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/*
 Copyright 2013 Red Hat, Inc. and/or its affiliates.

 This file is part of lightblue.

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program.  If not, see .
 */
package com.redhat.lightblue.eval;

import com.redhat.lightblue.util.Path;

import com.redhat.lightblue.metadata.FieldTreeNode;

import com.redhat.lightblue.query.ArrayRangeProjection;
import com.redhat.lightblue.query.Projection;

/**
 * Projector that returns a range of elements from an array
 */
public class ArrayRangeProjector extends ArrayProjector {

    private final Integer from;
    private final Integer to;

    /**
     * Ctor
     *
     * @param p The projection expression
     * @param ctxPath The absolute path relative to which this is to be
     * interpreted
     * @param context The metadata node at which this is to be interpreted
     */
    public ArrayRangeProjector(ArrayRangeProjection p, Path ctxPath, FieldTreeNode ctx) {
        super(p, ctxPath, ctx);
        from = p.getFrom();
        to = p.getTo();
    }

    @Override
    protected Projection.Inclusion projectArray(Path p, QueryEvaluationContext ctx) {
        // Is this array element in range?
        int index = p.getIndex(p.numSegments() - 1);
        if (to == null) {
            if (index >= from) {
                // This array element is selected.
                return isIncluded() ? Projection.Inclusion.explicit_inclusion : Projection.Inclusion.explicit_exclusion;
            } else {
                return Projection.Inclusion.explicit_exclusion;
            }
        } else if (to < 0) {
            return Projection.Inclusion.explicit_exclusion;
        } else if (from <= to && index >= from && index <= to) {
            // This array element is selected.
            return isIncluded() ? Projection.Inclusion.explicit_inclusion : Projection.Inclusion.explicit_exclusion;
        } else {
            return Projection.Inclusion.explicit_exclusion;
        }
    }
}