Fix template parser

Author: RomanSoloweow

src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Common.cs

@@ -6,8 +6,8 @@ public static void Test1()
     {
         int? result;
         int? temp1 = 5;
-        int? temp2 = 5; 
-        
+        int? temp2 = 5;
+
         if (temp1 is null)
             result = temp1 ?? temp2;
         else

src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Common2.cs

@@ -0,0 +1,27 @@
+using System.Linq;
+using Xunit;
+
+namespace SimpleStateMachine.StructuralSearch.Tests;
+
+public static class PlaceholderParserTests
+{
+    [Theory]
+    [InlineData("($test$)", "(value )", "value ")]
+    [InlineData("($test$ )", "(value )", "value")]
+    [InlineData("($test$)", "(value (test))", "value (test)")]
+    [InlineData("($test$)", "(value (test) )", "value (test) ")]
+    [InlineData("$var$;", "test;;",  "test")]
+    [InlineData("$var$;.", "test;;;.", "test;;")]
+    [InlineData("$value2$", "temp1 ?? temp2", "temp1 ?? temp2")]
+    [InlineData("= $value2$;", "= temp1 ?? temp2;", "temp1 ?? temp2")]
+    public static void PlaceholderParsingShouldBeSuccess(string template, string source, string expectedResult)
+    {
+        var input = Input.Input.String(source);
+        var templateParser = StructuralSearch.StructuralSearch.ParseFindTemplate(template);
+        var matches = templateParser.Parse(input);
+        Assert.Single(matches);
+        var match = matches.First();
+        var placeholder = match.Placeholders.First();
+        Assert.Equal(expectedResult, placeholder.Value.Value);
+    }
+}

…ralSearch.Tests/ExamplesInput/Methods.cs …alSearch.Tests/ExamplesInput/Methods.txtsrc/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Methods.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Methods.txt src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Methods.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/Methods.txt

@@ -8,8 +8,8 @@ namespace SimpleStateMachine.StructuralSearch.Tests;
 public static class StructuralSearchParserTests
 {
     [Theory]
-    [InlineData("NullUnionOperator", "ExamplesInput/NullUnionOperator.cs", 2)]
-    [InlineData("TernaryOperator", "ExamplesInput/TernaryOperator.cs", 3)]
+    [InlineData("NullUnionOperator", "ExamplesInput/NullUnionOperator.txt", 2)]
+    [InlineData("TernaryOperator", "ExamplesInput/TernaryOperator.txt", 3)]
     public static void StructuralSearchShouldBeSuccess(string exampleName, string exampleFilePath, int matchesCount)
     {
         var config = ConfigurationMock.GetConfigurationFromFiles(exampleName);

…Tests/ExamplesInput/NullUnionOperator.cs …ests/ExamplesInput/NullUnionOperator.txtsrc/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/NullUnionOperator.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/NullUnionOperator.txt src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/NullUnionOperator.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/NullUnionOperator.txt

@@ -41,7 +41,7 @@ public static void StructuralSearchShouldBeSuccess(string inputText, string temp
 
 
     [Theory]
-    [InlineData("ExamplesInput/Methods.cs")]
+    [InlineData("ExamplesInput/Methods.txt")]
     public static void StructuralSearchFileParsingShouldBeSuccess(string filePath)
     {
         var configuration = new Configuration

…h.Tests/ExamplesInput/TernaryOperator.cs ….Tests/ExamplesInput/TernaryOperator.txtsrc/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/TernaryOperator.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/TernaryOperator.txt src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/TernaryOperator.cs renamed to src/SimpleStateMachine.StructuralSearch.Tests/ExamplesInput/TernaryOperator.txt

@@ -20,12 +20,13 @@ internal static class FindTemplateParser
         Grammar.WhiteSpaces.SelectToParser((_, parser) => parser);
 
     // template_component = placeholder | template_string_literal | whitespace
-    private static readonly Parser<char, IEnumerable<Parser<char, string>>> TemplateComponent
-        = Parser.OneOf(Placeholder, TemplateStringLiteral, WhiteSpaces).AtLeastOnce();
+    private static readonly Parser<char, Parser<char, string>> TemplateComponent
+        = Parser.OneOf(Placeholder, TemplateStringLiteral, WhiteSpaces);
 
     // template_between_parentheses = '(' template ')' | '{' template '}' | '[' template ']
     private static readonly Parser<char, IEnumerable<Parser<char, string>>> TemplateBetweenParentheses
-        = Parser.Rec(() => Template ?? throw new ArgumentNullException(nameof(Template))).Optional()
+        = Parser.Rec(() => Template ?? throw new ArgumentNullException(nameof(Template)))
+            .Optional() // To support empty Parentheses
             .BetweenAnyParentheses((left, result, right) =>
             {
                 var leftParser = Parser.Char(left).AsString();
@@ -36,6 +37,9 @@ private static readonly Parser<char, IEnumerable<Parser<char, string>>> Template
 
     // template = (template_component | template_between_parentheses)+
     internal static readonly Parser<char, IEnumerable<Parser<char, string>>> Template =
-        Parser.OneOf(TemplateBetweenParentheses, TemplateComponent)
-            .AtLeastOnce().Select(list => list.SelectMany(x => x));
+        Parser.OneOf
+        (
+            TemplateBetweenParentheses, 
+            TemplateComponent.Select<IEnumerable<Parser<char, string>>>(x => new List<Parser<char, string>> { x })
+        ).AtLeastOnce().Select(list => list.SelectMany(x => x));
 }