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/*
 * eXist-db Open Source Native XML Database
 * Copyright (C) 2001 The eXist-db Authors
 *
 * [email protected]
 * http://www.exist-db.org
 *
 * 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.exist.xquery;

import org.exist.xquery.value.Type;

/**
 * Holds context information and execution hints for XQuery expressions.
 * Instances of this class are passed to {@link Expression#analyze(AnalyzeContextInfo)}
 * during the analysis phase of the query.
 * 
 * @author wolf
 *
 */
public class AnalyzeContextInfo {

    private XQueryContext context = null;

    private Expression parent = null;
    private int flags = 0;
    private int contextId = Expression.NO_CONTEXT_ID;

    private int staticType = Type.ITEM;
    private int staticReturnType = Type.ITEM;

    private Expression contextStep = null;

    public AnalyzeContextInfo() {
        //Nothing to do
    }

    /**
     * Create a new AnalyzeContextInfo using the given parent and flags.
     * 
     * @param parent the parent expression which calls this method
     * @param flags int value containing a set of flags. See the constants defined
     * in this class.
	 */
    public AnalyzeContextInfo(Expression parent, int flags) {
        this.parent = parent;
        this.flags = flags;
    }

    /**
     * Create a new object as a clone of other.
     * 
     * @param other object to clone
     */
    public AnalyzeContextInfo(AnalyzeContextInfo other) {
        this.parent = other.parent;
        this.flags = other.flags;
        this.contextId = other.contextId;
        this.contextStep = other.contextStep;
        this.staticType = other.staticType;
        this.context = other.context;
    }

    public AnalyzeContextInfo(XQueryContext context) {
        this.context = context;
    }

    public XQueryContext getContext() {
        return context;
    }

    /**
     * Returns the current context id. The context id is used
     * to keep track of the context node set within a predicate
     * expression or where-clause. The id identifies the ancestor 
     * expression to which the context applies.
     * 
     * @return  current context id.
     */
    public int getContextId() {
        return contextId;
    }

    public void setContextId(int contextId) {
        this.contextId = contextId;
    }

    /**
     * Returns the processing flags. Every expression may pass
     * execution hints to its child expressions, encoded as bit flags. 
     * 
     * @return processing flags
     */
    public int getFlags() {
        return flags;
    }

    /**
     * Sets the processing flags to be passed to a child expression.
     * 
     * @param flags processing flags to be passed to child expression
     */
    public void setFlags(final int flags) {
        this.flags = flags;
    }

    public void addFlag(final int flag) {
        flags |= flag;
    }

    public void removeFlag(final int flag) {
        flags &= ~flag;
    }

    /**
     * Determines if a flag is set.
     *
     * @param flag the flag to test for
     *
     * @return true if the flag is set, false otherwise.
     */
    public boolean hasFlag(final int flag) {
        return (flags & flag) == flag;
    }

    /**
     * Returns the parent of the current expression.
     *
     * @return the parent expression
     */
    public Expression getParent() {
        return parent;
    }

    public void setParent(Expression parent) {
        this.parent = parent;
    }

    public int getStaticType() {
        return staticType;
    }

    public void setStaticType(int staticType) {
        this.staticType = staticType;
    }

    public int getStaticReturnType() {
        return staticReturnType;
    }

    public void setStaticReturnType(int type) {
        this.staticReturnType = type;
    }

    public void setContextStep(Expression step) {
        this.contextStep = step;
    }

    public Expression getContextStep() {
        return contextStep;
    }

    public String toString() {
        final StringBuilder buf = new StringBuilder();
        buf.append("ID: ").append(contextId);
        buf.append(" Type: ").append(Type.getTypeName(staticType)).append(" Flags: ");
        if ((flags & Expression.SINGLE_STEP_EXECUTION) > 0)
            {buf.append("single ");}
        if ((flags & Expression.IN_PREDICATE) > 0)
            {buf.append("in-predicate ");}
        if ((flags & Expression.IN_WHERE_CLAUSE) > 0)
            {buf.append("in-where-clause ");}
        if ((flags & Expression.IN_UPDATE) > 0)
            {buf.append("in-update ");}
        if ((flags & Expression.DOT_TEST) > 0)
            {buf.append("dot-test ");}
        buf.append('(').append(flags).append(')');
        return buf.toString();
    }
}