[GitHub] [nifi] kevdoran commented on a change in pull request #5458: NIFI-7865 amqp$header is splitted in the wrong way for "," and "}"

[GitBox <gi...@apache.org>]

kevdoran commented on a change in pull request #5458:
URL: https://github.com/apache/nifi/pull/5458#discussion_r737576297



##########
File path: nifi-commons/nifi-properties/src/main/java/org/apache/nifi/util/StringUtils.java
##########
@@ -510,4 +514,27 @@ public static String toTitleCase(String input) {
                 .map(word -> Character.toTitleCase(word.charAt(0)) + word.substring(1))
                 .collect(Collectors.joining(" "));
     }
+
+    /**
+     * Escape {@code str} by replacing occurrences of {@code charToEscape} with {@code escapeChar+charToEscape}
+     * @param str the input string
+     * @param escapeChar the character used for escaping
+     * @param charToEscape the character that needs to be escaped
+     * @return the escaped string
+     */
+    public static String escapeString(String str, char escapeChar, char charToEscape) {
+        if (str == null || str.isEmpty()) {
+            return null;
+        }
+        StringBuilder result = new StringBuilder();
+        for (int i=0; i<str.length(); i++) {
+            char curChar = str.charAt(i);
+            if (curChar == escapeChar || curChar == charToEscape) {
+                // special char
+                result.append(escapeChar);
+            }
+            result.append(curChar);

Review comment:
       Minor, but it would be nice if this utility method were idempotent, meaning that if I pass it a string that contains some already escaped characters, it has not effect on those, in order words, all of these invocations would return the same result:
   
   ```
   StringUtils.escapeString("key=(value0,value1,value2)", '\\', ',');
   StringUtils.escapeString("key=(value0\\,value1,value2)", '\\', ',');
   StringUtils.escapeString("key=(value0\\,value1\\,value2)", '\\', ',');
   ```
   




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