The default encoding to use for isomorphism signatures. More...

#include <triangulation/isosigencoding.h>

Inheritance diagram for regina::IsoSigPrintable< dim >:

Public Types
using	Signature = std::string
	The data type used to store an isomorphism signature. More...

Static Public Member Functions
static Signature	emptySig ()
	Returns the isomorphism signature of an empty dim-dimensional triangulation. More...

static Signature	encode (size_t size, size_t nFacetActions, const uint8_t facetAction, size_t nJoins, const size_t joinDest, const typename Perm< dim+1 >::Index *joinGluing)
	Encodes data for a single connected component of a dim-dimensional triangulation. More...

static constexpr unsigned	decodeSingle (char c)
	Determine the integer value represented by the given base64 character. More...

static constexpr char	encodeSingle (unsigned c)
	Determine the base64 character that represents the given integer value. More...

static constexpr bool	isValid (char c)
	Is the given character a valid base64 character? More...

template<typename IntType >
static void	encodeInt (std::string &s, IntType val, unsigned nChars)
	Append a base64 encoding of the given integer to the given string. More...

template<typename IntType >
static IntType	decodeInt (const char *s, unsigned nChars)
	Read the integer that is encoded at the beginning of the given base64 string. More...

template<typename InputIterator >
static char	encodeTrits (InputIterator trits, unsigned nTrits)
	Returns a single base64 character that encodes up to three trits, given using an input iterator. More...

template<int nTrits>
static constexpr char	encodeTrits (const std::array< uint8_t, nTrits > &trits)
	Returns a single base64 character that encodes up to three trits, given using a fixed-size array. More...

template<typename OutputIterator >
static void	decodeTrits (char c, OutputIterator result)
	Decodes a single base64 character into three trits, and returns these using an output iterator. More...

static constexpr std::array< uint8_t, 3 >	decodeTrits (char c)
	Decodes a single base64 character into three trits, and returns these as a fixed-size array. More...

Static Public Attributes
static constexpr unsigned	charsPerPerm
	The number of characters that we use in our encoding to represent a single gluing permutation. More...

Detailed Description

template<int dim>
class regina::IsoSigPrintable< dim >

The default encoding to use for isomorphism signatures.

This printable encoding is consistent with the original isomorphism signatures that were implemented in Regina 4.90. It represents an isomorphism signature as a std::string, using only printable characters from the 7-bit ASCII range.

This class is designed to be used as a template parameter for Triangulation<dim>::isoSig() and Triangulation<dim>::isoSigDetail(). Typical users would have no need to create objects of this class or call any of its functions directly.

Python: Python does not support templates. Instead this class can be used by appending the dimension as a suffix (e.g., IsoSigPrintable2 and IsoSigPrintable3 for dimensions 2 and 3).

Member Typedef Documentation

◆ Signature

template<int dim>

using regina::IsoSigPrintable< dim >::Signature = std::string

The data type used to store an isomorphism signature.

Member Function Documentation

◆ decodeInt()

template<typename IntType >

static IntType regina::Base64SigEncoding::decodeInt	(	const char *	s,
		unsigned	nChars
	)

inlinestaticinherited

Read the integer that is encoded at the beginning of the given base64 string.

It will be assumed that the integer is encoded using nChars base64 characters, each containing 6 bits of the integer, with the lowest-significance bits encoded in the first characters.

The inverse to this routine is encodeInt().

Precondition: The given string contains at least nChars characters.

Python: The template argument IntType is taken to be a native C++ long.

Template Parameters

IntType a native C++ integer type, such as uint8_t, or unsigned, or long long. The result will be assembled using bitwise OR and bitwise shift lefts, and it is assumed that the programmer has chosen an integer type large enough to contain whatever values they expect to read.

Parameters

s	the string from which the encoded base64 characters should be read.
nChars	the number of base64 characters to read.

Returns: the native integer that was encoded.

◆ decodeSingle()

static constexpr unsigned regina::Base64SigEncoding::decodeSingle ( char c )

inlinestaticconstexprinherited

Determine the integer value represented by the given base64 character.

The inverse to this routine is encodeSingle().

Parameters

c	a base64 character, which must be one of the 64 printable characters described in the class notes.

Returns: the corresponding integer, which will be between 0 and 63 inclusive.

◆ decodeTrits() [1/2]

static constexpr std::array< uint8_t, 3 > regina::Base64SigEncoding::decodeTrits ( char c )

inlinestaticconstexprinherited

Decodes a single base64 character into three trits, and returns these as a fixed-size array.

A trit is either 0, 1 or 2.

The inverse to this routine is encodeTrits(); see that routine for details of the encoding.

Parameters

c	the base64 character to decode.

Returns: an array containing the three trits that had been encoded in the given base64 character.

◆ decodeTrits() [2/2]

template<typename OutputIterator >

static void regina::Base64SigEncoding::decodeTrits	(	char	c,
		OutputIterator	result
	)

inlinestaticinherited

Decodes a single base64 character into three trits, and returns these using an output iterator.

A trit is either 0, 1 or 2.

The inverse to this routine is encodeTrits(); see that routine for details of the encoding.

Python: Not present; instead you can use the variant of this routine that takes one argument and returns a fixed-size array.

Parameters

c	the base64 character to decode.
result	an output iterator pointing to the location where the resulting trits will be stored; it must be possible to write and advance this iterator at least three times. Each trit will be written as a `uint8_t`.

