Add optional var keyword

Author: Sébastien Geiser

CodingSeb.ExpressionEvaluator.Tests/ExpressionEvaluatorScriptEvaluateTests.cs

@@ -1219,6 +1219,16 @@ public static IEnumerable<TestCaseData> TestCasesForScriptEvaluateTests
 
                 #endregion
 
+                #region var keyword
+
+                yield return new TestCaseData(Resources.Script0060, null, null, null)
+                    .SetCategory("Script")
+                    .SetCategory("var keyword")
+                    .SetCategory("=")
+                    .Returns("A text for 4 test");
+
+                #endregion
+
                 #region More complex script
 
                 yield return new TestCaseData(Resources.Script0007, null, null, null)

CodingSeb.ExpressionEvaluator.Tests/Resources.Designer.cs

@@ -295,4 +295,7 @@
   <data name="Script0059" type="System.Resources.ResXFileRef, System.Windows.Forms">
     <value>resources\script0059.txt;System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089;utf-8</value>
   </data>
+  <data name="Script0060" type="System.Resources.ResXFileRef, System.Windows.Forms">
+    <value>resources\script0060.txt;System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089;utf-8</value>
+  </data>
 </root>

CodingSeb.ExpressionEvaluator.Tests/Resources.resx

@@ -0,0 +1,5 @@
+/* Script0060 */
+var x = 4;
+var textVar = "A text for {0} test";
+
+return string.Format(textVar, x);

CodingSeb.ExpressionEvaluator.Tests/Resources/Script0060.txt

@@ -31,7 +31,7 @@ public partial class ExpressionEvaluator
         private const string diactitics = "áàâãåǎăāąæéèêëěēĕėęěìíîïīĭįijóôõöōŏőøðœùúûüǔũūŭůűųýþÿŷıćĉċčçďđĝğġģĥħĵķĺļľŀłńņňŋñŕŗřśŝşšţťŧŵźżžÁÀÂÃÅǍĂĀĄÆÉÈÊËĚĒĔĖĘĚÌÍÎÏĪĬĮIJÓÔÕÖŌŎŐØÐŒÙÚÛÜǓŨŪŬŮŰŲÝÞŸŶIĆĈĊČÇĎĐĜĞĠĢĤĦĴĶĹĻĽĿŁŃŅŇŊÑŔŖŘŚŜŞŠŢŤŦŴŹŻŽß";
         private const string diactiticsKeywordsRegexPattern = "a-zA-Z_" + diactitics;
 
-        private static readonly Regex varOrFunctionRegEx = new Regex($@"^((?<sign>[+-])|(?<prefixOperator>[+][+]|--)|(?<inObject>(?<nullConditional>[?])?\.)?)(?<name>[{ diactiticsKeywordsRegexPattern }](?>[{ diactiticsKeywordsRegexPattern }0-9]*))(?>\s*)((?<assignationOperator>(?<assignmentPrefix>[+\-*/%&|^]|<<|>>)?=(?![=>]))|(?<postfixOperator>([+][+]|--)(?![{ diactiticsKeywordsRegexPattern}0-9]))|((?<isgeneric>[<](?>([{ diactiticsKeywordsRegexPattern }](?>[{ diactiticsKeywordsRegexPattern }0-9]*)|(?>\s+)|[,\.])+|(?<gentag>[<])|(?<-gentag>[>]))*(?(gentag)(?!))[>])?(?<isfunction>[(])?))", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+        private static readonly Regex varOrFunctionRegEx = new Regex($@"^((?<sign>[+-])|(?<prefixOperator>[+][+]|--)|(?<varKeyword>var\s+)|(?<inObject>(?<nullConditional>[?])?\.)?)(?<name>[{ diactiticsKeywordsRegexPattern }](?>[{ diactiticsKeywordsRegexPattern }0-9]*))(?>\s*)((?<assignationOperator>(?<assignmentPrefix>[+\-*/%&|^]|<<|>>)?=(?![=>]))|(?<postfixOperator>([+][+]|--)(?![{ diactiticsKeywordsRegexPattern}0-9]))|((?<isgeneric>[<](?>([{ diactiticsKeywordsRegexPattern }](?>[{ diactiticsKeywordsRegexPattern }0-9]*)|(?>\s+)|[,\.])+|(?<gentag>[<])|(?<-gentag>[>]))*(?(gentag)(?!))[>])?(?<isfunction>[(])?))", RegexOptions.IgnoreCase | RegexOptions.Compiled);
 
         private const string numberRegexOrigPattern = @"^(?<sign>[+-])?([0-9][0-9_{1}]*[0-9]|\d)(?<hasdecimal>{0}?([0-9][0-9_]*[0-9]|\d)(e[+-]?([0-9][0-9_]*[0-9]|\d))?)?(?<type>ul|[fdulm])?";
         private string numberRegexPattern = null;
@@ -1735,10 +1735,17 @@ void Init(object element, List<string> initArgs)
             }
         }
 
+
         private bool EvaluateVarOrFunc(string expr, string restOfExpression, Stack<object> stack, ref int i)
         {
             Match varFuncMatch = varOrFunctionRegEx.Match(restOfExpression);
 
+            if (varFuncMatch.Groups["varKeyword"].Success
+                && !varFuncMatch.Groups["assignationOperator"].Success)
+            {
+                throw new ExpressionEvaluatorSyntaxErrorException("Implicit variables must be initialized");
+            }
+
             if (varFuncMatch.Success
             && (!varFuncMatch.Groups["sign"].Success
                 || stack.Count == 0