feat: Parser Combinator库和词法分析器 (#2)

Reviewed-on: https://git.bupt-hpc.cn/jackfiled/CanonSharp/pulls/2
Co-authored-by: jackfiled <xcrenchangjun@outlook.com>
Co-committed-by: jackfiled <xcrenchangjun@outlook.com>

CanonSharp.Tests/CombinatorsTests/BasicParsersTests.cs

@@ -0,0 +1,84 @@
+using CanonSharp.Combinator;
+using CanonSharp.Combinator.Abstractions;
+using CanonSharp.Combinator.Extensions;
+using CanonSharp.Tests.Utils;
+using static CanonSharp.Combinator.ParserBuilder;
+
+namespace CanonSharp.Tests.CombinatorsTests;
+
+public class BasicParsersTests : ParserTestsBase
+{
+    [Fact]
+    public void AlternativeTest()
+    {
+        Parser<char, char> parser = Token('a') | Token('b');
+
+        ValidateSuccessfulResult(parser, 'a', "abc");
+        ValidateSuccessfulResult(parser, 'b', "bcd");
+        ValidateFailedResult(parser, "cde");
+
+        parser = Token('a').Alternative(_ => Token('b'));
+        ValidateSuccessfulResult(parser, 'a', "abc");
+        ValidateSuccessfulResult(parser, 'b', "bcd");
+        ValidateFailedResult(parser, "cde");
+    }
+
+    [Fact]
+    public void BindTest()
+    {
+        Parser<char, char> parser = Token('a').Bind(_ => Token('b')).Bind(_ => Token('c'));
+        ValidateSuccessfulResult(parser, 'c', "abc");
+        ValidateFailedResult(parser, "acd");
+
+        ValidateFailedResult(parser, "ab");
+    }
+
+    [Fact]
+    public void MapTest()
+    {
+        Parser<char, string> parser = Token('a').Map(c => $"{c}");
+        ValidateSuccessfulResult(parser, "a", "abc");
+
+        parser = Token('a').Map("test");
+        ValidateSuccessfulResult(parser, "test", "abc");
+    }
+
+    [Fact]
+    public void NextTest()
+    {
+        Parser<char, char> parser = Token('a').Next(_ => Token('a'), _ => Token('b'));
+        ValidateSuccessfulResult(parser, 'a', "aaa");
+        ValidateSuccessfulResult(parser, 'b', "bbb");
+
+        parser = Token('a').Next(_ => Token('a'), _ => 'b');
+        ValidateSuccessfulResult(parser, 'b', "bbb");
+
+        parser = Token('a').Next(_ => Pure<char, char>('1'), '2');
+        ValidateSuccessfulResult(parser, '1', "aaa");
+        ValidateSuccessfulResult(parser, '2', "bbb");
+    }
+
+    [Fact]
+    public void NextTest2()
+    {
+        Parser<char, string> parser = Token('a').Next(_ => "123", _ => Pure<char, string>("456"));
+        ValidateSuccessfulResult(parser, "123", "aaa");
+        ValidateSuccessfulResult(parser, "456", "bbb");
+
+        parser = Token('a').Next(_ => "123", _ => "456");
+        ValidateSuccessfulResult(parser, "123", "aaa");
+        ValidateSuccessfulResult(parser, "456", "bbb");
+
+        parser = Token('a').Next(_ => "123", "456");
+        ValidateSuccessfulResult(parser, "123", "aaa");
+        ValidateSuccessfulResult(parser, "456", "bbb");
+    }
+
+    [Fact]
+    public void FixTest()
+    {
+        Parser<char, char> parser = Fix<char, Unit>(self => Token('a').Next(_ => self, Unit.Instance))
+            .Bind(_ => Token('b'));
+        ValidateSuccessfulResult(parser, 'b', "aaaaab");
+    }
+}