com.github.rutledgepaulv.qbuilders.visitors.RSQLVisitor Maven / Gradle / Ivy

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A type-safe and database agnostic query building library.
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/*
 *
 *  *  com.github.rutledgepaulv.qbuilders.visitors.RSQLVisitor
 *  *  *
 *  *  * Copyright (C) 2016 Paul Rutledge 
 *  *  *
 *  *  * This software may be modified and distributed under the terms
 *  *  * of the MIT license.  See the LICENSE file for details.
 *  *
 *
 */

package com.github.rutledgepaulv.qbuilders.visitors;

import com.github.rutledgepaulv.qbuilders.nodes.AbstractNode;
import com.github.rutledgepaulv.qbuilders.nodes.AndNode;
import com.github.rutledgepaulv.qbuilders.nodes.ComparisonNode;
import com.github.rutledgepaulv.qbuilders.nodes.OrNode;
import com.github.rutledgepaulv.qbuilders.operators.ComparisonOperator;

import java.util.Objects;
import java.util.function.Function;

import static java.util.stream.Collectors.joining;

@SuppressWarnings("WeakerAccess")
public class RSQLVisitor extends AbstractVoidContextNodeVisitor {

    private final Function serializer;

    public RSQLVisitor() {
        this(DefaultSerializationStrategy.INSTANCE);
    }

    public RSQLVisitor(Function serializationStrategy) {
        this.serializer = serializationStrategy;
    }

    @Override
    protected String visit(AndNode node) {
        String body = node.getChildren().stream().map(this::visitAny).collect(joining(";"));
        return nodeBelongsToParentExpression(node) ? "(" + body + ")" : body;
    }

    @Override
    protected String visit(OrNode node) {
        String body = node.getChildren().stream().map(this::visitAny).collect(joining(","));
        return nodeBelongsToParentExpression(node) ? "(" + body + ")" : body;
    }

    @Override
    protected String visit(ComparisonNode node) {

        ComparisonOperator operator = node.getOperator();

        if(ComparisonOperator.EQ.equals(operator)) {
            return single(node, "==");
        } else if(ComparisonOperator.NE.equals(operator)) {
            return single(node, "!=");
        } else if (ComparisonOperator.EX.equals(operator)) {
            return single(node, "=ex=");
        } else if (ComparisonOperator.GT.equals(operator)) {
            return single(node, "=gt=");
        } else if (ComparisonOperator.LT.equals(operator)) {
            return single(node, "=lt=");
        } else if (ComparisonOperator.GTE.equals(operator)) {
            return single(node, "=ge=");
        } else if (ComparisonOperator.LTE.equals(operator)) {
            return single(node, "=le=");
        } else if (ComparisonOperator.IN.equals(operator)) {
            return list(node, "=in=");
        } else if (ComparisonOperator.NIN.equals(operator)) {
            return list(node, "=out=");
        } else if (ComparisonOperator.RE.equals(operator)) {
            return single(node, "=re=");
        } else if (ComparisonOperator.SUB_CONDITION_ANY.equals(operator)) {
            return node.getField().asKey() + "=q=" + serialize(condition(node));
        }

        throw new UnsupportedOperationException("This visitor does not support the operator " + operator + ".");
    }

    protected boolean nodeBelongsToParentExpression(AbstractNode node) {
        return node.getParent() != null;
    }

    protected String single(ComparisonNode node, String op) {
        return node.getField().asKey() + op + serialize(single(node.getValues()));
    }

    protected String list(ComparisonNode node, String op) {
        return node.getField().asKey() + op + node.getValues().stream()
                .map(this::serialize).collect(joining(",", "(", ")"));
    }

    protected String serialize(Object value) {
        return this.serializer.apply(value);
    }


    protected static class DefaultSerializationStrategy implements Function