cloud-fan commented on code in PR #46511: URL: https://github.com/apache/spark/pull/46511#discussion_r1609843913
########## common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationAwareUTF8String.java: ########## @@ -34,6 +34,155 @@ * 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, starting from the + * specified position (0-based index referring to character position in UTF8String), 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, starting from the specified position (0-based index referring to character position + * in UTF8String), 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 (inclusive) position (that is, the method does not look at UTF8 + * characters of the target string at or after position `endPos`). If the prefix is not found, + * MATCH_NOT_FOUND is returned. + * + * @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 length of the target substring that ends with the specified prefix 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; + } + } + return MATCH_NOT_FOUND; + } + + /** + * Returns the position of the first occurrence of the pattern string in the target string, + * starting from the specified position (0-based index referring to character position in + * UTF8String), with respect to the UTF8_BINARY_LCASE collation. The method assumes that the + * pattern string is already lowercased prior to call. If the pattern is not found, + * MATCH_NOT_FOUND is returned. + * + * @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 the position of the first occurrence of pattern in target + */ + public static int lowercaseFind( + final UTF8String target, + final UTF8String lowercasePattern, + int startPos) { + assert startPos >= 0; + for (int i = startPos; i <= target.numChars(); ++i) { + if (lowercaseMatchFrom(target, lowercasePattern, i)) { + return i; + } + } + return MATCH_NOT_FOUND; + } + + /** + * Returns whether the target string ends with the specified suffix, ending at the specified + * position (0-based index referring to character position in UTF8String), with respect to the + * UTF8_BINARY_LCASE collation. The method assumes that the suffix is already lowercased prior + * to method call to avoid the overhead of calling .toLowerCase() multiple times on the same + * suffix string. + * + * @param target the string to be searched in + * @param lowercasePattern the string to be searched for + * @param endPos the end position for searching (in the target string) + * @return whether the target string ends with the specified suffix in lowercase + */ + public static boolean lowercaseMatchUntil( + final UTF8String target, + final UTF8String lowercasePattern, + int endPos) { + return lowercaseMatchLengthUntil(target, lowercasePattern, endPos) != MATCH_NOT_FOUND; + } + + /** + * Returns the length of the substring of the target string that ends with the specified + * suffix, ending at the specified position (0-based index referring to character position in + * UTF8String), with respect to the UTF8_BINARY_LCASE collation. The method assumes that the + * suffix is already lowercased. The method only considers the part of target string that ends + * at the specified (non-inclusive) position (that is, the method does not look at UTF8 + * characters of the target string at or after position `endPos`). If the suffix is not found, + * MATCH_NOT_FOUND is returned. + * + * @param target the string to be searched in + * @param lowercasePattern the string to be searched for + * @param endPos 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 lowercaseMatchLengthUntil( + final UTF8String target, + final UTF8String lowercasePattern, + int endPos) { + assert endPos <= target.numChars(); + for (int len = 0; len <= endPos; ++len) { + if (target.substring(endPos - len, endPos).toLowerCase().equals(lowercasePattern)) { Review Comment: I don't know the details very well. Is it the same if we lower case the entire target string first, and then call `substring` repeatedly? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org