jhugomoore commented on code in PR #3184:
URL: https://github.com/apache/calcite/pull/3184#discussion_r1182819017
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core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
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@@ -3104,23 +3104,106 @@ public static int position(ByteString seek, ByteString
s) {
/** SQL {@code POSITION(seek IN string FROM integer)} function. */
public static int position(String seek, String s, int from) {
- final int from0 = from - 1; // 0-based
- if (from0 > s.length() || from0 < 0) {
+ if (from == 0) {
+ throw RESOURCE.fromNotZero().ex();
+ }
+ // Case when from is positive
+ if (from > 0) {
+ final int from0 = from - 1; // 0-based
+ if (from0 >= s.length() || from0 < 0) {
+ return 0;
+ } else {
+ return s.indexOf(seek, from0) + 1;
+ }
+ }
+ // Case when from is negative
+ final int rightIndex = from + s.length(); // negative position to positive
index
+ if (rightIndex <= 0) {
return 0;
}
-
- return s.indexOf(seek, from0) + 1;
+ return s.substring(0, rightIndex + 1).lastIndexOf(seek) + 1;
}
/** SQL {@code POSITION(seek IN string FROM integer)} function for byte
* strings. */
public static int position(ByteString seek, ByteString s, int from) {
- final int from0 = from - 1;
- if (from0 > s.length() || from0 < 0) {
+ if (from == 0) {
+ throw RESOURCE.fromNotZero().ex();
+ }
+ // Case when from is positive
+ if (from > 0) {
+ final int from0 = from - 1; // 0-based
+ if (from0 >= s.length() || from0 < 0) {
+ return 0;
+ } else {
+ return s.indexOf(seek, from0) + 1;
+ }
+ }
+ // Case when from is negative
+ final int rightIndex = from + s.length();
+ if (rightIndex <= 0) {
return 0;
}
+ int lastIndex = 0;
+ while (lastIndex < rightIndex) {
+ int indexOf = s.substring(lastIndex, rightIndex + 1).indexOf(seek) + 1;
+ if (indexOf == 0) {
+ break;
+ }
+ lastIndex += indexOf;
+ }
+ return lastIndex;
+ }
- return s.indexOf(seek, from0) + 1;
+ /** SQL {@code POSITION(seek, string, from, occurrence)} function. */
+ public static int position(String seek, String s, int from, int occurrence) {
+ if (occurrence == 0) {
+ throw RESOURCE.occurrenceNotZero().ex();
+ }
+ for (int i = 0; i < occurrence; i++) {
Review Comment:
Not sure I understand what you mean. From gets updated every time the for
loop runs, so we have to check whether to use the logic for from being positive
or negative each time. I think checking if from is 0 after assignment is
necessary because it will error if we continue running
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