Sync

Migrate to Sdk projects.
Migrate tests to xUnit.
Bump version 0.2.3.
Migrate to NetStandar2.0.

.idea/.idea.VAR.ExpressionEvaluator/.idea/.gitignore

@@ -0,0 +1,13 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Rider ignored files
+/.idea.VAR.ExpressionEvaluator.iml
+/modules.xml
+/contentModel.xml
+/projectSettingsUpdater.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/.idea.VAR.ExpressionEvaluator/.idea/encodings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding" addBOMForNewFiles="with BOM under Windows, with no BOM otherwise" />
+</project>

.idea/.idea.VAR.ExpressionEvaluator/.idea/indexLayout.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="UserContentModel">
+    <attachedFolders />
+    <explicitIncludes />
+    <explicitExcludes />
+  </component>
+</project>

.idea/.idea.VAR.ExpressionEvaluator/.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>

LICENSE.txt

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2019-2021 Valeriano Alfonso Rodriguez
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,26 @@
+# Expression Evaluation Library
+
+## Usage
+
+### VAR.ExpressionEvaluator
+Add the resulting assembly as reference in your projects, and this line on code:
+
+```csharp
+using VAR.ExpressionEvaluator;
+```
+
+
+## Building
+A Visual Studio solution is provided. Simply, click build on the IDE.
+
+The build generates a DLL and a Nuget package.
+
+## Contributing
+1. Fork it!
+2. Create your feature branch: `git checkout -b my-new-feature`
+3. Commit your changes: `git commit -am 'Add some feature'`
+4. Push to the branch: `git push origin my-new-feature`
+5. Submit a pull request :D
+
+## Credits
+* Valeriano Alfonso Rodriguez.

VAR.ExpressionEvaluator.Tests/ExpressionBinaryNodeTests.cs

@@ -1,11 +1,10 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Xunit;
 
 namespace VAR.ExpressionEvaluator.Tests
 {
-    [TestClass()]
     public class ExpressionBinaryNodeTests
     {
-        [TestMethod()]
+        [Fact]
         public void ExpressionBinaryNode__Plus()
         {
             var expr = new ExpressionBinaryNode(
@@ -16,10 +15,10 @@ namespace VAR.ExpressionEvaluator.Tests
 
             var result = expr.Eval(null);
 
-            Assert.AreEqual(30m, result);
+            Assert.Equal(30m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionBinaryNode__Minus()
         {
             var expr = new ExpressionBinaryNode(
@@ -30,10 +29,10 @@ namespace VAR.ExpressionEvaluator.Tests
 
             var result = expr.Eval(null);
 
-            Assert.AreEqual(-10m, result);
+            Assert.Equal(-10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionBinaryNode__Multiply()
         {
             var expr = new ExpressionBinaryNode(
@@ -44,10 +43,10 @@ namespace VAR.ExpressionEvaluator.Tests
 
             var result = expr.Eval(null);
 
-            Assert.AreEqual(200m, result);
+            Assert.Equal(200m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionBinaryNode__Division()
         {
             var expr = new ExpressionBinaryNode(
@@ -58,7 +57,7 @@ namespace VAR.ExpressionEvaluator.Tests
 
             var result = expr.Eval(null);
 
-            Assert.AreEqual(2m, result);
+            Assert.Equal(2m, result);
         }
     }
 }

VAR.ExpressionEvaluator.Tests/ExpressionNumberNodeTests.cs

@@ -1,29 +1,28 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Xunit;
 
 namespace VAR.ExpressionEvaluator.Tests
 {
-    [TestClass()]
     public class ExpressionNumberNodeTests
     {
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__One()
         {
             IExpressionNode node = new ExpressionNumberNode(1);
-            Assert.AreEqual(1m, node.Eval(null));
+            Assert.Equal(1m, node.Eval(null));
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__Two()
         {
             IExpressionNode node = new ExpressionNumberNode(2);
-            Assert.AreEqual(2m, node.Eval(null));
+            Assert.Equal(2m, node.Eval(null));
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__OneHundredDotFortyFive()
         {
             IExpressionNode node = new ExpressionNumberNode(100.45m);
-            Assert.AreEqual(100.45m, node.Eval(null));
+            Assert.Equal(100.45m, node.Eval(null));
         }
     }
 }

VAR.ExpressionEvaluator.Tests/ExpressionStringNodeTests.cs

@@ -1,29 +1,28 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Xunit;
 
 namespace VAR.ExpressionEvaluator.Tests
 {
-    [TestClass()]
     public class ExpressionStringNodeTests
     {
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__Hello()
         {
             IExpressionNode node = new ExpressionStringNode("Hello");
-            Assert.AreEqual("Hello", node.Eval(null));
+            Assert.Equal("Hello", node.Eval(null));
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__World()
         {
             IExpressionNode node = new ExpressionStringNode("World");
-            Assert.AreEqual("World", node.Eval(null));
+            Assert.Equal("World", node.Eval(null));
         }
 
-        [TestMethod()]
+        [Fact]
         public void ExpressionNumberNode__Hello_World()
         {
             IExpressionNode node = new ExpressionStringNode("Hello World");
-            Assert.AreEqual("Hello World", node.Eval(null));
+            Assert.Equal("Hello World", node.Eval(null));
         }
     }
 }

VAR.ExpressionEvaluator.Tests/ParserTests.cs

@@ -1,155 +1,174 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System;
+using System;
 using System.Linq;
+using Xunit;
 
 namespace VAR.ExpressionEvaluator.Tests
 {
-    [TestClass()]
     public class ParserTests
     {
         #region Plus and Minus
 
-        [TestMethod()]
+        [Fact]
         public void PlusAndMinus__Ten_EqualsTen()
         {
             string expression = "10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(10m, result);
+            Assert.Equal(10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void PlusAndMinus__OnePlusTwo_EqualsThree()
         {
             string expression = "1   + 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(3m, result);
+            Assert.Equal(3m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void PlusAndMinus__OneMinusTwo_EqualsMinusOne()
         {
             string expression = "1   - 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(-1m, result);
+            Assert.Equal(-1m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void PlusAndMinus__OneMillionMinusHundredThousands_EqualsNineHundredThousands()
         {
             string expression = "1000000   - 100000";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(900000m, result);
+            Assert.Equal(900000m, result);
         }
 
         #endregion Plus and minus
 
         #region Number signs
 
-        [TestMethod()]
+        [Fact]
         public void Signs__MinusTen()
         {
             string expression = "-10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(-10m, result);
+            Assert.Equal(-10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Signs__PlusTen()
         {
             string expression = "+10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(10m, result);
+            Assert.Equal(10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Signs__MinusMinusTen()
         {
             string expression = "--10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(10m, result);
+            Assert.Equal(10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Signs__MinusPlusChainTen()
         {
             string expression = "--++-+-10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(10m, result);
+            Assert.Equal(10m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Signs__10Minus20Minus30()
         {
             string expression = "10 + -20 - +30";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(-40m, result);
+            Assert.Equal(-40m, result);
         }
 
         #endregion Number signs
 
+        #region Decimal numbers
+
+        [Fact]
+        public void Decimals__OnePointZero()
+        {
+            string expression = "1.0";
+            object result = Parser.EvaluateString(expression);
+            Assert.Equal(1.0m, result);
+        }
+
+        [Fact]
+        public void Decimals__OnePointOne()
+        {
+            string expression = "1.1";
+            object result = Parser.EvaluateString(expression);
+            Assert.Equal(1.1m, result);
+        }
+
+        #endregion Decimal numbers
+
         #region Multiplication and division
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__10MutiplyBy2()
         {
             string expression = "10 * 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(20m, result);
+            Assert.Equal(20m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__10DividedBy2()
         {
             string expression = "10 / 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(5m, result);
+            Assert.Equal(5m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__5DividedBy2()
         {
             string expression = "5 / 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(2.5m, result);
+            Assert.Equal(2.5m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__5DividedBy2Plus1()
         {
             string expression = "5 / 2 + 1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(3.5m, result);
+            Assert.Equal(3.5m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__1Plus5DividedBy2()
         {
             string expression = "1 + 5 / 2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(3.5m, result);
+            Assert.Equal(3.5m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__5DividedByParen1Plus1()
         {
             string expression = "5 / (1 + 1)";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(2.5m, result);
+            Assert.Equal(2.5m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void MultAndDiv__Paren2Plus2DividedByParen1Plus1()
         {
             string expression = "(2 + 2) / (1 + 1)";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(2m, result);
+            Assert.Equal(2m, result);
         }
 
