Introduce fictitious numbered Function class descriptors

generators/src/org/jetbrains/kotlin/generators/builtins/functionImpl.kt

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.generators.builtins.functionImpl
+
+import org.jetbrains.kotlin.generators.builtins.functions.MAX_PARAM_COUNT
+import org.jetbrains.kotlin.generators.builtins.generateBuiltIns.BuiltInsSourceGenerator
+import org.jetbrains.kotlin.generators.builtins.generateBuiltIns.BuiltInsSourceGenerator.Language
+import java.io.PrintWriter
+
+class GenerateFunctionImpl(out: PrintWriter) : BuiltInsSourceGenerator(out) {
+    override fun getPackage() = "kotlin.jvm.internal"
+
+    override val language = Language.JAVA
+
+    override fun generateBody() {
+        val n = MAX_PARAM_COUNT
+
+        out.print("""import kotlin.Function;
+import kotlin.jvm.functions.*;
+
+import java.io.Serializable;
+
+public abstract class FunctionImpl
+        implements Function, Serializable,""")
+
+        for (i in 0..n) {
+            if (i % 10 == 0) {
+                // Insert newline sometimes to avoid very long lines
+                out.println()
+                out.print("                   ")
+            }
+            out.print("Function$i")
+            if (i < n) out.print(", ")
+        }
+
+        out.println(" {")
+
+        out.println("""
+    public abstract int getArity();
+
+    public Object invokeVararg(Object... p) {
+        throw new UnsupportedOperationException();
+    }
+
+    private void checkArity(int expected) {
+        if (getArity() != expected) {
+            throwWrongArity(expected);
+        }
+    }
+
+    private void throwWrongArity(int expected) {
+        throw new IllegalStateException("Wrong function arity, expected: " + expected + ", actual: " + getArity());
+    }""")
+
+        for (i in 0..n) {
+            out.println()
+            out.println("    @Override")
+            out.println("    public Object invoke(" + (1..i).joinToString { "Object p$it" } + ") {")
+            out.println("        checkArity($i);")
+            out.println("        return invokeVararg(" + (1..i).joinToString { "p$it" } + ");")
+            out.println("    }")
+        }
+
+        out.println("}")
+    }
+}

generators/src/org/jetbrains/kotlin/generators/builtins/generateBuiltIns.kt

@@ -18,6 +18,7 @@ package org.jetbrains.kotlin.generators.builtins.generateBuiltIns
 
 import org.jetbrains.kotlin.generators.builtins.arrayIterators.GenerateArrayIterators
 import org.jetbrains.kotlin.generators.builtins.arrays.GenerateArrays
+import org.jetbrains.kotlin.generators.builtins.functionImpl.GenerateFunctionImpl
 import org.jetbrains.kotlin.generators.builtins.functions.FunctionKind
 import org.jetbrains.kotlin.generators.builtins.functions.GenerateFunctions
 import org.jetbrains.kotlin.generators.builtins.iterators.GenerateIterators
@@ -40,13 +41,21 @@ abstract class BuiltInsSourceGenerator(val out: PrintWriter) {
 
     protected open fun getPackage(): String = "kotlin"
 
+    protected open val language: Language = Language.KOTLIN
+
+    enum class Language {
+        KOTLIN
+        JAVA
+    }
+
     final fun generate() {
         out.println(File("license/LICENSE.txt").readText())
         // Don't include generator class name in the message: these are built-in sources,
         // and we don't want to scare users with any internal information about our project
         out.println("// Auto-generated file. DO NOT EDIT!")
         out.println()
-        out.println("package ${getPackage()}")
+        out.print("package ${getPackage()}")
+        if (language == Language.KOTLIN) out.println() else out.println(";")
         out.println()
 
         generateBody()
@@ -63,6 +72,7 @@ fun generateBuiltIns(generate: (File, (PrintWriter) -> BuiltInsSourceGenerator)
         generate(File(dir, kind.fileName)) { GenerateFunctions(it, kind) }
     }
 
+    generate(File(RUNTIME_JVM_DIR, "kotlin/jvm/internal/FunctionImpl.java")) { GenerateFunctionImpl(it) }
     generate(File(BUILT_INS_NATIVE_DIR, "kotlin/Arrays.kt")) { GenerateArrays(it) }
     generate(File(BUILT_INS_NATIVE_DIR, "kotlin/Primitives.kt")) { GeneratePrimitives(it) }
     generate(File(BUILT_INS_SRC_DIR, "kotlin/Iterators.kt")) { GenerateIterators(it) }