Documentation

Overview

Package number contains tools and data for formatting numbers.

Index

Constants

View Source
const (
	AlwaysSign PatternFlag = 1 << iota
	ElideSign              // Use space instead of plus sign. AlwaysSign must be true.
	AlwaysExpSign
	AlwaysDecimalSeparator
	ParenthesisForNegative // Common pattern. Saves space.

	PadAfterNumber
	PadAfterAffix

	PadBeforePrefix = 0 // Default
	PadAfterPrefix  = PadAfterAffix
	PadBeforeSuffix = PadAfterNumber
	PadAfterSuffix  = PadAfterNumber | PadAfterAffix
	PadMask         = PadAfterNumber | PadAfterAffix
)
View Source
const CLDRVersion = "32"

CLDRVersion is the CLDR version from which the tables in this package are derived.

Variables

This section is empty.

Functions

This section is empty.

Types

type Converter

type Converter interface {
	Convert(d *Decimal, r RoundingContext)
}

A Converter converts a number into decimals according to the given rounding criteria.

type Decimal

type Decimal struct {
	// contains filtered or unexported fields
}

A Decimal represents a floating point number in decimal format. Digits represents a number [0, 1.0), and the absolute value represented by Decimal is Digits * 10^Exp. Leading and trailing zeros may be omitted and Exp may point outside a valid position in Digits.

Examples:

Number     Decimal
12345      Digits: [1, 2, 3, 4, 5], Exp: 5
12.345     Digits: [1, 2, 3, 4, 5], Exp: 2
12000      Digits: [1, 2],          Exp: 5
12000.00   Digits: [1, 2],          Exp: 5
0.00123    Digits: [1, 2, 3],       Exp: -2
0          Digits: [],              Exp: 0

func (*Decimal) Convert

func (d *Decimal) Convert(r RoundingContext, number interface{})

Convert converts the given number to the decimal representation using the supplied RoundingContext.

func (*Decimal) ConvertFloat

func (d *Decimal) ConvertFloat(r RoundingContext, x float64, size int)

ConvertFloat converts a floating point number to decimals.

func (*Decimal) ConvertInt

func (d *Decimal) ConvertInt(r RoundingContext, signed bool, x uint64)

ConvertInt converts an integer to decimals.

func (*Decimal) String

func (x *Decimal) String() string

type Digits

type Digits struct {

	// End indicates the end position of the number.
	End int32 // For decimals Exp <= End. For scientific len(Digits) <= End.
	// Comma is used for the comma position for scientific (always 0 or 1) and
	// engineering notation (always 0, 1, 2, or 3).
	Comma uint8
	// IsScientific indicates whether this number is to be rendered as a
	// scientific number.
	IsScientific bool
	// contains filtered or unexported fields
}

Digits represents a floating point number represented in digits of the base in which a number is to be displayed. It is similar to Decimal, but keeps track of trailing fraction zeros and the comma placement for engineering notation. Digits must have at least one digit.

Examples:

  Number     Decimal
decimal
  12345      Digits: [1, 2, 3, 4, 5], Exp: 5  End: 5
  12.345     Digits: [1, 2, 3, 4, 5], Exp: 2  End: 5
  12000      Digits: [1, 2],          Exp: 5  End: 5
  12000.00   Digits: [1, 2],          Exp: 5  End: 7
  0.00123    Digits: [1, 2, 3],       Exp: -2 End: 3
  0          Digits: [],              Exp: 0  End: 1
scientific (actual exp is Exp - Comma)
  0e0        Digits: [0],             Exp: 1, End: 1, Comma: 1
  .0e0       Digits: [0],             Exp: 0, End: 1, Comma: 0
  0.0e0      Digits: [0],             Exp: 1, End: 2, Comma: 1
  1.23e4     Digits: [1, 2, 3],       Exp: 5, End: 3, Comma: 1
  .123e5     Digits: [1, 2, 3],       Exp: 5, End: 3, Comma: 0
engineering
  12.3e3     Digits: [1, 2, 3],       Exp: 5, End: 3, Comma: 2

func FormatDigits

func FormatDigits(d *Decimal, r RoundingContext) Digits

func (*Digits) NumFracDigits

func (d *Digits) NumFracDigits() int

type Formatter

type Formatter struct {
	Pattern
	Info
}

Formatter contains all the information needed to render a number.

func (*Formatter) Append

func (f *Formatter) Append(dst []byte, x interface{}) []byte

func (*Formatter) Format

func (f *Formatter) Format(dst []byte, d *Decimal) []byte

func (*Formatter) InitDecimal

func (f *Formatter) InitDecimal(t language.Tag)

InitDecimal initializes a Formatter using the default Pattern for the given language.

func (*Formatter) InitEngineering

func (f *Formatter) InitEngineering(t language.Tag)

InitEngineering initializes a Formatter using the default Pattern for the given language.

func (*Formatter) InitPattern

func (f *Formatter) InitPattern(t language.Tag, pat *Pattern)

InitPattern initializes a Formatter for the given Pattern.

func (*Formatter) InitPerMille

func (f *Formatter) InitPerMille(t language.Tag)

InitPerMille initializes a Formatter using the default Pattern for the given language.

func (*Formatter) InitPercent

func (f *Formatter) InitPercent(t language.Tag)

InitPercent initializes a Formatter using the default Pattern for the given language.

func (*Formatter) InitScientific

func (f *Formatter) InitScientific(t language.Tag)

