JsoniterTraversal

dev.constructive.eo.jsoniter.JsoniterTraversal

Read-WRITE Traversal over JSON byte buffers. Resolves a wildcard-bearing JSONPath against Array[Byte], decodes each matched span via JsonValueCodec[A] on read, and encodes-and- splices every focus back in one pass on write. No runtime AST.

Carrier: MultiFocus[PSVec] — the same carrier Traversal.each uses, peer to all the classical Traversal idioms. The choice over MultiFocus[List] matters for downstream composition: JsoniterTraversal[A].andThen(Traversal.each[List, A]) and similar same-carrier chains work via the existing mfAssocPSVec AssociativeFunctor instance, with zero-copy per-element reassembly. A List-carrier traversal would force a Composer hop or a manual .modify rebuild.

type X = (Array[Byte], List[JsonPathScanner.Span]) — original bytes + each KEPT focus's span, 1:1 aligned with the foci (spans whose decode throws are dropped TOGETHER with their focus, so the write side can trust the pairing).
to: Array[Byte] => (X, PSVec[A]) — runs JsonPathScanner.findAll, decodes every span via the codec into a single Array[AnyRef] allocation, wraps it as a PSVec. Spans whose decode throws are silently dropped (matches the read semantic "fold the focuses that exist") — and stay byte-untouched on write.
from: ((X, PSVec[A])) => Array[Byte] — encodes each focus via writeToArray and splices all spans back in a single pass (segments between spans are arraycopyd verbatim). A span↔foci length mismatch (an aggregate from after a shape-changing carrier op) passes the original bytes through unchanged, as does an empty focus set.

Composability: standard cats-eo extensions on Optic[..., MultiFocus[PSVec]] light up automatically via mfFold[PSVec], mfFunctor[PSVec], mfAssocPSVec, etc. — .foldMap, .modify, .headOption, .length, .exists, .modifyA, same-carrier .andThen all work without anything new shipping in this module. Mirrors dev.constructive.eo.avro.AvroTraversal's byte-carried write semantics. JsoniterPrism's '''Laws & preconditions''' apply verbatim: laws hold up to canonical re-encoding of the focused slices, and writes need decodable current focuses.

Attributes

Source: JsoniterTraversal.scala
Graph
Supertypes: class Object

trait Matchable

class Any
Self type: JsoniterTraversal.type

Members list

Grouped members

Optics

Build a read-write Traversal over a JSON byte buffer at the given JSONPath. The path MAY contain [*] wildcard steps (without them, this collapses to a single-or-zero-focus Traversal that still uses the MultiFocus[PSVec] carrier — fine, just narrower).

Throws IllegalArgumentException if the path string is not parseable.

Attributes

Example

import com.github.plokhotnyuk.jsoniter_scala.macros.JsonCodecMaker
given codec: JsonValueCodec[Long] = JsonCodecMaker.make
val itemsT = JsoniterTraversal[Long]("$.cart.items[*]")
val bytes: Array[Byte] = ...
itemsT.foldMap(identity[Long])(bytes)  // Long — sum of all items, zero AST allocation
itemsT.modify(_ * 10)(bytes)           // Array[Byte] — every item spliced in place

Source

JsoniterTraversal.scala

Build a Traversal from an already-parsed step list.

Attributes

Source: JsoniterTraversal.scala

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