StringRange

Defined in word-range.hpp.

This class implements a range object for strings and produces the same output as WordRange() | ToString("ab"), but is more convenient in some cases.

Note

There is a small overhead to using a StringRange object rather than using cbegin_wislo or cbegin_wilo directly.

The order and range of the words in a StringRange instance can be set using the member functions:

• order
• alphabet
• min
• max
• first
• last

Example

StringRange strings;
strings.order(Order::shortlex) // strings in shortlex order
       .alphabet("ab")         // on 2 letters
       .min(1)                 // of length in the range from 1
       .max(5);                // to 5

See also

WordRange

Public Types
using	output_type = std::string const&
	The type of the output of the range object.
using	size_type = typename std::vector<std::string>::size_type
	Alias for the size type.

Public Member Functions
	StringRange ()
	Default constructor.
	StringRange (StringRange &&)
	Default move constructor.
	StringRange (StringRange const &)
	Default copy constructor.
std::string const &	alphabet () const noexcept
	The current alphabet.
StringRange &	alphabet (std::string const &x)
	Set the alphabet.
bool	at_end () const noexcept
	Check if the range object is exhausted.
auto	begin () const noexcept
	Returns an input iterator pointing to the first string in the range.
size_t	count () const noexcept
	The actual size of the range.
auto	end () const noexcept
	Returns an input iterator pointing one beyond the last string in the range.
std::string	first () const noexcept
	The current first string in the range.
StringRange &	first (std::string const &frst)
	Set the first string in the range.
output_type	get () const
	Get the current value.
StringRange &	init ()
	Initialize an existing StringRange object.
std::string	last () const noexcept
	The current one past the last string in the range.
StringRange &	last (std::string const &lst)
	Set one past the last string in the range.
StringRange &	max (size_type val)
	Set one past the last string in the range by length.
StringRange &	min (size_type val)
	Set the first string in the range by length.
void	next () noexcept
	Advance to the next value.
StringRange &	operator= (StringRange &&)
	Default move assignment operator.
StringRange &	operator= (StringRange const &)
	Default copy assignment operator.
Order	order () const noexcept
	The current order of the strings in the range.
StringRange &	order (Order val)
	Set the order of the strings in the range.
size_t	size_hint () const noexcept
	The possible size of the range.
size_type	upper_bound () const noexcept
	The current upper bound on the length of a string in the range.
StringRange &	upper_bound (size_type n)
	Set an upper bound for the length of a string in the range.

Constructor & Destructor Documentation

StringRange()

StringRange ( )

inline

Constructs an empty range with:

• min() equal to 0;
• max() equal to 0;
• order() equal to Order::shortlex;
• first() equal to the empty string;
• last() equal to the empty string;
• upper_bound() equal to 0;
• alphabet() equal to "".

Member Function Documentation

alphabet() [1/2]

std::string const & alphabet ( ) const

inlinenodiscardnoexcept

Returns the current alphabet in a StringRange object.

Returns

A value of type string.

Exceptions

This function is noexcept and is guaranteed never to throw.

alphabet() [2/2]

StringRange & alphabet

(

std::string const &

x

)

Sets the alphabet in a StringRange object.

Parameters

x	the alphabet.

Returns

A reference to *this.

Exceptions

LibsemigroupsException

if x contains repeated letters.

at_end()

bool at_end ( ) const

inlinenoexcept

Returns true if a StringRange object is exhausted, and false if not.

Returns

A value of type bool.

Exceptions

This function is noexcept and is guaranteed never to throw.

begin()

auto begin ( ) const

inlinenoexcept

This function returns an input iterator pointing to the first string in a StringRange object.

Returns

An input iterator.

Exceptions

This function is noexcept and is guaranteed never to throw.

Note

The return type of end might be different from the return type of begin.

See also

end.

count()

size_t count ( ) const

inlinenoexcept

Returns the number of words in the range object. If order() is Order::shortlex, then size_hint() is used. If order() is not Order::shortlex, then a copy of the range may have to be looped over in order to find the return value of this function.

Returns

A value of type size_t.

Exceptions

This function is noexcept and is guaranteed never to throw.

end()

auto end ( ) const

inlinenoexcept

This function returns an input iterator pointing one beyond the last string in a StringRange object.

