@gmsoft/spel2js/src/ast/MethodReference.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';
import { Stack } from '../lib/Stack';

/**
 * Expression language AST node that represents a method reference.
 *
 * @author Andy Clement
 * @author Juergen Hoeller
 * @author Ben March
 * @since 0.2.0
 */

function createNode(nullSafeNavigation, methodName, position, args) {
  var node = SpelNode.create('method', position);

  node.getValue = function (state) {
    var context = state.activeContext.peek(),
      compiledArgs = [],
      method;

    if (!context) {
      throw {
        name: 'ContextDoesNotExistException',
        message: "Attempting to look up property '" + methodName + "' for an undefined context.",
      };
    }

    //handle safe navigation
    function maybeHandleNullSafeNavigation(member) {
      if (member === undefined || member === null) {
        if (nullSafeNavigation) {
          return null;
        }

        throw {
          name: 'NullPointerException',
          message: 'Method ' + methodName + ' does not exist.',
        };
      }

      return member;
    }

    //populate arguments
    args.forEach(function (arg) {
      // reset the active context to root context for evaluating argument
      const currentActiveContext = state.activeContext;
      state.activeContext = new Stack();
      state.activeContext.push(state.rootContext);

      // evaluate argument
      compiledArgs.push(arg.getValue(state));

      // reset the active context
      state.activeContext = currentActiveContext;
    });

    //accessors might not be available
    if (methodName.substr(0, 3) === 'get' && !context[methodName]) {
      return maybeHandleNullSafeNavigation(
        context[methodName.charAt(3).toLowerCase() + methodName.substring(4)]
      );
    }
    if (methodName.substr(0, 3) === 'set' && !context[methodName]) {
      /*jshint -W093 */
      return (context[methodName.charAt(3).toLowerCase() + methodName.substring(4)] =
        compiledArgs[0]);
      /*jshint +W093 */
    }

    //array methods
    if (Array.isArray(context)) {
      //size() -> length
      if (methodName === 'size') {
        return context.length;
      }

      if (methodName === 'contains') {
        return context.includes(compiledArgs[0]);
      }
    }

    method = maybeHandleNullSafeNavigation(context[methodName]);
    if (method) {
      return method.apply(context, compiledArgs);
    }
    return null;
  };

  return node;
}

export var MethodReference = {
  create: createNode,
};