         #endregion Multiplication and division
 
         #region Variables
 
-        [TestMethod()]
+        [Fact]
         public void Variables__Var1PlusVar2()
         {
             EvaluationContext evaluationContex = new EvaluationContext();
@@ -157,10 +176,10 @@ namespace VAR.ExpressionEvaluator.Tests
             evaluationContex.SetVariable("v2", 1);
             string expression = "v1 + v2";
             object result = Parser.EvaluateString(expression, evaluationContex);
-            Assert.AreEqual(2m, result);
+            Assert.Equal(2m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Variables__Var1MultiplyVar2()
         {
             EvaluationContext evaluationContex = new EvaluationContext();
@@ -168,10 +187,10 @@ namespace VAR.ExpressionEvaluator.Tests
             evaluationContex.SetVariable("v2", 5);
             string expression = "v1 * v2";
             object result = Parser.EvaluateString(expression, evaluationContex);
-            Assert.AreEqual(50m, result);
+            Assert.Equal(50m, result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Variables__Var1DivideVar2()
         {
             EvaluationContext evaluationContex = new EvaluationContext();
@@ -179,14 +198,14 @@ namespace VAR.ExpressionEvaluator.Tests
             evaluationContex.SetVariable("$v2", 20);
             string expression = "_v1 / $v2";
             object result = Parser.EvaluateString(expression, evaluationContex);
-            Assert.AreEqual(5m, result);
+            Assert.Equal(5m, result);
         }
 
         #endregion Variables
 
-        #region Funcitions
+        #region Functions
 
-        [TestMethod()]
+        [Fact]
         public void Functions__MaxFunction()
         {
             EvaluationContext evaluationContex = new EvaluationContext();
@@ -196,22 +215,66 @@ namespace VAR.ExpressionEvaluator.Tests
             });
             string expression = "max(1,2,10,5)";
             object result = Parser.EvaluateString(expression, evaluationContex);
-            Assert.AreEqual(10m, result);
+            Assert.Equal(10m, result);
+        }
+
+        [Fact]
+        public void Functions__NestedTest()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("linea1", 1);
+            evaluationContex.SetVariable("linea2", 1);
+            evaluationContex.SetVariable("linea4", 4);
+            evaluationContex.SetFunction("iif", (parameters) =>
+            {
+                if (((bool)parameters[0]) == true)
+                {
+                    return parameters[1];
+                }
+                else
+                {
+                    return parameters[2];
+                }
+            });
+            string expression = "iif(linea1>linea2,iif(linea1>linea4, linea1, iif(linea4>linea2,linea4,linea2)),iif(linea2>linea4,linea2,linea4))";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.Equal(4m, result);
+        }
+
+        [Fact]
+        public void Functions__ZeroParameters()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetFunction("constant", (parameters) =>
+            {
+                return 9m;
+            });
+            string expression = "constant()";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.Equal(9m, result);
         }
 
         #endregion Functions
 
         #region Strings
 
-        [TestMethod()]
+        [Fact]
         public void Strings__Contatenate_Hello_World()
         {
             string expression = "\"Hello\" + ' ' +\"World\"";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual("Hello World", result);
+            Assert.Equal("Hello World", result);
         }
         
-        [TestMethod()]
+        [Fact]
+        public void Strings__Contatenate_Hello_World_SimpleQuotes()
+        {
+            string expression = "'Hello' + ' ' +'World'";
+            object result = Parser.EvaluateString(expression);
+            Assert.Equal("Hello World", result);
+        }
+
+        [Fact]
         public void Strings__Contatenate_Hello_World_WithVariables()
         {
             EvaluationContext evaluationContex = new EvaluationContext();
@@ -220,45 +283,45 @@ namespace VAR.ExpressionEvaluator.Tests
             evaluationContex.SetVariable("v3", "World");
             string expression = "v1 + v2 + v3";
             object result = Parser.EvaluateString(expression, evaluationContex);
-            Assert.AreEqual("Hello World", result);
+            Assert.Equal("Hello World", result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Strings__Fail_Minus()
         {
             string expression = "'Hello' - 'World'";
             try
             {
                 object result = Parser.EvaluateString(expression);
-                Assert.Fail();
+                Assert.True(false);
             }
             catch (Exception)
             {
             }
         }
 
-        [TestMethod()]
+        [Fact]
         public void Strings__Fail_Multiply()
         {
             string expression = "'Hello' * 'World'";
             try
             {
                 object result = Parser.EvaluateString(expression);
-                Assert.Fail();
+                Assert.True(false);
             }
             catch (Exception)
             {
             }
         }
 
-        [TestMethod()]
+        [Fact]
         public void Strings__Fail_Division()
         {
             string expression = "'Hello' / 'World'";
             try
             {
                 object result = Parser.EvaluateString(expression);
-                Assert.Fail();
+                Assert.True(false);
             }
             catch (Exception)
             {
@@ -269,114 +332,570 @@ namespace VAR.ExpressionEvaluator.Tests
 
         #region Relations
 
-        [TestMethod()]
+        [Fact]
         public void Relations_1GreatherThan2_EqualsFalse()
         {
             string expression = "1>2";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(false, result);
+            Assert.False((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
+        public void Relations_StringEmptyGreatherThan1_EqualsFalse()
+        {
+            string expression = "\"\">1";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1GreatherThanStringEmpty_EqualsFalse()
+        {
+            string expression = "1>\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
         public void Relations_1Equals1_EqualsTrue()
         {
             string expression = "1=1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(true, result);
+            Assert.True((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
+        public void Relations_StringEmptyEquals1_EqualsFalse()
+        {
+            string expression = "\"\"=1";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1EqualsStringEmpty_EqualsFalse()
+        {
+            string expression = "1=\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
         public void Relations_10NotEquals1_EqualsTrue()
         {
             string expression = "10!=1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(true, result);
+            Assert.True((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
+        public void Relations_StringEmptyNotEquals1_EqualsTrue()
+        {
+            string expression = "\"\"!=1";
+            object result = Parser.EvaluateString(expression);
+            Assert.True((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1NotEqualsStringEmpty_EqualsTrue()
+        {
+            string expression = "1!=\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.True((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_10Different1_EqualsTrue()
+        {
+            string expression = "10<>1";
+            object result = Parser.EvaluateString(expression);
+            Assert.True((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_StringEmptyDifferent1_EqualsTrue()
+        {
+            string expression = "\"\"<>1";
+            object result = Parser.EvaluateString(expression);
+            Assert.True((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1DifferentStringEmpty_EqualsTrue()
+        {
+            string expression = "1<>\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.True((bool?)result);
+        }
+
+        [Fact]
         public void Relations_10LessThan1_EqualsFalse()
         {
             string expression = "10<1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(false, result);
+            Assert.False((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
+        public void Relations_StringEmptyLessThan1_EqualsFalse()
+        {
+            string expression = "\"\"<1";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1LessThanStringEmpty_EqualsFalse()
+        {
+            string expression = "1<\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
         public void Relations_1GreaterOrEqualThan1_EqualsTrue()
         {
             string expression = "1>=1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(true, result);
+            Assert.True((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
+        public void Relations_StringEmptyGreaterOrEqualThan1_EqualsFalse()
+        {
+            string expression = "\"\">=1";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1GreaterOrEqualThanStringEmpty_EqualsFalse()
+        {
+            string expression = "1>=\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
         public void Relations_1LessOrEqualThan1_EqualsTrue()
         {
             string expression = "1<=1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(true, result);
+            Assert.True((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Relations_1GreaterOrEqualThan10_EqualsFalse()
         {
             string expression = "1>=10";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(false, result);
+            Assert.False((bool?)result);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Relations_10LessOrEqualThan1_EqualsFalse()
         {
             string expression = "10<=1";
             object result = Parser.EvaluateString(expression);
-            Assert.AreEqual(false, result);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_StringEmptyLessOrEqualThan1_EqualsFalse()
+        {
+            string expression = "\"\"<=1";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact]
+        public void Relations_1LessOrEqualThanStringEmpty_EqualsFalse()
+        {
+            string expression = "1<=\"\"";
+            object result = Parser.EvaluateString(expression);
+            Assert.False((bool?)result);
+        }
+
+        [Fact()]
+        public void Relations__Var1NullEquals666_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", null);
+            string expression = "v1 = 666";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.False((bool?)result);
+        }
+
+        [Fact()]
+        public void Relations__Var1NullEqualsStringHello_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", null);
+            string expression = "v1 = \"Hello\"";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.False((bool?)result);
+        }
+
+        [Fact()]
+        public void Relations__Var1666Equals666_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", 666);
+            string expression = "v1 = 666";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.True((bool?)result);
+        }
+
+        [Fact()]
+        public void Relations__Var1HelloEqualsStringHello_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", "Hello");
+            string expression = "v1 = \"Hello\"";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.True((bool?)result);
         }
 
