add: constant parser and variable parser.

CanonSharp.Pascal/Parser/GrammarParser.cs

@@ -10,21 +10,6 @@ public sealed class GrammarParser : GrammarParserBuilder
 {
     public static IParser<LexicalToken, SyntaxNodeBase> FactorParser()
     {
-        // factor -> true | false | num
-        IParser<LexicalToken, SyntaxNodeBase> trueParser = from _ in Keyword("true")
-            select new BooleanValueNode(true);
-
-        IParser<LexicalToken, SyntaxNodeBase> falseParser = from _ in Keyword("false")
-            select new BooleanValueNode(false);
-
-        IParser<LexicalToken, SyntaxNodeBase> integerParser =
-            from token in Satisfy<LexicalToken>(x => x.TokenType == LexicalTokenType.ConstInteger)
-            select new IntegerValueNode(int.Parse(token.LiteralValue));
-
-        IParser<LexicalToken, SyntaxNodeBase> floatParser =
-            from token in Satisfy<LexicalToken>(x => x.TokenType == LexicalTokenType.ConstFloat)
-            select new FloatValueNode(double.Parse(token.LiteralValue));
-
         // factor -> - factor | + factor
         IParser<LexicalToken, SyntaxNodeBase> minusParser =
             from _ in Operator("-")
@@ -48,10 +33,9 @@ public sealed class GrammarParser : GrammarParserBuilder
             select node;
 
         return Choice(
-            trueParser,
+            TrueParser(),
-            falseParser,
+            FalseParser(),
-            integerParser,
+            NumberParser(),
-            floatParser,
             minusParser,
             plusParser,
             notParser,
@@ -177,10 +161,66 @@ public sealed class GrammarParser : GrammarParserBuilder
             select new BlockNode(statements);
     }
 
+    public static IParser<LexicalToken, SyntaxNodeBase> ConstValueParser()
+    {
+        return Choice(
+            from _ in Operator("-")
+            from num in NumberParser()
+            select new UnaryOperatorNode(UnaryOperatorType.Minus, num),
+            from _ in Operator("+")
+            from num in NumberParser()
+            select new UnaryOperatorNode(UnaryOperatorType.Plus, num),
+            NumberParser(),
+            CharParser(),
+            TrueParser(),
+            FalseParser()
+        );
+    }
+
+    public static IParser<LexicalToken, SyntaxNodeBase> ConstDeclarationParser()
+    {
+        return from identifier in Satisfy<LexicalToken>(token =>
+                token.TokenType == LexicalTokenType.Identifier)
+            from _ in Operator("=")
+            from node in ConstValueParser()
+            select new ConstantNode(identifier, node);
+    }
+
+    public static IParser<LexicalToken, SyntaxNodeBase> ConstDeclarationsParser()
+    {
+        return (from _ in Keyword("const")
+            from tokens in ConstDeclarationParser().SeparatedOrEndBy1(Delimiter(";"))
+            select new BlockNode(tokens)).Try(new BlockNode([]));
+    }
+
+    public static IParser<LexicalToken, SyntaxNodeBase> TypeParser()
+    {
+        return from token in BasicTypeParser()
+            select new TypeNode(token);
+    }
+
+    public static IParser<LexicalToken, VariableDeclarationNode> VariableDeclarationParser()
+    {
+        return from tokens in Satisfy<LexicalToken>(
+                token => token.TokenType == LexicalTokenType.Identifier).SeparatedBy1(Delimiter(","))
+            from _1 in Delimiter(":")
+            from type in TypeParser()
+            select new VariableDeclarationNode(tokens, type.Convert<TypeNode>());
+    }
+
+    public static IParser<LexicalToken, BlockNode> VariableDeclarationsParser()
+    {
+        return (from _ in Keyword("var")
+            from nodes in VariableDeclarationParser().SeparatedOrEndBy1(Delimiter(";"))
+            select new BlockNode(nodes)).Try(new BlockNode([]));
+    }
+
     public static IParser<LexicalToken, ProgramBody> ProgramBodyParser()
     {
-        return from block in CompoundStatementParser()
+        return from constant in ConstDeclarationsParser()
-            select new ProgramBody(block);
+            from variables in VariableDeclarationsParser()
+            from block in CompoundStatementParser()
+            select new ProgramBody(constant.Convert<BlockNode>(), variables, block);
     }
 
     public static IParser<LexicalToken, ProgramHead> ProgramHeadParser()

