uros-db commented on code in PR #46511:
URL: https://github.com/apache/spark/pull/46511#discussion_r1604437739
##########
common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationAwareUTF8String.java:
##########
@@ -34,6 +34,143 @@
* Utility class for collation-aware UTF8String operations.
*/
public class CollationAwareUTF8String {
+
+ /**
+ * The constant value to indicate that the match is not found
+ * when searching for a pattern string in a target string.
+ */
+ private static final int MATCH_NOT_FOUND = -1;
+
+ /**
+ * Returns whether the target string starts with the specified prefix,
+ * with respect to the UTF8_BINARY_LCASE collation. The method assumes
+ * that the prefix is already lowercased prior to method call to avoid the
+ * overhead of calling .toLowerCase() multiple times on the same prefix
string.
+ *
+ * @param target the string to be searched in
+ * @param lowercasePattern the string to be searched for
+ * @param startPos the start position for searching (in the target string)
+ * @return whether the target string starts with the specified prefix in
UTF8_BINARY_LCASE
+ */
+ public static boolean lowercaseMatchFrom(
+ final UTF8String target,
+ final UTF8String lowercasePattern,
+ int startPos) {
+ return lowercaseMatchLengthFrom(target, lowercasePattern, startPos) !=
MATCH_NOT_FOUND;
+ }
+
+ /**
+ * Returns the length of the substring of the target string that starts with
+ * the specified prefix, with respect to the UTF8_BINARY_LCASE collation.
+ * The method assumes that the prefix is already lowercased. The method only
+ * considers the part of target string that starts from the specified
position.
+ *
+ * @param target the string to be searched in
+ * @param lowercasePattern the string to be searched for
+ * @param startPos the end position for searching (in the target string)
+ * @return length of the target substring that ends with the specified
suffix in lowercase
+ */
+ public static int lowercaseMatchLengthFrom(
+ final UTF8String target,
+ final UTF8String lowercasePattern,
+ int startPos) {
+ assert startPos >= 0;
+ for (int len = 0; len <= target.numChars() - startPos; ++len) {
+ if (target.substring(startPos, startPos +
len).toLowerCase().equals(lowercasePattern)) {
+ return len;
+ }
+ }
Review Comment:
Yes, we'll address perf optimizations separately - so I'll create a ticket
for that
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