/*
 * eXist Open Source Native XML Database
 * Copyright (C) 2001-2007 The eXist Project
 * http://exist-db.org
 *
 * This program 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
 * of the License, or (at your option) any later version.
 *  
 * 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *  
 *  $Id$
 */
package org.exist.xquery;

import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;
import org.exist.xquery.value.ValueSequence;

import java.util.Iterator;

/**
 * An XQuery sequence constructor ",". For example, ($a, $b) constructs a new
 * sequence containing items $a and $b.
 * 
 * @author wolf
 */
public class SequenceConstructor extends PathExpr {
	
	/**
	 * @param context
	 */
	public SequenceConstructor(XQueryContext context) {
		super(context);
	}
	
    public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
        contextInfo.setParent(this);
        inPredicate = (contextInfo.getFlags() & IN_PREDICATE) > 0;
        contextId = contextInfo.getContextId();

        int staticType = Type.ANY_TYPE;
        for (int i = 0; i < steps.size(); i++) {
            Expression expr = steps.get(i);
            //Create a new context info because each sequence expression could modify it (add/remove flags...)
            AnalyzeContextInfo info = new AnalyzeContextInfo(contextInfo);
            expr.analyze(info);
            if (staticType == Type.ANY_TYPE)
                staticType = info.getStaticReturnType();
            else if (staticType != Type.ITEM && staticType != info.getStaticReturnType())
                staticType = Type.ITEM;
        }
        contextInfo.setStaticReturnType(staticType);
    }
    
	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
	 */
	public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
        if (context.getProfiler().isEnabled()) {
            context.getProfiler().start(this);       
            context.getProfiler().message(this, Profiler.DEPENDENCIES, "DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
            if (contextSequence != null)
                context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT SEQUENCE", contextSequence);
            if (contextItem != null)
                context.getProfiler().message(this, Profiler.START_SEQUENCES, "CONTEXT ITEM", contextItem.toSequence());
        }
        
        ValueSequence result = new ValueSequence();
        for(Iterator i = steps.iterator(); i.hasNext(); ) {
            context.pushDocumentContext();
            try {
                Sequence temp = ((Expression)i.next()).eval(contextSequence, contextItem);
                if(temp != null && !temp.isEmpty()) {
                      result.addAll(temp);
                }
            } finally {
                context.popDocumentContext();
            }
        } 
		
        if (context.getProfiler().isEnabled()) 
            context.getProfiler().end(this, "", result);
        
		return result;
	}

	/* (non-Javadoc)
     * @see org.exist.xquery.PathExpr#dump(org.exist.xquery.util.ExpressionDumper)
     */
    public void dump(ExpressionDumper dumper) {
        dumper.display("(");
        dumper.startIndent();
    	boolean moreThanOne = false;
        for(Iterator i = steps.iterator(); i.hasNext(); ) {
            if (moreThanOne) dumper.display(", ");
        	moreThanOne = true;
            ((Expression) i.next()).dump(dumper);
        }
        dumper.endIndent();
        dumper.nl().display(")");
    }
    
    public String toString() {
    	StringBuilder result = new StringBuilder();
    	result.append("( ");
    	boolean moreThanOne = false;
        for(Iterator i = steps.iterator(); i.hasNext(); ) {
        	if (moreThanOne) result.append(", ");
        	moreThanOne = true;
        	result.append(((Expression) i.next()).toString());        	
        }        
        result.append(" )");
        return result.toString();
    }    
    
	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#returnsType()
	 */
	public int returnsType() {
		return Type.ITEM;
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.AbstractExpression#getCardinality()
	 */
	public int getCardinality() {
		return Cardinality.ZERO_OR_MORE;
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.AbstractExpression#resetState()
	 */
	public void resetState(boolean postOptimization) {
		super.resetState(postOptimization);
	}
}