Added support for #3

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## [0.0.3] - 31/08/2018
 
+- Added one environmental symbol (`$ruleName`)
 - Removed unnecessary output
 
 ## [0.0.2] - 30/08/2018

README.md

@@ -61,6 +61,8 @@ So each clause matches one type of fact, followed by zero or more conditions or
 
   In the above clause, the attribute `amount` is assigned to a symbol with name `$amount`.
 
+  For convenience, the rule name is by default available as `$ruleName`, this can be overwritten. Support for additional variables is planned, but not yet implemented.
+
 - **Conditions**: both sides have to be comparable, and the condition should be true for the clause to finish.
   The environment supports equality for strings, numbers and objects and comparisons for numbers.
 

lib/src/rule.dart

@@ -23,6 +23,7 @@ class Rule {
     bool firstFact = true;
     Map<Clause, Fact> clauseMap = new Map();
     Map<String, dynamic> _symbolTable = new Map();
+    _symbolTable["\$ruleName"] = _name;
 
     var iterator = _clauses.iterator;
     while (iterator.moveNext()) {

test/symbol_test.dart

@@ -0,0 +1,64 @@
+import 'package:rule_engine/src/fact.dart';
+import 'package:rule_engine/rule_engine.dart';
+import 'package:test/test.dart';
+
+void _basicTest() {
+  String code = r"""
+rule "Bob saved some money"
+  when
+    not Achievement( title ==  $ruleName )
+    Expense( amount > 10, $amount: amount )
+  then
+    publish Achievement( "01", $ruleName, $amount )
+end
+""";
+  var ruleEngine = new RuleEngine(code);
+
+  var results = new List();
+  ruleEngine.registerListener((t, a) {
+    if (t == "Achievement") results.add(new Achievement(a[0], a[1], a[2]));
+  });
+
+  ruleEngine.insertFact(new Expense("Bob", 1000, "Cheese", new DateTime.now()));
+  expect(results.length, equals(1));
+  expect(results[0].attributeMap()["title"], "Bob saved some money");
+  ruleEngine.insertFact(new Achievement("01", "Bob saved some money", 100));
+
+  ruleEngine.insertFact(new Expense("Bob", 2000, "Cheese", new DateTime.now()));
+  expect(results.length, equals(1));
+}
+
+void main() {
+  test('Test symbol of rule name', _basicTest);
+}
+
+class Expense extends Fact {
+  Map<String, dynamic> attributes = new Map<String, dynamic>();
+
+  Expense(name, amount, category, created) {
+    attributes["name"] = name;
+    attributes["amount"] = amount;
+    attributes["category"] = category;
+    attributes["created"] = created;
+  }
+
+  @override
+  Map<String, dynamic> attributeMap() {
+    return attributes;
+  }
+}
+
+class Achievement extends Fact {
+  Map<String, dynamic> attributes = new Map<String, dynamic>();
+
+  Achievement(badge, title, descr) {
+    attributes["badge"] = badge;
+    attributes["title"] = title;
+    attributes["descr"] = descr;
+  }
+
+  @override
+  Map<String, dynamic> attributeMap() {
+    return attributes;
+  }
+}