Refactored Glob.globMatch by using iterative approach; added unit tes…

…ts (#12065) Signed-off-by: Robin Friedmann <[email protected]>
opensearch-project · Feb 7, 2024 · fa59c6c · fa59c6c
1 parent 758a388
commit fa59c6c
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Showing 2 changed files with 57 additions and 30 deletions.
diff --git a/libs/common/src/main/java/org/opensearch/common/Glob.java b/libs/common/src/main/java/org/opensearch/common/Glob.java
@@ -39,47 +39,50 @@
  */
 public class Glob {
 
+    private Glob() {}
     /**
-     * Match a String against the given pattern, supporting the following simple
-     * pattern styles: "xxx*", "*xxx", "*xxx*" and "xxx*yyy" matches (with an
-     * arbitrary number of pattern parts), as well as direct equality.
+     * Match a String against the given pattern, supporting the following simple pattern styles: "xxx*", "*xxx", "*xxx*"
+     * and "xxx*yyy" matches (with an arbitrary number of pattern parts), as well as direct equality.
      *
      * @param pattern the pattern to match against
-     * @param str     the String to match
+     * @param str the String to match
      * @return whether the String matches the given pattern
      */
     public static boolean globMatch(String pattern, String str) {
+
         if (pattern == null || str == null) {
             return false;
         }
-        int firstIndex = pattern.indexOf('*');
-        if (firstIndex == -1) {
-            return pattern.equals(str);
-        }
-        if (firstIndex == 0) {
-            if (pattern.length() == 1) {
-                return true;
-            }
-            int nextIndex = pattern.indexOf('*', firstIndex + 1);
-            if (nextIndex == -1) {
-                return str.endsWith(pattern.substring(1));
-            } else if (nextIndex == 1) {
-                // Double wildcard "**" - skipping the first "*"
-                return globMatch(pattern.substring(1), str);
-            }
-            String part = pattern.substring(1, nextIndex);
-            int partIndex = str.indexOf(part);
-            while (partIndex != -1) {
-                if (globMatch(pattern.substring(nextIndex), str.substring(partIndex + part.length()))) {
-                    return true;
-                }
-                partIndex = str.indexOf(part, partIndex + 1);
+
+        int stringIndex=0;
+        int patternIndex = 0;
+        int wildcardIndex = -1;
+
+        while (stringIndex < str.length()) {
+            // pattern and string match
+            if (patternIndex < pattern.length() && str.charAt(stringIndex) == pattern.charAt(patternIndex)) {
+                stringIndex++;
+                patternIndex++;
+            } else if (patternIndex < pattern.length() && pattern.charAt(patternIndex) == '*') {
+                // wildcard found
+                wildcardIndex = patternIndex;
+                patternIndex++;
+            } else if (wildcardIndex != -1) {
+                // last pattern pointer was a wildcard
+                patternIndex = wildcardIndex + 1;
+                stringIndex++;
+            } else {
+                // characters do not match
+                return false;
             }
-            return false;
         }
-        return (str.length() >= firstIndex
-            && pattern.substring(0, firstIndex).equals(str.substring(0, firstIndex))
-            && globMatch(pattern.substring(firstIndex), str.substring(firstIndex)));
+
+        while (patternIndex < pattern.length() && pattern.charAt(patternIndex) == '*') {
+            patternIndex++;
+        }
+
+        return patternIndex == pattern.length();
     }
 
+
 }
diff --git a/libs/common/src/test/java/org/opensearch/common/GlobTests.java b/libs/common/src/test/java/org/opensearch/common/GlobTests.java
@@ -40,6 +40,30 @@ public void testGlobMatchWildcardAtMiddle() {
     public void testGlobMatchMultipleWildcards() {
         assertTrue(Glob.globMatch("*test*", "thisisatesting"));
         assertFalse(Glob.globMatch("*test*", "thisisatesing"));
+        assertTrue(Glob.globMatch("*test*test", "thisisatestingtest"));
+        assertFalse(Glob.globMatch("*test*test", "thisisatesting"));
+    }
+
+    public void testGlobMatchMultipleCharactersWithSingleWildcard() {
+        assertTrue(Glob.globMatch("a*b", "acb"));
+        assertTrue(Glob.globMatch("a*b", "aab"));
+        assertTrue(Glob.globMatch("a*b", "aaab"));
+        assertFalse(Glob.globMatch("a*b", "ac"));
+    }
+
+    public void testGlobMatchWildcardWithEmptyString() {
+        assertTrue(Glob.globMatch("*", ""));
+        assertTrue(Glob.globMatch("a*", "a"));
+        assertFalse(Glob.globMatch("a*", ""));
+    }
+
+    public void testGlobMatchMultipleWildcardsWithMultipleCharacters() {
+        assertTrue(Glob.globMatch("a*b*c", "abc"));
+        assertTrue(Glob.globMatch("a*b*c", "axxxbxbc"));
+        assertTrue(Glob.globMatch("a*b*c", "aabc"));
+        assertTrue(Glob.globMatch("a*b*c", "abac"));
+        assertFalse(Glob.globMatch("a*b*c", "abca"));
+        assertFalse(Glob.globMatch("a*b*c", "ac"));
     }