CanonSharp.Pascal/Parser/GrammarParserBase.cs

@@ -1,5 +1,7 @@
 using CanonSharp.Combinator.Abstractions;
+using CanonSharp.Combinator.Extensions;
 using CanonSharp.Pascal.Scanner;
+using CanonSharp.Pascal.SyntaxTree;
 using static CanonSharp.Combinator.ParserBuilder;
 
 namespace CanonSharp.Pascal.Parser;
@@ -14,4 +16,42 @@ public abstract class GrammarParserBuilder
 
     protected static IParser<LexicalToken, LexicalToken> Delimiter(string value)
         => Satisfy<LexicalToken>(token => token.TokenType == LexicalTokenType.Delimiter && token.LiteralValue == value);
+
+    protected static IParser<LexicalToken, BooleanValueNode> TrueParser()
+    {
+        return from _ in Keyword("true")
+            select new BooleanValueNode(true);
+    }
+
+    protected static IParser<LexicalToken, BooleanValueNode> FalseParser()
+    {
+        return from _ in Keyword("false")
+            select new BooleanValueNode(false);
+    }
+
+    protected static IParser<LexicalToken, SyntaxNodeBase> NumberParser()
+    {
+        return Choice<LexicalToken, SyntaxNodeBase>(
+            from token in Satisfy<LexicalToken>(x => x.TokenType == LexicalTokenType.ConstInteger)
+            select new IntegerValueNode(int.Parse(token.LiteralValue)),
+            from token in Satisfy<LexicalToken>(x => x.TokenType == LexicalTokenType.ConstFloat)
+            select new FloatValueNode(double.Parse(token.LiteralValue))
+        );
+    }
+
+    protected static IParser<LexicalToken, CharValueNode> CharParser()
+    {
+        return Satisfy<LexicalToken>(token => token.TokenType == LexicalTokenType.Character)
+            .Map(x => new CharValueNode(char.Parse(x.LiteralValue)));
+    }
+
+    protected static IParser<LexicalToken, LexicalToken> BasicTypeParser()
+    {
+        return Choice(
+            Keyword("integer"),
+            Keyword("real"),
+            Keyword("boolean"),
+            Keyword("char")
+        );
+    }
 }

CanonSharp.Pascal/SyntaxTree/CharValueNode.cs

@@ -0,0 +1,8 @@
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class CharValueNode(char value) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.CharValue;
+
+    public char Value => value;
+}

CanonSharp.Pascal/SyntaxTree/ConstantNode.cs

@@ -0,0 +1,12 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class ConstantNode(LexicalToken identifier, SyntaxNodeBase value) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.Constant;
+
+    public LexicalToken Identifier = identifier;
+
+    public SyntaxNodeBase Value = value;
+}

CanonSharp.Pascal/SyntaxTree/ProgramBody.cs

@@ -1,8 +1,12 @@
 namespace CanonSharp.Pascal.SyntaxTree;
 
-public sealed class ProgramBody(BlockNode block) : SyntaxNodeBase
+public sealed class ProgramBody(BlockNode constantDeclarations, BlockNode variableDeclarations, BlockNode mainBlock) : SyntaxNodeBase
 {
     public override SyntaxNodeType NodeType => SyntaxNodeType.ProgramBody;
 
-    public BlockNode MainBlock => block;
+    public BlockNode ConstantDeclarations => constantDeclarations;
+
+    public BlockNode VariableDeclarations => variableDeclarations;
+
+    public BlockNode MainBlock => mainBlock;
 }

CanonSharp.Pascal/SyntaxTree/SyntaxNodeBase.cs

@@ -7,9 +7,13 @@ public enum SyntaxNodeType
     IntegerValue,
     FloatValue,
     BooleanValue,
+    CharValue,
     Variable,
+    Type,
     Assign,
     Block,
+    Constant,
+    VariableDeclaration,
     ProgramBody,
     ProgramHead,
     Program

CanonSharp.Pascal/SyntaxTree/TypeNode.cs

@@ -0,0 +1,10 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class TypeNode(LexicalToken typeToken) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.Type;
+
+    public LexicalToken TypeToken => typeToken;
+}

CanonSharp.Pascal/SyntaxTree/VariableDeclarationNode.cs

@@ -0,0 +1,12 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class VariableDeclarationNode(IEnumerable<LexicalToken> identifiers, TypeNode typeNode) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.VariableDeclaration;
+
+    public IList<LexicalToken> Identifiers => identifiers.ToList();
+
+    public TypeNode TypeNode => typeNode;
+}

