Refactor FilterPath parse function (opensearch-project#12067)

Signed-off-by: Robin Friedmann <robinfriedmann.rf@gmail.com>
robinf95 · Feb 1, 2024 · 5abffd7 · 5abffd7
1 parent 2f8d267
commit 5abffd7
Showing 1 changed file with 12 additions and 17 deletions.
diff --git a/libs/core/src/main/java/org/opensearch/core/xcontent/filtering/FilterPath.java b/libs/core/src/main/java/org/opensearch/core/xcontent/filtering/FilterPath.java
@@ -58,7 +58,8 @@ protected FilterPath(String filter, String segment, FilterPath next) {
         this.segment = segment;
         this.next = next;
         this.simpleWildcard = (segment != null) && (segment.length() == 1) && (segment.charAt(0) == '*');
-        this.doubleWildcard = (segment != null) && (segment.length() == 2) && (segment.charAt(0) == '*') && (segment.charAt(1) == '*');
+        this.doubleWildcard =
+            (segment != null) && (segment.length() == 2) && (segment.charAt(0) == '*') && (segment.charAt(1) == '*');
     }
 
     private FilterPath() {
@@ -99,32 +100,26 @@ public static FilterPath[] compile(Set<String> filters) {
 
         List<FilterPath> paths = new ArrayList<>();
         for (String filter : filters) {
-            if (filter != null) {
+            if (filter != null && !filter.isEmpty()) {
                 filter = filter.trim();
                 if (filter.length() > 0) {
-                    paths.add(parse(filter, filter));
+                    paths.add(parse(filter));
                 }
             }
         }
         return paths.toArray(new FilterPath[0]);
     }
 
-    private static FilterPath parse(final String filter, final String segment) {
-        int end = segment.length();
+    private static FilterPath parse(final String filter) {
+        String[] segments = filter.split("(?<!\\\\)\\.");
+        FilterPath next = EMPTY;
 
-        for (int i = 0; i < end;) {
-            char c = segment.charAt(i);
-
-            if (c == '.') {
-                String current = segment.substring(0, i).replaceAll("\\\\.", ".");
-                return new FilterPath(filter, current, parse(filter, segment.substring(i + 1)));
-            }
-            ++i;
-            if ((c == '\\') && (i < end) && (segment.charAt(i) == '.')) {
-                ++i;
-            }
+        for (int i = segments.length - 1; i >= 0; i--) {
+            String segment = segments[i].replaceAll("\\\\.", ".");
+            next = new FilterPath(filter, segment, next);
         }
-        return new FilterPath(filter, segment.replaceAll("\\\\.", "."), EMPTY);
+
+        return next;
     }
 
     @Override