getOptionDecoder

Call Signature

function getOptionDecoder<TTo, TSize>(
    item,
    config,
): FixedSizeDecoder<Option<TTo>, TSize>;

Returns a decoder for optional values using the Option type.

This decoder deserializes an Option<T> value using a configurable approach:

By default, a u8 prefix is used (0 = None, 1 = Some). This can be customized or disabled.
If noneValue: 'zeroes' is set, None values are identified by zeroes.
If noneValue is a byte array, None values match the provided constant.

Unlike getNullableDecoder, this decoder always outputs an Option type.

For more details, see getOptionCodec.

Type Parameters

Type Parameter	Description
`TTo`	The type of the main value being decoded.
`TSize` extends `number`	-

Parameters

Parameter	Type	Description
`item`	`FixedSizeDecoder`<`TTo`, `TSize`>	The decoder for the value that may be present.
`config`	`OptionCodecConfig`<`NumberDecoder`> & `object`	Configuration options for decoding optional values.

Returns

FixedSizeDecoder<Option<TTo>, TSize>

A FixedSizeDecoder or VariableSizeDecoder for decoding option values.

Example

Decoding an optional string with a size prefix.

const stringCodec = addCodecSizePrefix(getUtf8Codec(), getU32Codec());
const decoder = getOptionDecoder(stringCodec);
 
decoder.decode(new Uint8Array([0x01, 0x02, 0x00, 0x00, 0x00, 0x48, 0x69]));
// some('Hi')
 
decoder.decode(new Uint8Array([0x00]));
// none()

See

getOptionCodec

Call Signature

function getOptionDecoder<TTo>(
    item,
    config,
): FixedSizeDecoder<Option<TTo>>;

Returns a decoder for optional values using the Option type.

This decoder deserializes an Option<T> value using a configurable approach:

By default, a u8 prefix is used (0 = None, 1 = Some). This can be customized or disabled.
If noneValue: 'zeroes' is set, None values are identified by zeroes.
If noneValue is a byte array, None values match the provided constant.

Unlike getNullableDecoder, this decoder always outputs an Option type.

For more details, see getOptionCodec.

Type Parameters

Type Parameter	Description
`TTo`	The type of the main value being decoded.

Parameters

Parameter	Type	Description
`item`	`FixedSizeDecoder`<`TTo`>	The decoder for the value that may be present.
`config`	`OptionCodecConfig`<`FixedSizeNumberDecoder`> & `object`	Configuration options for decoding optional values.

Returns

FixedSizeDecoder<Option<TTo>>

A FixedSizeDecoder or VariableSizeDecoder for decoding option values.

Example

Decoding an optional string with a size prefix.

const stringCodec = addCodecSizePrefix(getUtf8Codec(), getU32Codec());
const decoder = getOptionDecoder(stringCodec);
 
decoder.decode(new Uint8Array([0x01, 0x02, 0x00, 0x00, 0x00, 0x48, 0x69]));
// some('Hi')
 
decoder.decode(new Uint8Array([0x00]));
// none()

See

getOptionCodec

Call Signature

function getOptionDecoder<TTo>(
    item,
    config,
): VariableSizeDecoder<Option<TTo>>;

Returns a decoder for optional values using the Option type.

This decoder deserializes an Option<T> value using a configurable approach:

By default, a u8 prefix is used (0 = None, 1 = Some). This can be customized or disabled.
If noneValue: 'zeroes' is set, None values are identified by zeroes.
If noneValue is a byte array, None values match the provided constant.

Unlike getNullableDecoder, this decoder always outputs an Option type.

For more details, see getOptionCodec.

Type Parameters

Type Parameter	Description
`TTo`	The type of the main value being decoded.

Parameters

Parameter	Type	Description
`item`	`FixedSizeDecoder`<`TTo`>	The decoder for the value that may be present.
`config`	`OptionCodecConfig`<`NumberDecoder`> & `object`	Configuration options for decoding optional values.

Returns

VariableSizeDecoder<Option<TTo>>

A FixedSizeDecoder or VariableSizeDecoder for decoding option values.

Example

Decoding an optional string with a size prefix.

const stringCodec = addCodecSizePrefix(getUtf8Codec(), getU32Codec());
const decoder = getOptionDecoder(stringCodec);
 
decoder.decode(new Uint8Array([0x01, 0x02, 0x00, 0x00, 0x00, 0x48, 0x69]));
// some('Hi')
 
decoder.decode(new Uint8Array([0x00]));
// none()

See

getOptionCodec

Call Signature

function getOptionDecoder<TTo>(
    item,
    config?,
): VariableSizeDecoder<Option<TTo>>;

Returns a decoder for optional values using the Option type.

This decoder deserializes an Option<T> value using a configurable approach:

By default, a u8 prefix is used (0 = None, 1 = Some). This can be customized or disabled.
If noneValue: 'zeroes' is set, None values are identified by zeroes.
If noneValue is a byte array, None values match the provided constant.

Unlike getNullableDecoder, this decoder always outputs an Option type.

For more details, see getOptionCodec.

Type Parameters

Type Parameter	Description
`TTo`	The type of the main value being decoded.

Parameters

Parameter	Type	Description
`item`	`Decoder`<`TTo`>	The decoder for the value that may be present.
`config?`	`OptionCodecConfig`<`NumberDecoder`> & `object`	Configuration options for decoding optional values.

Returns

VariableSizeDecoder<Option<TTo>>

A FixedSizeDecoder or VariableSizeDecoder for decoding option values.

Example

Decoding an optional string with a size prefix.

const stringCodec = addCodecSizePrefix(getUtf8Codec(), getU32Codec());
const decoder = getOptionDecoder(stringCodec);
 
decoder.decode(new Uint8Array([0x01, 0x02, 0x00, 0x00, 0x00, 0x48, 0x69]));
// some('Hi')
 
decoder.decode(new Uint8Array([0x00]));
// none()

See

getOptionCodec

getOptionDecoder

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