CanonSharp.Tests/ParserTests/ConstDeclarationTests.cs

@@ -0,0 +1,62 @@
+using CanonSharp.Pascal.Parser;
+using CanonSharp.Pascal.SyntaxTree;
+using CanonSharp.Tests.Utils;
+
+namespace CanonSharp.Tests.ParserTests;
+
+public class ConstDeclarationTests : GrammarParserTestBase
+{
+    [Fact]
+    public void BooleanConstValueTest()
+    {
+        BooleanValueNode node = RunParser<BooleanValueNode>(GrammarParser.ConstValueParser(), "true");
+        Assert.True(node.Value);
+
+        node = RunParser<BooleanValueNode>(GrammarParser.ConstValueParser(), "false");
+        Assert.False(node.Value);
+    }
+
+    [Fact]
+    public void CharConstValueTest()
+    {
+        CharValueNode node = RunParser<CharValueNode>(GrammarParser.ConstValueParser(), "'a'");
+        Assert.Equal('a', node.Value);
+    }
+
+    [Fact]
+    public void NumberConstValueTest()
+    {
+        IntegerValueNode integerValueNode = RunParser<IntegerValueNode>(GrammarParser.ConstValueParser(), "250");
+        Assert.Equal(250, integerValueNode.Value);
+
+        FloatValueNode floatValueNode = RunParser<FloatValueNode>(GrammarParser.ConstValueParser(), "100.5");
+        Assert.Equal(100.5, floatValueNode.Value);
+
+        UnaryOperatorNode node = RunParser<UnaryOperatorNode>(GrammarParser.ConstValueParser(), "+250");
+        Assert.Equal(UnaryOperatorType.Plus, node.OperatorType);
+        node = RunParser<UnaryOperatorNode>(GrammarParser.ConstValueParser(), "-100.5");
+        Assert.Equal(UnaryOperatorType.Minus, node.OperatorType);
+    }
+
+    [Fact]
+    public void ConstDeclarationTest()
+    {
+        ConstantNode node = RunParser<ConstantNode>(GrammarParser.ConstDeclarationParser(), "a = true");
+
+        Assert.Equal("a", node.Identifier.LiteralValue);
+        Assert.True(node.Value.Convert<BooleanValueNode>().Value);
+    }
+
+    [Theory]
+    [InlineData("", 0)]
+    [InlineData("const INFINITE = 100;", 1)]
+    [InlineData("const a = true; b = false", 2)]
+    [InlineData("const code1 = 100.4;code2 = 'a'", 2)]
+    public void ConstDeclarationsCountTest(string input, int count)
+    {
+        BlockNode blockNode = RunParser<BlockNode>(GrammarParser.ConstDeclarationsParser(), input);
+        List<ConstantNode> constantNodes = blockNode.Statements.Select(node => node.Convert<ConstantNode>()).ToList();
+
+        Assert.Equal(count, constantNodes.Count);
+    }
+}

CanonSharp.Tests/ParserTests/ProgramParserTests.cs

@@ -38,4 +38,32 @@ public class ProgramParserTests : GrammarParserTestBase
         Assert.Equal(1, binaryOperatorNode.Left.Convert<IntegerValueNode>().Value);
         Assert.Equal(1, binaryOperatorNode.Right.Convert<IntegerValueNode>().Value);
     }
+
+    [Fact]
+    public void ProgramParseTest3()
+    {
+        Program program = ProgramParse("""
+                                       program main;
+                                       const a = 1; b = true;
+                                       begin
+                                       temp := 1 + 1;
+                                       end.
+                                       """);
+
+        Assert.Equal("main", program.Head.ProgramName.LiteralValue);
+
+        List<ConstantNode> constantNodes = program.Body.ConstantDeclarations.Statements
+            .Select(x => x.Convert<ConstantNode>()).ToList();
+        Assert.Equal(2, constantNodes.Count);
+        Assert.Equal("a", constantNodes[0].Identifier.LiteralValue);
+        Assert.Equal("b", constantNodes[1].Identifier.LiteralValue);
+
+        AssignNode assignNode = program.Body.MainBlock.Statements[0].Convert<AssignNode>();
+        Assert.Equal("temp", assignNode.Variable.IdentifierName);
+
+        BinaryOperatorNode binaryOperatorNode = assignNode.Expression.Convert<BinaryOperatorNode>();
+        Assert.Equal(BinaryOperatorType.Add, binaryOperatorNode.OperatorType);
+        Assert.Equal(1, binaryOperatorNode.Left.Convert<IntegerValueNode>().Value);
+        Assert.Equal(1, binaryOperatorNode.Right.Convert<IntegerValueNode>().Value);
+    }
 }