@pru-rt/spel2js/src/ast/FunctionReference.js

Parse Spring Expression Language in JavaScript

/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {SpelNode} from './SpelNode';

/**
 * A function reference is of the form "#someFunction(a,b,c)". Functions may be defined in
 * the context prior to the expression being evaluated or within the expression itself
 * using a lambda function definition. For example: Lambda function definition in an
 * expression: "(#max = {|x,y|$x>$y?$x:$y};max(2,3))" Calling context defined function:
 * "#isEven(37)". Functions may also be static java methods, registered in the context
 * prior to invocation of the expression.
 *
 * <p>Functions are very simplistic, the arguments are not part of the definition (right
 * now), so the names must be unique.
 *
 * @author Andy Clement
 * @author Ben March
 * @since 0.2.0
 */

function createNode(parent, functionName) {
    var node = SpelNode.create('method', parent);

    node.getValue = function () {
        var refNode = node,
            context = null;
        do {
            if (refNode.getParent()) {
                refNode = refNode.getParent();
            } else {
                context = refNode.getContext();
            }
        } while (refNode);
        if (context[functionName]) {
            return context[functionName].call(context);
        }
        throw {
            name: 'FunctionDoesNotExistException',
            message: 'Function \'' + functionName + '\' does not exist.'
        };
    };

    return node;
}

export var FunctionReference =  {
    create: createNode
};