Unify module loading for js and wasmJs

Author: fzhinkin

core/js/src/node/nodeModulesJs.kt

@@ -5,6 +5,8 @@
 
 package kotlinx.io.node
 
+import kotlinx.io.withCaughtException
+
 internal external interface BufferModule {
     val Buffer: BufferObj
 }
@@ -22,4 +24,8 @@ internal external interface Buffer {
     fun writeInt8(value: Byte, offset: Int)
 }
 
-internal expect val buffer: BufferModule
+internal val buffer: BufferModule by lazy {
+    loadModule("buffer", ::bufferInitializer)
+}
+
+private fun bufferInitializer(): BufferModule? = js("eval('require')('buffer')")

core/nodeFilesystemShared/src/node/buffer.kt

@@ -86,4 +86,8 @@ internal external interface realpathSync {
     fun native(path: String): String
 }
 
-internal expect val fs: Fs
+internal val fs: Fs by lazy {
+    loadModule("fs", ::fsInitializer)
+}
+
+private fun fsInitializer(): Fs? = js("eval('require')('fs')")

core/nodeFilesystemShared/src/node/fs.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language 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.io.node
+
+import kotlinx.io.withCaughtException
+
+internal fun <T> loadModule(name: String, initializer: () -> T?): T {
+    var mod: T? = null
+    val ex = withCaughtException {
+        mod = initializer()
+    }
+    if (mod == null) {
+        throw UnsupportedOperationException("Module '$name' could not be loaded", ex)
+    }
+    return mod!!
+}

core/nodeFilesystemShared/src/node/modLoader.kt

@@ -18,4 +18,8 @@ internal external interface Os {
     fun platform(): String
 }
 
-internal expect val os: Os
+internal val os: Os by lazy {
+    loadModule("os", ::osInitializer)
+}
+
+private fun osInitializer(): Os? = js("eval('require')('os')")

core/nodeFilesystemShared/src/node/os.kt

@@ -14,4 +14,8 @@ internal external interface Path {
     val sep: String
 }
 
-internal expect val path: Path
+internal val path: Path by lazy {
+    loadModule("path", ::pathInitializer)
+}
+
+private fun pathInitializer(): Path? = js("eval('require')('path')")