fundef.java

来自「数据仓库展示程序」· Java 代码 · 共 91 行

/*
// $Id: //open/mondrian/src/main/mondrian/olap/FunDef.java#11 $
// This software is subject to the terms of the Common Public License
// Agreement, available at the following URL:
// http://www.opensource.org/licenses/cpl.html.
// (C) Copyright 1999-2005 Kana Software, Inc. and others.
// All Rights Reserved.
// You must accept the terms of that agreement to use this software.
//
// jhyde, 21 April, 1999
*/

package mondrian.olap;

import java.io.PrintWriter;

/**
 * <code>FunDef</code> is the definition of an MDX function. See also {@link
 * FunTable}.
 **/
public interface FunDef {
    /**
     * Returns the syntactic type of the function. */
    Syntax getSyntax();

    /**
     * Returns the name of this function.
     **/
    String getName();

    /**
     * Returns the description of this function.
     **/
    String getDescription();

    /**
     * Returns the {@link Category} code of the value returned by this
     * function.
     **/
    int getReturnCategory();

    /**
     * Returns the types of the arguments of this function. Values are the same
     * as those returned by {@link Exp#getType}. The 0<sup>th</sup>
     * argument of methods and properties are the object they are applied
     * to. Infix operators have two arguments, and prefix operators have one
     * argument.
     **/
    int[] getParameterTypes();

    /**
     * Validates a call to this function.
     * <p/>
     * If it returns the <code>call</code> argument (which is the usual case)
     * it must call {@link FunCall#setType(mondrian.olap.type.Type)}.
     */
    Exp validateCall(Validator validator, FunCall call);

    /**
     * Returns an English description of the signature of the function, for
     * example "&lt;Numeric Expression&gt; / &lt;Numeric Expression&gt;".
     **/
    String getSignature();

    /**
     * Converts a function call into source code.
     **/
    void unparse(Exp[] args, PrintWriter pw);

    /**
     * Applies this function to a set of arguments in the context provided
     * by an evaluator, and returns the result.
     **/
    Object evaluate(Evaluator evaluator, Exp[] args);

    /**
     * Computes how the result of the function depends on members
     * of the dimension. For example, the add operation "+" has two
     * arguments. If one argument depends on Customers and the other
     * depends on Products, the result will depend on both (union of
     * dependencies).
     * <p>
     * For <code>Tuple</code>, <code>Filter</code> and some other functions
     * this is not true. They must compute the intersection. TopCount has to
     * omit its Count argument etc.
     */
    boolean callDependsOn(FunCall call, Dimension dimension);
}

// End FunDef.java