         #endregion Relations
 
         #region BooleanOps
 
-        [TestMethod()]
+        [Fact]
         public void BooleanOps_And()
         {
-            Assert.AreEqual(false, Parser.EvaluateString("false and false"));
-            Assert.AreEqual(false, Parser.EvaluateString("false and true"));
-            Assert.AreEqual(false, Parser.EvaluateString("true and false"));
-            Assert.AreEqual(true, Parser.EvaluateString("true and true"));
+            Assert.False((bool?)Parser.EvaluateString("false and false"));
+            Assert.False((bool?)Parser.EvaluateString("false and true"));
+            Assert.False((bool?)Parser.EvaluateString("true and false"));
+            Assert.True((bool?)Parser.EvaluateString("true and true"));
 
-            Assert.AreEqual(false, Parser.EvaluateString("false && false"));
-            Assert.AreEqual(false, Parser.EvaluateString("false && true"));
-            Assert.AreEqual(false, Parser.EvaluateString("true && false"));
-            Assert.AreEqual(true, Parser.EvaluateString("true && true"));
+            Assert.False((bool?)Parser.EvaluateString("False And False"));
+            Assert.False((bool?)Parser.EvaluateString("False And True"));
+            Assert.False((bool?)Parser.EvaluateString("True And False"));
+            Assert.True((bool?)Parser.EvaluateString("True And True"));
+
+            Assert.False((bool?)Parser.EvaluateString("false && false"));
+            Assert.False((bool?)Parser.EvaluateString("false && true"));
+            Assert.False((bool?)Parser.EvaluateString("true && false"));
+            Assert.True((bool?)Parser.EvaluateString("true && true"));
         }
 
-        [TestMethod()]
+        [Fact]
         public void BooleanOps_Or()
         {
-            Assert.AreEqual(false, Parser.EvaluateString("false or false"));
-            Assert.AreEqual(true, Parser.EvaluateString("false or true"));
-            Assert.AreEqual(true, Parser.EvaluateString("true or false"));
-            Assert.AreEqual(true, Parser.EvaluateString("true or true"));
+            Assert.False((bool?)Parser.EvaluateString("false or false"));
+            Assert.True((bool?)Parser.EvaluateString("false or true"));
+            Assert.True((bool?)Parser.EvaluateString("true or false"));
+            Assert.True((bool?)Parser.EvaluateString("true or true"));
 
-            Assert.AreEqual(false, Parser.EvaluateString("false || false"));
-            Assert.AreEqual(true, Parser.EvaluateString("false || true"));
-            Assert.AreEqual(true, Parser.EvaluateString("true || false"));
-            Assert.AreEqual(true, Parser.EvaluateString("true || true"));
+            Assert.False((bool?)Parser.EvaluateString("False Or False"));
+            Assert.True((bool?)Parser.EvaluateString("False Or True"));
+            Assert.True((bool?)Parser.EvaluateString("True Or False"));
+            Assert.True((bool?)Parser.EvaluateString("True Or True"));
+
+            Assert.False((bool?)Parser.EvaluateString("false || false"));
+            Assert.True((bool?)Parser.EvaluateString("false || true"));
+            Assert.True((bool?)Parser.EvaluateString("true || false"));
+            Assert.True((bool?)Parser.EvaluateString("true || true"));
         }
 
-        [TestMethod()]
+        [Fact]
         public void BooleanOps_Not()
         {
-            Assert.AreEqual(true, Parser.EvaluateString("!false"));
-            Assert.AreEqual(false, Parser.EvaluateString("!true"));
+            Assert.True((bool?)Parser.EvaluateString("!false"));
+            Assert.False((bool?)Parser.EvaluateString("!true"));
 
-            Assert.AreEqual(true, Parser.EvaluateString("not false"));
-            Assert.AreEqual(false, Parser.EvaluateString("not true"));
+            Assert.True((bool?)Parser.EvaluateString("not false"));
+            Assert.False((bool?)Parser.EvaluateString("not true"));
         }
 
-
         #endregion BooleanOps
 
+        #region Null value
+
+
+        [Fact]
+        public void NullValue_NullPlusAnything_EqualsNull()
+        {
+            Assert.Null((bool?)Parser.EvaluateString("null + 1"));
+            Assert.Null((bool?)Parser.EvaluateString("null + 100"));
+            Assert.Null((bool?)Parser.EvaluateString("1 + null"));
+            Assert.Null((bool?)Parser.EvaluateString("100 + null"));
+            Assert.Null((bool?)Parser.EvaluateString("null + null"));
+        }
+
+        [Fact]
+        public void NullValue_NullMinusAnything_EqualsNull()
+        {
+            Assert.Null((bool?)Parser.EvaluateString("null - 1"));
+            Assert.Null((bool?)Parser.EvaluateString("null - 100"));
+            Assert.Null((bool?)Parser.EvaluateString("1 - null"));
+            Assert.Null((bool?)Parser.EvaluateString("100 - null"));
+            Assert.Null((bool?)Parser.EvaluateString("null - null"));
+        }
+
+        [Fact]
+        public void NullValue_NullByAnything_EqualsNull()
+        {
+            Assert.Null((bool?)Parser.EvaluateString("null * 1"));
+            Assert.Null((bool?)Parser.EvaluateString("null * 100"));
+            Assert.Null((bool?)Parser.EvaluateString("1 * null"));
+            Assert.Null((bool?)Parser.EvaluateString("100 * null"));
+            Assert.Null((bool?)Parser.EvaluateString("null * null"));
+
+            Assert.Null((bool?)Parser.EvaluateString("null / 1"));
+            Assert.Null((bool?)Parser.EvaluateString("null / 100"));
+            Assert.Null((bool?)Parser.EvaluateString("1 / null"));
+            Assert.Null((bool?)Parser.EvaluateString("100 / null"));
+            Assert.Null((bool?)Parser.EvaluateString("null / null"));
+        }
+
+        #endregion
+
+        #region String coercions
+
+        [Fact()]
+        public void StringCoercions__Var1NullEqualsStringEmpty_EqualsTrue()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", null);
+            string expression = "v1 = \"\"";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.True((bool?)result);
+        }
+
+        [Fact()]
+        public void StringCoercions__Var1TrueStringEqualsTrue_EqualsTrue()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", "True");
+            string expression = "v1 = true";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.True((bool?)result);
+        }
+
+        [Fact()]
+        public void StringCoercions__Var1FalseStringEqualsFalse_EqualsTrue()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("v1", "False");
+            string expression = "v1 = false";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.True((bool?)result);
+        }
+
+        #endregion String coercions
+
+        #region Exceptions
+
+        [Fact]
+        public void Exceptions__HelloAtEnd__UnexpectedCharactersAtEndException()
+        {
+            try
+            {
+                string expression = "1 + 1 \"Hello\"";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedCharactersAtEndException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__TrueAtEndInsideParens__MissingCloseParenthesisException()
+        {
+            try
+            {
+                string expression = "(1+1 true)";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.MissingCloseParenthesisException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__TrueAtEndInsideFunctionCall__MissingCloseParenthesisException()
+        {
+            try
+            {
+                string expression = "Func(1 true)";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.MissingCloseParenthesisException>(ex);
+            }
+        }
+
+
+        [Fact]
+        public void Exceptions__EOF__UnexpectedEOFException()
+        {
+            try
+            {
+                string expression = "";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedEOFException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Plus__UnexpectedEOFException()
+        {
+            try
+            {
+                string expression = "+";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedEOFException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Minus__UnexpectedEOFException()
+        {
+            try
+            {
+                string expression = "-";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedEOFException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__OpenParens__UnexpectedEOFException()
+        {
+            try
+            {
+                string expression = "(";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedEOFException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Comma__UnexpectedTokenException()
+        {
+            try
+            {
+                string expression = ",";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedTokenException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Division__UnexpectedTokenException()
+        {
+            try
+            {
+                string expression = "/";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedTokenException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Multiply__UnexpectedTokenException()
+        {
+            try
+            {
+                string expression = "*";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedTokenException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__CloseParens__UnexpectedTokenException()
+        {
+            try
+            {
+                string expression = ")";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedTokenException>(ex);
+            }
+        }
+
+        [Fact]
+        public void Exceptions__Parens__UnexpectedTokenException()
+        {
+            try
+            {
+                string expression = "()";
+                object result = Parser.EvaluateString(expression);
+                Assert.True(false);
+            }
+            catch (Exception ex)
+            {
+                Assert.IsType<Parser.UnexpectedTokenException>(ex);
+            }
+        }
+
+
+        #endregion Exceptions
+
+        #region Misc
+
+        [Fact()]
+        public void Misc__MixedExpression_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("QI_86", null);
+            evaluationContex.SetVariable("QI_87", null);
+            evaluationContex.SetVariable("QI_104", null);
+            string expression = "( QI_86 = 0 Or QI_86 = null ) And ( QI_87 = 0 Or QI_87 = null ) And QI_104 > 0";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.False((bool?)result);
+        }
+
+        [Fact()]
+        public void Misc__ProductWithStringDecimals_EqualsFalse()
+        {
+            EvaluationContext evaluationContex = new EvaluationContext();
+            evaluationContex.SetVariable("$1109", "1933");
+            evaluationContex.SetVariable("$1150", "02.00000");
+            string expression = "$1109 * $1150";
+            object result = Parser.EvaluateString(expression, evaluationContex);
+            Assert.Equal(3866.00000M, result);
+        }
+
+        #endregion Misc
     }
 }

