CanonSharp/CanonSharp.Pascal/Parser/GrammarParserBase.cs

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;

public abstract class GrammarParserBuilder
{
    protected static IParser<LexicalToken, LexicalToken> Keyword(string value)
        => Satisfy<LexicalToken>(token =>
            token.TokenType == LexicalTokenType.Keyword &&
            token.LiteralValue.Equals(value, StringComparison.OrdinalIgnoreCase));

    protected static IParser<LexicalToken, LexicalToken> Operator(string value)
        => Satisfy<LexicalToken>(token => token.TokenType == LexicalTokenType.Operator && token.LiteralValue == value);

    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, IntegerValueNode> IntegerParser()
    {
        return from token in Satisfy<LexicalToken>(token => token.TokenType == LexicalTokenType.ConstInteger)
            select new IntegerValueNode(int.Parse(token.LiteralValue));
    }

    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")
        );
    }

    protected static IParser<LexicalToken, LexicalToken> IdentifierParser()
    {
        return Satisfy<LexicalToken>(token => token.TokenType == LexicalTokenType.Identifier);
    }
}