xiedeyantu commented on code in PR #4400:
URL: https://github.com/apache/calcite/pull/4400#discussion_r2122529268
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core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
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@@ -2364,6 +2366,43 @@ 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) {
+ RexCall childNode = (RexCall) e.getOperands().get(2);
+ // only strings with the same trim method and deduplication will be
eliminated.
+ if (childNode.getKind() == SqlKind.TRIM
+ &&
simplify(e.operands.get(0)).equals(simplify(childNode.operands.get(0)))
+ &&
simplify(e.operands.get(1)).equals(simplify(childNode.operands.get(1)))) {
+ return simplifyTrim(childNode);
+ }
+ }
+
+ ArrayList<RexNode> rexNodes = new ArrayList<>();
+ for (RexNode node : e.operands) {
+ rexNodes.add(simplify(node));
Review Comment:
This may simplify the same RexNode twice. Since it will be done once in the
above if, we can just do it once.
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