VAR.ExpressionEvaluator.Tests/Properties/AssemblyInfo.cs

@@ -1,15 +0,0 @@
-using System.Reflection;
-using System.Runtime.InteropServices;
-
-[assembly: AssemblyTitle("VAR.ExpressionEvaluator.Tests")]
-[assembly: AssemblyDescription("")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("VAR")]
-[assembly: AssemblyProduct("VAR.ExpressionEvaluator.Tests")]
-[assembly: AssemblyCopyright("Copyright © VAR 2019")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-[assembly: ComVisible(false)]
-[assembly: Guid("3195f0e0-9489-49ce-8fc2-627a73f80cc7")]
-[assembly: AssemblyVersion("0.1.1.0")]
-[assembly: AssemblyFileVersion("0.1.1.0")]

VAR.ExpressionEvaluator.Tests/TokenizerTests.cs

@@ -1,225 +1,229 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
-using System.IO;
+using System.IO;
+using Xunit;
 
 namespace VAR.ExpressionEvaluator.Tests
 {
-    [TestClass()]
     public class TokenizerTests
     {
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__Plus()
         {
             var testString = "10 + 20";
             var t = new Tokenizer(new StringReader(testString));
 
             // "10"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 10);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(10, t.Number);
             t.NextToken();
 
             // "+"
-            Assert.AreEqual(t.Token, Token.Plus);
+            Assert.Equal(Token.Plus, t.Token);
             t.NextToken();
 
             // "20"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 20);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(20, t.Number);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__PlusMinusAndDecimal()
         {
             var testString = "10 + 20 - 30.123";
             var t = new Tokenizer(new StringReader(testString));
 
             // "10"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 10);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(10, t.Number);
             t.NextToken();
 
             // "+"
-            Assert.AreEqual(t.Token, Token.Plus);
+            Assert.Equal(Token.Plus, t.Token);
             t.NextToken();
 
             // "20"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 20);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(20, t.Number);
             t.NextToken();
 
             // "-"
-            Assert.AreEqual(t.Token, Token.Minus);
+            Assert.Equal(Token.Minus, t.Token);
             t.NextToken();
 
             // "20"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 30.123m);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(30.123m, t.Number);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__SimpleString()
         {
             var testString = "\"Hello World\"";
             var t = new Tokenizer(new StringReader(testString));
 
             // "Hello World"
-            Assert.AreEqual(t.Token, Token.String);
-            Assert.AreEqual(t.Text, "Hello World");
+            Assert.Equal(Token.String, t.Token);
+            Assert.Equal("Hello World", t.Text);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__StringWithEscaping()
         {
             var testString = "\"Hello \\\"World\\\"\"";
             var t = new Tokenizer(new StringReader(testString));
 
             // "Hello \"World\""
-            Assert.AreEqual(t.Token, Token.String);
-            Assert.AreEqual(t.Text, "Hello \"World\"");
+            Assert.Equal(Token.String, t.Token);
+            Assert.Equal("Hello \"World\"", t.Text);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__Identifiers()
         {
-            var testString = "null true false _$variable1 $variable2";
+            var testString = "null true false _$variable1 $variable2 [;{}#]";
             var t = new Tokenizer(new StringReader(testString));
 
             // "null"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "null");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("null", t.Text);
             t.NextToken();
 
             // "true"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "true");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("true", t.Text);
             t.NextToken();
 
             // "false"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "false");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("false", t.Text);
             t.NextToken();
 
             // "_$variable1"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "_$variable1");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("_$variable1", t.Text);
             t.NextToken();
 
             // "$variable2"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "$variable2");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("$variable2", t.Text);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            // ";{}#"
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal(";{}#", t.Text);
+            t.NextToken();
+
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__AllTogether()
         {
             var testString = "(10 + 20) * -30.123 + \"Hello \\\"World\\\"\" = false";
             var t = new Tokenizer(new StringReader(testString));
 
             // "("
-            Assert.AreEqual(t.Token, Token.ParenthesisStart);
+            Assert.Equal(Token.ParenthesisStart, t.Token);
             t.NextToken();
 
             // "10"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 10);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(10, t.Number);
             t.NextToken();
 
             // "+"
-            Assert.AreEqual(t.Token, Token.Plus);
+            Assert.Equal(Token.Plus, t.Token);
             t.NextToken();
 
             // "20"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 20);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(20, t.Number);
             t.NextToken();
 
             // ")"
-            Assert.AreEqual(t.Token, Token.ParenthesisEnd);
+            Assert.Equal(Token.ParenthesisEnd, t.Token);
             t.NextToken();
 
             // "*"
-            Assert.AreEqual(t.Token, Token.Multiply);
+            Assert.Equal(Token.Multiply, t.Token);
             t.NextToken();
 
             // "-"
-            Assert.AreEqual(t.Token, Token.Minus);
+            Assert.Equal(Token.Minus, t.Token);
             t.NextToken();
 
             // "20"
-            Assert.AreEqual(t.Token, Token.Number);
-            Assert.AreEqual(t.Number, 30.123m);
+            Assert.Equal(Token.Number, t.Token);
+            Assert.Equal(30.123m, t.Number);
             t.NextToken();
 
             // "+"
-            Assert.AreEqual(t.Token, Token.Plus);
+            Assert.Equal(Token.Plus, t.Token);
             t.NextToken();
 
             // "Hello \"World\""
-            Assert.AreEqual(t.Token, Token.String);
-            Assert.AreEqual(t.Text, "Hello \"World\"");
+            Assert.Equal(Token.String, t.Token);
+            Assert.Equal("Hello \"World\"", t.Text);
             t.NextToken();
 
             // "="
-            Assert.AreEqual(t.Token, Token.Equals);
+            Assert.Equal(Token.Equals, t.Token);
             t.NextToken();
 
