Bounding
A length Codec that narrows ReadBuffer.limit to bound the subsequent decode region.
Codec authors implement this sub-interface (instead of plain Codec) when the length value should constrain the buffer for following fields — e.g. MQTT v3.1.1 §2.2.3 remaining-length, ASN.1 BER short/long-form length, or any other "the next N bytes are payload" framing. The processor detects this sub-interface on a @UseCodec-targeted field and wraps the bounded region in:
val outerLimit = buffer.limit()
val value = lengthCodec.decode(buffer, ctx)
lengthCodec.applyBound(buffer, value)
try {
// ... decode bounded fields ...
} finally {
buffer.setLimit(outerLimit)
}Codecs whose decoded value is consumed by a sibling @LengthFrom/@LengthPrefixed (rather than narrowing the buffer) implement plain Codec and skip this sub-interface.
Properties
The maximum number of bytes this codec ever writes for a single encoded value. Used by the @FramedBy slicing-scheme emitter to size the slack region at the front of the encode buffer so the prefix can be right-flushed against the body without shifting body bytes. For variable-width codecs (e.g. MQTT remaining-length: 1..4 bytes), this is the upper bound; for fixed-width codecs it equals the wire width. Implementations should pick the smallest value that satisfies wireSize(maxValueOnWire).asExact == maxWireSize.
Functions
Narrows buffer's limit so that the bounded region ends after decodedValue bytes from the current position. Called after decode returns. Implementations typically call buffer.setLimit(buffer.position() + decodedValue.toInt()).
Reports the on-wire byte size. Defaults to WireSize.BackPatch.