111 lines
3.4 KiB
Kotlin
111 lines
3.4 KiB
Kotlin
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.Serializable
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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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@Serializable(GeoJsonSerializer::class)
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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 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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/**
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* A builder function for [GeoJsonFeature]
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*/
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public fun GeoJsonFeature(
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geometry: GeoJsonGeometry?,
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properties: JsonObject? = null,
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builder: JsonObjectBuilder.() -> Unit = {},
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): GeoJsonFeature = GeoJsonFeature(
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buildJsonObject {
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put(TYPE_KEY, "Feature")
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geometry?.json?.let { put(GeoJsonFeature.GEOMETRY_KEY, it) }
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properties?.let { put(PROPERTIES_KEY, it) }
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builder()
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}
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)
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public fun GeoJsonFeature.getProperty(key: String): JsonElement? = json[key] ?: properties?.get(key)
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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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* A builder for [GeoJsonFeatureCollection]
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*/
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public fun GeoJsonFeatureCollection(
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features: List<GeoJsonFeature>,
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properties: JsonObject? = null,
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builder: JsonObjectBuilder.() -> Unit = {},
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): GeoJsonFeatureCollection = GeoJsonFeatureCollection(
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buildJsonObject {
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put(TYPE_KEY, "FeatureCollection")
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putJsonArray(FEATURES_KEY) {
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features.forEach {
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add(it.json)
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}
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}
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properties?.let { put(PROPERTIES_KEY, it) }
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builder()
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}
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)
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/**
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* Generic Json to GeoJson converter
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*/
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public fun GeoJson(json: JsonObject): GeoJson =
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when (json[TYPE_KEY]?.jsonPrimitive?.contentOrNull ?: error("Not a GeoJson")) {
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"Feature" -> GeoJsonFeature(json)
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"FeatureCollection" -> GeoJsonFeatureCollection(json)
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else -> GeoJsonGeometry(json)
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} |