Returns

An input iterator.

Exceptions

This function is noexcept and is guaranteed never to throw.

Note

The return type of end might be different from the return type of begin.

See also

begin.

first() [1/2]

std::string first ( ) const

inlinenodiscardnoexcept

Returns the first string in a StringRange object.

Returns

A string by value.

Exceptions

This function is noexcept and is guaranteed never to throw.

See also

min

first() [2/2]

StringRange & first ( std::string const & frst )

inline

Sets the first string in a StringRange object to be frst.

Parameters

frst	the first string.

Returns

A reference to *this.

Note

Unlike WordRange::first, this function will throw if frst contains letters not belonging to alphabet().

See also

min

get()

output_type get ( ) const

inline

Returns the current string in a StringRange object.

Returns

A value of type output_type.

Exceptions

This function is noexcept and is guaranteed never to throw.

Warning

If at_end() returns true, then the return value of this function could be anything.

init()

StringRange & init

(

)

This function puts a StringRange object back into the same state as if it had been newly default constructed.

Returns

A reference to *this.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

last() [1/2]

std::string last ( ) const

inlinenodiscardnoexcept

Returns one past the last string in a StringRange object.

Returns

A string by value.

Exceptions

This function is noexcept and is guaranteed never to throw.

See also

max

last() [2/2]

StringRange & last ( std::string const & lst )

inline

Sets one past the last string in a StringRange object to be lst.

Parameters

lst	one past the last string.

Returns

A reference to *this.

Exceptions

LibsemigroupsException

if lst contains letters not belonging to alphabet().

Note

The behaviour of this function is not exactly the same as WordRange::last(word_type const&). That function will not throw if a word contains letters not in the alphabet.

See also

max

max()

StringRange & max ( size_type val )

inline

Sets one past the last string in a StringRange object to be \(\alpha^n\) where \(\alpha\) is the first letter of alphabet() (or "a" if the alphabet is empty) and \(n\) corresponds to val.

Parameters

val	the exponent.

Returns

A reference to *this.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

min()

StringRange & min ( size_type val )

inline

Sets the first string in a StringRange object to be pow("a", val) (the string consisting of val letters equal to "a").

Parameters

val	the exponent.

Returns

A reference to *this.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

next()

void next ( )

inlinenoexcept

Advances a StringRange object to the next value (if any).

Exceptions

This function is noexcept and is guaranteed never to throw.

See also

at_end

order() [1/2]

Order order ( ) const

inlinenodiscardnoexcept

Returns the current order of the strings in a StringRange object.

Returns

A value of type Order.

Exceptions

This function is noexcept and is guaranteed never to throw.

order() [2/2]

StringRange & order ( Order val )

inline

Sets the order of the strings in a StringRange object to val.

Parameters

val	the order.

Returns

A reference to *this.

Exceptions

LibsemigroupsException

if val is not Order::shortlex or Order::lex.

size_hint()

size_t size_hint ( ) const

inlinenoexcept

Returns the number of words in a StringRange object if order() is Order::shortlex. If order() is not Order::shortlex, then the return value of this function is meaningless.

Returns

A value of type size_t.

Exceptions

This function is noexcept and is guaranteed never to throw.

upper_bound() [1/2]

size_type upper_bound ( ) const

inlinenodiscardnoexcept

Returns the current upper bound on the length of a string in a StringRange object. This setting is only used if order() is Order::lex.

Returns

A value of type size_type.

Exceptions

This function is noexcept and is guaranteed never to throw.

upper_bound() [2/2]

StringRange & upper_bound ( size_type n )

inline

Sets an upper bound for the length of a string in a StringRange object. This setting is only used if order() is Order::lex.

Parameters

n	the upper bound.

Returns

A reference to *this.

Exceptions

This function guarantees not to throw a LibsemigroupsException.

Member Data Documentation

is_idempotent

bool is_idempotent = true

staticconstexpr

Value indicating that if get() is called twice on a StringRange object that is not changed between the two calls, then the return value of get() is the same both times.

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The documentation for this class was generated from the following file:

• /Users/jdm/libsemigroups/include/libsemigroups/word-range.hpp