Ruby: Add RegExpAnchor to RegExpTreeView

Author: hmac

ruby/ql/lib/codeql/ruby/regexp/RegExpTreeView.qll

@@ -860,6 +860,21 @@ class RegExpDot extends RegExpSpecialChar {
   override string getAPrimaryQlClass() { result = "RegExpDot" }
 }
 
+/**
+ * A term that matches a specific position between characters in the string.
+ *
+ * Example:
+ *
+ * ```
+ * \A
+ * ```
+ */
+class RegExpAnchor extends RegExpSpecialChar {
+  RegExpAnchor() { this.getChar() = ["^", "$", "\\A", "\\Z", "\\z"] }
+
+  override string getAPrimaryQlClass() { result = "RegExpAnchor" }
+}
+
 /**
  * A dollar assertion `$` or `\Z` matching the end of a line.
  *
@@ -869,7 +884,7 @@ class RegExpDot extends RegExpSpecialChar {
  * $
  * ```
  */
-class RegExpDollar extends RegExpSpecialChar {
+class RegExpDollar extends RegExpAnchor {
   RegExpDollar() { this.getChar() = ["$", "\\Z", "\\z"] }
 
   override string getAPrimaryQlClass() { result = "RegExpDollar" }
@@ -884,7 +899,7 @@ class RegExpDollar extends RegExpSpecialChar {
  * ^
  * ```
  */
-class RegExpCaret extends RegExpSpecialChar {
+class RegExpCaret extends RegExpAnchor {
   RegExpCaret() { this.getChar() = ["^", "\\A"] }
 
   override string getAPrimaryQlClass() { result = "RegExpCaret" }