IndexKeys.java

package org.exist.xquery.modules.range;

import org.exist.dom.QName;
import org.exist.indexing.range.RangeIndexWorker;
import org.exist.util.Occurrences;
import org.exist.xquery.*;
import org.exist.xquery.value.*;

public class IndexKeys extends BasicFunction {

    public final static FunctionSignature[] signatures = {
        new FunctionSignature(
            new QName("index-keys-for-field", RangeIndexModule.NAMESPACE_URI, RangeIndexModule.PREFIX),
            "Retrieve all index keys contained in a range index which has been defined with a field name. Similar to" +
            "util:index-keys, but works with fields.",
            new SequenceType[] {
                new FunctionParameterSequenceType("field", Type.STRING, Cardinality.EXACTLY_ONE, "The field to use"),
                new FunctionParameterSequenceType("function-reference", Type.FUNCTION_REFERENCE, Cardinality.EXACTLY_ONE, "The function reference as created by the util:function function. " +
                        "It can be an arbitrary user-defined function, but it should take exactly 2 arguments: " +
                        "1) the current index key as found in the range index as an atomic value, 2) a sequence " +
                        "containing three int values: a) the overall frequency of the key within the node set, " +
                        "b) the number of distinct documents in the node set the key occurs in, " +
                        "c) the current position of the key in the whole list of keys returned."),
                new FunctionParameterSequenceType("max-number-returned", Type.INT, Cardinality.ZERO_OR_ONE , "The maximum number of returned keys")
            },
            new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the results of the eval of the $function-reference")),
        new FunctionSignature(
                new QName("index-keys-for-field", RangeIndexModule.NAMESPACE_URI, RangeIndexModule.PREFIX),
                "Retrieve all index keys contained in a range index which has been defined with a field name. Similar to" +
                        "util:index-keys, but works with fields.",
                new SequenceType[] {
                        new FunctionParameterSequenceType("field", Type.STRING, Cardinality.EXACTLY_ONE, "The field to use"),
                        new FunctionParameterSequenceType("start-value", Type.ATOMIC, Cardinality.ZERO_OR_ONE, "Only index keys of the same type but being greater than $start-value will be reported for non-string types. For string types, only keys starting with the given prefix are reported."),
                        new FunctionParameterSequenceType("function-reference", Type.FUNCTION_REFERENCE, Cardinality.EXACTLY_ONE, "The function reference as created by the util:function function. " +
                                "It can be an arbitrary user-defined function, but it should take exactly 2 arguments: " +
                                "1) the current index key as found in the range index as an atomic value, 2) a sequence " +
                                "containing three int values: a) the overall frequency of the key within the node set, " +
                                "b) the number of distinct documents in the node set the key occurs in, " +
                                "c) the current position of the key in the whole list of keys returned."),
                        new FunctionParameterSequenceType("max-number-returned", Type.INT, Cardinality.ZERO_OR_ONE , "The maximum number of returned keys")
                },
                new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the results of the eval of the $function-reference"))
    };

    public IndexKeys(XQueryContext context, FunctionSignature signature) {
        super(context, signature);
    }

    @Override
    public Sequence eval(final Sequence[] args, final Sequence contextSequence) throws XPathException {
        int arg = 0;
        final String field = args[arg++].getStringValue();
        String start = null;
        if (args.length == 4) {
            start = args[arg++].getStringValue();
        }
        final FunctionReference ref = (FunctionReference) args[arg++].itemAt(0);
        int max = -1;
        if (!args[arg].isEmpty()) {
            max = ((IntegerValue)args[arg].itemAt(0)).getInt();
        }

        final Sequence result = new ValueSequence();
        final RangeIndexWorker worker = (RangeIndexWorker) context.getBroker().getIndexController().getWorkerByIndexName("range-index");
        Occurrences[] occur = worker.scanIndexByField(field, contextSequence == null ? context.getStaticallyKnownDocuments() : contextSequence.getDocumentSet(), start, max);
        final int len = (max != -1 && occur.length > max ? max : occur.length);
        final Sequence params[] = new Sequence[2];
        ValueSequence data = new ValueSequence();
        for (int j = 0; j < len; j++) {
            params[0] = new StringValue(occur[j].getTerm().toString());
            data.add(new IntegerValue(occur[j].getOccurrences(),
                    Type.UNSIGNED_INT));
            data.add(new IntegerValue(occur[j].getDocuments(),
                    Type.UNSIGNED_INT));
            data.add(new IntegerValue(j + 1, Type.UNSIGNED_INT));
            params[1] = data;

            result.addAll(ref.evalFunction(Sequence.EMPTY_SEQUENCE, null, params));
            data.clear();
        }
        return result;
    }
}