aghalg

Documentation

Overview

Package aghalg contains common generic algorithms and data structures.

TODO(a.garipov): Move parts of this into golibs.

Index

• func Coalesce[T comparable](values ...T) (res T)
• func CoalesceSlice[E any, S []E](values ...S) (res S)
• type NullBool
  • func BoolToNullBool(cond bool) (nb NullBool)
  • func (nb NullBool) MarshalJSON() (b []byte, err error)
  • func (nb NullBool) String() (s string)
  • func (nb *NullBool) UnmarshalJSON(b []byte) (err error)
• type UniqChecker
  • func (uc UniqChecker[T]) Add(elems ...T)
  • func (uc UniqChecker[T]) Merge(other UniqChecker[T]) (merged UniqChecker[T])
  • func (uc UniqChecker[T]) Validate() (err error)

Functions

func Coalesce

func Coalesce[T comparable](values ...T) (res T)

Coalesce returns the first non-zero value. It is named after function COALESCE in SQL. If values or all its elements are empty, it returns a zero value.

T is comparable, because Go currently doesn't have a comparableWithZeroValue constraint.

TODO(a.garipov): Think of ways to merge with CoalesceSlice.

func CoalesceSlice

func CoalesceSlice[E any, S []E](values ...S) (res S)

CoalesceSlice returns the first non-zero value. It is named after function COALESCE in SQL. If values or all its elements are empty, it returns nil.

TODO(a.garipov): Think of ways to merge with Coalesce.

Types

type NullBool

type NullBool uint8

NullBool is a nullable boolean. Use these in JSON requests and responses instead of pointers to bool.

const (
	NBNull NullBool = iota
	NBTrue
	NBFalse
)

NullBool values

func BoolToNullBool

func BoolToNullBool(cond bool) (nb NullBool)

BoolToNullBool converts a bool into a NullBool.

func (NullBool) MarshalJSON

func (nb NullBool) MarshalJSON() (b []byte, err error)

MarshalJSON implements the json.Marshaler interface for NullBool.

func (NullBool) String

func (nb NullBool) String() (s string)

String implements the fmt.Stringer interface for NullBool.

func (*NullBool) UnmarshalJSON

func (nb *NullBool) UnmarshalJSON(b []byte) (err error)

UnmarshalJSON implements the json.Unmarshaler interface for *NullBool.

type UniqChecker

type UniqChecker[T constraints.Ordered] map[T]int64

UniqChecker allows validating uniqueness of comparable items.

TODO(a.garipov): The Ordered constraint is only really necessary in Validate. Consider ways of making this constraint comparable instead.

func (UniqChecker[T]) Add

func (uc UniqChecker[T]) Add(elems ...T)

Add adds a value to the validator. v must not be nil.

func (UniqChecker[T]) Merge

func (uc UniqChecker[T]) Merge(other UniqChecker[T]) (merged UniqChecker[T])

Merge returns a checker containing data from both uc and other.

func (UniqChecker[T]) Validate

func (uc UniqChecker[T]) Validate() (err error)

Validate returns an error enumerating all elements that aren't unique.