             // "false"
-            Assert.AreEqual(t.Token, Token.Identifier);
-            Assert.AreEqual(t.Text, "false");
+            Assert.Equal(Token.Identifier, t.Token);
+            Assert.Equal("false", t.Text);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
-        [TestMethod()]
+        [Fact]
         public void Tokenizer__MoreTokens()
         {
             var testString = "= < > <= >= == === ";
             var t = new Tokenizer(new StringReader(testString));
 
             // "="
-            Assert.AreEqual(t.Token, Token.Equals);
+            Assert.Equal(Token.Equals, t.Token);
             t.NextToken();
 
             // "<"
-            Assert.AreEqual(t.Token, Token.LessThan);
+            Assert.Equal(Token.LessThan, t.Token);
             t.NextToken();
 
             // ">"
-            Assert.AreEqual(t.Token, Token.GreaterThan);
+            Assert.Equal(Token.GreaterThan, t.Token);
             t.NextToken();
 
             // "<="
-            Assert.AreEqual(t.Token, Token.LessOrEqualThan);
+            Assert.Equal(Token.LessOrEqualThan, t.Token);
             t.NextToken();
 
             // ">="
-            Assert.AreEqual(t.Token, Token.GreaterOrEqualThan);
+            Assert.Equal(Token.GreaterOrEqualThan, t.Token);
             t.NextToken();
 
             // "=="
-            Assert.AreEqual(t.Token, Token.Equals);
+            Assert.Equal(Token.Equals, t.Token);
             t.NextToken();
 
             // "==="
-            Assert.AreEqual(t.Token, Token.ExclusiveEquals);
+            Assert.Equal(Token.ExclusiveEquals, t.Token);
             t.NextToken();
 
-            Assert.AreEqual(t.Token, Token.EOF);
+            Assert.Equal(Token.EOF, t.Token);
         }
 
     }

VAR.ExpressionEvaluator.Tests/VAR.ExpressionEvaluator.Tests.csproj

@@ -1,94 +1,26 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project Sdk="Microsoft.NET.Sdk">
+
   <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{3195F0E0-9489-49CE-8FC2-627A73F80CC7}</ProjectGuid>
-    <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>VAR.ExpressionEvaluator.Tests</RootNamespace>
-    <AssemblyName>VAR.ExpressionEvaluator.Tests</AssemblyName>
-    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <ProjectTypeGuids>{3AC096D0-A1C2-E12C-1390-A8335801FDAB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
-    <VisualStudioVersion Condition="'$(VisualStudioVersion)' == ''">10.0</VisualStudioVersion>
-    <VSToolsPath Condition="'$(VSToolsPath)' == ''">$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)</VSToolsPath>
-    <ReferencePath>$(ProgramFiles)\Common Files\microsoft shared\VSTT\$(VisualStudioVersion)\UITestExtensionPackages</ReferencePath>
-    <IsCodedUITest>False</IsCodedUITest>
-    <TestProjectType>UnitTest</TestProjectType>
-    <TargetFrameworkProfile />
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
+    <TargetFramework>net5.0</TargetFramework>
+
+    <IsPackable>false</IsPackable>
   </PropertyGroup>
+
   <ItemGroup>
-    <Reference Include="System" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
+    <PackageReference Include="xunit" Version="2.4.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="3.0.2">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
   </ItemGroup>
-  <Choose>
-    <When Condition="('$(VisualStudioVersion)' == '10.0' or '$(VisualStudioVersion)' == '') and '$(TargetFrameworkVersion)' == 'v3.5'">
+
   <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework, Version=10.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
+    <ProjectReference Include="..\VAR.ExpressionEvaluator\VAR.ExpressionEvaluator.csproj" />
   </ItemGroup>
-    </When>
-    <Otherwise>
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.UnitTestFramework" />
-      </ItemGroup>
-    </Otherwise>
-  </Choose>
-  <ItemGroup>
-    <Compile Include="ExpressionBinaryNodeTests.cs" />
-    <Compile Include="ExpressionNumberNodeTests.cs" />
-    <Compile Include="ExpressionStringNodeTests.cs" />
-    <Compile Include="ParserTests.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="TokenizerTests.cs" />
-  </ItemGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\VAR.ExpressionEvaluator\VAR.ExpressionEvaluator.csproj">
-      <Project>{74635F68-55B1-4819-84A3-9EA818D396D9}</Project>
-      <Name>VAR.ExpressionEvaluator</Name>
-    </ProjectReference>
-  </ItemGroup>
-  <Choose>
-    <When Condition="'$(VisualStudioVersion)' == '10.0' And '$(IsCodedUITest)' == 'True'">
-      <ItemGroup>
-        <Reference Include="Microsoft.VisualStudio.QualityTools.CodedUITestFramework, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITest.Extension, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-        <Reference Include="Microsoft.VisualStudio.TestTools.UITesting, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
-          <Private>False</Private>
-        </Reference>
-      </ItemGroup>
-    </When>
-  </Choose>
-  <Import Project="$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets" Condition="Exists('$(VSToolsPath)\TeamTest\Microsoft.TestTools.targets')" />
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
+
 </Project>

VAR.ExpressionEvaluator.sln

@@ -1,11 +1,17 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 15
-VisualStudioVersion = 15.0.28307.902
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.31402.337
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "VAR.ExpressionEvaluator", "VAR.ExpressionEvaluator\VAR.ExpressionEvaluator.csproj", "{74635F68-55B1-4819-84A3-9EA818D396D9}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "VAR.ExpressionEvaluator.Tests", "VAR.ExpressionEvaluator.Tests\VAR.ExpressionEvaluator.Tests.csproj", "{3195F0E0-9489-49CE-8FC2-627A73F80CC7}"
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Notes", "Notes", "{E4F0EB17-0866-42A7-A1BE-2357C3245C12}"
+	ProjectSection(SolutionItems) = preProject
+		LICENSE.txt = LICENSE.txt
+		README.md = README.md
+	EndProjectSection
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "VAR.ExpressionEvaluator.Tests", "VAR.ExpressionEvaluator.Tests\VAR.ExpressionEvaluator.Tests.csproj", "{89474ADF-B420-4774-BAC8-EFB3FBE28DA6}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -17,10 +23,10 @@ Global
 		{74635F68-55B1-4819-84A3-9EA818D396D9}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{74635F68-55B1-4819-84A3-9EA818D396D9}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{74635F68-55B1-4819-84A3-9EA818D396D9}.Release|Any CPU.Build.0 = Release|Any CPU
-		{3195F0E0-9489-49CE-8FC2-627A73F80CC7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{3195F0E0-9489-49CE-8FC2-627A73F80CC7}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{3195F0E0-9489-49CE-8FC2-627A73F80CC7}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{3195F0E0-9489-49CE-8FC2-627A73F80CC7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{89474ADF-B420-4774-BAC8-EFB3FBE28DA6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{89474ADF-B420-4774-BAC8-EFB3FBE28DA6}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{89474ADF-B420-4774-BAC8-EFB3FBE28DA6}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{89474ADF-B420-4774-BAC8-EFB3FBE28DA6}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

VAR.ExpressionEvaluator/Build.NuGet.cmd

@@ -1,25 +0,0 @@
-@echo off
-
-:: MSBuild and tools path
-if exist "%windir%\Microsoft.Net\Framework\v4.0.30319" set MsBuildPath=%windir%\Microsoft.NET\Framework\v4.0.30319
-if exist "%windir%\Microsoft.Net\Framework64\v4.0.30319" set MsBuildPath=%windir%\Microsoft.NET\Framework64\v4.0.30319
-if exist "C:\Program Files (x86)\MSBuild\14.0\Bin" set MsBuildPath=C:\Program Files (x86)\MSBuild\14.0\Bin
-if exist "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\Bin" set MsBuildPath=C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\MSBuild\15.0\Bin
-set PATH=%MsBuildPath%;%PATH%
-
-echo %MsBuildPath%
-
-:: NuGet
-set nuget="nuget"
-if exist "%~dp0\..\packages\NuGet.CommandLine.5.3.1\tools\NuGet.exe" set nuget="%~dp0\..\packages\NuGet.CommandLine.5.3.1\tools\NuGet.exe"
-
-:: Release
-Title Building Release
-msbuild VAR.ExpressionEvaluator.csproj /t:Build /p:Configuration="Release" /p:Platform="AnyCPU"
-
-:: Packing Nuget
-Title Packing Nuget
-%nuget% pack VAR.ExpressionEvaluator.csproj -Verbosity detailed -OutputDir "NuGet" -Properties Configuration="Release" -Prop Platform=AnyCPU
-
-title Finished
-pause

