Getting method parameter names (#210)

jacodb-core/src/main/kotlin/org/jacodb/impl/fs/ByteCodeConverter.kt

@@ -114,7 +114,7 @@ private fun MethodNode.asMethodInfo(): MethodInfo {
         parametersInfo = List(params.size) { index ->
             ParameterInfo(
                 index = index,
-                name = parameters?.get(index)?.name,
+                name = argumentName(index),
                 access = parameters?.get(index)?.access ?: Opcodes.ACC_PUBLIC,
                 type = params[index],
                 annotations = visibleParameterAnnotations?.get(index)?.asAnnotationInfos(true).orEmpty()
@@ -124,6 +124,17 @@ private fun MethodNode.asMethodInfo(): MethodInfo {
     )
 }
 
+private fun MethodNode.argumentName(argIndex :Int): String? {
+    localVariables?.let {
+        (argIndex + 1 - (access and Opcodes.ACC_STATIC).countOneBits()).run {
+            if (it.size > this) {
+                return ArrayList(it).sortedBy(LocalVariableNode::index)[this].name
+            }
+        }
+    }
+    return parameters?.get(argIndex)?.name
+}
+
 private fun FieldNode.asFieldInfo() = FieldInfo(
     name = name,
     signature = signature,

jacodb-core/src/test/kotlin/org/jacodb/testing/ParameterNamesTest.kt

@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2022 UnitTestBot contributors (utbot.org)
+ * <p>
+ *  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
+ * <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ *  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.jacodb.testing
+
+import kotlinx.coroutines.runBlocking
+import org.jacodb.api.JcMethod
+import org.jacodb.api.JcParameter
+import org.jacodb.api.ext.findClass
+import org.jacodb.api.ext.methods
+import org.jacodb.impl.fs.asClassInfo
+import org.jacodb.impl.types.ParameterInfo
+import org.junit.jupiter.api.Assertions
+import org.junit.jupiter.api.Test
+import java.nio.file.Files
+
+class ParameterNamesTest : BaseTest() {
+    companion object : WithDB()
+
+    private val target = Files.createTempDirectory("jcdb-temp")
+
+    @Test
+    fun checkParameterName() {
+        val clazz = cp.findClass("GenericsApi")
+        runBlocking {
+            cp.db.load(target.toFile())
+        }
+        val method = clazz.methods.firstOrNull { jcMethod -> jcMethod.name == "call" }
+        Assertions.assertNotNull(method)
+        Assertions.assertNull(method?.parameters?.get(0)?.name)
+        Assertions.assertEquals("arg", method?.parameterNames?.get(0))
+    }
+
+    private val JcMethod.parameterNames: List<String?>
+        get() {
+            return enclosingClass.asmNode()
+                .asClassInfo(enclosingClass.bytecode()).methods.find { info -> info.name == name && info.desc == description }
+                ?.parametersInfo?.map(ParameterInfo::name)
+                ?: parameters.map(JcParameter::name)
+        }
+}