query.java

JoSQL 1.5的源代码。JoSQL(SQL for Java Objects)为Java开发者提供运用SQL语句来操作Java对象集的能力.利用JoSQL可以像操作数据库中的数据一样对任何Java

/*
 * Copyright 2004-2005 Gary Bentley 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may 
 * not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 *    http://www.apache.org/licenses/LICENSE-2.0 
 *
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 */
package org.josql;

import java.io.File;
import java.io.StringReader;
import java.io.BufferedReader;

import java.util.Map;
import java.util.HashMap;
import java.util.SortedMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.util.Iterator;
import java.util.Collections;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Set;
import java.util.LinkedHashSet;
import java.util.Collection;

import org.josql.parser.JoSQLParser;

import org.josql.expressions.*;

import org.josql.functions.*;

import org.josql.internal.*;

import org.josql.events.*;

/** 
 * This class provides the ability for a developer to apply an arbitrary SQL statement
 * (using suitable syntax) to a collection of Java objects.
 * <p>
 * Basic usage:
 * <pre>
 *   Query q = new Query ();
 *   q.parse (myStatement);
 *   List results = q.execute (myObjects);
 * </pre>
 * <p>
 * An example statement would look like:
 * <pre>
 *   SELECT lastModified,
 *          name
 *   FROM   java.io.File
 *   WHERE  name LIKE '%.html'
 * </pre>
 * <p>
 * The JoSQL functionality is large and complex, whilst basic queries like the one above are
 * perfectly possible, very complex queries are also possible, for example:
 * <pre>
 *   SELECT name,
 *          formatDate(lastModified),
 *          formatNumber(length),
 *          formatNumber(length - @avg_length),
 *          formatTimeDuration(@max_last_modified - lastModified)
 *   FROM   java.io.File
 *   WHERE  lastModified > @avg_last_modified
 *   AND    length > @avg_length
 *   AND    lower(name) LIKE '%.html'
 *   GROUP BY path
 *   ORDER BY name, lastModified DESC
 *   EXECUTE ON ALL avg (:_allobjs, length) avg_length,
 *                  avg (:_allobjs, lastModified) avg_last_modified,
 *                  max (:_allobjs, lastModified) max_last_modified
 * </pre>
 * <p>
 * Note: the "EXECUTE ON ALL" syntax is an extension used by JoSQL because it has no notion
 * of "aggregate functions".
 * <p>
 * For full details of how a query works and what is possible, see the 
 * <a href="http://josql.sourceforge.net/manual/index.html">JoSQL User Manual</a>.
 * <p>
 * Please note that the package structure for JoSQL is deliberate, JoSQL is designed to be a 
 * black box and lightweight thus only the <code>Query</code> object and associated exceptions
 * are exposed in the main package.  Also, the class structure for JoSQL is not designed to 
 * exactly represent the SQL statement passed to it, rather the classes are optimised for
 * ease of execution of the statement.  If you wish to have a completely accurate Java object
 * view of ANY SQL statement then please see: 
 *   <a href="http://sourceforge.net/projects/jsqlparser">JSqlParser</a>
 * which will provide what you need.
 */
public class Query
{

    public static String QUERY_BIND_VAR_NAME = "_query";
    public static String PARENT_BIND_VAR_NAME = "_parent";
    public static String CURR_OBJ_VAR_NAME = "_currobj";
    public static String ALL_OBJS_VAR_NAME = "_allobjs";
    public static String GRPBY_OBJ_VAR_NAME = "_grpby";
    public static String GRPBY_OBJ_VAR_NAME_SYNONYM = "_groupby";
    public static final String INT_BIND_VAR_PREFIX = "^^^";

    public static final String ALL = "ALL";
    public static final String RESULTS = "RESULTS";
    public static final String GROUP_BY_RESULTS = "GROUP_BY_RESULTS";
    public static final String WHERE_RESULTS = "WHERE_RESULTS";
    public static final String HAVING_RESULTS = "HAVING_RESULTS";

    public static final String ORDER_BY_ASC = "ASC";
    public static final String ORDER_BY_DESC = "DESC";

    public static final List nullQueryList = new ArrayList ();

    static
    {

	Query.nullQueryList.add (new Object ());

