json-rules-engine
Version:
Rules Engine expressed in simple json
255 lines (210 loc) • 8.72 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", {
value: true
});
var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();
var _fact = require('./fact');
var _fact2 = _interopRequireDefault(_fact);
var _errors = require('./errors');
var _debug = require('./debug');
var _debug2 = _interopRequireDefault(_debug);
var _jsonpathPlus = require('jsonpath-plus');
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
function defaultPathResolver(value, path) {
return (0, _jsonpathPlus.JSONPath)({ path: path, json: value, wrap: false });
}
/**
* Fact results lookup
* Triggers fact computations and saves the results
* A new almanac is used for every engine run()
*/
var Almanac = function () {
function Almanac() {
var options = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
_classCallCheck(this, Almanac);
this.factMap = new Map();
this.factResultsCache = new Map(); // { cacheKey: Promise<factValu> }
this.allowUndefinedFacts = Boolean(options.allowUndefinedFacts);
this.pathResolver = options.pathResolver || defaultPathResolver;
this.events = { success: [], failure: [] };
this.ruleResults = [];
}
/**
* Adds a success event
* @param {Object} event
*/
_createClass(Almanac, [{
key: 'addEvent',
value: function addEvent(event, outcome) {
if (!outcome) throw new Error('outcome required: "success" | "failure"]');
this.events[outcome].push(event);
}
/**
* retrieve successful events
*/
}, {
key: 'getEvents',
value: function getEvents() {
var outcome = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : '';
if (outcome) return this.events[outcome];
return this.events.success.concat(this.events.failure);
}
/**
* Adds a rule result
* @param {Object} event
*/
}, {
key: 'addResult',
value: function addResult(ruleResult) {
this.ruleResults.push(ruleResult);
}
/**
* retrieve successful events
*/
}, {
key: 'getResults',
value: function getResults() {
return this.ruleResults;
}
/**
* Retrieve fact by id, raising an exception if it DNE
* @param {String} factId
* @return {Fact}
*/
}, {
key: '_getFact',
value: function _getFact(factId) {
return this.factMap.get(factId);
}
/**
* Registers fact with the almanac
* @param {[type]} fact [description]
*/
}, {
key: '_addConstantFact',
value: function _addConstantFact(fact) {
this.factMap.set(fact.id, fact);
this._setFactValue(fact, {}, fact.value);
}
/**
* Sets the computed value of a fact
* @param {Fact} fact
* @param {Object} params - values for differentiating this fact value from others, used for cache key
* @param {Mixed} value - computed value
*/
}, {
key: '_setFactValue',
value: function _setFactValue(fact, params, value) {
var cacheKey = fact.getCacheKey(params);
var factValue = Promise.resolve(value);
if (cacheKey) {
this.factResultsCache.set(cacheKey, factValue);
}
return factValue;
}
/**
* Add a fact definition to the engine. Facts are called by rules as they are evaluated.
* @param {object|Fact} id - fact identifier or instance of Fact
* @param {function} definitionFunc - function to be called when computing the fact value for a given rule
* @param {Object} options - options to initialize the fact with. used when "id" is not a Fact instance
*/
}, {
key: 'addFact',
value: function addFact(id, valueOrMethod, options) {
var factId = id;
var fact = void 0;
if (id instanceof _fact2.default) {
factId = id.id;
fact = id;
} else {
fact = new _fact2.default(id, valueOrMethod, options);
}
(0, _debug2.default)('almanac::addFact', { id: factId });
this.factMap.set(factId, fact);
if (fact.isConstant()) {
this._setFactValue(fact, {}, fact.value);
}
return this;
}
/**
* Adds a constant fact during runtime. Can be used mid-run() to add additional information
* @deprecated use addFact
* @param {String} fact - fact identifier
* @param {Mixed} value - constant value of the fact
*/
}, {
key: 'addRuntimeFact',
value: function addRuntimeFact(factId, value) {
(0, _debug2.default)('almanac::addRuntimeFact', { id: factId });
var fact = new _fact2.default(factId, value);
return this._addConstantFact(fact);
}
/**
* Returns the value of a fact, based on the given parameters. Utilizes the 'almanac' maintained
* by the engine, which cache's fact computations based on parameters provided
* @param {string} factId - fact identifier
* @param {Object} params - parameters to feed into the fact. By default, these will also be used to compute the cache key
* @param {String} path - object
* @return {Promise} a promise which will resolve with the fact computation.
*/
}, {
key: 'factValue',
value: function factValue(factId) {
var _this = this;
var params = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};
var path = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : '';
var factValuePromise = void 0;
var fact = this._getFact(factId);
if (fact === undefined) {
if (this.allowUndefinedFacts) {
return Promise.resolve(undefined);
} else {
return Promise.reject(new _errors.UndefinedFactError('Undefined fact: ' + factId));
}
}
if (fact.isConstant()) {
factValuePromise = Promise.resolve(fact.calculate(params, this));
} else {
var cacheKey = fact.getCacheKey(params);
var cacheVal = cacheKey && this.factResultsCache.get(cacheKey);
if (cacheVal) {
factValuePromise = Promise.resolve(cacheVal);
(0, _debug2.default)('almanac::factValue cache hit for fact', { id: factId });
} else {
(0, _debug2.default)('almanac::factValue cache miss, calculating', { id: factId });
factValuePromise = this._setFactValue(fact, params, fact.calculate(params, this));
}
}
if (path) {
(0, _debug2.default)('condition::evaluate extracting object', { property: path });
return factValuePromise.then(function (factValue) {
if (factValue != null && (typeof factValue === 'undefined' ? 'undefined' : _typeof(factValue)) === 'object') {
var pathValue = _this.pathResolver(factValue, path);
(0, _debug2.default)('condition::evaluate extracting object', { property: path, received: pathValue });
return pathValue;
} else {
(0, _debug2.default)('condition::evaluate could not compute object path of non-object', { path: path, factValue: factValue, type: typeof factValue === 'undefined' ? 'undefined' : _typeof(factValue) });
return factValue;
}
});
}
return factValuePromise;
}
/**
* Interprets value as either a primitive, or if a fact, retrieves the fact value
*/
}, {
key: 'getValue',
value: function getValue(value) {
if (value != null && (typeof value === 'undefined' ? 'undefined' : _typeof(value)) === 'object' && Object.prototype.hasOwnProperty.call(value, 'fact')) {
// value = { fact: 'xyz' }
return this.factValue(value.fact, value.params, value.path);
}
return Promise.resolve(value);
}
}]);
return Almanac;
}();
exports.default = Almanac;