xuzifu666 commented on code in PR #4360:
URL: https://github.com/apache/calcite/pull/4360#discussion_r2074497816
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core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java:
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@@ -68,6 +68,43 @@ public static void unparseHiveTrim(
}
}
+ /**
+ * For usage of TRIM, LTRIM and RTRIM in BQ see
+ * <a
href="https://cloud.google.com/bigquery/docs/reference/standard-sql/functions-and-operators#trim";>
+ * BQ Trim Function</a>,
+ * <a
href="https://prestodb.io/docs/current/functions/string.html#trim-string-varchar";>
+ * Presto Trim Function</a>.
+ */
+ public static void unparseTrim(SqlWriter writer, SqlCall call, int leftPrec,
+ int rightPrec) {
+ final String operatorName;
+ SqlLiteral trimFlag = call.operand(0);
+ SqlLiteral valueToTrim = call.operand(1);
+ switch (trimFlag.getValueAs(SqlTrimFunction.Flag.class)) {
+ case LEADING:
+ operatorName = "LTRIM";
+ break;
+ case TRAILING:
+ operatorName = "RTRIM";
+ break;
+ default:
+ operatorName = call.getOperator().getName();
+ break;
+ }
+ final SqlWriter.Frame trimFrame = writer.startFunCall(operatorName);
+ call.operand(2).unparse(writer, leftPrec, rightPrec);
+
+ // If the trimmed character is a non-space character, add it to the target
SQL.
+ // eg: TRIM(BOTH 'A' from 'ABCD'
+ // Output Query: TRIM('ABC', 'A')
+ String value = requireNonNull(valueToTrim.toValue(),
"valueToTrim.toValue()");
+ if (!value.matches("\\s+")) {
Review Comment:
Yes，you are right，maybe we can use StringUtils.isWhitespace(value) to
instead of it? which can only match write spaces. @mihaibudiu
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