/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
package com.espertech.esper.client.soda;
import java.io.Serializable;
import java.io.StringWriter;
import java.util.List;
/**
* Interface representing an expression for use in select-clauses, where-clauses, having-clauses, order-by clauses and
* streams based on filters and pattern filter expressions.
* <p>
* Expressions are organized into a tree-like structure with nodes representing sub-expressions.
* <p>
* Certain types of nodes have certain requirements towards the number or types of nodes that
* are expected as sub-expressions to an expression.
*/
public interface Expression extends Serializable {
/**
* Returns the list of sub-expressions (child expressions) to the current expression node.
*
* @return child expressions or empty list if there are no child expressions
*/
public List<Expression> getChildren();
/**
* Sets the list of sub-expressions (child expressions) to the current expression node.
*
* @param children child expressions or empty list if there are no child expressions
*/
public void setChildren(List<Expression> children);
/**
* Returns the tree of object name, for use by tools to assign an identifier to an expression.
*
* @return tree object id
*/
public String getTreeObjectName();
/**
* Sets the tree of object name, for use by tools to assign an identifier to an expression.
*
* @param objectName tree object id
*/
public void setTreeObjectName(String objectName);
/**
* Returns precedence.
*
* @return precedence
*/
public ExpressionPrecedenceEnum getPrecedence();
/**
* Write expression considering precedence.
*
* @param writer to use
* @param parentPrecedence precedence
*/
public void toEPL(StringWriter writer, ExpressionPrecedenceEnum parentPrecedence);
}