JS: Add UnionOrIntersectionTypeExpr

Author: asgerf

javascript/ql/lib/semmle/javascript/TypeScript.qll

@@ -896,21 +896,28 @@ class ArrayTypeExpr extends @array_typeexpr, TypeExpr {
   override string getAPrimaryQlClass() { result = "ArrayTypeExpr" }
 }
 
+private class RawUnionOrIntersectionTypeExpr = @union_typeexpr or @intersection_typeexpr;
+
 /**
- * A union type, such as `string|number|boolean`.
+ * A union or intersection type, such as `string|number|boolean` or `A & B`.
  */
-class UnionTypeExpr extends @union_typeexpr, TypeExpr {
-  /** Gets the `n`th type in the union, starting at 0. */
+class UnionOrIntersectionTypeExpr extends RawUnionOrIntersectionTypeExpr, TypeExpr {
+  /** Gets the `n`th type in the union or intersection, starting at 0. */
   TypeExpr getElementType(int n) { result = this.getChildTypeExpr(n) }
 
-  /** Gets any of the types in the union. */
+  /** Gets any of the types in the union or intersection. */
   TypeExpr getAnElementType() { result = this.getElementType(_) }
 
-  /** Gets the number of types in the union. This is always at least two. */
+  /** Gets the number of types in the union or intersection. This is always at least two. */
   int getNumElementType() { result = count(this.getAnElementType()) }
 
   override TypeExpr getAnUnderlyingType() { result = this.getAnElementType().getAnUnderlyingType() }
+}
 
+/**
+ * A union type, such as `string|number|boolean`.
+ */
+class UnionTypeExpr extends @union_typeexpr, UnionOrIntersectionTypeExpr {
   override string getAPrimaryQlClass() { result = "UnionTypeExpr" }
 }
 
@@ -932,18 +939,7 @@ class IndexedAccessTypeExpr extends @indexed_access_typeexpr, TypeExpr {
  *
  * In general, there are can more than two operands to an intersection type.
  */
-class IntersectionTypeExpr extends @intersection_typeexpr, TypeExpr {
-  /** Gets the `n`th operand of the intersection type, starting at 0. */
-  TypeExpr getElementType(int n) { result = this.getChildTypeExpr(n) }
-
-  /** Gets any of the operands to the intersection type. */
-  TypeExpr getAnElementType() { result = this.getElementType(_) }
-
-  /** Gets the number of operands to the intersection type. This is always at least two. */
-  int getNumElementType() { result = count(this.getAnElementType()) }
-
-  override TypeExpr getAnUnderlyingType() { result = this.getAnElementType().getAnUnderlyingType() }
-
+class IntersectionTypeExpr extends @intersection_typeexpr, UnionOrIntersectionTypeExpr {
   override string getAPrimaryQlClass() { result = "IntersectionTypeExpr" }
 }