CompoundLens for python

[SDelgado-21]

Original implementation:

selfie/jvm/selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/Lens.kt

Lines 59 to 92 in b15b912

	open class CompoundLens : Lens {
	private val lenses = mutableListOf<Lens>()
	fun add(lens: Lens): CompoundLens {
	lenses.add(lens)
	return this
	}
	fun replaceAll(toReplace: String, replacement: String): CompoundLens = mutateAllFacets {
	it.replace(toReplace, replacement)
	}
	fun replaceAllRegex(regex: String, replacement: String): CompoundLens = mutateAllFacets {
	it.replace(regex.toRegex(), replacement)
	}
	fun mutateAllFacets(perString: StringOptionalFunction): CompoundLens = add { snapshot ->
	Snapshot.ofEntries(
	snapshot.allEntries().mapNotNull { e ->
	if (e.value.isBinary) e
	else perString.apply(e.value.valueString())?.let { entry(e.key, SnapshotValue.of(it)) }
	})
	}
	fun setFacetFrom(target: String, source: String, function: StringOptionalFunction) =
	add { snapshot ->
	val sourceValue = snapshot.subjectOrFacetMaybe(source)
	if (sourceValue == null) snapshot
	else setFacetOf(snapshot, target, function.apply(sourceValue.valueString()))
	}
	fun mutateFacet(target: String, function: StringOptionalFunction) =
	setFacetFrom(target, target, function)
	private fun setFacetOf(snapshot: Snapshot, target: String, newValue: String?): Snapshot =
	if (newValue == null) snapshot else snapshot.plusOrReplace(target, SnapshotValue.of(newValue))
	override fun transform(snapshot: Snapshot): Snapshot {
	var current = snapshot
	lenses.forEach { current = it.transform(current) }
	return current
	}