add: basic grammar parser including expression and program.

CanonSharp.Tests/Utils/GrammarParserTestBase.cs

@@ -0,0 +1,31 @@
+using CanonSharp.Combinator.Abstractions;
+using CanonSharp.Pascal.Parser;
+using CanonSharp.Pascal.Scanner;
+using CanonSharp.Pascal.SyntaxTree;
+
+namespace CanonSharp.Tests.Utils;
+
+public abstract class GrammarParserTestBase
+{
+    protected static T RunParser<T>(IParser<LexicalToken, SyntaxNodeBase> parser, string input) where T : SyntaxNodeBase
+    {
+        LexicalScanner scanner = new();
+        LexicalTokenReadState state = new(scanner.Tokenize(new StringReadState(input)));
+        IParseResult<LexicalToken, SyntaxNodeBase> parseResult = parser.Parse(state);
+
+        return parseResult.Value.Convert<T>();
+    }
+
+    protected static List<T> RunParser<T>(IParser<LexicalToken, IEnumerable<SyntaxNodeBase>> parser,
+        string input) where T : SyntaxNodeBase
+    {
+        LexicalScanner scanner = new();
+        LexicalTokenReadState state = new(scanner.Tokenize(new StringReadState(input)));
+        IParseResult<LexicalToken, IEnumerable<SyntaxNodeBase>> parseResult = parser.Parse(state);
+
+        return parseResult.Value.Select(node => node.Convert<T>()).ToList();
+    }
+
+    protected static Program ProgramParse(string input)
+        => RunParser<Program>(GrammarParser.ProgramParser(), input);
+}