uros-db commented on code in PR #47771:
URL: https://github.com/apache/spark/pull/47771#discussion_r1718415270
##########
common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationAwareUTF8String.java:
##########
@@ -1267,6 +1268,119 @@ public static UTF8String[] icuSplitSQL(final UTF8String
string, final UTF8String
return strings.toArray(new UTF8String[0]);
}
+ /**
+ * Title casing a string according to a new behaviour.
+ * Iterates over the string and title cases the first character in each
word, and lowercases
+ * every other character.
+ * Handles lowercasing greek sigma(Σ) separately, taking into account if
+ * it should be a small final sigma(ς) or small non-final sigma(σ).
+ * Words are separated by ASCII space(\u0020).
+ *
+ * @param target UTF8String to be title cased
+ * @return title cased target
+ */
+ public static UTF8String toTitleCaseICU(UTF8String target) {
+
+ Iterator<Integer> codepointIterator = target.
+
codePointIterator(CodePointIteratorType.CODE_POINT_ITERATOR_MAKE_VALID);
+
+ // building the title cased target with sb
+ StringBuilder sb=new StringBuilder();
+ // newWord is true if the current character is the beginning of a word,
false otherwise
+ // it is true on the i-th character if i==0 or target at (i-1)-th
character is ' '
+ boolean newWord = true;
+ // we are maintaining if the current character is preceded by a cased
letter
+ // this is used when lowercasing Σ, to figure out if it should be
lowercased into σ or ς
+ boolean precededByCasedLetter = false;
+
+ // byte offset in target's byte array pointing to the beginning of the
character that we
+ // need to process next(this is only actually used in
appendLowerCasedGreekCapitalSigma)
+ int offset = 0;
+
+ while(codepointIterator.hasNext()) {
+ int codepoint = codepointIterator.next();
+ // appending the correctly cased character onto sb
+ appendTitleCasedCodepoint(sb, codepoint, newWord, precededByCasedLetter,
target, offset);
+ // updating newWord, precededByCasedLetter and offset to be ready for
+ // the next character that we will process
+ newWord = (codepoint == ASCII_SPACE_CODEPOINT);
+ if(!UCharacter.hasBinaryProperty(codepoint, UProperty.CASE_IGNORABLE)){
+ precededByCasedLetter = UCharacter.hasBinaryProperty(codepoint,
UProperty.CASED);
+ }
+ offset+= UTF8String.numBytesForFirstByte(target.getByte(offset));
+ }
+ return UTF8String.fromString(sb.toString());
+ }
+
+ private static void appendTitleCasedCodepoint(StringBuilder sb, int
codepoint,
+ boolean isAfterAsciiSpace,
+ boolean precededByCasedLetter,
UTF8String target,
+ int offset) {
+ if(isAfterAsciiSpace) {
+ // titlecasing a character if it is in the beginning of a new word
+ sb.append(codepointToTitleString(codepoint));
+ return;
+ }
+ if(codepoint == CAPITAL_SIGMA) {
+ // handling Σ separately
+ appendLowerCasedGreekCapitalSigma(sb, precededByCasedLetter, target,
offset);
+ return;
+ }
+ // if it's not the beginning of a word, or a Σ, we lowercase the character
+ sb.append(toLowerCase(UTF8String.fromString(new
String(Character.toChars(codepoint)))).
+ toString());
+ }
+
+ private static void appendLowerCasedGreekCapitalSigma(StringBuilder sb,
+ boolean
precededByCasedLetter,
+ UTF8String target, int
offset) {
+ int codepoint = (!followedByCasedLetter(target,offset) &&
precededByCasedLetter)?
+ SMALL_FINAL_SIGMA : SMALL_NON_FINAL_SIGMA;
+ sb.appendCodePoint(codepoint);
+ }
+
+ /**
+ * Checks if the character beginning at offset(in targets byte array) is
followed
+ * by a cased letter
+ *
+ * @param target
+ * @param offset
+ * @return
+ */
+ private static boolean followedByCasedLetter(UTF8String target, int offset) {
+ // moving the offset one character forward, so we could start our linear
search from there
Review Comment:
```suggestion
// Moving the offset one character forward, so we could start the linear
search from there.
```
comments should be proper English sentences (whenever possible)
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