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A module that is everything required to understands Druid Segments
/*
* 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 org.apache.druid.query.expression;
import com.google.common.annotations.VisibleForTesting;
import org.apache.druid.math.expr.Expr;
import org.apache.druid.math.expr.ExprEval;
import org.apache.druid.math.expr.ExprMacroTable;
import org.apache.druid.math.expr.ExpressionType;
import org.apache.druid.math.expr.InputBindings;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.List;
public abstract class TrimExprMacro implements ExprMacroTable.ExprMacro
{
private static final char[] EMPTY_CHARS = new char[0];
private static final char[] DEFAULT_CHARS = new char[]{' '};
enum TrimMode
{
BOTH("trim", true, true),
LEFT("ltrim", true, false),
RIGHT("rtrim", false, true);
private final String name;
private final boolean left;
private final boolean right;
TrimMode(final String name, final boolean left, final boolean right)
{
this.name = name;
this.left = left;
this.right = right;
}
public String getFnName()
{
return name;
}
public boolean isLeft()
{
return left;
}
public boolean isRight()
{
return right;
}
}
private final TrimMode mode;
public TrimExprMacro(final TrimMode mode)
{
this.mode = mode;
}
@Override
public String name()
{
return mode.getFnName();
}
@Override
public Expr apply(final List args)
{
validationHelperCheckAnyOfArgumentCount(args, 1, 2);
if (args.size() == 1) {
return new TrimStaticCharsExpr(this, args, DEFAULT_CHARS);
} else {
final Expr charsArg = args.get(1);
if (charsArg.isLiteral()) {
final String charsString = charsArg.eval(InputBindings.nilBindings()).asString();
final char[] chars = charsString == null ? EMPTY_CHARS : charsString.toCharArray();
return new TrimStaticCharsExpr(this, args, chars);
} else {
return new TrimDynamicCharsExpr(this, args);
}
}
}
@VisibleForTesting
static class TrimStaticCharsExpr extends ExprMacroTable.BaseScalarMacroFunctionExpr
{
private final TrimMode mode;
private final char[] chars;
private final Expr stringExpr;
public TrimStaticCharsExpr(
final TrimExprMacro macro,
final List args,
final char[] chars
)
{
super(macro, args);
this.mode = macro.mode;
this.stringExpr = args.get(0);
this.chars = chars;
}
@Nonnull
@Override
public ExprEval eval(final ObjectBinding bindings)
{
final ExprEval stringEval = stringExpr.eval(bindings);
if (chars.length == 0 || stringEval.value() == null) {
return stringEval;
}
final String s = stringEval.asString();
int start = 0;
int end = s.length();
if (mode.isLeft()) {
while (start < s.length()) {
if (arrayContains(chars, s.charAt(start))) {
start++;
} else {
break;
}
}
}
if (mode.isRight()) {
while (end > start) {
if (arrayContains(chars, s.charAt(end - 1))) {
end--;
} else {
break;
}
}
}
if (start == 0 && end == s.length()) {
return stringEval;
} else {
return ExprEval.of(s.substring(start, end));
}
}
@Nullable
@Override
public ExpressionType getOutputType(InputBindingInspector inspector)
{
return ExpressionType.STRING;
}
}
@VisibleForTesting
static class TrimDynamicCharsExpr extends ExprMacroTable.BaseScalarMacroFunctionExpr
{
private final TrimMode mode;
private final Expr stringExpr;
private final Expr charsExpr;
public TrimDynamicCharsExpr(
final TrimExprMacro macro,
final List args
)
{
super(macro, args);
this.mode = macro.mode;
this.stringExpr = args.get(0);
this.charsExpr = args.get(1);
}
@Nonnull
@Override
public ExprEval eval(final ObjectBinding bindings)
{
final ExprEval stringEval = stringExpr.eval(bindings);
if (stringEval.value() == null) {
return stringEval;
}
final ExprEval charsEval = charsExpr.eval(bindings);
if (charsEval.value() == null) {
return stringEval;
}
final String s = stringEval.asString();
final String chars = charsEval.asString();
int start = 0;
int end = s.length();
if (mode.isLeft()) {
while (start < s.length()) {
if (stringContains(chars, s.charAt(start))) {
start++;
} else {
break;
}
}
}
if (mode.isRight()) {
while (end > start) {
if (stringContains(chars, s.charAt(end - 1))) {
end--;
} else {
break;
}
}
}
if (start == 0 && end == s.length()) {
return stringEval;
} else {
return ExprEval.of(s.substring(start, end));
}
}
@Nullable
@Override
public ExpressionType getOutputType(InputBindingInspector inspector)
{
return ExpressionType.STRING;
}
}
private static boolean arrayContains(char[] array, char c)
{
for (final char arrayChar : array) {
if (arrayChar == c) {
return true;
}
}
return false;
}
private static boolean stringContains(String string, char c)
{
for (int i = 0; i < string.length(); i++) {
if (string.charAt(i) == c) {
return true;
}
}
return false;
}
public static class BothTrimExprMacro extends TrimExprMacro
{
public BothTrimExprMacro()
{
super(TrimMode.BOTH);
}
}
public static class LeftTrimExprMacro extends TrimExprMacro
{
public LeftTrimExprMacro()
{
super(TrimMode.LEFT);
}
}
public static class RightTrimExprMacro extends TrimExprMacro
{
public RightTrimExprMacro()
{
super(TrimMode.RIGHT);
}
}
}