colltab

Documentation

Index

• Constants
• type Elem
  • func MakeElem(primary, secondary, tertiary int, ccc uint8) (Elem, error)
  • func MakeQuaternary(v int) Elem
  • func (ce Elem) CCC() uint8
  • func (ce Elem) Mask(l Level) uint32
  • func (ce Elem) Primary() int
  • func (ce Elem) Quaternary() int
  • func (ce Elem) Secondary() int
  • func (ce Elem) Tertiary() uint8
  • func (ce Elem) Weight(l Level) int
• type Level
• type Weighter
  • func Init(data interface{}) Weighter
  • func NewNumericWeighter(w Weighter) Weighter

Constants

const (
	Ignore = ceType4
)

For normal collation elements, we assume that a collation element either has a primary or non-default secondary value, not both. Collation elements with a primary value are of the form 01pppppp pppppppp ppppppp0 ssssssss

• p* is primary collation value
• s* is the secondary collation value

00pppppp pppppppp ppppppps sssttttt, where

• p* is primary collation value
• s* offset of secondary from default value.
• t* is the tertiary collation value

100ttttt cccccccc pppppppp pppppppp

• t* is the tertiar collation value
• c* is the cannonical combining class
• p* is the primary collation value

Collation elements with a secondary value are of the form 1010cccc ccccssss ssssssss tttttttt, where

• c* is the canonical combining class
• s* is the secondary collation value
• t* is the tertiary collation value

11qqqqqq qqqqqqqq qqqqqqq0 00000000

• q* quaternary value

const (
	MaxQuaternary = 0x1FFFFF // 21 bits.
)

const (
	PrivateUse = minContract
)

Types

type Elem

type Elem uint32

Elem is a representation of a collation element. This API provides ways to encode and decode Elems. Implementations of collation tables may use values greater or equal to PrivateUse for their own purposes. However, these should never be returned by AppendNext.

func MakeElem

func MakeElem(primary, secondary, tertiary int, ccc uint8) (Elem, error)

MakeElem returns an Elem for the given values. It will return an error if the given combination of values is invalid.

func MakeQuaternary

func MakeQuaternary(v int) Elem

MakeQuaternary returns an Elem with the given quaternary value.

func (Elem) CCC

func (ce Elem) CCC() uint8

CCC returns the canonical combining class associated with the underlying character, if applicable, or 0 otherwise.

func (Elem) Mask

func (ce Elem) Mask(l Level) uint32

Mask sets weights for any level smaller than l to 0. The resulting Elem can be used to test for equality with other Elems to which the same mask has been applied.

func (Elem) Primary

func (ce Elem) Primary() int

Primary returns the primary collation weight for ce.

func (Elem) Quaternary

func (ce Elem) Quaternary() int

Quaternary returns the quaternary value if explicitly specified, 0 if ce == Ignore, or MaxQuaternary otherwise. Quaternary values are used only for shifted variants.

func (Elem) Secondary

func (ce Elem) Secondary() int

Secondary returns the secondary collation weight for ce.

func (Elem) Tertiary

func (ce Elem) Tertiary() uint8

Tertiary returns the tertiary collation weight for ce.

func (Elem) Weight

func (ce Elem) Weight(l Level) int

Weight returns the collation weight for the given level.

type Level

type Level int

Level identifies the collation comparison level. The primary level corresponds to the basic sorting of text. The secondary level corresponds to accents and related linguistic elements. The tertiary level corresponds to casing and related concepts. The quaternary level is derived from the other levels by the various algorithms for handling variable elements.

const (
	Primary Level = iota
	Secondary
	Tertiary
	Quaternary
	Identity

	NumLevels
)

type Weighter

type Weighter interface {
	// Start finds the start of the segment that includes position p.
	Start(p int, b []byte) int

	// StartString finds the start of the segment that includes position p.
	StartString(p int, s string) int

	// AppendNext appends Elems to buf corresponding to the longest match
	// of a single character or contraction from the start of s.
	// It returns the new buf and the number of bytes consumed.
	AppendNext(buf []Elem, s []byte) (ce []Elem, n int)

	// AppendNextString appends Elems to buf corresponding to the longest match
	// of a single character or contraction from the start of s.
	// It returns the new buf and the number of bytes consumed.
	AppendNextString(buf []Elem, s string) (ce []Elem, n int)

	// Domain returns a slice of all single characters and contractions for which
	// collation elements are defined in this table.
	Domain() []string

	// Top returns the highest variable primary value.
	Top() uint32
}

A Weighter can be used as a source for Collator and Searcher.

func Init

func Init(data interface{}) Weighter

Init is for internal use only.

func NewNumericWeighter

func NewNumericWeighter(w Weighter) Weighter

NewNumericWeighter wraps w to replace individual digits to sort based on their numeric value.

Weighter w must have a free primary weight after the primary weight for 9. If this is not the case, numeric value will sort at the same primary level as the first primary sorting after 9.