xuzifu666 commented on code in PR #4400:
URL: https://github.com/apache/calcite/pull/4400#discussion_r2107045853
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core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
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@@ -2364,6 +2366,37 @@ private RexNode simplifyCeilFloor(RexCall e) {
ImmutableList.of(operand, e.getOperands().get(1)));
}
+ /** Simplify TRIM function by eliminating nested duplication.
+ *
+ * <p>Examples:
+ * <ul>
+ *
+ * <li>{@code trim(trim(' aa '))} returns {@code trim(' aa ')}
+ *
+ * <li>{@code trim(BOTH ' ' from trim(BOTH ' ' from ' aa '))}
+ * returns {@code trim(BOTH ' ' from ' aa ')}
+ *
+ * <li>{@code trim(LEADING 'a' from trim(BOTH ' ' from ' aa '))} does not
change
+ *
+ * </ul>
+ */
+ private RexNode simplifyTrim(RexCall e) {
+ if (e.getOperands().size() != 3) {
+ return e;
+ }
+
+ if (e.getOperands().get(2) instanceof RexCall) {
Review Comment:
Thanks for your case, I understand what you mean now, but this depends on
other functions or grammar simplifications, and may not be directly related to
the related issue.This PR can first solve the idempotent duplication problem in
the most basic case.
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