (...). There has to be some method for reporting sub-expression matches back to the user: this is achieved this by defining a class `match_results` that acts as an indexed collection of sub-expression matches, each sub-expression match being contained in an object of type [sub_match]. Template class `match_results` denotes a collection of character sequences representing the result of a regular expression match. Objects of type `match_results` are passed to the algorithms [regex_match] and [regex_search], and are returned by the iterator [regex_iterator]. Storage for the collection is allocated and freed as necessary by the member functions of class `match_results`. The template class `match_results` conforms to the requirements of a Sequence, as specified in (lib.sequence.reqmts), except that only operations defined for const-qualified Sequences are supported. Class template `match_results` is most commonly used as one of the typedefs `cmatch`, `wcmatch`, `smatch`, or `wsmatch`: template > class match_results; typedef match_results cmatch; typedef match_results wcmatch; typedef match_results smatch; typedef match_results wsmatch; template > class match_results { public: typedef sub_match value_type; typedef const value_type& const_reference; typedef const_reference reference; typedef implementation defined const_iterator; typedef const_iterator iterator; typedef typename iterator_traits::difference_type difference_type; typedef typename Allocator::size_type size_type; typedef Allocator allocator_type; typedef typename iterator_traits::value_type char_type; typedef basic_string string_type; // construct/copy/destroy: ``[link boost_regex.match_results.construct explicit match_results]``(const Allocator& a = Allocator()); ``[link boost_regex.match_results.copy_construct match_results]``(const match_results& m); ``[link boost_regex.match_results.assign match_results& operator=]``(const match_results& m); ~match_results(); // size: size_type ``[link boost_regex.match_results.size size]``() const; size_type ``[link boost_regex.match_results.max_size max_size]``() const; bool ``[link boost_regex.match_results.empty empty]``() const; // element access: difference_type ``[link boost_regex.match_results.length length]``(int sub = 0) const; difference_type ``[link boost_regex.match_results.length length]``(const char_type* sub) const; template difference_type ``[link boost_regex.match_results.length length]``(const charT* sub) const; template difference_type ``[link boost_regex.match_results.length length]``(const std::basic_string& sub) const; difference_type ``[link boost_regex.match_results.position position]``(unsigned int sub = 0) const; difference_type ``[link boost_regex.match_results.position position]``(const char_type* sub) const; template difference_type ``[link boost_regex.match_results.position position]``(const charT* sub) const; template difference_type ``[link boost_regex.match_results.position position]``(const std::basic_string& sub) const; string_type ``[link boost_regex.match_results.str str]``(int sub = 0) const; string_type ``[link boost_regex.match_results.str str]``(const char_type* sub)const; template string_type ``[link boost_regex.match_results.str str]``(const std::basic_string& sub)const; template string_type ``[link boost_regex.match_results.str str]``(const charT* sub)const; template string_type ``[link boost_regex.match_results.str str]``(const std::basic_string& sub)const; const_reference ``[link boost_regex.match_results.subscript operator\[\]]``(int n) const; const_reference ``[link boost_regex.match_results.subscript operator\[\]]``(const char_type* n) const; template const_reference ``[link boost_regex.match_results.subscript operator\[\]]``(const std::basic_string& n) const; template const_reference ``[link boost_regex.match_results.subscript operator\[\]]``(const charT* n) const; template const_reference ``[link boost_regex.match_results.subscript operator\[\]]``(const std::basic_string& n) const; const_reference ``[link boost_regex.match_results.prefix prefix]``() const; const_reference ``[link boost_regex.match_results.suffix suffix]``() const; const_iterator ``[link boost_regex.match_results.begin begin]``() const; const_iterator ``[link boost_regex.match_results.end end]``() const; // format: template OutputIterator ``[link boost_regex.match_results.format format]``(OutputIterator out, Formatter fmt, match_flag_type flags = format_default) const; template string_type ``[link boost_regex.match_results.format2 format]``(Formatter fmt, match_flag_type flags = format_default) const; allocator_type ``[link boost_regex.match_results.get_allocator get_allocator]``() const; void ``[link boost_regex.match_results.swap swap]``(match_results& that); #ifdef BOOST_REGEX_MATCH_EXTRA typedef typename value_type::capture_sequence_type capture_sequence_type; const capture_sequence_type& ``[link boost_regex.match_results.captures captures]``(std::size_t i)const; #endif }; template bool ``[link boost_regex.match_results.op_eq operator ==]`` (const match_results& m1, const match_results& m2); template bool ``[link boost_regex.match_results.op_ne operator !