Skip to content

MessagePackZeroCopyDecoder

[Source]

Implements low-level zero-copy decoding from the MessagePack serialization format.

This decoder mirrors MessagePackDecoder but takes a ZeroCopyReader instead of a buffered.Reader. Variable-length values (strings, binary data, extensions) are returned as val views into the reader's internal buffer rather than freshly allocated copies. Fixed-size values (integers, floats, booleans) are decoded identically to MessagePackDecoder.

You should be familiar with how MessagePack encodes messages if you use this API directly. There are very few guardrails preventing you from incorrectly decoding documents. This is particularly true when using the array and map format family decoding methods, which only read headers — the caller must read each element individually afterward.

Two styles of decode methods are provided:

  • Compact methods (uint, int, str, byte_array, ext, array, map) peek at the format byte to determine the wire format and accept any format within the family.
  • Format-specific methods (u8, u16, str_8, str_16, bin_8, fixext_1, ext_8, etc.) validate a single expected format byte, then read the data directly. Use these when you know the exact wire format in advance.

This decoder assumes all data is available when decoding begins. For streaming use, MessagePackStreamingDecoder uses zero-copy decoding internally.

primitive val MessagePackZeroCopyDecoder

Constructors

create

[Source]

new val create()
: MessagePackZeroCopyDecoder val^

Returns

Public Functions

uint

[Source]

Decodes an unsigned integer from any uint or positive fixint format.

fun box uint(
  b: ZeroCopyReader ref)
: U64 val ?

Parameters

Returns

int

[Source]

Decodes a signed integer from any int, uint, or fixint format. Errors if a uint_64 value exceeds I64.max_value().

fun box int(
  b: ZeroCopyReader ref)
: I64 val ?

Parameters

Returns

array

[Source]

Reads an array header from any array format. Returns the element count. The caller must read that many elements afterward.

fun box array(
  b: ZeroCopyReader ref)
: U32 val ?

Parameters

Returns

map

[Source]

Reads a map header from any map format. Returns the pair count. The caller must read that many key-value pairs afterward.

fun box map(
  b: ZeroCopyReader ref)
: U32 val ?

Parameters

Returns

nil

[Source]

Returns nothing. Throws an error if the next byte isn't a MessagePack nil.

fun box nil(
  b: ZeroCopyReader ref)
: None val ?

Parameters

Returns

bool

[Source]

fun box bool(
  b: ZeroCopyReader ref)
: Bool val ?

Parameters

Returns

positive_fixint

[Source]

fun box positive_fixint(
  b: ZeroCopyReader ref)
: U8 val ?

Parameters

Returns

  • U8 val ?

negative_fixint

[Source]

fun box negative_fixint(
  b: ZeroCopyReader ref)
: I8 val ?

Parameters

Returns

  • I8 val ?

u8

[Source]

fun box u8(
  b: ZeroCopyReader ref)
: U8 val ?

Parameters

Returns

  • U8 val ?

u16

[Source]

fun box u16(
  b: ZeroCopyReader ref)
: U16 val ?

Parameters

Returns

u32

[Source]

fun box u32(
  b: ZeroCopyReader ref)
: U32 val ?

Parameters

Returns

u64

[Source]

fun box u64(
  b: ZeroCopyReader ref)
: U64 val ?

Parameters

Returns

i8

[Source]

fun box i8(
  b: ZeroCopyReader ref)
: I8 val ?

Parameters

Returns

  • I8 val ?

i16

[Source]

fun box i16(
  b: ZeroCopyReader ref)
: I16 val ?

Parameters

Returns

i32

[Source]

fun box i32(
  b: ZeroCopyReader ref)
: I32 val ?

Parameters

Returns

i64

[Source]

fun box i64(
  b: ZeroCopyReader ref)
: I64 val ?

Parameters

Returns

f32

[Source]

fun box f32(
  b: ZeroCopyReader ref)
: F32 val ?

Parameters

Returns

f64

[Source]

fun box f64(
  b: ZeroCopyReader ref)
: F64 val ?

