#34 - DateString parser.

Author: techyian

readme.md

@@ -284,7 +284,7 @@ https://github.com/Apress/beg-sql-server-reporting-services/blob/master/Beginnin
 | Date & Time  | DateDiff        | Complete      |                            |
 | Date & Time  | DatePart        | Partial       | Not yet tested with all time intervals                            |
 | Date & Time  | DateSerial      | Complete      |                            |
-| Date & Time  | DateString      | Not started   |                            |
+| Date & Time  | DateString      | Complete      |                            |
 | Date & Time  | DateValue       | Complete      |                            |
 | Date & Time  | Day             | Complete      |                            |
 | Date & Time  | FormatDateTime  | Complete      |                            |

src/ReportViewer.NET/Parsers/DateAndTime/DateStringParser.cs

@@ -0,0 +1,44 @@
+using ReportViewer.NET.DataObjects;
+using ReportViewer.NET.Extensions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace ReportViewer.NET.Parsers.DateAndTime
+{
+    public class DateStringParser : BaseParser
+    {
+        public static Regex DateStringRegex = RegexCommon.GenerateParserRegex("DateString");
+
+        public DateStringParser(
+            string currentString,
+            ExpressionFieldOperator op,
+            ReportExpression currentExpression,
+            IEnumerable<IDictionary<string, object>> dataSetResults,
+            IDictionary<string, object> values,
+            int currentRowNumber,
+            IEnumerable<DataSet> dataSets,
+            DataSet activeDataset,
+            ReportRDL report
+        ) : base(currentString, op, currentExpression, dataSetResults, values, currentRowNumber, dataSets, activeDataset, DateStringRegex, report)
+        {
+        }
+
+        public override (Type, object) ExtractExpressionValue(string fieldName, string dataSetName)
+        {
+            throw new NotImplementedException();
+        }
+
+        public override void Parse()
+        {
+            var match = DateStringRegex.Match(CurrentString);
+
+            CurrentExpression.Index = match.Index;
+            CurrentExpression.ResolvedType = typeof(DateTime);
+            CurrentExpression.Value = DateTime.Now;
+        }
+    }
+}

src/ReportViewer.NET/Parsers/ExpressionFieldOperator.cs

@@ -57,6 +57,7 @@ public enum ExpressionFieldOperator
         DateDiff,
         DatePart,
         DateSerial,
+        DateString,
         Day,
         Now,
         DateValue,

src/ReportViewer.NET/Parsers/ExpressionParser.cs

@@ -524,6 +524,15 @@ ref string proposedString
                 proposedString = dateSerialParser.GetProposedString();
             }
 
+            if (DateStringParser.DateStringRegex.IsMatch(currentString) &&
+                (currentExpression.Operator == ExpressionFieldOperator.None || DateStringParser.DateStringRegex.Match(currentString).Index < currentExpression.Index)
+            )
+            {
+                var dateStringParser = new DateStringParser(currentString, ExpressionFieldOperator.DateString, currentExpression, dataSetResults, values, currentRowNumber, dataSets, activeDataset, _report);
+                dateStringParser.Parse();
+                proposedString = dateStringParser.GetProposedString();
+            }
+
             if (DayParser.DayRegex.IsMatch(currentString) &&
                 ((WeekdayParser.WeekdayRegex.IsMatch(currentString) && DayParser.DayRegex.Match(currentString).Index < WeekdayParser.WeekdayRegex.Match(currentString).Index) || !WeekdayParser.WeekdayRegex.IsMatch(currentString)) &&
                 (currentExpression.Operator == ExpressionFieldOperator.None || DayParser.DayRegex.Match(currentString).Index < currentExpression.Index)

test/ReportViewer.NET.Tests/Parsers/DateAndTime/DateStringParserTests.cs

@@ -0,0 +1,75 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using ReportViewer.NET.DataObjects;
+using ReportViewer.NET.Extensions;
+using ReportViewer.NET.Parsers;
+using System.Globalization;
+
+namespace ReportViewer.NET.Tests.Parsers.DateAndTime
+{
+    [TestClass]
+    public class DateStringParserTests
+    {
+        private ExpressionParser _expressionParser;
+        private ReportRDL _report;
+
+        public DateStringParserTests()
+        {
+            var report = TestHelper.PrimeReport();
+
+            _report = report;
+            _expressionParser = new ExpressionParser(report);
+        }
+
+        [TestMethod]
+        public void DateString_Return_String()
+        {          
+            // Arrange
+            var expr = "=FormatDateTime(DateString(), DateFormat.ShortDate)";
+
+            // Act            
+            var cultureInfo = new CultureInfo("en-GB");
+            CultureInfo originalCulture = Thread.CurrentThread.CurrentCulture;
+            CultureInfo.DefaultThreadCurrentCulture = cultureInfo;
+            CultureInfo.DefaultThreadCurrentUICulture = cultureInfo;
+
+            var now = DateTime.Now;
+            var result = _expressionParser.ParseReportExpressionString(
+                expr,
+                null,
+                null,
+                1,
+                _report.DataSets,
+                null,
+                null
+            ).ExpressionAsString();
+
+            // Assert
+            Assert.AreEqual(now.ToShortDateString(), result);
+
+            CultureInfo.DefaultThreadCurrentCulture = originalCulture;
+            CultureInfo.DefaultThreadCurrentUICulture = originalCulture;
+        }
+
+        [TestMethod]
+        public void DateString_Return_String_Nested_DatePart()
+        {
+            // Arrange
+            var now = DateTime.Now;
+            var expr = "=MonthName(DatePart(\"m\", DateString()))";            
+                                    
+            // Act                                    
+            var result = _expressionParser.ParseReportExpressionString(
+                expr,
+                null,
+                null,
+                1,
+                _report.DataSets,
+                null,
+                null
+            ).ExpressionAsString();
+
+            // Assert
+            Assert.AreEqual(CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(now.Month), result);
+        }
+    }
+}