=]`` (const match_results& m1, const match_results& m2); template basic_ostream& ``[link boost_regex.match_results.op_stream operator <<]`` (basic_ostream& os, const match_results& m); template void ``[link boost_regex.match_results.op_swap swap]``(match_results& m1, match_results& m2); [h4 Description] In all `match_results` constructors, a copy of the Allocator argument is used for any memory allocation performed by the constructor or member functions during the lifetime of the object. [#boost_regex.match_results.construct] match_results(const Allocator& a = Allocator()); [*Effects]: Constructs an object of class `match_results`. The postconditions of this function are indicated in the table: [table [[Element][Value]] [[empty()][true]] [[size()][0]] [[str()][basic_string()]] ] [#boost_regex.match_results.copy_construct] match_results(const match_results& m); [*Effects]: Constructs an object of class match_results, as a copy of m. [#boost_regex.match_results.assign] match_results& operator=(const match_results& m); [*Effects]: Assigns m to *this. The postconditions of this function are indicated in the table: [table [[Element][Value]] [[empty()][m.empty().]] [[size()][m.size().]] [[str(n)][m.str(n) for all integers n < m.size().]] [[prefix()][m.prefix().]] [[suffix()][m.suffix().]] [[(*this)\[n\]][m\[n\] for all integers n < m.size().]] [[length(n)][m.length(n) for all integers n < m.size().]] [[position(n)][m.position(n) for all integers n < m.size().]] ] [#boost_regex.match_results.size] size_type size()const; [*Effects]: Returns the number of [sub_match] elements stored in *this; that is the number of marked sub-expressions in the regular expression that was matched plus one. [#boost_regex.match_results.max_size] size_type max_size()const; [*Effects]: Returns the maximum number of [sub_match] elements that can be stored in *this. [#boost_regex.match_results.empty] bool empty()const; [*Effects]: Returns size() == 0. [#boost_regex.match_results.length] difference_type length(int sub = 0)const; difference_type length(const char_type* sub)const; template difference_type length(const charT* sub)const; template difference_type length(const std::basic_string&)const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns the length of sub-expression /sub/, that is to say: `(*this)[sub].length()`. The overloads that accept a string refer to a named sub-expression /n/. In the event that there is no such named sub-expression then returns zero. The template overloads of this function, allow the string and\/or character type to be different from the character type of the underlying sequence and\/or regular expression: in this case the characters will be widened to the underlying character type of the original regular expression. A compiler error will occur if the argument passes a wider character type than the underlying sequence. These overloads allow a normal narrow character C string literal to be used as an argument, even when the underlying character type of the expression being matched may be something more exotic such as a Unicode character type. [#boost_regex.match_results.position] difference_type position(unsigned int sub = 0)const; difference_type position(const char_type* sub)const; template difference_type position(const charT* sub)const; template difference_type position(const std::basic_string&)const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns the starting location of sub-expression /sub/, or -1 if /sub/ was not matched. Note that if this represents a partial match , then `position()` will return the location of the partial match even though `(*this)[0].matched` is false. The overloads that accept a string refer to a named sub-expression /n/. In the event that there is no such named sub-expression then returns -1. The template overloads of this function, allow the string and\/or character type to be different from the character type of the underlying sequence and\/or regular expression: in this case the characters will be widened to the underlying character type of the original regular expression. A compiler error will occur if the argument passes a wider character type than the underlying sequence. These overloads allow a normal narrow character C string literal to be used as an argument, even when the underlying character type of the expression being matched may be something more exotic such as a Unicode character type. [#boost_regex.match_results.str] string_type str(int sub = 0)const; string_type str(const char_type* sub)const; template string_type str(const std::basic_string& sub)const; template string_type str(const charT* sub)const; template string_type str(const std::basic_string& sub)const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns sub-expression /sub/ as a string: `string_type((*this)[sub])`. The overloads that accept a string, return the string that matched the named sub-expression /n/. In the event that there is no such named sub-expression then returns