/*
* JBoss, Home of Professional Open Source.
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership. Some portions may be licensed
* to Red Hat, Inc. under one or more contributor license agreements.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA.
*/
package org.teiid.query.sql.lang;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import org.teiid.core.util.EquivalenceUtil;
import org.teiid.core.util.HashCodeUtil;
import org.teiid.query.sql.LanguageObject;
import org.teiid.query.sql.LanguageVisitor;
import org.teiid.query.sql.symbol.AllInGroupSymbol;
import org.teiid.query.sql.symbol.AllSymbol;
import org.teiid.query.sql.symbol.ElementSymbol;
import org.teiid.query.sql.symbol.GroupSymbol;
import org.teiid.query.sql.symbol.MultipleElementSymbol;
import org.teiid.query.sql.symbol.SelectSymbol;
import org.teiid.query.sql.symbol.SingleElementSymbol;
import org.teiid.query.sql.visitor.SQLStringVisitor;
/**
* This class represents the SELECT clause of a query, which defines what elements
* or expressions are returned from the query.
*/
public class Select implements LanguageObject {
/** The set of symbols for the data elements to be selected. */
private List symbols; // List<SelectSymbols>
/** Flag for whether duplicate removal should be performed on the results */
private boolean distinct;
// =========================================================================
// C O N S T R U C T O R S
// =========================================================================
/**
* Constructs a default instance of this class.
*/
public Select() {
symbols = new ArrayList();
}
/**
* Constructs an instance of this class from an ordered set of symbols.
* @param symbols The ordered list of symbols
*/
public Select( List symbols ) {
this.symbols = new ArrayList( symbols );
}
// =========================================================================
// M E T H O D S
// =========================================================================
/**
* Returns the number of symbols in select.
* @return Get count of number of symbols in select
*/
public int getCount() {
return symbols.size();
}
/**
* Checks for a Select * clause
* @return True if Select * is used
*/
public boolean isStar() {
return (symbols.size() == 1 && symbols.get(0) instanceof AllSymbol);
}
/**
* Returns an ordered list of the symbols in the select.
* @param Get list of SelectSymbol in SELECT
*/
public List getSymbols() {
return symbols;
}
/**
* Sets an ordered list of the symbols in the select.
* @param symbols list of SelectSymbol in SELECT
*/
public void setSymbols(List symbols) {
this.symbols = symbols;
}
/**
* Returns the select symbol at the specified index.
* @param index Index to get
* @return The variable identifier at the index
*/
public SelectSymbol getSymbol( int index ) {
return (SelectSymbol) symbols.get(index);
}
/**
* Adds a new symbol to the list of symbols.
* @param symbol New symbol
*/
public void addSymbol( SelectSymbol symbol ) {
if(symbol != null) {
symbols.add(symbol);
}
}
/**
* Adds a new collection of symbols to the list of symbols.
* @param symbols Collection of SelectSymbols
*/
public void addSymbols( Collection symbols) {
if(symbols != null) {
this.symbols.addAll(symbols);
}
}
/**
* Remove all current symbols
*/
public void clearSymbols() {
symbols.clear();
}
/**
* Checks if a symbol is in the Select.
* @param symbol Symbol to check for
* @return True if the Select contains the symbol
*/
public boolean containsSymbol( SelectSymbol symbol ) {
return symbols.contains(symbol);
}
/**
* Check is the element symbol is being selected by this
* select clause. This includes checking for select start
* and select group.star for the group of this element symbol.
* ElementSymbol is assumed to be fully resolved.
* @param elementSymbol fully resolved ElementSymbol
* @return whether this select will select the element symbol
*/
public boolean isElementBeingSelected(ElementSymbol elementSymbol){
boolean isBeingSelected = this.containsSymbol(elementSymbol);
if (!isBeingSelected){
GroupSymbol g = elementSymbol.getGroupSymbol();
String groupDotStarName = g.getName() + ".*"; //$NON-NLS-1$
Iterator i = this.getSymbols().iterator();
while (i.hasNext()) {
Object selectSymbol = i.next();
if (selectSymbol instanceof AllSymbol){
isBeingSelected = true;
break;
} else if (selectSymbol instanceof AllInGroupSymbol){
AllInGroupSymbol aigSymbol = (AllInGroupSymbol)selectSymbol;
if (aigSymbol.getName().equalsIgnoreCase(groupDotStarName)){
isBeingSelected = true;
break;
}
}
}
}
return isBeingSelected;
}
/**
* Set whether select is distinct.
* @param isDistinct True if SELECT is distinct
*/
public void setDistinct(boolean isDistinct) {
this.distinct = isDistinct;
}
/**
* Checks whether the select is distinct
* @return True if select is distinct
*/
public boolean isDistinct() {
return this.distinct;
}
public void acceptVisitor(LanguageVisitor visitor) {
visitor.visit(this);
}
/**
* Get the ordered list of all elements returned by this select. These elements
* may be ElementSymbols or ExpressionSymbols but in all cases each represents a
* single column.
* @return Ordered list of SingleElementSymbol
*/
public List<SingleElementSymbol> getProjectedSymbols() {
ArrayList<SingleElementSymbol> projectedSymbols = new ArrayList<SingleElementSymbol>();
Iterator iter = symbols.iterator();
while(iter.hasNext()) {
SelectSymbol symbol = (SelectSymbol) iter.next();
if(symbol instanceof SingleElementSymbol) {
projectedSymbols.add((SingleElementSymbol)symbol);
} else {
List<ElementSymbol> multiSymbols = ((MultipleElementSymbol)symbol).getElementSymbols();
if(multiSymbols != null) {
projectedSymbols.addAll(multiSymbols);
}
}
}
return projectedSymbols;
}
// =========================================================================
// O V E R R I D D E N O B J E C T M E T H O D S
// =========================================================================
/**
* Return a deep copy of this Select.
* @return Deep clone
*/
public Object clone() {
List thisSymbols = getSymbols();
List copySymbols = new ArrayList(thisSymbols.size());
Iterator iter = thisSymbols.iterator();
while(iter.hasNext()) {
SelectSymbol ss = (SelectSymbol) iter.next();
copySymbols.add(ss.clone());
}
Select copy = new Select(copySymbols);
copy.setDistinct( isDistinct() );
return copy;
}
/**
* Compare two Selects for equality. Order is important in the select (for
* determining the order of the returned columns), so this is a compare
* with order, not just a set comparison.
* @param obj Other object
* @return True if equal
*/
public boolean equals(Object obj) {
if(obj == this) {
return true;
}
if(!(obj instanceof Select)) {
return false;
}
Select other = (Select) obj;
return other.isDistinct() == isDistinct() &&
EquivalenceUtil.areEqual(getSymbols(), other.getSymbols());
}
/**
* Get hashcode for Select. WARNING: The hash code relies on the variables
* in the select, so changing the variables will change the hash code, causing
* a select to be lost in a hash structure. Do not hash a Select if you plan
* to change it.
* @return Hash code
*/
public int hashCode() {
return HashCodeUtil.hashCode(0, getSymbols());
}
/**
* Returns a string representation of an instance of this class.
* @return String representation of object
*/
public String toString() {
return SQLStringVisitor.getSQLString(this);
}
} // END CLASS