## Documentation ¶

### Overview ¶

Package number contains tools and data for formatting numbers.

### 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.

)```
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.
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.

#### 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.