an empty string. The template overloads of this function, allow the string and\/or character type to be different from the character type of the underlying sequence and\/or regular expression: in this case the characters will be widened to the underlying character type of the original regular expression. A compiler error will occur if the argument passes a wider character type than the underlying sequence. These overloads allow a normal narrow character C string literal to be used as an argument, even when the underlying character type of the expression being matched may be something more exotic such as a Unicode character type. [#boost_regex.match_results.subscript] const_reference operator[](int n) const; const_reference operator[](const char_type* n) const; template const_reference operator[](const std::basic_string& n) const; template const_reference operator[](const charT* n) const; template const_reference operator[](const std::basic_string& n) const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns a reference to the [sub_match] object representing the character sequence that matched marked sub-expression /n/. If `n == 0` then returns a reference to a [sub_match] object representing the character sequence that matched the whole regular expression. If /n/ is out of range, or if /n/ is an unmatched sub-expression, then returns a [sub_match] object whose matched member is false. The overloads that accept a string, return a reference to the [sub_match] object representing the character sequence that matched the named sub-expression /n/. In the event that there is no such named sub-expression then returns a [sub_match] object whose matched member is false. The template overloads of this function, allow the string and\/or character type to be different from the character type of the underlying sequence and\/or regular expression: in this case the characters will be widened to the underlying character type of the original regular expression. A compiler error will occur if the argument passes a wider character type than the underlying sequence. These overloads allow a normal narrow character C string literal to be used as an argument, even when the underlying character type of the expression being matched may be something more exotic such as a Unicode character type. [#boost_regex.match_results.prefix] const_reference prefix()const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns a reference to the [sub_match] object representing the character sequence from the start of the string being matched or searched, to the start of the match found. [#boost_regex.match_results.suffix] const_reference suffix()const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: Returns a reference to the [sub_match] object representing the character sequence from the end of the match found to the end of the string being matched or searched. [#boost_regex.match_results.begin] const_iterator begin()const; [*Effects]: Returns a starting iterator that enumerates over all the marked sub-expression matches stored in *this. [#boost_regex.match_results.end] const_iterator end()const; [*Effects]: Returns a terminating iterator that enumerates over all the marked sub-expression matches stored in *this. [#boost_regex.match_results_format] [#boost_regex.match_results.format] template OutputIterator format(OutputIterator out, Formatter fmt, match_flag_type flags = format_default); [*Requires]: The type `OutputIterator` conforms to the Output Iterator requirements (C++ std 24.1.2). The type `Formatter` must be either a pointer to a null-terminated string of type `char_type[]`, or be a container of `char_type`'s (for example `std::basic_string`) or be a unary, binary or ternary functor that computes the replacement string from a function call: either `fmt(*this)` which must return a container of `char_type`'s to be used as the replacement text, or either `fmt(*this, out)` or `fmt(*this, out, flags)`, both of which write the replacement text to `*out`, and then return the new OutputIterator position. Note that if the formatter is a functor, then it is ['passed by value]: users that want to pass function objects with internal state might want to use [@../../../../doc/html/ref.html Boost.Ref] to wrap the object so that it's passed by reference. [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: If `fmt` is either a null-terminated string, or a container of `char_type`'s, then copies the character sequence `[fmt.begin(), fmt.end())` to `OutputIterator` /out/. For each format specifier or escape sequence in /fmt/, replace that sequence with either the character(s) it represents, or the sequence of characters within `*this` to which it refers. The bitmasks specified in flags determines what format specifiers or escape sequences are recognized, by default this is the format used by ECMA-262, ECMAScript Language Specification, Chapter 15 part 5.4.11 String.prototype.replace. If `fmt` is a function object, then depending on the number of arguments the function object accepts, it will either: * Call `fmt(*this)` and