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package org.jooq.impl;

import static org.jooq.SQLDialect.DERBY;
import static org.jooq.impl.DSL.selectFrom;
import static org.jooq.impl.Names.N_SELECT;
import static org.jooq.impl.Tools.selectQueryImpl;
import static org.jooq.impl.Tools.visitSubquery;
import static org.jooq.impl.Tools.DataKey.DATA_SELECT_ALIASES;

import org.jooq.Clause;
import org.jooq.Context;
import org.jooq.Name;
import org.jooq.Record;
import org.jooq.Select;
import org.jooq.Table;
import org.jooq.TableOptions;

A Select query that re-aliases its projection, or produces a derived table if re-aliasing is not possible (e.g. in the presence of ORDER BY).
Author:
Lukas Eder/**
 * A {@link Select} query that re-aliases its projection, or produces a derived
 * table if re-aliasing is not possible (e.g. in the presence of
 * <code>ORDER BY</code>).
 *
 * @author Lukas Eder
 */
final class AliasedSelect<R extends Record> extends AbstractTable<R> {

    private static final long serialVersionUID = 6763689261249123076L;

    private final Select<R>   query;
    private final Name[]      aliases;

    AliasedSelect(Select<R> query) {
        this(query, Tools.fieldNames(Tools.degree(query)));
    }

    AliasedSelect(Select<R> query, Name... aliases) {
        super(TableOptions.expression(), N_SELECT);

        this.query = query;
        this.aliases = aliases;
    }

    final Select<R> query() {
        return query;
    }

    @Override
    public final Table<R> as(Name alias) {
        SelectQueryImpl<R> q = selectQueryImpl(query);

        if (q != null && (!q.getOrderBy().isEmpty() || Tools.hasEmbeddedFields(q.getSelect())))
            return query.asTable(alias, aliases);
        else
            return new TableAlias<>(this, alias, true);
    }

    @Override
    public final Table<R> as(Name alias, Name... fieldAliases) {
        return new TableAlias<>(this, alias, fieldAliases, true);
    }

    @Override
    final Fields<R> fields0() {
        return new Fields<>(query.asTable(DSL.name("t"), aliases).fields());
    }

    @Override
    public final Class<? extends R> getRecordType() {
        return query.getRecordType();
    }

    @Override
    public final void accept(Context<?> ctx) {
        SelectQueryImpl<R> q = selectQueryImpl(query);

        // [#3679] [#10540] Without standardised UNION subquery column names,
        //                  Derby projects column indexes 1, 2, 3 as names, but
        //                  they cannot be referenced. In that case, revert to
        //                  actual derived table usage.
        if (ctx.family() == DERBY && q != null && q.hasUnions()) {
            visitSubquery(ctx, selectFrom(query.asTable(DSL.name("t"), aliases)));
        }
        else {
            Object previous = ctx.data(DATA_SELECT_ALIASES);

             ctx.data(DATA_SELECT_ALIASES, aliases);
             visitSubquery(ctx, query);
             ctx.data(DATA_SELECT_ALIASES, previous);
        }
    }

    @Override // Avoid AbstractTable implementation
    public final Clause[] clauses(Context<?> ctx) {
        return null;
    }
}