transformCodec

Call Signature

function transformCodec<TOldFrom, TNewFrom, TTo, TSize>(
    codec,
    unmap,
): FixedSizeCodec<TNewFrom, TTo, TSize>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TTo`	-
`TSize` extends `number`	-

Parameters

Parameter	Type	Description
`codec`	`FixedSizeCodec`<`TOldFrom`, `TTo`, `TSize`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.

Returns

FixedSizeCodec<TNewFrom, TTo, TSize>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

See

Call Signature

function transformCodec<TOldFrom, TNewFrom, TTo>(
    codec,
    unmap,
): VariableSizeCodec<TNewFrom, TTo>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TTo`	-

Parameters

Parameter	Type	Description
`codec`	`VariableSizeCodec`<`TOldFrom`, `TTo`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.

Returns

VariableSizeCodec<TNewFrom, TTo>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

See

Call Signature

function transformCodec<TOldFrom, TNewFrom, TTo>(
    codec,
    unmap,
): Codec<TNewFrom, TTo>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TTo`	-

Parameters

Parameter	Type	Description
`codec`	`Codec`<`TOldFrom`, `TTo`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.

Returns

Codec<TNewFrom, TTo>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

See

Call Signature

function transformCodec<TOldFrom, TNewFrom, TOldTo, TNewTo, TSize>(
    codec,
    unmap,
    map,
): FixedSizeCodec<TNewFrom, TNewTo, TSize>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TOldTo`	The original type returned by the codec.
`TNewTo`	The new type that will be transformed after decoding.
`TSize` extends `number`	-

Parameters

Parameter	Type	Description
`codec`	`FixedSizeCodec`<`TOldFrom`, `TOldTo`, `TSize`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.
`map`	(`value`, `bytes`, `offset`) => `TNewTo`	A function that converts values of `TOldTo` into `TNewTo` after decoding (optional).

Returns

FixedSizeCodec<TNewFrom, TNewTo, TSize>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

See

Call Signature

function transformCodec<TOldFrom, TNewFrom, TOldTo, TNewTo>(
    codec,
    unmap,
    map,
): VariableSizeCodec<TNewFrom, TNewTo>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TOldTo`	The original type returned by the codec.
`TNewTo`	The new type that will be transformed after decoding.

Parameters

Parameter	Type	Description
`codec`	`VariableSizeCodec`<`TOldFrom`, `TOldTo`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.
`map`	(`value`, `bytes`, `offset`) => `TNewTo`	A function that converts values of `TOldTo` into `TNewTo` after decoding (optional).

Returns

VariableSizeCodec<TNewFrom, TNewTo>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

See

Call Signature

function transformCodec<TOldFrom, TNewFrom, TOldTo, TNewTo>(
    codec,
    unmap,
    map,
): Codec<TNewFrom, TNewTo>;

Transforms a codec by mapping its input and output values.

This function takes an existing Codec<A, B> and returns a Codec<C, D>, allowing:

Values of type C to be transformed into A before encoding.
Values of type B to be transformed into D after decoding.

This is useful for adapting codecs to work with different representations, handling default values, or converting between primitive and structured types.

Type Parameters

Type Parameter	Description
`TOldFrom`	The original type expected by the codec.
`TNewFrom`	The new type that will be transformed before encoding.
`TOldTo`	The original type returned by the codec.
`TNewTo`	The new type that will be transformed after decoding.

Parameters

Parameter	Type	Description
`codec`	`Codec`<`TOldFrom`, `TOldTo`>	The codec to transform.
`unmap`	(`value`) => `TOldFrom`	A function that converts values of `TNewFrom` into `TOldFrom` before encoding.
`map`	(`value`, `bytes`, `offset`) => `TNewTo`	A function that converts values of `TOldTo` into `TNewTo` after decoding (optional).

Returns

Codec<TNewFrom, TNewTo>

A new codec that encodes TNewFrom and decodes into TNewTo.

Example

Mapping a u32 codec to encode string lengths and decode them into 'x' characters.

const codec = transformCodec(
    getU32Codec(),
    (value: string) => value.length, // Encode string length
    (length) => 'x'.repeat(length)  // Decode length into a string of 'x's
);
 
const bytes = codec.encode("hello"); // 0x05000000 (stores length 5)
const value = codec.decode(bytes);   // "xxxxx"

Remarks

If only input transformation is needed, use transformEncoder. If only output transformation is needed, use transformDecoder.

const bytes = transformEncoder(getU32Encoder(), (value: string) => value.length).encode("hello");
const value = transformDecoder(getU32Decoder(), (length) => 'x'.repeat(length)).decode(bytes);

transformCodec

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