getPredicateDecoder

Call Signature

function getPredicateDecoder<TTo, TSize>(
    predicate,
    ifTrue,
    ifFalse,
): FixedSizeDecoder<TTo, TSize>;

Returns a decoder that selects between two decoders based on a predicate.

This decoder uses a boolean predicate function on the raw bytes to determine which of two decoders to use. If the predicate returns true, the ifTrue decoder is used; otherwise, the ifFalse decoder is used.

Type Parameters

Type Parameter	Description
`TTo`	The type of the value to decode.
`TSize` extends `number`	-

Parameters

Parameter	Type	Description
`predicate`	(`value`) => `boolean`	A function that returns `true` or `false` for a given byte array.
`ifTrue`	`FixedSizeDecoder`<`TTo`, `TSize`>	The decoder to use when the predicate returns `true`.
`ifFalse`	`FixedSizeDecoder`<`TTo`, `TSize`>	The decoder to use when the predicate returns `false`.

Returns

FixedSizeDecoder<TTo, TSize>

A Decoder based on the provided decoders.

Example

Decoding small and large numbers based on byte length.

const decoder = getPredicateDecoder(
  bytes => bytes.length === 1,
  getU8Decoder(),
  getU32Decoder()
);
 
decoder.decode(new Uint8Array([0x2a]));
// 42 (decoded as u8)
 
decoder.decode(new Uint8Array([0xe8, 0x03, 0x00, 0x00]));
// 1000 (decoded as u32)

See

getPredicateCodec

Call Signature

function getPredicateDecoder<TTo>(
    predicate,
    ifTrue,
    ifFalse,
): FixedSizeDecoder<TTo>;

Returns a decoder that selects between two decoders based on a predicate.

Type Parameters

Type Parameter	Description
`TTo`	The type of the value to decode.

Parameters

Parameter	Type	Description
`predicate`	(`value`) => `boolean`	A function that returns `true` or `false` for a given byte array.
`ifTrue`	`FixedSizeDecoder`<`TTo`>	The decoder to use when the predicate returns `true`.
`ifFalse`	`FixedSizeDecoder`<`TTo`>	The decoder to use when the predicate returns `false`.

Returns

FixedSizeDecoder<TTo>

A Decoder based on the provided decoders.

Example

Decoding small and large numbers based on byte length.

const decoder = getPredicateDecoder(
  bytes => bytes.length === 1,
  getU8Decoder(),
  getU32Decoder()
);
 
decoder.decode(new Uint8Array([0x2a]));
// 42 (decoded as u8)
 
decoder.decode(new Uint8Array([0xe8, 0x03, 0x00, 0x00]));
// 1000 (decoded as u32)

See

getPredicateCodec

Call Signature

function getPredicateDecoder<TTo>(
    predicate,
    ifTrue,
    ifFalse,
): VariableSizeDecoder<TTo>;

Returns a decoder that selects between two decoders based on a predicate.

Type Parameters

Type Parameter	Description
`TTo`	The type of the value to decode.

Parameters

Parameter	Type	Description
`predicate`	(`value`) => `boolean`	A function that returns `true` or `false` for a given byte array.
`ifTrue`	`VariableSizeDecoder`<`TTo`>	The decoder to use when the predicate returns `true`.
`ifFalse`	`VariableSizeDecoder`<`TTo`>	The decoder to use when the predicate returns `false`.

Returns

VariableSizeDecoder<TTo>

A Decoder based on the provided decoders.

Example

Decoding small and large numbers based on byte length.

const decoder = getPredicateDecoder(
  bytes => bytes.length === 1,
  getU8Decoder(),
  getU32Decoder()
);
 
decoder.decode(new Uint8Array([0x2a]));
// 42 (decoded as u8)
 
decoder.decode(new Uint8Array([0xe8, 0x03, 0x00, 0x00]));
// 1000 (decoded as u32)

See

getPredicateCodec

Call Signature

function getPredicateDecoder<TTo>(
    predicate,
    ifTrue,
    ifFalse,
): Decoder<TTo>;

Returns a decoder that selects between two decoders based on a predicate.

Type Parameters

Type Parameter	Description
`TTo`	The type of the value to decode.

Parameters

Parameter	Type	Description
`predicate`	(`value`) => `boolean`	A function that returns `true` or `false` for a given byte array.
`ifTrue`	`Decoder`<`TTo`>	The decoder to use when the predicate returns `true`.
`ifFalse`	`Decoder`<`TTo`>	The decoder to use when the predicate returns `false`.

Returns

Decoder<TTo>

A Decoder based on the provided decoders.

Example

Decoding small and large numbers based on byte length.

const decoder = getPredicateDecoder(
  bytes => bytes.length === 1,
  getU8Decoder(),
  getU32Decoder()
);
 
decoder.decode(new Uint8Array([0x2a]));
// 42 (decoded as u8)
 
decoder.decode(new Uint8Array([0xe8, 0x03, 0x00, 0x00]));
// 1000 (decoded as u32)

See

getPredicateCodec

getPredicateDecoder

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