Class template basic_string_literal

boost::log::basic_string_literal — String literal wrapper.

Synopsis

// In header: <boost/log/utility/string_literal.hpp>

template<typename CharT, typename TraitsT> 
class basic_string_literal {
public:
  // types
  typedef CharT                                        value_type;            
  typedef TraitsT                                      traits_type;           
  typedef std::size_t                                  size_type;             
  typedef std::ptrdiff_t                               difference_type;       
  typedef const value_type *                           const_pointer;         
  typedef value_type const &                           const_reference;       
  typedef const value_type *                           const_iterator;        
  typedef std::reverse_iterator< const_iterator >      const_reverse_iterator;
  typedef std::basic_string< value_type, traits_type > string_type;             // Corresponding STL string type. 

  // construct/copy/destruct
  basic_string_literal() noexcept;
  template<typename T, size_type LenV> basic_string_literal(T(&)) noexcept;
  basic_string_literal(basic_string_literal const &) noexcept;
  this_type & operator=(this_type const &) noexcept;
  template<typename T, size_type LenV> this_type & operator=(T(&)) noexcept;

  // public member functions
  bool operator==(this_type const &) const noexcept;
  bool operator==(const_pointer) const noexcept;
  bool operator==(string_type const &) const;
  bool operator<(this_type const &) const noexcept;
  bool operator<(const_pointer) const noexcept;
  bool operator<(string_type const &) const;
  bool operator>(this_type const &) const noexcept;
  bool operator>(const_pointer) const noexcept;
  bool operator>(string_type const &) const;
  const_reference operator[](size_type) const noexcept;
  const_reference at(size_type) const;
  const_pointer c_str() const noexcept;
  const_pointer data() const noexcept;
  size_type size() const noexcept;
  size_type length() const noexcept;
  bool empty() const noexcept;
  const_iterator begin() const noexcept;
  const_iterator end() const noexcept;
  const_reverse_iterator rbegin() const noexcept;
  const_reverse_iterator rend() const noexcept;
  string_type str() const;
  void clear() noexcept;
  void swap(this_type &) noexcept;
  this_type & assign(this_type const &) noexcept;
  template<typename T, size_type LenV> this_type & assign(T(&)) noexcept;
  size_type copy(value_type *, size_type, size_type = 0) const;
  int compare(size_type, size_type, const_pointer, size_type) const;
  int compare(size_type, size_type, const_pointer) const noexcept;
  int compare(size_type, size_type, this_type const &) const noexcept;
  int compare(const_pointer, size_type) const noexcept;
  int compare(const_pointer) const noexcept;
  int compare(this_type const &) const noexcept;
};

Description

The basic_string_literal is a thin wrapper around a constant string literal. It provides interface similar to STL strings, but because of read-only nature of string literals, lacks ability to modify string contents. However, basic_string_literal objects can be assigned to and cleared.

The main advantage of this class comparing to other string classes is that it doesn't dynamically allocate memory and therefore is fast, thin and exception safe.

`basic_string_literal` public construct/copy/destruct

```
basic_string_literal() noexcept;
```
Constructor

Postconditions:

empty() == true
```
template<typename T, size_type LenV> basic_string_literal(T(&) p) noexcept;
```
Constructor from a string literal

Parameters:

p

A zero-terminated constant sequence of characters

Postconditions:

*this == p
```
basic_string_literal(basic_string_literal const & that) noexcept;
```
Copy constructor

Parameters:

that

Source literal to copy string from

Postconditions:

*this == that
```
this_type & operator=(this_type const & that) noexcept;
```
Assignment operator

Parameters:

that

Source literal to copy string from

Postconditions:

*this == that
```
template<typename T, size_type LenV> this_type & operator=(T(&) p) noexcept;
```
Assignment from a string literal

Parameters:

p

A zero-terminated constant sequence of characters

Postconditions:

*this == p

`basic_string_literal` public member functions

```
bool operator==(this_type const & that) const noexcept;
```
Lexicographical comparison (equality)

Parameters:

that

Comparand

Returns:

true if the comparand string equals to this string, false otherwise
```
bool operator==(const_pointer str) const noexcept;
```
Lexicographical comparison (equality)

Parameters:

str

Comparand. Must point to a zero-terminated sequence of characters, must not be NULL.

Returns:

true if the comparand string equals to this string, false otherwise
```
bool operator==(string_type const & that) const;
```
Lexicographical comparison (equality)

Parameters:

that

Comparand

Returns:

true if the comparand string equals to this string, false otherwise
```
bool operator<(this_type const & that) const noexcept;
```
Lexicographical comparison (less ordering)

Parameters:

that

Comparand

Returns:

true if this string is less than the comparand, false otherwise
```
bool operator<(const_pointer str) const noexcept;
```
Lexicographical comparison (less ordering)

Parameters:

str

Comparand. Must point to a zero-terminated sequence of characters, must not be NULL.

