typutil

README

type conversion utils

This is useful when dealing with json parsed types for example.

Assign

Assign is a tool that allows assigning any value to any other value and let the library handle the conversion in a somewhat intelligent way.

For example a map[string]any can be assigned to a struct (json tags will be taken into account for variable names) and values will be converted.

Func

It is possible to transform any func into a generic callable that can be used in various ways, with its arguments automatically converted to match the required values.

For example:

func Add(a, b int) int {
    return a + b
}

f := typutil.Func(Add)
res, err := typutil.Call[int](f, ctx, 1, "2") // res=3

Func with default arguments

Arguably, default arguments are something missing with Go. Well, here we go.

func Add(a, b int) int {
    return a + b
}

f := typutil.Func(Add).WithDefaults(typutil.Required, 42)
res, err := typutil.Call[int](f, ctx, 58) // res=100

Documentation

Index

• Constants
• Variables
• func As[T any](v any) (T, error)
• func AsBool(v any) bool
• func AsByteArray(v any) ([]byte, bool)
• func AsFloat(v any) (float64, bool)
• func AsInt(v any) (int64, bool)
• func AsNumber(v any) (any, bool)
• func AsString(v any) (string, bool)
• func AsUint(v any) (uint64, bool)
• func Assign(dst, src any) error
• func AssignReflect(vdst, vsrc reflect.Value) error
• func BaseType(v any) any
• func Call[T any](s *Callable, ctx context.Context, arg ...any) (T, error)
• func DeepClone[T any](v T) T
• func DeepCloneReflect(src reflect.Value) reflect.Value
• func Equal(a, b any) bool
• func Flatten(a any) any
• func FormatSize(x uint64) string
• func IsNil(v any) bool
• func Math(mathop string, a, b any) (any, bool)
• func OffsetGet(ctx context.Context, v any, offset string) (any, error)
• func SetValidator[T any](validator string, fnc func(T) error)
• func SetValidatorArgs(validator string, fnc any)
• func StrictArgs(c *Callable)
• func ToType(ref, v any) (any, bool)
• func Validate(obj any) error
• type AssignableTo
• type Callable
  • func Func(method any, options ...funcOption) *Callable
  • func (s *Callable) ArgKind(n int) reflect.Kind
  • func (s *Callable) Call(ctx context.Context) (any, error)
  • func (s *Callable) CallArg(ctx context.Context, arg ...any) (any, error)
  • func (s *Callable) IsStringArg(n int) bool
  • func (s *Callable) String() string
  • func (s *Callable) WithDefaults(args ...any) *Callable
• type RawJsonMessage
  • func (m RawJsonMessage) AssignTo(v any) error
  • func (m RawJsonMessage) MarshalJSON() ([]byte, error)
  • func (m *RawJsonMessage) UnmarshalJSON(data []byte) error
• type Signed
• type Unsigned

Constants

const Required requiredArg = 1 // Required denotes a default argument that must be specified

Variables

var (
	ErrAssignDestNotPointer      = errors.New("assign destination must be a pointer")
	ErrAssignImpossible          = errors.New("the requested assign is not possible")
	ErrNilPointerRead            = errors.New("attempt to read from a nil pointer")
	ErrEmptyValue                = errors.New("validator: value must not be empty")
	ErrDestinationNotAddressable = errors.New("assign: destination cannot be addressed")
	ErrStructPtrRequired         = errors.New("parameter must be a pointer to a struct")
	ErrBadOffset                 = errors.New("bad offset type")
	ErrMissingArgs               = errors.New("missing arguments")
	ErrTooManyArgs               = errors.New("too many arguments")
	ErrDifferentType             = errors.New("wrong type in function call")
	ErrInvalidSource             = errors.New("assign source is not valid")
)

Functions

func As

func As[T any](v any) (T, error)

func AsBool

func AsBool(v any) bool

AsBool loosely converts the value to a boolean

func AsByteArray

func AsByteArray(v any) ([]byte, bool)

AsByteArray will loosely convert the given value to a byte array

func AsFloat

func AsFloat(v any) (float64, bool)

AsFloat loosely converts the given value to a float64

func AsInt

func AsInt(v any) (int64, bool)

AsInt loosely converts the given value to a int64

func AsNumber

func AsNumber(v any) (any, bool)

AsNumber will loosely convert n in one of int64, uint64 or float64 depending on what feels best

func AsString

func AsString(v any) (string, bool)

AsString will loosely converts the given value to a string

func AsUint

func AsUint(v any) (uint64, bool)

AsUint loosely converts the given value to a uint64

func Assign

func Assign(dst, src any) error

Assign sets dst to the value of src. In case src is any kind of container, a shallow copy is performed

func AssignReflect

func AssignReflect(vdst, vsrc reflect.Value) error

func BaseType

func BaseType(v any) any

BaseType attempts to convert v into its base type, that is if v is a type that is defined as `type foo string`, a simple string will be returned.