VAR.ExpressionEvaluator/EvaluationContext.cs

@@ -39,11 +39,16 @@ namespace VAR.ExpressionEvaluator
 
         public void SetVariable(string name, object value)
         {
+            if (value is DBNull)
+            {
+                value = null;
+            }
+
             if (value is DateTime)
             {
                 value = ((DateTime)value).ToString("s");
             }
-            if ((value is string) == false && (value is bool) == false)
+            if ((value is string) == false && (value is bool) == false && value != null)
             {
                 value = Convert.ToDecimal(value);
             }
@@ -60,7 +65,7 @@ namespace VAR.ExpressionEvaluator
         {
             if (_variables.ContainsKey(name) == false)
             {
-                return null;
+                throw new Exception(string.Format("Variable {0} not found", name));
             }
             return _variables[name];
         }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionBooleanAndNode.cs

@@ -9,9 +9,10 @@
 
         private static object BooleanAndOp(object leftValue, object rightValue)
         {
-            bool bLeftValue = ExpressionBooleanNode.ConvertToBoolean(leftValue);
-            bool brightValue = ExpressionBooleanNode.ConvertToBoolean(rightValue);
-            return bLeftValue && brightValue;
+            bool? bLeftValue = ExpressionBooleanNode.ConvertToBoolean(leftValue);
+            bool? brightValue = ExpressionBooleanNode.ConvertToBoolean(rightValue);
+            if (bLeftValue == null || bLeftValue == null) { return null; }
+            return bLeftValue.Value && brightValue.Value;
         }
     }
 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionBooleanNode.cs

@@ -14,8 +14,13 @@
             return _value;
         }
 
-        public static bool ConvertToBoolean(object value)
+        public static bool? ConvertToBoolean(object value)
         {
+            if (value == null)
+            {
+                return null;
+            }
+
             if (value is bool)
             {
                 return (bool)value;

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionBooleanNotNode.cs

@@ -10,6 +10,7 @@
         private static object BooleanNotOp(object value)
         {
             value = ExpressionBooleanNode.ConvertToBoolean(value);
+            if (value == null) { return null; }
             return !(bool)value;
         }
     }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionBooleanOrNode.cs

@@ -9,9 +9,10 @@
 
         private static object BooleanOrOp(object leftValue, object rightValue)
         {
-            bool bLeftValue = ExpressionBooleanNode.ConvertToBoolean(leftValue);
-            bool brightValue = ExpressionBooleanNode.ConvertToBoolean(rightValue);
-            return bLeftValue || brightValue;
+            bool? bLeftValue = ExpressionBooleanNode.ConvertToBoolean(leftValue);
+            bool? brightValue = ExpressionBooleanNode.ConvertToBoolean(rightValue);
+            if (bLeftValue == null || bLeftValue == null) { return null; }
+            return bLeftValue.Value || brightValue.Value;
         }
     }
 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionDivisionNode.cs

@@ -11,9 +11,14 @@ namespace VAR.ExpressionEvaluator
 
         private static object DivisionOp(object leftValue, object rightValue)
         {
+            if (leftValue == null || rightValue == null)
+            {
+                return null;
+            }
+
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                 }
@@ -21,7 +26,7 @@ namespace VAR.ExpressionEvaluator
             }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionEqualsNode.cs

@@ -1,6 +1,4 @@
-using System;
-
-namespace VAR.ExpressionEvaluator
+namespace VAR.ExpressionEvaluator
 {
     public class ExpressionEqualsNode : ExpressionBinaryNode
     {
@@ -9,35 +7,105 @@ namespace VAR.ExpressionEvaluator
         {
         }
 
-        private static object EqualsOp(object leftValue, object rightValue)
+        public static object EqualsOp(object leftValue, object rightValue)
         {
+            // Null
+            if (leftValue is string && string.IsNullOrEmpty(leftValue as string))
+            {
+                leftValue = null;
+            }
+            if (rightValue is string && string.IsNullOrEmpty(rightValue as string))
+            {
+                rightValue = null;
+            }
+            if (leftValue == null && rightValue == null)
+            {
+                return true;
+            }
+            if (leftValue == null || rightValue == null)
+            {
+                return false;
+            }
+
+            // String
             if (leftValue is string && rightValue is string)
             {
                 return string.Compare((string)leftValue, (string)rightValue) == 0;
             }
 
+            // Bool
+            if (leftValue is bool || rightValue is bool)
+            {
+                bool? leftBool = ConvertToNullableBool(leftValue);
+                bool? rightBool = ConvertToNullableBool(rightValue);
+                return leftBool == rightBool;
+            }
+
+            // Decimal
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
-                    throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
+                    leftValue = null;
                 }
+                else
+                {
                     leftValue = dec;
                 }
+            }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
-                    throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
+                    rightValue = null;
                 }
+                else
+                {
                     rightValue = dec;
                 }
-
+            }
             if ((leftValue is decimal) == false || (rightValue is decimal) == false)
             {
-                throw new Exception("Can't compare non decimal values");
+                return false;
             }
             return (decimal)leftValue == (decimal)rightValue;
         }
+
+        private static bool? ConvertToNullableBool(object value)
+        {
+            if (value is bool)
+            {
+                return (bool)value;
+            }
+            if (value is string)
+            {
+                string text = value as string;
+                if (string.IsNullOrEmpty(text))
+                {
+                    return null;
+                }
+                decimal decValue;
+                if (decimal.TryParse(text, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decValue))
+                {
+                    return decValue != 0;
+                }
+                string textLower = text.ToLower();
+                if (textLower == "false" || textLower == "no" || textLower == "ez" || textLower == "non" || textLower == "nein")
+                {
+                    return false;
+                }
+                if (textLower == "true" || textLower == "si" || textLower == "sí" || textLower == "yes" || textLower == "bai" || textLower == "oui" || textLower == "ja")
+                {
+                    return true;
+                }
+
+                return null;
+            }
+            if (value is decimal)
+            {
+                return ((decimal)value) != 0;
+            }
+            return false;
+        }
     }
 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionGreaterOrEqualThanNode.cs

@@ -18,20 +18,39 @@ namespace VAR.ExpressionEvaluator
 
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)leftValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                     }
                     leftValue = dec;
                 }
+            }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)rightValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                     }
                     rightValue = dec;
                 }
+            }
+
+            if (leftValue == null || rightValue == null)
+            {
+                return false;
+            }
 
             if ((leftValue is decimal) == false || (rightValue is decimal) == false)
             {

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionGreaterThanNode.cs

@@ -18,20 +18,39 @@ namespace VAR.ExpressionEvaluator
 
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)leftValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                     }
                     leftValue = dec;
                 }
+            }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)rightValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                     }
                     rightValue = dec;
                 }
+            }
+
+            if (leftValue == null || rightValue == null)
+            {
+                return false;
+            }
 
             if ((leftValue is decimal) == false || (rightValue is decimal) == false)
             {

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionLessOrEqualThanNode.cs

@@ -18,20 +18,39 @@ namespace VAR.ExpressionEvaluator
 
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)leftValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                     }
                     leftValue = dec;
                 }
+            }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)rightValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                     }
                     rightValue = dec;
                 }
+            }
+
+            if (leftValue == null || rightValue == null)
+            {
+                return false;
+            }
 
             if ((leftValue is decimal) == false || (rightValue is decimal) == false)
             {

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionLessThanNode.cs

@@ -18,20 +18,39 @@ namespace VAR.ExpressionEvaluator
 
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)leftValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                     }
                     leftValue = dec;
                 }
+            }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (string.IsNullOrEmpty((string)rightValue))
+                {
+                    leftValue = null;
+                }
+                else
+                {
+                    if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                     {
                         throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                     }
                     rightValue = dec;
                 }
+            }
+
+            if (leftValue == null || rightValue == null)
+            {
+                return false;
+            }
 
             if ((leftValue is decimal) == false || (rightValue is decimal) == false)
             {

