BoxBodyRun.kt

src/jvmMain/kotlin/afield/runtime/execution/BoxBodyRun.kt · 34 lines

package afield.runtime.execution

Which boxes are executing their body right now, as distinct from a frame loop or callback the body started: BoxBodyRun counts each box's nested body runs, and a source-backed block reads it to refuse re-entering its own box.

import afield.document.graph.Box

object BoxBodyRun

Which boxes' bodies are executing right now: set by execution around a box's run or launch, and not by its frame loop or callbacks, which run after the body has returned.

This is what lets a saved sourceBlock refuse to hydrate on its own box's engine while that box's body is still running. Evaluating there would run the body again (see SourceBackedBlockSelfBoxReentry).

object BoxBodyRun {
    private val running = java.util.concurrent.ConcurrentHashMap<String, Int>()

inline fun <T> during(box: Box, block: () -> T): T {

Run block as the body of box.

    inline fun <T> during(box: Box, block: () -> T): T {
        enter(box.id)
        try { return block() } finally { exit(box.id) }
    }

@PublishedApi internal fun enter(id: String) { running.merge(id, 1, Int::plus) }

@PublishedApi internal fun exit(id: String)

    @PublishedApi internal fun exit(id: String) { running.computeIfPresent(id) { _, n -> (n - 1).takeIf { it > 0 } } }

fun isRunning(id: String): Boolean = running.containsKey(id)

Whether the box with id is running its body (rather than a frame loop or a callback).