    }

    private List bfhs = new ArrayList ();
    private Map bfhsMap = new HashMap ();

    private char wildcardChar = '%';

    private Map aliases = new HashMap ();
    private List groupBys = null;
    private Comparator orderByComp = null;
    private Comparator groupOrderByComp = null;
    private Grouper grouper = null;
    private List orderBys = null;
    private List groupOrderBys = null;
    private List cols = null;
    private boolean retObjs = false;
    private Expression where = null;
    private Expression having = null;
    private Map bindVars = null;
    private String query = null;
    private boolean wantTimings = false;
    private List functionHandlers = null;
    private int anonVarIndex = 1;
    private Expression from = null;
    private Class objClass = null;
    private Limit limit = null;
    private Limit groupByLimit = null;
    private Map executeOn = null;
    private boolean isParsed = false;
    private boolean distinctResults = false;
    private ClassLoader classLoader = null;
    private Query parent = null;
    private Map listeners = new HashMap ();

    // Execution data.
    private transient Object currentObject = null;
    private transient List allObjects = null;
    private transient List currGroupBys = null;

    private QueryResults qd = null;

    /**
     * Return the WHERE clause expression.
     *
     * @return The WHERE clause as an expression.
     */
    public Expression getWhereClause ()
    {

	return this.where;

    }

    /**
     * Return the HAVING clause expression.
     *
     * @return The HAVING clause as an expression.
     */
    public Expression getHavingClause ()
    {

	return this.having;

    }

    /**
     * Return the {@link Comparator} we will use to do the ordering of the results, may be null.
     *
     * @return The Comparator.
     */
    public Comparator getOrderByComparator ()
    {

	return this.orderByComp;

    }

    public FunctionHandler getFunctionHandler (String id)
    {

	if (this.parent != null)
	{

	    return this.parent.getFunctionHandler (id);

	}

	return (FunctionHandler) this.bfhsMap.get (id);

    }

    private void initFunctionHandlers ()
    {

	FunctionHandler o = new CollectionFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (CollectionFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

	o = new StringFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (StringFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

	o = new ConversionFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (ConversionFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

	o = new FormattingFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (FormattingFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

	o = new GroupingFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (GroupingFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

	o = new MiscellaneousFunctions ();
	o.setQuery (this);

	this.bfhsMap.put (MiscellaneousFunctions.HANDLER_ID,
			  o);

	this.bfhs.add (o);

    }

    public Map getExecuteOnFunctions ()
    {

	return this.executeOn;

    }

    public void setExecuteOnFunctions (Map ex)
    {

	this.executeOn = ex;

    }

    public String getAnonymousBindVariableName ()
    {

	if (this.parent != null)
	{

	    return this.parent.getAnonymousBindVariableName ();

	}

	String n = Query.INT_BIND_VAR_PREFIX + this.anonVarIndex;

	this.anonVarIndex++;

	return n;

    }

    public List getDefaultFunctionHandlers ()
    {

	if (this.parent != null)
	{

	    return this.parent.getDefaultFunctionHandlers ();

	}

	return new ArrayList (this.bfhs);

    }

    public List getFunctionHandlers ()
    {

	if (this.parent != null)
	{

	    return this.parent.getFunctionHandlers ();

	}

	return this.functionHandlers;

    }

    public void addFunctionHandler (Object o)
    {

	if (this.parent != null)
	{

	    this.parent.addFunctionHandler (o);

	}

	if (this.functionHandlers == null)
	{

	    this.functionHandlers = new ArrayList ();

	}

	if (o instanceof FunctionHandler)
	{

	    FunctionHandler fh = (FunctionHandler) o;

	    fh.setQuery (this);

	}

	this.functionHandlers.add (o);

    }

    public void setFrom (Expression exp)
    {

	this.from = exp;

    }

    public Expression getFrom ()
    {

	return this.from;

    }

    public void setClassName (String n)
    {

	ConstantExpression ce = new ConstantExpression ();
	this.from = ce;
	ce.setValue (n);

    }

    public void setOrderByColumns (List cols)
    {

	this.orderBys = cols;

    }

    public void setGroupByLimit (Limit g)
    {

	this.groupByLimit = g;

