Java/Ruby: Replace recursive algorithm string builders

java/ql/lib/semmle/code/java/security/Encryption.qll

@@ -271,19 +271,15 @@ string getASecureAlgorithmName() {
 
 private string rankedSecureAlgorithm(int i) { result = rank[i](getASecureAlgorithmName()) }
 
-private string secureAlgorithmString(int i) {
-  i = 1 and result = rankedSecureAlgorithm(i)
-  or
-  result = rankedSecureAlgorithm(i) + "|" + secureAlgorithmString(i - 1)
+private string secureAlgorithmString() {
+  result = concat(int i | | rankedSecureAlgorithm(i), "|" order by i desc)
 }
 
 /**
  * Gets a regular expression for matching strings that look like they
  * contain an algorithm that is known to be secure.
  */
-string getSecureAlgorithmRegex() {
-  result = algorithmRegex(secureAlgorithmString(max(int i | exists(rankedSecureAlgorithm(i)))))
-}
+string getSecureAlgorithmRegex() { result = algorithmRegex(secureAlgorithmString()) }
 
 /**
  * Any use of a cryptographic element that specifies an encryption

java/ql/src/experimental/quantum/Examples/BrokenCrypto.ql

@@ -34,19 +34,15 @@ private string rankedInsecureAlgorithm(int i) {
   result = rank[i](string s | s = getAnInsecureAlgorithmName())
 }
 
-private string insecureAlgorithmString(int i) {
-  i = 1 and result = rankedInsecureAlgorithm(i)
-  or
-  result = rankedInsecureAlgorithm(i) + "|" + insecureAlgorithmString(i - 1)
+private string insecureAlgorithmString() {
+  result = concat(int i | | rankedInsecureAlgorithm(i), "|" order by i desc)
 }
 
 /**
  * Gets the regular expression used for matching strings that look like they
  * contain an algorithm that is known to be insecure.
  */
-string getInsecureAlgorithmRegex() {
-  result = algorithmRegex(insecureAlgorithmString(max(int i | exists(rankedInsecureAlgorithm(i)))))
-}
+string getInsecureAlgorithmRegex() { result = algorithmRegex(insecureAlgorithmString()) }
 
 bindingset[algorithmString]
 private string algorithmRegex(string algorithmString) {

ruby/ql/lib/codeql/ruby/security/OpenSSL.qll

@@ -35,37 +35,29 @@ private string rankedInsecureAlgorithm(int i) {
     )
 }
 
-private string insecureAlgorithmString(int i) {
-  i = 1 and result = rankedInsecureAlgorithm(i)
-  or
-  result = rankedInsecureAlgorithm(i) + "|" + insecureAlgorithmString(i - 1)
+private string insecureAlgorithmString() {
+  result = concat(int i | | rankedInsecureAlgorithm(i), "|" order by i desc)
 }
 
 /**
  * Gets the regular expression used for matching strings that look like they
  * contain an algorithm that is known to be insecure.
  */
-private string getInsecureAlgorithmRegex() {
-  result = algorithmRegex(insecureAlgorithmString(max(int i | exists(rankedInsecureAlgorithm(i)))))
-}
+private string getInsecureAlgorithmRegex() { result = algorithmRegex(insecureAlgorithmString()) }
 
 private string rankedSecureAlgorithm(int i) {
   result = rank[i](string s | isStrongEncryptionAlgorithm(s))
 }
 
-private string secureAlgorithmString(int i) {
-  i = 1 and result = rankedSecureAlgorithm(i)
-  or
-  result = rankedSecureAlgorithm(i) + "|" + secureAlgorithmString(i - 1)
+private string secureAlgorithmString() {
+  result = concat(int i | | rankedSecureAlgorithm(i), "|" order by i desc)
 }
 
 /**
  * Gets a regular expression for matching strings that look like they
  * contain an algorithm that is known to be secure.
  */
-string getSecureAlgorithmRegex() {
-  result = algorithmRegex(secureAlgorithmString(max(int i | exists(rankedSecureAlgorithm(i)))))
-}
+string getSecureAlgorithmRegex() { result = algorithmRegex(secureAlgorithmString()) }
 
 /**
  * Names of known ciphers supported by the Ruby `OpenSSL` library, and