xuzifu666 commented on code in PR #4460:
URL: https://github.com/apache/calcite/pull/4460#discussion_r2203726220
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core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
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@@ -500,17 +501,66 @@ private RexNode simplifyDivide(RexCall e) {
private RexNode simplifyLike(RexCall e, RexUnknownAs unknownAs) {
if (e.operands.get(1) instanceof RexLiteral) {
final RexLiteral literal = (RexLiteral) e.operands.get(1);
- if ("%".equals(literal.getValueAs(String.class))) {
- // "x LIKE '%'" simplifies to "x = x"
+ String likeStr = requireNonNull(literal.getValueAs(String.class));
+ Pattern pattern = Pattern.compile("%+");
+ String value = pattern.matcher(likeStr).replaceAll("%");
+ if ("%".equals(value)) {
+ // "x LIKE '%'" or "x LIKE '%...'" simplifies to "x = x"
final RexNode x = e.operands.get(0);
return simplify(
rexBuilder.makeCall(
e.getParserPosition(), SqlStdOperatorTable.EQUALS, x, x),
unknownAs);
}
+ // simplify "x LIKE '%%\%%a%%%'" to "x LIKE '%\%%a%'", default escape is
'\'
+ if (e.operands.size() == 2) {
+ ArrayList<RexNode> rexNodes = new ArrayList<>(e.operands);
+ rexNodes.set(1, rexBuilder.makeLiteral(simplifyLikeString(likeStr,
"\\", "%")));
+ e = (RexCall) rexBuilder.makeCall(e.getParserPosition(),
e.getOperator(), rexNodes);
+ }
+ if (e.operands.size() == 3 && e.operands.get(2) instanceof RexLiteral) {
+ final RexLiteral escapeLiteral = (RexLiteral) e.operands.get(2);
+ String escape = requireNonNull(escapeLiteral.getValueAs(String.class));
+ ArrayList<RexNode> rexNodes = new ArrayList<>(e.operands);
+ rexNodes.set(1, rexBuilder.makeLiteral(simplifyLikeString(likeStr,
escape, "%")));
+ e = (RexCall) rexBuilder.makeCall(e.getParserPosition(),
e.getOperator(), rexNodes);
+ }
}
return simplifyGenericNode(e);
}
+ /**
+ * Simplifies like string with escape.
+ * A like '%%#%%A%%' escape '#' should simplify to A like '%#%%A%' escape
'#'.
+ */
+ private String simplifyLikeString(String content, String escape, String
wildcard) {
+ ArrayList<String> result = new ArrayList<>();
Review Comment:
I had change to StringBuilder to append char which seems more suitable.
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