while loop support, and native functions (including ffi!)

ffi/build.gradle.kts

@@ -0,0 +1,10 @@
+plugins {
+  id("gay.pizza.pork.module")
+}
+
+dependencies {
+  api(project(":evaluator"))
+
+  implementation(project(":common"))
+  implementation("net.java.dev.jna:jna:5.13.0")
+}

ffi/src/main/kotlin/gay/pizza/pork/ffi/JnaNativeProvider.kt

@@ -0,0 +1,26 @@
+package gay.pizza.pork.ffi
+
+import com.sun.jna.Function
+import gay.pizza.pork.evaluator.CallableFunction
+import gay.pizza.pork.evaluator.NativeFunctionProvider
+
+class JnaNativeProvider : NativeFunctionProvider {
+  override fun provideNativeFunction(definition: String): CallableFunction {
+    val (libraryName, functionSymbol, returnType, _) =
+      definition.split(":", limit = 3)
+    val function = Function.getFunction(libraryName, functionSymbol)
+    return CallableFunction {
+      return@CallableFunction invoke(function, it.values.toTypedArray(), returnType)
+    }
+  }
+
+  private fun invoke(function: Function, values: Array<Any>, type: String): Any = when (type) {
+    "void*" -> function.invokePointer(values)
+    "int" -> function.invokeInt(values)
+    "long" -> function.invokeLong(values)
+    "float" -> function.invokeFloat(values)
+    "double" -> function.invokeDouble(values)
+    "void" -> function.invokeVoid(values)
+    else -> throw RuntimeException("Unsupported ffi return type: $type")
+  }
+}