InitScientific initializes a Formatter using the default Pattern for the given language.

func (*Formatter) Render

func (f *Formatter) Render(dst []byte, d Digits) []byte

type Info

type Info struct {
	// contains filtered or unexported fields
}

Info holds number formatting configuration data.

func InfoFromLangID

func InfoFromLangID(compactIndex compact.ID, numberSystem string) Info

InfoFromLangID returns a Info for the given compact language identifier and numbering system identifier. If system is the empty string, the default numbering system will be taken for that language.

func InfoFromTag

func InfoFromTag(t language.Tag) Info

InfoFromTag returns a Info for the given language tag.

func (Info) AppendDigit

func (n Info) AppendDigit(dst []byte, digit byte) []byte

AppendDigit appends the UTF-8 sequence for n corresponding to the given digit to dst and reports the number of bytes written. dst must be large enough to hold the rune (can be up to utf8.UTFMax bytes).

func (Info) Digit

func (n Info) Digit(asciiDigit rune) rune

Digit returns the digit for the numbering system for the corresponding ASCII value. For example, ni.Digit('3') could return '三'. Note that the argument is the rune constant '3', which equals 51, not the integer constant 3.

func (Info) IsDecimal

func (n Info) IsDecimal() bool

IsDecimal reports if the numbering system can convert decimal to native symbols one-to-one.

func (Info) Symbol

func (n Info) Symbol(t SymbolType) string

Symbol returns the string for the given symbol type.

func (Info) WriteDigit

func (n Info) WriteDigit(dst []byte, asciiDigit rune) int

WriteDigit writes the UTF-8 sequence for n corresponding to the given ASCII digit to dst and reports the number of bytes written. dst must be large enough to hold the rune (can be up to utf8.UTFMax bytes).

type Pattern

type Pattern struct {
	RoundingContext

	Affix       string // includes prefix and suffix. First byte is prefix length.
	Offset      uint16 // Offset into Affix for prefix and suffix
	NegOffset   uint16 // Offset into Affix for negative prefix and suffix or 0.
	PadRune     rune
	FormatWidth uint16

	GroupingSize [2]uint8
	Flags        PatternFlag
}

Pattern holds information for formatting numbers. It is designed to hold information from CLDR number patterns.

This pattern is precompiled for all patterns for all languages. Even though the number of patterns is not very large, we want to keep this small.

This type is only intended for internal use.

func ParsePattern

func ParsePattern(s string) (f *Pattern, err error)

ParsePattern extracts formatting information from a CLDR number pattern.

See https://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns.

type PatternFlag

type PatternFlag uint8

A PatternFlag is a bit mask for the flag field of a Pattern.

type RoundingContext

type RoundingContext struct {
	// TODO: unify these two fields so that there is a more unambiguous meaning
	// of how precision is handled.
	MaxSignificantDigits int16 // -1 is unlimited
	MaxFractionDigits    int16 // -1 is unlimited

	Increment      uint32
	IncrementScale uint8 // May differ from printed scale.

	Mode RoundingMode

	DigitShift uint8 // Number of decimals to shift. Used for % and ‰.

	// Number of digits.
	MinIntegerDigits uint8

	MaxIntegerDigits     uint8
	MinFractionDigits    uint8
	MinSignificantDigits uint8

	MinExponentDigits uint8
}

A RoundingContext indicates how a number should be converted to digits. It contains all information needed to determine the "visible digits" as required by the pluralization rules.

func (*RoundingContext) RoundFractionDigits

func (r *RoundingContext) RoundFractionDigits() (n int)

RoundFractionDigits returns the number of fraction digits an implementation of Convert may round to or n < 0 if there is no maximum or a maximum is not recommended.

func (*RoundingContext) RoundSignificantDigits

func (r *RoundingContext) RoundSignificantDigits() (n int)

RoundSignificantDigits returns the number of significant digits an implementation of Convert may round to or n < 0 if there is no maximum or a maximum is not recommended.

func (*RoundingContext) SetPrecision

func (r *RoundingContext) SetPrecision(prec int)

func (*RoundingContext) SetScale

func (r *RoundingContext) SetScale(scale int)

SetScale fixes the RoundingContext to a fixed number of fraction digits.

type RoundingMode

type RoundingMode byte

RoundingMode determines how a number is rounded to the desired precision.

const (
	ToNearestEven RoundingMode = iota // towards the nearest integer, or towards an even number if equidistant.
	ToNearestZero                     // towards the nearest integer, or towards zero if equidistant.
	ToNearestAway                     // towards the nearest integer, or away from zero if equidistant.
	ToPositiveInf                     // towards infinity
	ToNegativeInf                     // towards negative infinity
	ToZero                            // towards zero
	AwayFromZero                      // away from zero

)

func (RoundingMode) String

func (i RoundingMode) String() string

type SymbolType

type SymbolType int

A SymbolType identifies a symbol of a specific kind.

const (
	SymDecimal SymbolType = iota
	SymGroup
	SymList
	SymPercentSign
	SymPlusSign
	SymMinusSign
	SymExponential
	SymSuperscriptingExponent
	SymPerMille
	SymInfinity
	SymNan
	SymTimeSeparator

	NumSymbolTypes
)

type VisibleDigits

type VisibleDigits interface {
	Digits(buf []byte, t language.Tag, scale int) Digits
}

A VisibleDigits computes digits, comma placement and trailing zeros as they will be shown to the user.