BinaryFormat.List

Returns a binary format that reads a sequence of items and returns a list.

Syntax

BinaryFormat.List(
    binaryFormat as function,
    optional countOrCondition as any
) as function

Remarks

Returns a binary format that reads a sequence of items and returns a list. The binaryFormat parameter specifies the binary format of each item. There are three ways to determine the number of items read:

• If the countOrCondition is not specified, then the binary format will read until there are no more items.
• If the countOrCondition is a number, then the binary format will read that many items.
• If the countOrCondition is a function, then that function will be invoked for each item read. The function returns true to continue, and false to stop reading items. The final item is included in the list.
• If the countOrCondition is a binary format, then the count of items is expected to precede the list, and the specified format is used to read the count.

Examples

Example #1

Read bytes until the end of the data.

let
    binaryData = #binary({1, 2, 3}),
    listFormat = BinaryFormat.List(BinaryFormat.Byte)
in
    listFormat(binaryData)

Result:

{1, 2, 3}

Example #2

Read two bytes.

let
    binaryData = #binary({1, 2, 3}),
    listFormat = BinaryFormat.List(BinaryFormat.Byte, 2)
in
    listFormat(binaryData)

Result:

{1, 2}

Example #3

Read bytes until the byte value is greater than or equal to two.

let
    binaryData = #binary({1, 2, 3}),
    listFormat = BinaryFormat.List(BinaryFormat.Byte, (x) => x < 2)
in
    listFormat(binaryData)

Result:

{1, 2}

Category

Binary Formats.Reading lists