Returns:

true if this string is less than the comparand, false otherwise
```
bool operator<(string_type const & that) const;
```
Lexicographical comparison (less ordering)

Parameters:

that

Comparand

Returns:

true if this string is less than the comparand, false otherwise
```
bool operator>(this_type const & that) const noexcept;
```
Lexicographical comparison (greater ordering)

Parameters:

that

Comparand

Returns:

true if this string is greater than the comparand, false otherwise
```
bool operator>(const_pointer str) const noexcept;
```
Lexicographical comparison (greater ordering)

Parameters:

str

Comparand. Must point to a zero-terminated sequence of characters, must not be NULL.

Returns:

true if this string is greater than the comparand, false otherwise
```
bool operator>(string_type const & that) const;
```
Lexicographical comparison (greater ordering)

Parameters:

that

Comparand

Returns:

true if this string is greater than the comparand, false otherwise
```
const_reference operator[](size_type i) const noexcept;
```
Subscript operator

Parameters:

i

Requested character index

Requires:

i < size()

Returns:

Constant reference to the requested character
```
const_reference at(size_type i) const;
```
Checked subscript

Throws: An std::exception-based exception if index i is out of string boundaries

Parameters:

i

Requested character index

Returns:

Constant reference to the requested character
```
const_pointer c_str() const noexcept;
```
Returns:

Pointer to the beginning of the literal
```
const_pointer data() const noexcept;
```
Returns:

Pointer to the beginning of the literal
```
size_type size() const noexcept;
```
Returns:

Length of the literal
```
size_type length() const noexcept;
```
Returns:

Length of the literal
```
bool empty() const noexcept;
```
Returns:

true if the literal is an empty string, false otherwise
```
const_iterator begin() const noexcept;
```
Returns:

Iterator that points to the first character of the literal
```
const_iterator end() const noexcept;
```
Returns:

Iterator that points after the last character of the literal
```
const_reverse_iterator rbegin() const noexcept;
```
Returns:

Reverse iterator that points to the last character of the literal
```
const_reverse_iterator rend() const noexcept;
```
Returns:

Reverse iterator that points before the first character of the literal
```
string_type str() const;
```
Returns:

STL string constructed from the literal
```
void clear() noexcept;
```
The method clears the literal

Postconditions:

empty() == true
```
void swap(this_type & that) noexcept;
```
The method swaps two literals
```
this_type & assign(this_type const & that) noexcept;
```
Assignment from another literal

Parameters:

that

Source literal to copy string from

Postconditions:

*this == that
```
template<typename T, size_type LenV> this_type & assign(T(&) p) noexcept;
```
Assignment from another literal

Parameters:

p

A zero-terminated constant sequence of characters

Postconditions:

*this == p

size_type copy(value_type * str, size_type n, size_type pos = 0) const;

The method copies the literal or its portion to an external buffer

Throws: An std::exception-based exception if pos is out of range.

Parameters:

`n`	Maximum number of characters to copy
`pos`	Starting position to start copying from
`str`	Pointer to the external buffer beginning. Must not be NULL. The buffer must have enough capacity to accommodate the requested number of characters.

Requires:

pos <= size()

Returns:

Number of characters copied

int compare(size_type pos, size_type n, const_pointer str, size_type len) const;

Lexicographically compares the argument string to a part of this string

Throws: An std::exception-based exception if pos is out of range.

Parameters:

`len`	Number of characters in the sequence str.
`n`	Length of the substring of this string to perform comparison to
`pos`	Starting position within this string to perform comparison to
`str`	Comparand. Must point to a sequence of characters, must not be NULL.

Requires:

pos <= size()

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

int compare(size_type pos, size_type n, const_pointer str) const noexcept;

Lexicographically compares the argument string to a part of this string

Throws: An std::exception-based exception if pos is out of range.

Parameters:

`n`	Length of the substring of this string to perform comparison to
`pos`	Starting position within this string to perform comparison to
`str`	Comparand. Must point to a zero-terminated sequence of characters, must not be NULL.

Requires:

pos <= size()

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

int compare(size_type pos, size_type n, this_type const & that) const noexcept;

Lexicographically compares the argument string literal to a part of this string

Throws: An std::exception-based exception if pos is out of range.

Parameters:

`n`	Length of the substring of this string to perform comparison to
`pos`	Starting position within this string to perform comparison to
`that`	Comparand

Requires:

pos <= size()

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

int compare(const_pointer str, size_type len) const noexcept;

Lexicographically compares the argument string to this string

Parameters:

`len`	Number of characters in the sequence str.
`str`	Comparand. Must point to a sequence of characters, must not be NULL.

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

int compare(const_pointer str) const noexcept;

Lexicographically compares the argument string to this string

Parameters:

str

Comparand. Must point to a zero-terminated sequence of characters, must not be NULL.

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

int compare(this_type const & that) const noexcept;

Lexicographically compares the argument string to this string

Parameters:

that

Comparand

Returns:

Zero if the comparand equals this string, a negative value if this string is less than the comparand, a positive value if this string is greater than the comparand.

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