    }

    public void setGroupByOrderColumns (List cols)
    {

	this.groupOrderBys = cols;

    }

    public List getGroupByColumns ()
    {

	return this.groupBys;

    }

    public void setGroupByColumns (List cols)
    {

	this.groupBys = cols;

    }

    public List getColumns ()
    {

	return this.cols;

    }

    public void setColumns (List cols)
    {

	this.cols = cols;

    }

    public void setHaving (Expression be)
    {

	this.having = be;

    }

    public void setWhere (Expression be)
    {

	this.where = be;

    }

    public Query ()
    {

	this.initFunctionHandlers ();

    }

    public void setWantTimings (boolean v)
    {

	this.wantTimings = v;

    }

    protected void addTiming (String id,
			      double time)
    {

	if (this.wantTimings)
	{

	    if (this.qd == null)
	    {

		return;

	    }

	    if (this.qd.timings == null)
	    {

		this.qd.timings = new LinkedHashMap ();

	    }

	    this.qd.timings.put (id,
				 new Double (time));

	}

    }

    public Object getVariable (int index)
    {

	if (this.parent != null)
	{

	    return this.parent.getVariable (index);

	}

	return this.getVariable (Query.INT_BIND_VAR_PREFIX + index);

    }

    public Class getVariableClass (String name)
    {

	String n = name.toLowerCase ();

	if (n.equals (Query.QUERY_BIND_VAR_NAME))
	{

	    // Return the query itself!
	    return Query.class;

	}

	if (n.equals (Query.PARENT_BIND_VAR_NAME))
	{

	    // Return the query itself!
	    return Query.class;

	}

	if (n.equals (Query.CURR_OBJ_VAR_NAME))
	{

	    // May be null if we aren't processing a while/having expression.
	    return this.objClass;

	}

	if (n.equals (Query.ALL_OBJS_VAR_NAME))
	{

	    // May change depending upon when it is called.
	    return List.class;

	}

	if (this.parent != null)
	{

	    return this.parent.getVariableClass (n);

	}

	if (this.bindVars == null)
	{

	    return Object.class;

	}

	Object v = (Object) this.bindVars.get (n);

	if (v == null)
	{

	    return Object.class;

	}

	return v.getClass ();

    }

    public Object getGroupByVariable (int ind)
    {

	// Get the current group bys.
	if (this.currGroupBys != null)
	{

	    return this.currGroupBys.get (ind - 1);

	}

	return null;

    }

    public Object getVariable (String name)
    {

	String n = name.toLowerCase ();

	if (n.equals (Query.QUERY_BIND_VAR_NAME))
	{

	    // Return the query itself!
	    return this;

	}

	if (n.equals (Query.PARENT_BIND_VAR_NAME))
	{

	    // Return the parent query.
	    return this.parent;

	}

	if (n.equals (Query.CURR_OBJ_VAR_NAME))
	{

	    // May be null if we aren't processing a while/having expression.
	    return this.currentObject;

	}

	if (n.equals (Query.ALL_OBJS_VAR_NAME))
	{

	    // May change depending upon when it is called.
	    return this.allObjects;

	}

	if (this.parent != null)
	{

	    return this.parent.getVariable (name);

	}

	if (this.bindVars == null)
	{

	    return null;

	}

	return this.bindVars.get (n);

    }    

    public void setVariable (String name,
			     Object v)
    {

	if (this.parent != null)
	{

	    this.parent.setVariable (name,
				     v);

	    return;

	}

	if (this.bindVars == null)
	{

	    this.bindVars = new HashMap ();

	}

	this.bindVars.put (name.toLowerCase (),
			   v);

    }

    public void setVariable (int    index,
			     Object v)
    {

	if (this.parent != null)
	{

	    this.parent.setVariable (index,
				     v);

	    return;

	}

	this.setVariable (Query.INT_BIND_VAR_PREFIX + index,
			  v);

    }

    public Map getVariables ()
    {

	if (this.parent != null)
	{

	    return this.parent.getVariables ();

	}

	return this.bindVars;

    }

    public boolean isWhereTrue (Object o)
                                throws QueryExecutionException 
    {

	if (this.where == null)
	{

	    // A null where means yes!