phoenix-core/src/main/java/org/apache/phoenix/expression/function/RegexpReplaceFunction.java

/*
 * 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.phoenix.expression.function;

import java.io.DataInput;
import java.io.IOException;
import java.util.List;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Determinism;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.util.regex.AbstractBasePattern;
import org.apache.phoenix.parse.FunctionParseNode;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.parse.RegexpReplaceParseNode;
import org.apache.phoenix.schema.SortOrder;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PVarchar;


/**
 * 
 * Function similar to the regexp_replace function in Postgres, which is used to pattern
 * match a segment of the string. Usage:
 * REGEXP_REPLACE(<source_char>,<pattern>,<replace_string>)
 * source_char is the string in which we want to perform string replacement. pattern is a
 * Java compatible regular expression string, and we replace all the matching part with 
 * replace_string. The first 2 arguments are required and are {@link org.apache.phoenix.schema.types.PVarchar},
 * the replace_string is default to empty string.
 * 
 * The function returns a {@link org.apache.phoenix.schema.types.PVarchar}
 * 
 * 
 * @since 0.1
 */
@BuiltInFunction(name=RegexpReplaceFunction.NAME,
    nodeClass = RegexpReplaceParseNode.class, args= {
    @Argument(allowedTypes={PVarchar.class}),
    @Argument(allowedTypes={PVarchar.class}),
    @Argument(allowedTypes={PVarchar.class},defaultValue="null")},
    classType = FunctionParseNode.FunctionClassType.ABSTRACT,
    derivedFunctions = {ByteBasedRegexpReplaceFunction.class, StringBasedRegexpReplaceFunction.class})
public abstract class RegexpReplaceFunction extends ScalarFunction {
    public static final String NAME = "REGEXP_REPLACE";

    private static final PVarchar TYPE = PVarchar.INSTANCE;
    private byte [] rStrBytes;
    private int rStrOffset, rStrLen;
    private AbstractBasePattern pattern;

    public RegexpReplaceFunction() { }

    // Expect 1 arguments, the pattern. 
    public RegexpReplaceFunction(List<Expression> children) {
        super(children);
        init();
    }

    protected abstract AbstractBasePattern compilePatternSpec(String value);

    private void init() {
        ImmutableBytesWritable tmpPtr = new ImmutableBytesWritable();
        Expression e = getPatternStrExpression();
        if (e.isStateless() && e.getDeterminism() == Determinism.ALWAYS && e.evaluate(null, tmpPtr)) {
            String patternStr = (String) TYPE.toObject(tmpPtr, e.getDataType(), e.getSortOrder());
            if (patternStr != null) pattern = compilePatternSpec(patternStr);
        }
        e = getReplaceStrExpression();
        if (e.isStateless() && e.getDeterminism() == Determinism.ALWAYS && e.evaluate(null, tmpPtr)) {
            TYPE.coerceBytes(tmpPtr, TYPE, e.getSortOrder(), SortOrder.ASC);
            rStrBytes = tmpPtr.get();
            rStrOffset = tmpPtr.getOffset();
            rStrLen = tmpPtr.getLength();
        } else {
            rStrBytes = null;
        }
    }

    @Override
    public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
        AbstractBasePattern pattern = this.pattern;
        if (pattern == null) {
            Expression e = getPatternStrExpression();
            if (!e.evaluate(tuple, ptr)) {
                return false;
            }
            if (ptr.getLength()==0) {
                return true;
            }
            String patternStr = (String) TYPE.toObject(ptr, e.getDataType(), e.getSortOrder());
            if (patternStr == null) {
                return false;
            } else {
                pattern = compilePatternSpec(patternStr);
            }
        }

        byte[] rStrBytes = this.rStrBytes;
        int rStrOffset = this.rStrOffset, rStrLen = this.rStrLen;
        if (rStrBytes == null) {
            Expression replaceStrExpression = getReplaceStrExpression();
            if (!replaceStrExpression.evaluate(tuple, ptr)) {
                return false;
            }
            if (ptr.getLength()==0) {
                return true;
            }
            TYPE.coerceBytes(ptr, TYPE, replaceStrExpression.getSortOrder(), SortOrder.ASC);
            rStrBytes = ptr.get();
            rStrOffset = ptr.getOffset();
            rStrLen = ptr.getLength();
        }

        Expression sourceStrExpression = getSourceStrExpression();
        if (!sourceStrExpression.evaluate(tuple, ptr)) {
            return false;
        }
        if (ptr.getLength()==0) {
            return true;
        }
        TYPE.coerceBytes(ptr, TYPE, sourceStrExpression.getSortOrder(), SortOrder.ASC);

        pattern.replaceAll(ptr, rStrBytes, rStrOffset, rStrLen);
        return true;
    }

    private Expression getSourceStrExpression() {
        return children.get(0);
    }

    private Expression getPatternStrExpression() {
        return children.get(1);
    }

    private Expression getReplaceStrExpression() {
        return children.get(2);
    }

    @Override
    public PDataType getDataType() {
        return PVarchar.INSTANCE;
    }

    @Override
    public void readFields(DataInput input) throws IOException {
        super.readFields(input);
        init();
    }

    @Override
    public String getName() {
        return NAME;
    }
}