74 lines
2.5 KiB
Kotlin
74 lines
2.5 KiB
Kotlin
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package center.sciprog.maps.geojson
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import center.sciprog.maps.geojson.GeoJson.Companion.PROPERTIES_KEY
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import center.sciprog.maps.geojson.GeoJson.Companion.TYPE_KEY
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import center.sciprog.maps.geojson.GeoJsonFeatureCollection.Companion.FEATURES_KEY
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import kotlinx.serialization.json.*
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import kotlin.jvm.JvmInline
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/**
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* A utility class to work with GeoJson (https://geojson.org/)
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*/
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public sealed interface GeoJson {
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public val json: JsonObject
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public val type: String get() = json[TYPE_KEY]?.jsonPrimitive?.content ?: error("Not a GeoJson")
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public companion object {
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public const val TYPE_KEY: String = "type"
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public const val PROPERTIES_KEY: String = "properties"
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}
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}
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@JvmInline
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public value class GeoJsonFeature(override val json: JsonObject) : GeoJson {
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init {
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require(type == "Feature") { "Not a GeoJson Feature" }
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}
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public val properties: JsonObject? get() = json[PROPERTIES_KEY]?.jsonObject
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public val geometry: GeoJsonGeometry? get() = json[GEOMETRY_KEY]?.jsonObject?.let { GeoJsonGeometry(it) }
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public fun getProperty(propertyName: String): JsonElement? = properties?.get(propertyName)
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public fun getString(propertyName: String): String? = getProperty(propertyName)?.jsonPrimitive?.contentOrNull
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public companion object{
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public const val GEOMETRY_KEY: String = "geometry"
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}
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}
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@JvmInline
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public value class GeoJsonFeatureCollection(override val json: JsonObject) : GeoJson, Iterable<GeoJsonFeature> {
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init {
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require(type == "FeatureCollection") { "Not a GeoJson FeatureCollection" }
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}
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public val properties: JsonObject? get() = json[PROPERTIES_KEY]?.jsonObject
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public val features: List<GeoJsonFeature>
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get() = json[FEATURES_KEY]?.jsonArray?.map {
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GeoJsonFeature(it.jsonObject)
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} ?: error("Features not defined in GeoJson features collection")
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override fun iterator(): Iterator<GeoJsonFeature> = features.iterator()
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public companion object {
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public const val FEATURES_KEY: String = "features"
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public fun parse(string: String): GeoJsonFeatureCollection = GeoJsonFeatureCollection(
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Json.parseToJsonElement(string).jsonObject
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)
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}
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}
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/**
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* Combine a collection of features to a new [GeoJsonFeatureCollection]
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*/
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public fun GeoJsonFeatureCollection(features: Collection<GeoJsonFeature>): GeoJsonFeatureCollection =
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GeoJsonFeatureCollection(
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buildJsonObject {
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put(TYPE_KEY, "FeatureCollection")
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put(FEATURES_KEY, JsonArray(features.map { it.json }))
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}
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)
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