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionMinusNode.cs

@@ -11,9 +11,14 @@ namespace VAR.ExpressionEvaluator
 
         private static object MinusOp(object leftValue, object rightValue)
         {
+            if (leftValue == null || rightValue == null)
+            {
+                return null;
+            }
+
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                 }
@@ -21,7 +26,7 @@ namespace VAR.ExpressionEvaluator
             }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionMultiplyNode.cs

@@ -11,9 +11,14 @@ namespace VAR.ExpressionEvaluator
 
         private static object MultiplyOp(object leftValue, object rightValue)
         {
+            if (leftValue == null || rightValue == null)
+            {
+                return null;
+            }
+
             if (leftValue is string)
             {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
+                if (decimal.TryParse((string)leftValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
                 }
@@ -21,7 +26,7 @@ namespace VAR.ExpressionEvaluator
             }
             if (rightValue is string)
             {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
+                if (decimal.TryParse((string)rightValue, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
                 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionNotEqualsNode.cs

@@ -1,6 +1,4 @@
-using System;
-
-namespace VAR.ExpressionEvaluator
+namespace VAR.ExpressionEvaluator
 {
     public class ExpressionNotEqualsNode : ExpressionBinaryNode
     {
@@ -11,33 +9,8 @@ namespace VAR.ExpressionEvaluator
 
         private static object NotEqualsOp(object leftValue, object rightValue)
         {
-            if (leftValue is string && rightValue is string)
-            {
-                return string.Compare((string)leftValue, (string)rightValue) != 0;
-            }
-
-            if (leftValue is string)
-            {
-                if (decimal.TryParse((string)leftValue, out decimal dec) == false)
-                {
-                    throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)leftValue));
-                }
-                leftValue = dec;
-            }
-            if (rightValue is string)
-            {
-                if (decimal.TryParse((string)rightValue, out decimal dec) == false)
-                {
-                    throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)rightValue));
-                }
-                rightValue = dec;
-            }
-
-            if ((leftValue is decimal) == false || (rightValue is decimal) == false)
-            {
-                throw new Exception("Can't compare non decimal values");
-            }
-            return (decimal)leftValue != (decimal)rightValue;
+            bool result = (bool)ExpressionEqualsNode.EqualsOp(leftValue, rightValue);
+            return !result;
         }
     }
 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionNullNode.cs

@@ -0,0 +1,10 @@
+namespace VAR.ExpressionEvaluator
+{
+    public class ExpressionNullNode : IExpressionNode
+    {
+        public object Eval(IEvaluationContext evaluationContext)
+        {
+            return null;
+        }
+    }
+}

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionNumberNegateNode.cs

@@ -11,9 +11,14 @@ namespace VAR.ExpressionEvaluator
 
         private static object NumberNegateOp(object value)
         {
+            if (value == null)
+            {
+                return null;
+            }
+
             if (value is string)
             {
-                if (decimal.TryParse((string)value, out decimal dec) == false)
+                if (decimal.TryParse((string)value, System.Globalization.NumberStyles.Any, System.Globalization.CultureInfo.InvariantCulture, out decimal dec) == false)
                 {
                     throw new Exception(string.Format("Can't convert to decimal string value \"{0}\"", (string)value));
                 }

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionPlusNode.cs

@@ -11,6 +11,11 @@ namespace VAR.ExpressionEvaluator
 
         private static object PlusOp(object leftValue, object rightValue)
         {
+            if (leftValue == null || rightValue == null)
+            {
+                return null;
+            }
+
             if (leftValue is string || rightValue is string)
             {
                 return string.Concat(Convert.ToString(leftValue), Convert.ToString(rightValue));

VAR.ExpressionEvaluator/ExpressionNodes/ExpressionVariableNode.cs

@@ -14,10 +14,6 @@ namespace VAR.ExpressionEvaluator
         public object Eval(IEvaluationContext evaluationContext)
         {
             object value = evaluationContext.GetVariable(_name);
-            if (value == null)
-            {
-                throw new Exception(string.Format("Variable {0} not found", _name));
-            }
             return value;
         }
     }

VAR.ExpressionEvaluator/Parser.cs

@@ -6,24 +6,42 @@ namespace VAR.ExpressionEvaluator
 {
     public class Parser
     {
-        private ITokenizer _tokenizer;
+        #region Custom exceptions
+
+        public class UnexpectedCharactersAtEndException : Exception
+        {
+            public UnexpectedCharactersAtEndException() : base("Unexpected characters at end of expression") { }
+        }
+
+        public class MissingCloseParenthesisException : Exception
+        {
+            public MissingCloseParenthesisException() : base("Missing close parenthesis") { }
+        }
+
+        public class UnexpectedEOFException : Exception
+        {
+            public UnexpectedEOFException() : base("Unexpected EOF") { }
+        }
+
+        public class UnexpectedTokenException : Exception
+        {
+            public UnexpectedTokenException(string token) : base(string.Format("Unexpected token: {0}", token)) { }
+        }
+
+        #endregion Custom exceptions
+
+        #region Creator
+
+        private readonly ITokenizer _tokenizer;
 
         public Parser(ITokenizer tokenizer)
         {
             _tokenizer = tokenizer;
         }
 
-        public IExpressionNode ParseExpression()
-        {
-            var expr = ParseBooleanOp();
+        #endregion Creator
 
-            if (_tokenizer.Token != Token.EOF)
-            {
-                throw new Exception("Unexpected characters at end of expression");
-            }
-
-            return expr;
-        }
+        #region Parsing methods
 
         private IExpressionNode ParseBooleanOp()
         {
@@ -42,7 +60,7 @@ namespace VAR.ExpressionEvaluator
                     IExpressionNode rightNode = ParseRelations();
                     leftNode = new ExpressionBooleanAndNode(leftNode, rightNode);
                 }
-                if (_tokenizer.Token == Token.Or)
+                else if (_tokenizer.Token == Token.Or)
                 {
                     _tokenizer.NextToken();
                     IExpressionNode rightNode = ParseRelations();
@@ -66,6 +84,13 @@ namespace VAR.ExpressionEvaluator
                     IExpressionNode rightNode = ParsePlusAndMinus();
                     leftNode = new ExpressionEqualsNode(leftNode, rightNode);
                 }
+                else if (_tokenizer.Token == Token.ExclusiveEquals)
+                {
+                    // TODO: Implement ExpressionExclusiveEqualsNode
+                    _tokenizer.NextToken();
+                    IExpressionNode rightNode = ParsePlusAndMinus();
+                    leftNode = new ExpressionEqualsNode(leftNode, rightNode);
+                }
                 else if (_tokenizer.Token == Token.NotEquals)
                 {
                     _tokenizer.NextToken();
@@ -197,6 +222,11 @@ namespace VAR.ExpressionEvaluator
                     _tokenizer.NextToken();
                     return new ExpressionBooleanNode(false);
                 }
+                if (identifierToLower == "null")
+                {
+                    _tokenizer.NextToken();
+                    return new ExpressionNullNode();
+                }
 
                 string identifier = _tokenizer.Text;
                 _tokenizer.NextToken();
@@ -209,9 +239,11 @@ namespace VAR.ExpressionEvaluator
                 {
                     _tokenizer.NextToken();
                     var parameters = new List<IExpressionNode>();
+                    if (_tokenizer.Token != Token.ParenthesisEnd)
+                    {
                         while (true)
                         {
-                        parameters.Add(ParsePlusAndMinus());
+                            parameters.Add(ParseBooleanOp());
                             if (_tokenizer.Token == Token.Comma)
                             {
                                 _tokenizer.NextToken();
@@ -219,9 +251,10 @@ namespace VAR.ExpressionEvaluator
                             }
                             break;
                         }
+                    }
                     if (_tokenizer.Token != Token.ParenthesisEnd)
                     {
-                        throw new Exception("Missing close parenthesis");
+                        throw new MissingCloseParenthesisException();
                     }
                     _tokenizer.NextToken();
 
@@ -236,13 +269,34 @@ namespace VAR.ExpressionEvaluator
                 IExpressionNode node = ParseBooleanOp();
                 if (_tokenizer.Token != Token.ParenthesisEnd)
                 {
-                    throw new Exception("Missing close parenthesis");
+                    throw new MissingCloseParenthesisException();
                 }
                 _tokenizer.NextToken();
                 return node;
             }
 
