Add RegExpIntersection class to support intersection terms in regex

Author: Napalys

javascript/ql/lib/semmle/javascript/MembershipCandidates.qll

@@ -146,6 +146,7 @@ module MembershipCandidate {
         child instanceof RegExpDollar or
         child instanceof RegExpConstant or
         child instanceof RegExpAlt or
+        child instanceof RegExpIntersection or
         child instanceof RegExpGroup
       ) and
       // exclude "length matches" that match every string

javascript/ql/lib/semmle/javascript/Regexp.qll

@@ -301,6 +301,29 @@ class RegExpAlt extends RegExpTerm, @regexp_alt {
   override string getAPrimaryQlClass() { result = "RegExpAlt" }
 }
 
+/**
+ * An intersection term, that is, a term of the form `a&&b`.
+ *
+ * Example:
+ *
+ * ```
+ * /\p{Script_Extensions=Greek}&&\p{Letter}/v
+ * ```
+ */
+class RegExpIntersection extends RegExpTerm, @regexp_intersection {
+  /** Gets an intersected term of this term. */
+  RegExpTerm getIntersectedTerm() { result = this.getAChild() }
+
+  /** Gets the number of intersected terms of this term. */
+  int getNumIntersectedTerm() { result = this.getNumChild() }
+
+  override predicate isNullable() { this.getIntersectedTerm().isNullable() }
+
+  override string getAMatchedString() { result = this.getIntersectedTerm().getAMatchedString() }
+
+  override string getAPrimaryQlClass() { result = "RegExpIntersection" }
+}
+
 /**
  * A sequence term.
  *

javascript/ql/test/library-tests/RegExp/RegExpIntersection/printAst.expected

@@ -3,7 +3,7 @@ nodes
 | intersection.js:1:1:1:17 | [ExprStmt] /[[abc]&&[bcd]]/v | semmle.order | 1 |
 | intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | semmle.label | [RegExpLiteral] /[[abc]&&[bcd]]/v |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | semmle.label | [RegExpCharacterClass] [[abc] |
-| intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | semmle.label | [???] [[abc]&&[bcd]] |
+| intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | semmle.label | [RegExpIntersection] [[abc]&&[bcd]] |
 | intersection.js:1:3:1:3 | [RegExpNormalConstant] [ | semmle.label | [RegExpNormalConstant] [ |
 | intersection.js:1:4:1:4 | [RegExpNormalConstant] a | semmle.label | [RegExpNormalConstant] a |
 | intersection.js:1:5:1:5 | [RegExpNormalConstant] b | semmle.label | [RegExpNormalConstant] b |
@@ -17,8 +17,8 @@ nodes
 edges
 | intersection.js:1:1:1:17 | [ExprStmt] /[[abc]&&[bcd]]/v | intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | semmle.label | 1 |
 | intersection.js:1:1:1:17 | [ExprStmt] /[[abc]&&[bcd]]/v | intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | semmle.order | 1 |
-| intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | semmle.label | 0 |
-| intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | semmle.order | 0 |
+| intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | semmle.label | 0 |
+| intersection.js:1:1:1:17 | [RegExpLiteral] /[[abc]&&[bcd]]/v | intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | semmle.order | 0 |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:3:1:3 | [RegExpNormalConstant] [ | semmle.label | 0 |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:3:1:3 | [RegExpNormalConstant] [ | semmle.order | 0 |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:4:1:4 | [RegExpNormalConstant] a | semmle.label | 1 |
@@ -27,10 +27,10 @@ edges
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:5:1:5 | [RegExpNormalConstant] b | semmle.order | 2 |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:6:1:6 | [RegExpNormalConstant] c | semmle.label | 3 |
 | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | intersection.js:1:6:1:6 | [RegExpNormalConstant] c | semmle.order | 3 |
-| intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | semmle.label | 0 |
-| intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | semmle.order | 0 |
-| intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | intersection.js:1:10:1:15 | [RegExpSequence] [bcd]] | semmle.label | 1 |
-| intersection.js:1:2:1:15 | [???] [[abc]&&[bcd]] | intersection.js:1:10:1:15 | [RegExpSequence] [bcd]] | semmle.order | 1 |
+| intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | semmle.label | 0 |
+| intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | intersection.js:1:2:1:7 | [RegExpCharacterClass] [[abc] | semmle.order | 0 |
+| intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | intersection.js:1:10:1:15 | [RegExpSequence] [bcd]] | semmle.label | 1 |
+| intersection.js:1:2:1:15 | [RegExpIntersection] [[abc]&&[bcd]] | intersection.js:1:10:1:15 | [RegExpSequence] [bcd]] | semmle.order | 1 |
 | intersection.js:1:10:1:14 | [RegExpCharacterClass] [bcd] | intersection.js:1:11:1:11 | [RegExpNormalConstant] b | semmle.label | 0 |
 | intersection.js:1:10:1:14 | [RegExpCharacterClass] [bcd] | intersection.js:1:11:1:11 | [RegExpNormalConstant] b | semmle.order | 0 |
 | intersection.js:1:10:1:14 | [RegExpCharacterClass] [bcd] | intersection.js:1:12:1:12 | [RegExpNormalConstant] c | semmle.label | 1 |