Add Wasm WASI target

Author: igoriakovlev

core/build.gradle.kts

@@ -129,6 +129,10 @@ kotlin {
         }
     }
 
+    wasmWasi {
+        nodejs()
+    }
+
     @OptIn(ExperimentalKotlinGradlePluginApi::class)
     compilerOptions {
         freeCompilerArgs.add("-Xexpect-actual-classes")

core/wasmWasi/src/internal/Platform.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2019-2024 JetBrains s.r.o. and contributors.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package kotlinx.datetime.internal
+
+import kotlinx.datetime.Instant
+import kotlin.wasm.WasmImport
+import kotlin.wasm.unsafe.UnsafeWasmMemoryApi
+import kotlin.wasm.unsafe.withScopedMemoryAllocator
+
+/**
+ * Return the time value of a clock. Note: This is similar to `clock_gettime` in POSIX.
+ */
+@WasmImport("wasi_snapshot_preview1", "clock_time_get")
+private external fun wasiRawClockTimeGet(clockId: Int, precision: Long, resultPtr: Int): Int
+
+private const val CLOCKID_REALTIME = 0
+
+@OptIn(UnsafeWasmMemoryApi::class)
+private fun clockTimeGet(): Long = withScopedMemoryAllocator { allocator ->
+    val rp0 = allocator.allocate(8)
+    val ret = wasiRawClockTimeGet(
+        clockId = CLOCKID_REALTIME,
+        precision = 1,
+        resultPtr = rp0.address.toInt()
+    )
+    if (ret == 0) {
+        rp0.loadLong()
+    } else {
+        error("WASI call failed with $ret")
+    }
+}
+
+internal actual fun currentTime(): Instant = clockTimeGet().let { time ->
+    // Instant.MAX and Instant.MIN are never going to be exceeded using just the Long number of nanoseconds
+    Instant(time.floorDiv(NANOS_PER_ONE.toLong()), time.mod(NANOS_PER_ONE.toLong()).toInt())
+}
+
+internal actual fun currentSystemDefaultZone(): Pair<String, TimeZoneRules?> =
+    throw UnsupportedOperationException("WASI platform does not support system timezone obtaining")
+
+internal actual val systemTzdb: TimeZoneDatabase = TzdbOnData()

core/wasmWasi/src/internal/TimeZonesInitializer.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2019-2023 JetBrains s.r.o. and contributors.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package kotlinx.datetime.internal
+
+import kotlinx.datetime.IllegalTimeZoneException
+
+@RequiresOptIn
+internal annotation class InternalDateTimeApi
+
+/*
+This is internal API which is not intended to use on user-side.
+ */
+@InternalDateTimeApi
+public interface TimeZonesProvider {
+    public fun zoneDataByName(name: String): ByteArray
+    public fun getTimeZones(): Set<String>
+}
+
+/*
+This is internal API which is not intended to use on user-side.
+ */
+@InternalDateTimeApi
+public fun initializeTimeZonesProvider(provider: TimeZonesProvider) {
+    check(timeZonesProvider != provider) { "TimeZone database redeclaration" }
+    timeZonesProvider = provider
+}
+
+@InternalDateTimeApi
+private var timeZonesProvider: TimeZonesProvider? = null
+
+internal class TzdbOnData: TimeZoneDatabase {
+    override fun rulesForId(id: String): TimeZoneRules {
+        @OptIn(InternalDateTimeApi::class)
+        val data = timeZonesProvider?.zoneDataByName(id)
+            ?: throw IllegalTimeZoneException("TimeZones are not supported")
+        return readTzFile(data).toTimeZoneRules()
+    }
+
+    override fun availableTimeZoneIds(): Set<String> =
+        @OptIn(InternalDateTimeApi::class)
+        timeZonesProvider?.getTimeZones() ?: emptySet()
+}

serialization/build.gradle.kts

@@ -58,6 +58,11 @@ kotlin {
         }
     }
 
+    wasmWasi {
+        nodejs {
+        }
+    }
+
     sourceSets.all {
         val suffixIndex = name.indexOfLast { it.isUpperCase() }
         val targetName = name.substring(0, suffixIndex)
@@ -103,6 +108,9 @@ kotlin {
             }
         }
 
+        val wasmWasiMain by getting
+        val wasmWasiTest by getting
+
         val nativeMain by getting
         val nativeTest by getting
     }