◆ emptySig()

template<int dim>

static Signature regina::IsoSigPrintable< dim >::emptySig ( )

inlinestatic

Returns the isomorphism signature of an empty dim-dimensional triangulation.

◆ encode()

template<int dim>

static Signature regina::IsoSigPrintable< dim >::encode	(	size_t	size,
		size_t	nFacetActions,
		const uint8_t *	facetAction,
		size_t	nJoins,
		const size_t *	joinDest,
		const typename Perm< dim+1 >::Index *	joinGluing
	)

static

Encodes data for a single connected component of a dim-dimensional triangulation.

The description consists of several arrays, describing facets of the top-dimensional simplices, as well as the ways that these facets are glued together. Which array elements represent which facets/gluings is an implementation detail; the purpose of this routine is simply to encode the given information. See the isoSig() implementation for further details.

Python: The arrays facetAction, joinDest and joinGluing should each be passed as Python lists of integers. The arguments nFacetActions and nJoins are not present, since Python lists already know their own sizes.

Parameters

size	the number of top-dimensional simplices in the component.
nFacetActions	the size of the array facetAction.
facetAction	an array of size nFacetActions, where each element is either 0, 1 or 2, respectively representing a boundary facet, a facet joined to a new simplex, or a facet joined to a simplex that has already been seen.
nJoins	the size of the arrays joinDest and joinGluing.
joinDest	an array whose elements are indices of top-dimensional simplices to which gluings are being made.
joinGluing	an array of gluing permutations.

Returns: the encoding of the component being described.

◆ encodeInt()

template<typename IntType >

static void regina::Base64SigEncoding::encodeInt	(	std::string &	s,
		IntType	val,
		unsigned	nChars
	)

inlinestaticinherited

Append a base64 encoding of the given integer to the given string.

The integer will be broken into nChars distinct 6-bit blocks, and the lowest-significance blocks will be written first.

The inverse to this routine is decodeInt().

Precondition: The given integer val is non-negative, and fits within 6nChars bits.

Python: The template argument IntType is taken to be a native C++ long.

Template Parameters

IntType a native C++ integer type, such as uint8_t, or unsigned, or long long.

Parameters

s	the string that resulting characters should be appended to.
val	the integer to encode.
nChars	the number of base64 characters to use.

◆ encodeSingle()

static constexpr char regina::Base64SigEncoding::encodeSingle ( unsigned c )

inlinestaticconstexprinherited

Determine the base64 character that represents the given integer value.

The inverse to this routine is decodeSingle().

Parameters

c	an integer between 0 and 63 inclusive.

Returns: the corresponding printable base64 character.

◆ encodeTrits() [1/2]

template<int nTrits>

static constexpr char regina::Base64SigEncoding::encodeTrits ( const std::array< uint8_t, nTrits > & trits )

inlinestaticconstexprinherited

Returns a single base64 character that encodes up to three trits, given using a fixed-size array.

A trit is either 0, 1 or 2.

The given trits will be packed into a single base64 character, with the first trit representing the lowest-significance bits of the underlying integer and so on.

The inverse to this routine is decodeTrits().

Template Parameters

mTrits the number of trits to encode; this must be between 0 and 3 inclusive.

Parameters

trits the array of trits to encode. Each trit must take the value 0, 1 or 2.

Returns: the resulting printable base64 character.

◆ encodeTrits() [2/2]

template<typename InputIterator >

static char regina::Base64SigEncoding::encodeTrits	(	InputIterator	trits,
		unsigned	nTrits
	)

inlinestaticinherited

Returns a single base64 character that encodes up to three trits, given using an input iterator.

A trit is either 0, 1 or 2.

The given trits will be packed into a single base64 character, with the first trit representing the lowest-significance bits of the underlying integer and so on.

The inverse to this routine is decodeTrits().

Python: Not present; instead you can use the variant of this routine that takes the trits as a fixed-size array.

Parameters

trits	an input iterator pointing to the first trit to encode; it must be possible to read and advance this iterator at least nTrits times. Each trit will be cast to a `uint8_t`, and must take the value 0, 1 or 2.
nTrits	the number of trits to encode; this must be at most 3.

Returns: the resulting printable base64 character.

◆ isValid()

static constexpr bool regina::Base64SigEncoding::isValid ( char c )

inlinestaticconstexprinherited

Is the given character a valid base64 character?

Returns: true if and only if the given character is one of the 64 printable characters described in the class notes.

Member Data Documentation

◆ charsPerPerm

template<int dim>

constexpr unsigned regina::IsoSigPrintable< dim >::charsPerPerm

staticconstexpr

Initial value:

=

((regina::bitsRequired(Perm<(dim)+1>::nPerms) + 5) / 6)

regina::bitsRequired

constexpr int bitsRequired(IntType n)

Returns the number of bits required to store integers in the range 0,...,n-1.

Definition: intutils.h:149

The number of characters that we use in our encoding to represent a single gluing permutation.

This must be large enough to encode an index into Perm<dim+1>::Sn.

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

triangulation/isosigencoding.h

Public Types

Static Public Member Functions

Static Public Attributes

Detailed Description

Member Typedef Documentation

◆ Signature

Member Function Documentation

◆ decodeInt()

◆ decodeSingle()

◆ decodeTrits() [1/2]

◆ decodeTrits() [2/2]

◆ emptySig()

◆ encode()

◆ encodeInt()

◆ encodeSingle()

◆ encodeTrits() [1/2]

◆ encodeTrits() [2/2]

◆ isValid()

Member Data Documentation

◆ charsPerPerm