Flee

CalcEngine/PublicTypes/SimpleCalcEngine.cs

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+using Flee.CalcEngine.InternalTypes;
+using Flee.PublicTypes;
+
+namespace Flee.CalcEngine.PublicTypes
+{
+    public class SimpleCalcEngine
+    {
+
+        #region "Fields"
+
+        private readonly IDictionary<string, IExpression> _myExpressions;
+
+        private ExpressionContext _myContext;
+        #endregion
+
+        #region "Constructor"
+
+        public SimpleCalcEngine()
+        {
+            _myExpressions = new Dictionary<string, IExpression>(StringComparer.OrdinalIgnoreCase);
+            _myContext = new ExpressionContext();
+        }
+
+        #endregion
+
+        #region "Methods - Private"
+
+        private void AddCompiledExpression(string expressionName, IExpression expression)
+        {
+            if (_myExpressions.ContainsKey(expressionName) == true)
+            {
+                throw new InvalidOperationException($"The calc engine already contains an expression named '{expressionName}'");
+            }
+            else
+            {
+                _myExpressions.Add(expressionName, expression);
+            }
+        }
+
+        private ExpressionContext ParseAndLink(string expressionName, string expression)
+        {
+            IdentifierAnalyzer analyzer = Context.ParseIdentifiers(expression);
+
+            ExpressionContext context2 = _myContext.CloneInternal(true);
+            this.LinkExpression(expressionName, context2, analyzer);
+
+            // Tell the expression not to clone the context since it's already been cloned
+            context2.NoClone = true;
+
+            // Clear our context's variables
+            _myContext.Variables.Clear();
+
+            return context2;
+        }
+
+        private void LinkExpression(string expressionName, ExpressionContext context, IdentifierAnalyzer analyzer)
+        {
+            foreach (string identifier in analyzer.GetIdentifiers(context))
+            {
+                this.LinkIdentifier(identifier, expressionName, context);
+            }
+        }
+
+        private void LinkIdentifier(string identifier, string expressionName, ExpressionContext context)
+        {
+            IExpression child = null;
+
+            if (_myExpressions.TryGetValue(identifier, out child) == false)
+            {
+                string msg = $"Expression '{expressionName}' references unknown name '{identifier}'";
+                throw new InvalidOperationException(msg);
+            }
+
+            context.Variables.Add(identifier, child);
+        }
+
+        #endregion
+
+        #region "Methods - Public"
+
+        public void AddDynamic(string expressionName, string expression)
+        {
+            ExpressionContext linkedContext = this.ParseAndLink(expressionName, expression);
+            IExpression e = linkedContext.CompileDynamic(expression);
+            this.AddCompiledExpression(expressionName, e);
+        }
+
+        public void AddGeneric<T>(string expressionName, string expression)
+        {
+            ExpressionContext linkedContext = this.ParseAndLink(expressionName, expression);
+            IExpression e = linkedContext.CompileGeneric<T>(expression);
+            this.AddCompiledExpression(expressionName, e);
+        }
+
+        public void Clear()
+        {
+            _myExpressions.Clear();
+        }
+
+        #endregion
+
+        #region "Properties - Public"
+        public IExpression this[string name]
+        {
+            get
+            {
+                IExpression e = null;
+                _myExpressions.TryGetValue(name, out e);
+                return e;
+            }
+        }
+
+        public ExpressionContext Context
+        {
+            get { return _myContext; }
+            set { _myContext = value; }
+        }
+        #endregion
+    }
+
+}