-            throw new Exception(string.Format("Unexpected token: {0}", _tokenizer.Token.ToString()));
+            if (_tokenizer.Token == Token.EOF)
+            {
+                throw new UnexpectedEOFException();
+            }
+
+            throw new UnexpectedTokenException(_tokenizer.Token.ToString());
+        }
+
+        #endregion Parsing methods
+
+        #region Public API
+
+        public IExpressionNode ParseExpression()
+        {
+            var expr = ParseBooleanOp();
+
+            if (_tokenizer.Token != Token.EOF)
+            {
+                throw new UnexpectedCharactersAtEndException();
+            }
+
+            return expr;
         }
 
         public static IExpressionNode ParseString(string str)
@@ -258,5 +312,7 @@ namespace VAR.ExpressionEvaluator
             IExpressionNode node = ParseString(str);
             return node.Eval(evaluationContext);
         }
+
+        #endregion Public API
     }
 }

VAR.ExpressionEvaluator/Properties/AssemblyInfo.cs

@@ -1,15 +0,0 @@
-using System.Reflection;
-using System.Runtime.InteropServices;
-
-[assembly: AssemblyTitle("VAR.ExpressionEvaluator")]
-[assembly: AssemblyDescription("Expression Evaluation Library")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("VAR")]
-[assembly: AssemblyProduct("VAR.ExpressionEvaluator")]
-[assembly: AssemblyCopyright("Copyright © VAR 2019")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-[assembly: ComVisible(false)]
-[assembly: Guid("74635f68-55b1-4819-84a3-9ea818d396d9")]
-[assembly: AssemblyVersion("0.1.1.0")]
-[assembly: AssemblyFileVersion("0.1.1.0")]

VAR.ExpressionEvaluator/Tokenizer.cs

@@ -144,6 +144,11 @@ namespace VAR.ExpressionEvaluator
                         NextChar();
                         _currentToken = Token.LessOrEqualThan;
                     }
+                    if (_currentChar == '>')
+                    {
+                        NextChar();
+                        _currentToken = Token.NotEquals;
+                    }
                     return;
 
                 case '&':
@@ -181,6 +186,41 @@ namespace VAR.ExpressionEvaluator
                     if (_currentChar == '\0') { break; }
                 }
                 _text = sb.ToString();
+                _currentToken = Token.Identifier;
+            }
+            else if (_currentChar == '[')
+            {
+                char stringEndsWith = ']';
+
+                NextChar();
+                StringBuilder sbString = new StringBuilder();
+                while (_currentChar != stringEndsWith && _currentChar != '\0')
+                {
+                    if (_currentChar != '\\')
+                    {
+                        sbString.Append(_currentChar);
+                    }
+                    else
+                    {
+                        NextChar();
+                        if (_currentChar == stringEndsWith)
+                        {
+                            sbString.Append(stringEndsWith);
+                        }
+                        else
+                        {
+                            // FIXME: Other escaped characters
+                            sbString.Append(_currentChar);
+                        }
+                    }
+                    NextChar();
+                }
+                NextChar();
+                _text = sbString.ToString();
+                _currentToken = Token.Identifier;
+            }
+            if (_currentToken == Token.Identifier)
+            {
                 string textLowercase = _text.ToLower();
                 if (textLowercase == "and")
                 {
@@ -257,6 +297,12 @@ namespace VAR.ExpressionEvaluator
                     haveDecimalPoint = _currentChar == '.';
                     NextChar();
                 }
+                if (haveDecimalPoint && sbNumber.Length == 1)
+                {
+                    _text = sbNumber.ToString();
+                    _currentToken = Token.String;
+                    return;
+                }
                 _number = decimal.Parse(sbNumber.ToString(), CultureInfo.InvariantCulture);
                 _currentToken = Token.Number;
                 return;

VAR.ExpressionEvaluator/VAR.ExpressionEvaluator.csproj

@@ -1,80 +1,27 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{74635F68-55B1-4819-84A3-9EA818D396D9}</ProjectGuid>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <OutputType>Library</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>VAR.ExpressionEvaluator</RootNamespace>
-    <AssemblyName>VAR.ExpressionEvaluator</AssemblyName>
-    <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <Deterministic>true</Deterministic>
+    <IsPackable>true</IsPackable>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
   </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
+  <PropertyGroup>
+    <PackageId>VAR.ExpressionEvaluator</PackageId>
+    <Title>VAR.ExpressionEvaluator</Title>
+    <Version>0.2.8</Version>
+    <Description>Expression Evaluation Library</Description>
+    <Authors>VAR</Authors>
+    <Company>VAR</Company>
+    <Copyright>Copyright © VAR 2019-2021</Copyright>
+    <RequireLicenseAcceptance>false</RequireLicenseAcceptance>
+    <PackageLicenseFile>LICENSE.txt</PackageLicenseFile>
+    <PackageProjectUrl>https://github.com/Kableado/VAR.ExpressionEvaluator</PackageProjectUrl>
+    <PackageTags>Expression;Evaluation;Expression Evaluation</PackageTags>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Xml.Linq" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="Microsoft.CSharp" />
-    <Reference Include="System.Data" />
-    <Reference Include="System.Net.Http" />
-    <Reference Include="System.Xml" />
+    <Content Include="..\LICENSE.txt" Link="LICENSE.txt" Pack="true" PackagePath="" />
   </ItemGroup>
-  <ItemGroup>
-    <Compile Include="EvaluationContext.cs" />
-    <Compile Include="ExpressionNodes\ExpressionBooleanAndNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionBooleanNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionBooleanNotNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionBooleanOrNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionDivisionNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionEqualsNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionFunctionNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionGreaterOrEqualThanNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionGreaterThanNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionLessOrEqualThanNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionLessThanNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionMultiplyNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionNotEqualsNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionUnaryNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionBinaryNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionMinusNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionNumberNegateNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionPlusNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionStringNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionNumberNode.cs" />
-    <Compile Include="ExpressionNodes\ExpressionVariableNode.cs" />
-    <Compile Include="IEvaluationContext.cs" />
-    <Compile Include="ExpressionNodes\IExpressionNode.cs" />
-    <Compile Include="ITokenizer.cs" />
-    <Compile Include="Parser.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="Token.cs" />
-    <Compile Include="Tokenizer.cs" />
-  </ItemGroup>
-  <ItemGroup>
-    <None Include="Build.NuGet.cmd" />
-    <None Include="packages.config" />
-    <None Include="VAR.ExpressionEvaluator.nuspec" />
-  </ItemGroup>
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
+  <Target Name="CopyPackage" AfterTargets="Pack">
+    <Copy SourceFiles="$(OutputPath)..\$(PackageId).$(PackageVersion).nupkg" DestinationFolder="Nuget\" />
+  </Target>
 </Project>

VAR.ExpressionEvaluator/VAR.ExpressionEvaluator.nuspec

@@ -1,20 +0,0 @@
-<?xml version="1.0"?>
-<package >
-  <metadata>
-    <id>$id$</id>
-    <version>$version$</version>
-    <title>$title$</title>
-    <authors>$author$</authors>
-    <owners>$author$</owners>
-    <licenseUrl>https://varstudio.net/VAR.ExpressionEvaluator/LICENSE.txt</licenseUrl>
-    <projectUrl>https://varstudio.net/VAR.ExpressionEvaluator</projectUrl>
-    <requireLicenseAcceptance>false</requireLicenseAcceptance>
-    <description>$description$</description>
-    <copyright>Copyright VAR 2019</copyright>
-    <tags>Expression Evaluation</tags>
-  </metadata>
-  <files>
-    <file src="bin\Release\VAR.ExpressionEvaluator.dll" target="lib\net461\VAR.ExpressionEvaluator.dll" />
-    <file src="bin\Release\VAR.ExpressionEvaluator.pdb" target="lib\net461\VAR.ExpressionEvaluator.pdb" />
-  </files>
-</package>

VAR.ExpressionEvaluator/packages.config

@@ -1,4 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<packages>
-  <package id="NuGet.CommandLine" version="5.3.1" targetFramework="net461" developmentDependency="true" />
-</packages>