com.hazelcast.org.apache.calcite.util.RelToSqlConverterUtil Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.org.apache.calcite.util;
import com.hazelcast.org.apache.calcite.sql.SqlCall;
import com.hazelcast.org.apache.calcite.sql.SqlCharStringLiteral;
import com.hazelcast.org.apache.calcite.sql.SqlKind;
import com.hazelcast.org.apache.calcite.sql.SqlLiteral;
import com.hazelcast.org.apache.calcite.sql.SqlNode;
import com.hazelcast.org.apache.calcite.sql.SqlSpecialOperator;
import com.hazelcast.org.apache.calcite.sql.SqlWriter;
import com.hazelcast.org.apache.calcite.sql.fun.SqlTrimFunction;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParserPos;
import static com.hazelcast.org.apache.calcite.sql.fun.SqlLibraryOperators.REGEXP_REPLACE;
import static java.util.Objects.requireNonNull;
/**
* Utilities used by multiple dialect for RelToSql conversion.
*/
public abstract class RelToSqlConverterUtil {
/**
* For usage of TRIM, LTRIM and RTRIM in Hive, see
* Hive UDF usage.
*/
public static void unparseHiveTrim(
SqlWriter writer,
SqlCall call,
int leftPrec,
int rightPrec) {
final SqlLiteral valueToTrim = call.operand(1);
String value = requireNonNull(valueToTrim.toValue(),
() -> "call.operand(1).toValue() for call " + call);
if (value.matches("\\s+")) {
unparseTrimWithSpace(writer, call, leftPrec, rightPrec);
} else {
// SELECT TRIM(both 'A' from "ABC") -> SELECT REGEXP_REPLACE("ABC", '^(A)*', '')
final SqlLiteral trimFlag = call.operand(0);
final SqlCharStringLiteral regexNode =
createRegexPatternLiteral(call.operand(1), trimFlag);
final SqlCharStringLiteral blankLiteral =
SqlLiteral.createCharString("", call.getParserPosition());
final SqlNode[] trimOperands = new SqlNode[] { call.operand(2), regexNode, blankLiteral };
final SqlCall regexReplaceCall = REGEXP_REPLACE.createCall(SqlParserPos.ZERO, trimOperands);
regexReplaceCall.unparse(writer, leftPrec, rightPrec);
}
}
/**
* Unparses TRIM function with value as space.
*
* For example :
*
*
* SELECT TRIM(both ' ' from "ABC") → SELECT TRIM(ABC)
*
*
* @param writer writer
* @param call the call
*/
private static void unparseTrimWithSpace(
SqlWriter writer, SqlCall call, int leftPrec, int rightPrec) {
final String operatorName;
final SqlLiteral trimFlag = call.operand(0);
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);
writer.endFunCall(trimFrame);
}
/**
* Creates regex pattern based on the TRIM flag.
*
* @param call SqlCall contains the values that need to be trimmed
* @param trimFlag the trimFlag, either BOTH, LEADING or TRAILING
* @return the regex pattern of the character to be trimmed
*/
public static SqlCharStringLiteral createRegexPatternLiteral(SqlNode call, SqlLiteral trimFlag) {
final String regexPattern = requireNonNull(((SqlCharStringLiteral) call).toValue(),
() -> "null value for SqlNode " + call);
String escaped = escapeSpecialChar(regexPattern);
final StringBuilder builder = new StringBuilder();
switch (trimFlag.getValueAs(SqlTrimFunction.Flag.class)) {
case LEADING:
builder.append("^(").append(escaped).append(")*");
break;
case TRAILING:
builder.append("(").append(escaped).append(")*$");
break;
default:
builder.append("^(")
.append(escaped)
.append(")*|(")
.append(escaped)
.append(")*$");
break;
}
return SqlLiteral.createCharString(builder.toString(),
call.getParserPosition());
}
/**
* Escapes the special character.
*
* @param inputString the string
* @return escape character if any special character is present in the string
*/
private static String escapeSpecialChar(String inputString) {
final String[] specialCharacters = {"\\", "^", "$", "{", "}", "[", "]", "(", ")", ".",
"*", "+", "?", "|", "<", ">", "-", "&", "%", "@"};
for (String specialCharacter : specialCharacters) {
if (inputString.contains(specialCharacter)) {
inputString = inputString.replace(specialCharacter, "\\" + specialCharacter);
}
}
return inputString;
}
/** Returns a {@link SqlSpecialOperator} with given operator name, mainly used for
* unparse override. */
public static SqlSpecialOperator specialOperatorByName(String opName) {
return new SqlSpecialOperator(opName, SqlKind.OTHER_FUNCTION) {
@Override public void unparse(
SqlWriter writer,
SqlCall call,
int leftPrec,
int rightPrec) {
writer.print(getName());
final SqlWriter.Frame frame =
writer.startList(SqlWriter.FrameTypeEnum.FUN_CALL, "(", ")");
for (SqlNode operand : call.getOperandList()) {
writer.sep(",");
operand.unparse(writer, 0, 0);
}
writer.endList(frame);
}
};
}
}
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