...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::xpressive::c_regex_traits — Encapsaulates the standard C locale functions for use by the basic_regex<>
class template.
// In header: <boost/xpressive/xpressive_fwd.hpp> template<typename Char> struct c_regex_traits { // construct/copy/destruct c_regex_traits(locale_type const & = locale_type()); // public member functions bool operator==(c_regex_traits< char_type > const &) const; bool operator!=(c_regex_traits< char_type > const &) const; string_type fold_case(char_type) const; locale_type imbue(locale_type); template<> char widen(char); template<> wchar_t widen(char); template<> unsigned char hash(char); template<> unsigned char hash(wchar_t); template<> int value(char, int); template<> int value(wchar_t, int); // public static functions static char_type widen(char); static unsigned char hash(char_type); static char_type translate(char_type); static char_type translate_nocase(char_type); static char_type tolower(char_type); static char_type toupper(char_type); static bool in_range(char_type, char_type, char_type); static bool in_range_nocase(char_type, char_type, char_type); template<typename FwdIter> static string_type transform(FwdIter, FwdIter); template<typename FwdIter> static string_type transform_primary(FwdIter, FwdIter); template<typename FwdIter> static string_type lookup_collatename(FwdIter, FwdIter); template<typename FwdIter> static char_class_type lookup_classname(FwdIter, FwdIter, bool); static bool isctype(char_type, char_class_type); static int value(char_type, int); static locale_type getloc(); };
c_regex_traits
public
construct/copy/destructc_regex_traits(locale_type const & loc = locale_type());
Initialize a c_regex_traits
object to use the global C locale.
c_regex_traits
public member functionsbool operator==(c_regex_traits< char_type > const &) const;
Checks two c_regex_traits
objects for equality
Returns: |
true. |
bool operator!=(c_regex_traits< char_type > const &) const;
Checks two c_regex_traits
objects for inequality
Returns: |
false. |
string_type fold_case(char_type ch) const;
Returns a string_type
containing all the characters that compare equal disregrarding case to the one passed in. This function can only be called if
is has_fold_case
<c_regex_traits
<Char> >::valuetrue
.
Parameters: |
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||
Returns: |
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locale_type imbue(locale_type loc);
No-op
template<> char widen(char ch);
template<> wchar_t widen(char ch);
template<> unsigned char hash(char ch);
template<> unsigned char hash(wchar_t ch);
template<> int value(char ch, int radix);
template<> int value(wchar_t ch, int radix);
c_regex_traits
public static functionsstatic char_type widen(char ch);
Convert a char to a Char
Parameters: |
|
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Returns: |
ch if Char is char, std::btowc(ch) if Char is wchar_t. |
static unsigned char hash(char_type ch);
Returns a hash value for a Char in the range [0, UCHAR_MAX]
Parameters: |
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Returns: |
a value between 0 and UCHAR_MAX, inclusive. |
static char_type translate(char_type ch);
No-op
Parameters: |
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Returns: |
ch |
static char_type translate_nocase(char_type ch);
Converts a character to lower-case using the current global C locale.
Parameters: |
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Returns: |
std::tolower(ch) if Char is char, std::towlower(ch) if Char is wchar_t. |
static char_type tolower(char_type ch);
Converts a character to lower-case using the current global C locale.
Parameters: |
|
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Returns: |
std::tolower(ch) if Char is char, std::towlower(ch) if Char is wchar_t. |
static char_type toupper(char_type ch);
Converts a character to upper-case using the current global C locale.
Parameters: |
|
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Returns: |
std::toupper(ch) if Char is char, std::towupper(ch) if Char is wchar_t. |
static bool in_range(char_type first, char_type last, char_type ch);
Checks to see if a character is within a character range.
Parameters: |
|
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Returns: |
first <= ch && ch <= last. |
static bool in_range_nocase(char_type first, char_type last, char_type ch);
Checks to see if a character is within a character range, irregardless of case.
Note | |
---|---|
The default implementation doesn't do proper Unicode case folding, but this is the best we can do with the standard C locale functions. |
Parameters: |
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Returns: |
in_range(first, last, ch) || in_range(first, last, tolower(ch)) || in_range(first, last, toupper(ch)) |
template<typename FwdIter> static string_type transform(FwdIter begin, FwdIter end);
Returns a sort key for the character sequence designated by the iterator range [F1, F2) such that if the character sequence [G1, G2) sorts before the character sequence [H1, H2) then v.transform(G1, G2) < v.transform(H1, H2).
Note | |
---|---|
Not currently used |
template<typename FwdIter> static string_type transform_primary(FwdIter begin, FwdIter end);
Returns a sort key for the character sequence designated by the iterator range [F1, F2) such that if the character sequence [G1, G2) sorts before the character sequence [H1, H2) when character case is not considered then v.transform_primary(G1, G2) < v.transform_primary(H1, H2).
Note | |
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Not currently used |
template<typename FwdIter> static string_type lookup_collatename(FwdIter begin, FwdIter end);
Returns a sequence of characters that represents the collating element consisting of the character sequence designated by the iterator range [F1, F2). Returns an empty string if the character sequence is not a valid collating element.
Note | |
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Not currently used |
template<typename FwdIter> static char_class_type lookup_classname(FwdIter begin, FwdIter end, bool icase);
For the character class name represented by the specified character sequence, return the corresponding bitmask representation.
Parameters: |
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Returns: |
A bitmask representing the character class. |
static bool isctype(char_type ch, char_class_type mask);
Tests a character against a character class bitmask.
Parameters: |
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Requires: |
mask is a bitmask returned by lookup_classname, or is several such masks bit-or'ed together. |
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Returns: |
true if the character is a member of any of the specified character classes, false otherwise. |
static int value(char_type ch, int radix);
Convert a digit character into the integer it represents.
Parameters: |
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Requires: |
radix is one of 8, 10, or 16. |
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Returns: |
-1 if ch is not a digit character, the integer value of the character otherwise. If char_type is char, std::strtol is used for the conversion. If char_type is wchar_t, std::wcstol is used. |
static locale_type getloc();
No-op