Grammar.cs

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using Mercury.Exceptions;
using Mercury.Nucleus.Collections;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Mercury.Syntax
{
//=============================================================================
//  Grammar
//=============================================================================

    public class Grammar
    {
        //--[  Properties  ]---------------------------------------------------

        public IReadOnlyList<Symbol> Nonterminals { get; internal set; }

        public IReadOnlyList<Symbol> Terminals { get; internal set; }

        public IReadOnlyList<Rule> Rules { get; internal set; }

        public Symbol Root { get; internal set; }

        public Symbol Epsilon { get; internal set; }
    }

//=============================================================================
//  ExtendedGrammar
//=============================================================================

    internal class ExtendedGrammar : Grammar
    {
        //--[  Internal fields  ]----------------------------------------------

        internal IMultiDictionary<Symbol, Rule> rulemap; // accessed by ExtendedGrammarBuilder

        //--[  Properties  ]---------------------------------------------------

        public IReadOnlyList<Rule> TerminalRules { get; internal set; }

        public IReadOnlyList<Rule> EpsilonRules { get; internal set; }

        //--[  Methods  ]------------------------------------------------------

        public IReadOnlyList<Rule> RulesWithInitial(Symbol s)
        {
            IReadOnlyList<Rule> rules;

            return rulemap.TryGetValue(s, out rules) ? new List<Rule>(rules) : new List<Rule>();
        }
    }

}