add static analyzer to engine for no rules warning

src/engine/Engine.js

@@ -6,6 +6,7 @@
 const lpsRequire = require('../lpsRequire');
 const LiteralTreeMap = lpsRequire('engine/LiteralTreeMap');
 const FunctorProvider = lpsRequire('engine/FunctorProvider');
+const StaticAnalyzer = lpsRequire('engine/StaticAnalyzer');
 
 const processRules = lpsRequire('utility/processRules');
 const goalTreeSorter = lpsRequire('utility/goalTreeSorter');
@@ -704,6 +705,7 @@ function Engine(programArg) {
  // we preprocess some of the built-in processors by looking at the facts
  // of the _program.
  this.on('loaded', () => {
+ StaticAnalyzer.analyze(_program, _engineEventManager);
  settingsProcessor(this, _program);
  timableProcessor(this, _program);
  initiallyProcessor(this, _program);

src/engine/StaticAnalyzer.js

@@ -0,0 +1,26 @@
+/*
+ This file is part of the lps.js project, released open source under
+ the BSD 3-Clause license. For more info, please see https://github.com/mauris/lps.js
+ */
+
+const lpsRequire = require('../lpsRequire');
+const stringLiterals = lpsRequire('utility/strings');
+
+const WARNING_EVENT = 'warning';
+
+function StaticAnalyzer() {
+}
+
+StaticAnalyzer.analyze = function (program, eventManager) {
+ const rules = program.getRules();
+ if (rules.length === 0) {
+ eventManager.notify(WARNING_EVENT, {
+ type: 'rule.empty',
+ message: stringLiterals(
+ 'engine.analyzer.noRules'
+ )
+ });
+ }
+};
+
+module.exports = StaticAnalyzer;