com.tesora.dve.sql.statement.dml.AliasInformation.java Source code

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Here is the source code for com.tesora.dve.sql.statement.dml.AliasInformation.java

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package com.tesora.dve.sql.statement.dml;

/*
 * #%L
 * Tesora Inc.
 * Database Virtualization Engine
 * %%
 * Copyright (C) 2011 - 2014 Tesora Inc.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 * 
 * 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.tesora.dve.db.DBNative;
import com.tesora.dve.server.global.HostService;
import com.tesora.dve.singleton.Singletons;
import org.apache.commons.lang.StringUtils;

import com.tesora.dve.sql.expression.Scope;
import com.tesora.dve.sql.expression.ScopeStack;
import com.tesora.dve.sql.schema.Name;
import com.tesora.dve.sql.schema.UnqualifiedName;

public class AliasInformation {

    // all aliases within the statement.
    private Map<String, Integer> aliases;

    public AliasInformation() {
        aliases = new HashMap<String, Integer>();
    }

    public AliasInformation(AliasInformation ai) {
        aliases = new HashMap<String, Integer>();
        aliases.putAll(ai.aliases);
    }

    public AliasInformation(ScopeStack scopes) {
        aliases = new HashMap<String, Integer>();
        if (scopes == null)
            return;
        List<Scope> ls = scopes.getCurrentStack();
        for (int i = ls.size() - 1; i > -1; i--) {
            take(ls.get(i));
        }
    }

    public boolean addAlias(String s) {
        Integer any = aliases.get(s);
        if (any == null)
            any = new Integer(1);
        else
            any = new Integer(any.intValue() + 1);
        return aliases.put(s, any) == null;
    }

    public void addAliases(Collection<String> coll) {
        for (String s : coll)
            addAlias(s);
    }

    private void take(Scope s) {
        addAliases(s.getAllAliases());
    }

    public void take(Set<String> existing) {
        addAliases(existing);
    }

    public void take(AliasInformation other) {
        aliases.putAll(other.aliases);
    }

    public void removeAlias(String s) {
        Integer any = aliases.get(s);
        if (any == null)
            return;
        if (any.intValue() < 2) {
            aliases.remove(s);
        } else {
            aliases.put(s, new Integer(any.intValue() - 1));
        }
    }

    public UnqualifiedName buildNewAlias(Name inprefix) {
        Name prefix = inprefix;
        if (inprefix == null)
            prefix = new UnqualifiedName("");
        UnqualifiedName un = prefix.getUnqualified();
        if (un.get().length() >= Singletons.require(DBNative.class).getMaxAliasNameLen()) {
            int maxLenLessSuffix = Singletons.require(DBNative.class).getMaxAliasNameLen() - 4;
            un = shortenAlias(un.get(), maxLenLessSuffix);
        }
        if (addAlias(un.get()))
            return un;
        int suffix = aliases.size() + 1;
        String raw = un.get();
        do {
            un = new UnqualifiedName(raw + "_" + suffix);
            suffix++;
        } while (!addAlias(un.get()));
        return un;
    }

    public boolean isDuplicateAlias(UnqualifiedName unq) {
        return getAliasCount(unq) >= 2;
    }

    public int getAliasCount(UnqualifiedName unq) {
        String n = unq.get();
        Integer count = aliases.get(n);
        return (count == null ? 0 : count.intValue());
    }

    private UnqualifiedName shortenAlias(String unq, int maxLen) {
        StringBuilder buf = new StringBuilder();

        // first look for '_' and pick the character following the '_' to make the alias
        String[] parts = StringUtils.splitByWholeSeparator(unq, "_");
        if (parts.length > 1) {
            buf.append(unq.charAt(0));
            for (String part : parts) {
                buf.append(part.charAt(0));
            }
        } else {
            // pick every other character
            for (int i = 0; i < unq.length(); i++) {
                if ((i & 1) == 0) {
                    buf.append(unq.charAt(i));
                }
            }
        }
        if (buf.length() > maxLen) {
            return shortenAlias(buf.toString(), maxLen);
        }

        return new UnqualifiedName(buf.toString());
    }
}