Added more basic interfaces

This PR adds more basic interfaces

cpg-analysis/src/main/kotlin/de/fraunhofer/aisec/cpg/analysis/ValueEvaluator.kt

@@ -180,7 +180,7 @@ open class ValueEvaluator(
             "<=" -> handleLEq(lhsValue, rhsValue, expr)
             "==" -> handleEq(lhsValue, rhsValue, expr)
             "!=" -> handleNEq(lhsValue, rhsValue, expr)
-            else -> cannotEvaluate(expr as Node, this)
+            else -> cannotEvaluate(expr, this)
         }
     }
 

cpg-analysis/src/test/kotlin/de/fraunhofer/aisec/cpg/query/QueryTest.kt

@@ -598,7 +598,7 @@ class QueryTest {
                     result
                         .all<FunctionDeclaration>(
                             { it.name.localName == "print" },
-                            { n2 -> dataFlow(n1 as Node, n2.parameters[0]).value }
+                            { n2 -> dataFlow(n1, n2.parameters[0]).value }
                         )
                         .first
                 }
@@ -613,7 +613,7 @@ class QueryTest {
                 { n1 ->
                     result.allExtended<FunctionDeclaration>(
                         { it.name.localName == "print" },
-                        { n2 -> dataFlow(n1 as Node, n2.parameters[0]) }
+                        { n2 -> dataFlow(n1, n2.parameters[0]) }
                     )
                 }
             )

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Interfaces.kt

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2021, Fraunhofer AISEC. All rights reserved.
+ *
+ * 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 de.fraunhofer.aisec.cpg.graph
+
+import de.fraunhofer.aisec.cpg.frontends.Language
+import de.fraunhofer.aisec.cpg.graph.scopes.Scope
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.*
+import de.fraunhofer.aisec.cpg.graph.types.HasType
+import de.fraunhofer.aisec.cpg.graph.types.Type
+import de.fraunhofer.aisec.cpg.sarif.PhysicalLocation
+
+/** Specifies that a certain node has a base on which it executes an operation. */
+interface HasBase : HasOperatorCode {
+
+    /** The base. If there is no actual base, it can be null. */
+    val base: Expression?
+
+    /**
+     * The operator that is used to access the [base]. Usually either `.` or `->`, but some
+     * languages offer additional operator codes. If the [base] is null, the [operatorCode] should
+     * also be null.
+     */
+    override val operatorCode: String?
+}
+
+/** A simple interface to denote that the implementing class has some kind of [operatorCode]. */
+interface HasOperatorCode {
+
+    /** The operator code, identifying an operation executed on one or more [Expression]s */
+    val operatorCode: String?
+}
+
+/**
+ * Interface that allows us to mark nodes that contain a default value
+ *
+ * @param <T> type of the default node </T>
+ */
+interface HasDefault<T : Node?> {
+    var default: T
+}
+
+/**
+ * Specifies that a certain node has an initializer. It is a special case of [ArgumentHolder], in
+ * which the initializer is treated as the first (and only) argument.
+ */
+interface HasInitializer : HasType, ArgumentHolder, AssignmentHolder {
+
+    var initializer: Expression?
+
+    override fun addArgument(expression: Expression) {
+        this.initializer = expression
+    }
+
+    override fun removeArgument(expression: Expression): Boolean {
+        return if (this.initializer == expression) {
+            this.initializer = null
+            true
+        } else {
+            false
+        }
+    }
+
+    override fun replaceArgument(old: Expression, new: Expression): Boolean {
+        this.initializer = new
+        return true
+    }
+
+    override val assignments: List<Assignment>
+        get() {
+            return initializer?.let { listOf(Assignment(it, this, this)) } ?: listOf()
+        }
+}
+
+/**
+ * Some nodes have aliases, i.e., it potentially references another variable. This means that
+ * writing to this node, also writes to its [aliases] and vice-versa.
+ */
+interface HasAliases {
+    /** The aliases which this node has. */
+    var aliases: MutableSet<HasAliases>
+}
+
+/** A simple interface that a node has [language]. */
+interface HasLanguage {
+
+    var language: Language<*>?
+}
+
+/** A simple interface that a node has [name] and [location]. */
+interface HasNameAndLocation {
+
+    val name: Name
+
+    val location: PhysicalLocation?
+}
+
+/** A simple interface that a node has [scope]. */
+interface HasScope {
+
+    /** The scope this node lives in. */
+    val scope: Scope?
+}
+
+/**
+ * This interface can be used to describe something similar to a "call", in a way that this node
+ * implements [HasBase], although [HasBase.base] is nullable and therefore optional and the node has
+ * some kind of [arguments]. The most prominent implementer of this interface is a [CallExpression],
+ * but other nodes might implement this as well, if suitable.
+ */
+interface HasArgumentsAndOptionalBase : HasLanguage, HasBase, HasNameAndLocation, HasScope {
+
+    /** A list of argument expressions. */
+    val arguments: List<Expression>
+
+    /** A type signature, built out of the [arguments]. */
+    val signature: List<Type>
+        get() = arguments.map(Expression::type)
+}

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Node.kt

@@ -52,7 +52,14 @@ import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
 /** The base class for all graph objects that are going to be persisted in the database. */
-open class Node : IVisitable<Node>, Persistable, LanguageProvider, ScopeProvider, ContextProvider {
+open class Node :
+    IVisitable<Node>,
+    Persistable,
+    LanguageProvider,
+    ScopeProvider,
+    ContextProvider,
+    HasNameAndLocation,
+    HasScope {
     /**
      * Because we are updating type information in the properties of the node, we need a reference
      * to managers such as the [TypeManager] instance which is responsible for this particular node.
@@ -61,11 +68,8 @@ open class Node : IVisitable<Node>, Persistable, LanguageProvider, ScopeProvider
      */
     @get:JsonIgnore @Transient override var ctx: TranslationContext? = null
 
-    /**
-     * This property holds the full name using our new [Name] class. It is currently not persisted
-     * in the graph database.
-     */
-    @Convert(NameConverter::class) open var name: Name = Name(EMPTY_NAME)
+    /** This property holds the full name using our new [Name] class. */
+    @Convert(NameConverter::class) override var name: Name = Name(EMPTY_NAME)
 
     /**
      * Original code snippet of this node. Most nodes will have a corresponding "code", but in cases
@@ -98,7 +102,7 @@ open class Node : IVisitable<Node>, Persistable, LanguageProvider, ScopeProvider
     var comment: String? = null
 
     /** Location of the finding in source code. */
-    @Convert(LocationConverter::class) var location: PhysicalLocation? = null
+    @Convert(LocationConverter::class) override var location: PhysicalLocation? = null
 
     /**
      * Name of the containing file. It can be null for artificially created nodes or if just