copy the string returned to `OutputIterator` /out/. * Call `fmt(*this, out)`. * Call `fmt(*this, out, flags)`. In all cases the new position of the `OutputIterator` is returned. See the [link boost_regex.format format syntax guide for more information]. [*Returns]: out. [#boost_regex.match_results.format2] template string_type format(Formatter fmt, match_flag_type flags = format_default); [*Requires] The type `Formatter` must be either a pointer to a null-terminated string of type `char_type[]`, or be a container of `char_type`'s (for example `std::basic_string`) or be a unary, binary or ternary functor that computes the replacement string from a function call: either `fmt(*this)` which must return a container of `char_type`'s to be used as the replacement text, or either `fmt(*this, out)` or `fmt(*this, out, flags)`, both of which write the replacement text to `*out`, and then return the new OutputIterator position. [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: If `fmt` is either a null-terminated string, or a container of `char_type`'s, then copies the string /fmt/: For each format specifier or escape sequence in /fmt/, replace that sequence with either the character(s) it represents, or the sequence of characters within `*this` to which it refers. The bitmasks specified in flags determines what format specifiers or escape sequences are recognized, by default this is the format used by ECMA-262, ECMAScript Language Specification, Chapter 15 part 5.4.11 String.prototype.replace. If `fmt` is a function object, then depending on the number of arguments the function object accepts, it will either: * Call `fmt(*this)` and return the result. * Call `fmt(*this, unspecified-output-iterator)`, where `unspecified-output-iterator` is an unspecified OutputIterator type used to copy the output to the string result. * Call `fmt(*this, unspecified-output-iterator, flags)`, where `unspecified-output-iterator` is an unspecified OutputIterator type used to copy the output to the string result. See the [link boost_regex.format format syntax guide for more information]. [#boost_regex.match_results.get_allocator] allocator_type get_allocator()const; [*Effects]: Returns a copy of the Allocator that was passed to the object's constructor. [#boost_regex.match_results.swap] void swap(match_results& that); [*Effects]: Swaps the contents of the two sequences. [*Postcondition]: *this contains the sequence of matched sub-expressions that were in that, that contains the sequence of matched sub-expressions that were in *this. [*Complexity]: constant time. [#boost_regex.match_results.capture_type] typedef typename value_type::capture_sequence_type capture_sequence_type; Defines an implementation-specific type that satisfies the requirements of a standard library Sequence (21.1.1 including the optional Table 68 operations), whose value_type is a `sub_match`. This type happens to be `std::vector >`, but you shouldn't actually rely on that. [#boost_regex.match_results.captures] const capture_sequence_type& captures(std::size_t i)const; [*Requires]: that the match_results object has been initialized as a result of a successful call to [regex_search] or [regex_match] or was returned from a [regex_iterator], and that the underlying iterators have not been subsequently invalidated. Will raise a `std::logic_error` if the match_results object was not initialized. [*Effects]: returns a sequence containing all the captures obtained for sub-expression i. [*Returns]: `(*this)[i].captures();` [*Preconditions]: the library must be built and used with BOOST_REGEX_MATCH_EXTRA defined, and you must pass the flag match_extra to the regex matching functions ([regex_match], [regex_search], [regex_iterator] or [regex_token_iterator]) in order for this member function to be defined and return useful information. [*Rationale]: Enabling this feature has several consequences: * sub_match occupies more memory resulting in complex expressions running out of memory or stack space more quickly during matching. * The matching algorithms are less efficient at handling some features (independent sub-expressions for example), even when match_extra is not used. * The matching algorithms are much less efficient (i.e. slower), when match_extra is used. Mostly this is down to the extra memory allocations that have to take place. [#boost_regex.match_results.op_eq] template bool operator == (const match_results& m1, const match_results& m2); [*Effects]: Compares the two sequences for equality. [#boost_regex.match_results.op_ne] template bool operator != (const match_results& m1, const match_results& m2); [*Effects]: Compares the two sequences for inequality. [#boost_regex.match_results.op_stream] template basic_ostream& operator << (basic_ostream& os, const match_results& m); [*Effects]: Writes the contents of /m/ to the stream /os/ as if by calling `os << m.str()`; Returns /os/. [#boost_regex.match_results.op_swap] template void swap(match_results& m1, match_results& m2); [*Effects]: Swaps the contents of the two sequences. [endsect]