func Call

func Call[T any](s *Callable, ctx context.Context, arg ...any) (T, error)

Call will call the callable with the provided arguments, and cast the return type to the specified type automatically. If the return type is not of the correct type, an error will be returned, unless there was already an error.

func DeepClone

func DeepClone[T any](v T) T

DeepClone performs a deep duplication of the provided argument, and returns the newly created object

func DeepCloneReflect

func DeepCloneReflect(src reflect.Value) reflect.Value

DeepCloneReflect performs a deep duplication of the provided reflect.Value

func Equal

func Equal(a, b any) bool

Equal returns true if a and b are somewhat equal

func Flatten

func Flatten(a any) any

Flatten transforms a into a simple interface, even if it is contains multiple levels. *string becomes string (or nil if it's nil), etc

func FormatSize

func FormatSize(x uint64) string

FormatSize is a simple method that will format a given integer value into something easier to read as a human

func IsNil

func IsNil(v any) bool

IsNil recursively checks if v is nil, even if it is a pointer of an interface of a ...

func Math

func Math(mathop string, a, b any) (any, bool)

Math performs a mathematical operation on two variables of any type and returns a numeric type and true if everything went fine.

For example Math("+", 40.000, "2") will return float64(42)

For now if passed any float value, the function will always return a float value in the end. This may change in the future.

func OffsetGet

func OffsetGet(ctx context.Context, v any, offset string) (any, error)

OffsetGet returns v[offset] dealing with various case of figure. ctx will be passed to some methods handling it

func SetValidator

func SetValidator[T any](validator string, fnc func(T) error)

SetValidator sets the given function as validator with the given name. This should be typically called in init()

func SetValidatorArgs

func SetValidatorArgs(validator string, fnc any)

func StrictArgs

func StrictArgs(c *Callable)

StrictArgs, when passed to Func, forces that function's arguments to be of the right type

func ToType

func ToType(ref, v any) (any, bool)

ToType returns v converted to ref's type

Deprecated: Use As[T](v) instead

func Validate

func Validate(obj any) error

Validate accept any struct as argument and returns if the struct is valid. The parameter should be a pointer to the struct so validators can edit values.

Types

type AssignableTo

type AssignableTo interface {
	AssignTo(any) error
}

AssignableTo is an interface that can be implemented by objects able to assign themselves to values. Do not use Assign() inside AssignTo or you risk generating an infinite loop.

This looks a bit like sql's Valuer, except instead of a returning a any interface, the parameter is a pointer to the target type. Typically, Unmarshal will be used in here.

type Callable

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

func Func

func Func(method any, options ...funcOption) *Callable

Func returns a Callable object for a func that accepts a context.Context and/or any number of arguments

func (*Callable) ArgKind

func (s *Callable) ArgKind(n int) reflect.Kind

ArgKind returns the kind for the nth argument. reflect.Invalid will be returned if there is no such argument

func (*Callable) Call

func (s *Callable) Call(ctx context.Context) (any, error)

Call invokes the func without any argument. If the func expects some kind of argument, Call will attempt to get input_json from the context, and if obtained it will be parsed and passed as argument to the method.

func (*Callable) CallArg

func (s *Callable) CallArg(ctx context.Context, arg ...any) (any, error)

CallArg calls the method with the specified arguments. If less arguments are provided than required, an error will be raised.

func (*Callable) IsStringArg

func (s *Callable) IsStringArg(n int) bool

IsStringArg returns true if the nth argument of the callable is a string, or a type related to string

func (*Callable) String

func (s *Callable) String() string

String returns a string representation of the function and its arguments

func (*Callable) WithDefaults

func (s *Callable) WithDefaults(args ...any) *Callable

WithDefaults sets default arguments for the given callable that will be used when a call doesn't have enough arguments to call the method. It will panic if there aren't enough arguments provided or if a value is not compatible with the function's expected argument type.

Example:

func myFunc(a, b, c int) { ... }
f := Func(myFunc).WithDefaults(typutil.Required, typutil.Required, 42) // c defaults to 42
f.CallArg(context.Background(), 10, 20) // equivalent to myFunc(10, 20, 42)

type RawJsonMessage

type RawJsonMessage []byte

RawJsonMessage is similar to json.RawMessage, but also implements

func (RawJsonMessage) AssignTo

func (m RawJsonMessage) AssignTo(v any) error

AssignTo will unmarshal the raw json message into v

func (RawJsonMessage) MarshalJSON

func (m RawJsonMessage) MarshalJSON() ([]byte, error)

func (*RawJsonMessage) UnmarshalJSON

func (m *RawJsonMessage) UnmarshalJSON(data []byte) error

type Signed

type Signed interface {
	~int | ~int8 | ~int16 | ~int32 | ~int64
}

type Unsigned

type Unsigned interface {
	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
}