Parameters

Returns

fixstr

[Source]

fun box fixstr(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str

[Source]

fun box str(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_8

[Source]

Decodes a MessagePack str 8 value. Validates that the format byte is str_8 (0xD9), then reads the 1-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any string wire format, use str() instead.

fun box str_8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_16

[Source]

Decodes a MessagePack str 16 value. Validates that the format byte is str_16 (0xDA), then reads the 2-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any string wire format, use str() instead.

fun box str_16(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_32

[Source]

Decodes a MessagePack str 32 value. Validates that the format byte is str_32 (0xDB), then reads the 4-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any string wire format, use str() instead.

fun box str_32(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_utf8

[Source]

Decodes a MessagePack str value using the smallest matching format, then validates that the bytes are valid UTF-8.

Errors if the format byte is not a str type, if insufficient data is available, or if the decoded bytes are not valid UTF-8. On a UTF-8 validation error the bytes have already been consumed from the reader. For the non-validating variant, use str(). To retain access to the raw bytes on validation failure, use str() followed by MessagePackValidateUTF8.

fun box str_utf8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

fixstr_utf8

[Source]

Decodes a MessagePack fixstr value, then validates that the bytes are valid UTF-8.

Errors if the format byte does not match, if insufficient data is available, or if the decoded bytes are not valid UTF-8. For the non-validating variant, use fixstr().

fun box fixstr_utf8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_8_utf8

[Source]

Decodes a MessagePack str 8 value, then validates that the bytes are valid UTF-8.

Errors if the format byte does not match, if insufficient data is available, or if the decoded bytes are not valid UTF-8. For the non-validating variant, use str_8().

fun box str_8_utf8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_16_utf8

[Source]

Decodes a MessagePack str 16 value, then validates that the bytes are valid UTF-8.

Errors if the format byte does not match, if insufficient data is available, or if the decoded bytes are not valid UTF-8. For the non-validating variant, use str_16().

fun box str_16_utf8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

str_32_utf8

[Source]

Decodes a MessagePack str 32 value, then validates that the bytes are valid UTF-8.

Errors if the format byte does not match, if insufficient data is available, or if the decoded bytes are not valid UTF-8. For the non-validating variant, use str_32().

fun box str_32_utf8(
  b: ZeroCopyReader ref)
: String val ?

Parameters

Returns

byte_array

[Source]

fun box byte_array(
  b: ZeroCopyReader ref)
: Array[U8 val] val ?

Parameters

Returns

bin_8

[Source]

Decodes a MessagePack bin 8 value. Validates that the format byte is bin_8 (0xC4), then reads the 1-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any bin wire format, use byte_array() instead.

fun box bin_8(
  b: ZeroCopyReader ref)
: Array[U8 val] val ?

Parameters

Returns

bin_16

[Source]

Decodes a MessagePack bin 16 value. Validates that the format byte is bin_16 (0xC5), then reads the 2-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any bin wire format, use byte_array() instead.

fun box bin_16(
  b: ZeroCopyReader ref)
: Array[U8 val] val ?

Parameters

Returns

bin_32

[Source]

Decodes a MessagePack bin 32 value. Validates that the format byte is bin_32 (0xC6), then reads the 4-byte length prefix and data.

Errors if the format byte does not match or if insufficient data is available. For a method that accepts any bin wire format, use byte_array() instead.

fun box bin_32(
  b: ZeroCopyReader ref)
: Array[U8 val] val ?

Parameters

Returns

fixarray

[Source]

Reads a header for a MessgePack "fixarray". This only reads the header. The number of array items returned by this method needs to be read via other methods after this is called.

fun box fixarray(
  b: ZeroCopyReader ref)
: U8 val ?

Parameters

Returns

  • U8 val ?

array_16

[Source]

Reads a header for a MessgePack "array_16". This only reads the header. The number of array items returned by this method needs to be read via other methods after this is called.

fun box array_16(
  b: ZeroCopyReader ref)
: U16 val ?

