JS: Add ClassDefinition.getInferredName

javascript/ql/src/semmle/javascript/Classes.qll

@@ -17,6 +17,16 @@ class ClassOrInterface extends @classorinterface, TypeParameterized {
   /** Gets the name of the defined class or interface, if any. */
   string getName() { result = getIdentifier().getName() }
 
+  /**
+   * Gets the name of the defined class or interface, possibly inferred
+   * from the context if this is an anonymous class expression.
+   *
+   * Has no result if no name could be determined.
+   */
+  string getInferredName() {
+    result = getName() // Overridden in ClassExpr
+  }
+
   /** Gets the nearest enclosing function or toplevel in which this class or interface occurs. */
   StmtContainer getContainer() { result = this.(ExprOrStmt).getContainer() }
 
@@ -210,6 +220,25 @@ class ClassDeclStmt extends @classdeclstmt, ClassDefinition, Stmt {
  * A class expression.
  */
 class ClassExpr extends @classexpr, ClassDefinition, Expr {
+  override string getInferredName() {
+    result = getName()
+    or
+    exists(VarDef vd | this = vd.getSource() |
+      result = vd.getTarget().(VarRef).getName()
+    )
+    or
+    exists(Property p |
+      this = p.getInit() and
+      result = p.getName()
+    )
+    or
+    exists(AssignExpr assign, DotExpr prop |
+      this = assign.getRhs().getUnderlyingValue() and
+      prop = assign.getLhs() and
+      result = prop.getPropertyName()
+    )
+  }
+
   override predicate isImpure() { none() }
 
   /** Gets the nearest enclosing function or toplevel in which this class expression occurs. */

javascript/ql/test/library-tests/ppNames/ppClassName.expected

@@ -1,5 +1,14 @@
+getInferredName
+| tst.js:16:1:19:1 | class C ... ss C"\\n} | C |
+| tst.js:21:2:23:1 | class D ... lass"\\n} | D |
+| tst.js:22:12:22:18 | class{} |  |
+| tst.js:25:11:25:18 | class {} | E |
+| tst.js:26:11:29:1 | class G ... ss G"\\n} | G |
+| tst.js:34:9:34:16 | class {} | Foo |
+#select
 | tst.js:16:1:19:1 | class C ... ss C"\\n} | class C |
 | tst.js:21:2:23:1 | class D ... lass"\\n} | class D |
 | tst.js:22:12:22:18 | class{} | anonymous class |
 | tst.js:25:11:25:18 | class {} | class E |
 | tst.js:26:11:29:1 | class G ... ss G"\\n} | class G |
+| tst.js:34:9:34:16 | class {} | class Foo |

javascript/ql/test/library-tests/ppNames/ppClassName.ql

@@ -1,4 +1,8 @@
 import javascript
 
+query string getInferredName(ClassDefinition c) {
+  result = c.getInferredName()
+}
+
 from ClassDefinition c
 select c, c.describe()

javascript/ql/test/library-tests/ppNames/ppFnName.expected

@@ -18,6 +18,7 @@ getInferredName
 | tst.js:27:8:27:12 | () {} | y |
 | tst.js:28:8:28:13 | (v) {} | y |
 | tst.js:31:9:31:21 | function() {} | foo |
+| tst.js:34:15:34:14 | () {} | constructor |
 #select
 | tst.js:1:1:1:15 | function f() {} | function f |
 | tst.js:2:2:2:16 | function g() {} | function g |
@@ -40,3 +41,4 @@ getInferredName
 | tst.js:28:8:28:13 | (v) {} | setter method for property y of class G |
 | tst.js:31:9:31:21 | function() {} | method foo |
 | tst.js:32:12:32:24 | function() {} | anonymous function |
+| tst.js:34:15:34:14 | () {} | default constructor of class Foo |

javascript/ql/test/library-tests/ppNames/tst.js

@@ -30,3 +30,5 @@ const E = class {},       // "class E", "default constructor of class E"
 
 o.foo = function() {};    // "method foo"
 o["Hey"] = function() {}; // "anonymous function"
+
+o.Foo = class {};         // "class Foo"