Parameters

Returns

array_32

[Source]

Reads a header for a MessgePack "array_32". This only reads the header. The number of array items returned by this method needs to be read via other methods after this is called.

fun box array_32(
  b: ZeroCopyReader ref)
: U32 val ?

Parameters

Returns

fixmap

[Source]

Reads a header for a MessgePack "fixmap". This only reads the header. The number of map items returned by this method needs to be read via other methods after this is called.

fun box fixmap(
  b: ZeroCopyReader ref)
: U8 val ?

Parameters

Returns

  • U8 val ?

map_16

[Source]

Reads a header for a MessgePack "map_16". This only reads the header. The number of map items returned by this method needs to be read via other methods after this is called.

fun box map_16(
  b: ZeroCopyReader ref)
: U16 val ?

Parameters

Returns

map_32

[Source]

Reads a header for a MessgePack "map_32". This only reads the header. The number of map items returned by this method needs to be read via other methods after this is called.

fun box map_32(
  b: ZeroCopyReader ref)
: U32 val ?

Parameters

Returns

ext

[Source]

Allows for the reading of user supplied extensions to the MessagePack format.

fixext * types return a tuple representing:

(user supplied type indentifier, data byte array)

fun box ext(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

fixext_1

[Source]

Decodes a MessagePack fixext 1 value. Validates that the format byte is fixext_1 (0xD4), then reads the ext type byte and 1 byte of data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box fixext_1(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

fixext_2

[Source]

Decodes a MessagePack fixext 2 value. Validates that the format byte is fixext_2 (0xD5), then reads the ext type byte and 2 bytes of data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box fixext_2(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

fixext_4

[Source]

Decodes a MessagePack fixext 4 value. Validates that the format byte is fixext_4 (0xD6), then reads the ext type byte and 4 bytes of data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box fixext_4(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

fixext_8

[Source]

Decodes a MessagePack fixext 8 value. Validates that the format byte is fixext_8 (0xD7), then reads the ext type byte and 8 bytes of data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box fixext_8(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

fixext_16

[Source]

Decodes a MessagePack fixext 16 value. Validates that the format byte is fixext_16 (0xD8), then reads the ext type byte and 16 bytes of data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box fixext_16(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

ext_8

[Source]

Decodes a MessagePack ext 8 value. Validates that the format byte is ext_8 (0xC7), then reads the 1-byte length prefix, ext type byte, and data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box ext_8(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

ext_16

[Source]

Decodes a MessagePack ext 16 value. Validates that the format byte is ext_16 (0xC8), then reads the 2-byte length prefix, ext type byte, and data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box ext_16(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

ext_32

[Source]

Decodes a MessagePack ext 32 value. Validates that the format byte is ext_32 (0xC9), then reads the 4-byte length prefix, ext type byte, and data.

Returns (ext_type, data). Errors if the format byte does not match. For a method that accepts any ext wire format, use ext() instead.

fun box ext_32(
  b: ZeroCopyReader ref)
: (U8 val , Array[U8 val] val) ?

Parameters

Returns

timestamp

[Source]

fun box timestamp(
  b: ZeroCopyReader ref)
: (I64 val , U32 val) ?

Parameters

Returns

skip

[Source]

Advances past one complete MessagePack value without decoding it. For containers (arrays and maps), skips all contained elements.

Errors if insufficient data is available or if the format byte is invalid (0xC1). On error, no bytes are consumed.

This method has no limit on the number of values traversed. For protection against container amplification attacks, use MessagePackStreamingDecoder.skip which enforces a configurable max_skip_values limit.

fun box skip(
  b: ZeroCopyReader ref)
: None val ?

Parameters

Returns

eq

[Source]

fun box eq(
  that: MessagePackZeroCopyDecoder val)
: Bool val

Parameters

Returns

ne

[Source]

fun box ne(
  that: MessagePackZeroCopyDecoder val)
: Bool val

Parameters

Returns