Symbol.cs :  » Script » IronRuby » gpcc » C# / CSharp Open Source

// Copyright (c) Microsoft Corporation. All rights reserved.


using System;
using System.Collections.Generic;
using System.Text;


namespace gpcc{
  public abstract class Symbol
  {
    private string name;
    public string kind;

    public abstract int num
    {
      get;
    }


    public Symbol(string name)
    {
      this.name = name;
    }


    public override string ToString()
    {
      return name;
    }


    public abstract bool IsNullable();
  }


  public class Terminal : Symbol
  {
        static int count = 0;
    static int max = 0;

    public Precedence prec = null;
    private int n;
    public bool symbolic;

    public override int num
    {
      get
      {
        if (symbolic)
          return max + n;
        else
          return n;
      }
    }

    public Terminal(bool symbolic, string name)
      : base(symbolic ? name : "'" + name.Replace("\n", @"\n") + "'")
    {
      this.symbolic = symbolic;

      if (symbolic)
        this.n = ++count;
      else
      {
        this.n = (int)name[0];
        if (n > max) max = n;
      }
    }


    public override bool IsNullable()
    {
      return false;
    }

        public override string ToString() {
            string name = base.ToString();

            // any lower case => return as is:
            for (int i = 0; i < name.Length; i++) {
                if (Char.IsLower(name[i])) return name;
            }

            // capitalize otherwise, remove underscores:
            StringBuilder result = new StringBuilder();
            bool doLower = false;
            for (int i = 0, j = 0; i < name.Length; i++, j++) {
                if (name[i] == '_') {
                    doLower = false;
                } else {
                    if (doLower) {
                        result.Append(Char.ToLower(name[i]));
                    } else {
                        result.Append(name[i]);
                        doLower = true;
                    }
                }
            }
            return result.ToString();
        }
    }



    public class NonTerminal : Symbol
  {
        public bool reached = false;
        static int count = 0;
    private int n;
    public List<Production> productions = new List<Production>();


    public NonTerminal(string name)
      : base(name)
    {
            n = ++count;
    }

    public override int num
    {
      get
      {
        return -n;
      }
    }

    private object isNullable;
    public override bool IsNullable()
    {
      if (isNullable == null)
      {
        isNullable = false;
        foreach (Production p in productions)
        {
          bool nullable = true;
          foreach (Symbol rhs in p.rhs)
            if (!rhs.IsNullable())
            {
              nullable = false;
              break;
            }
          if (nullable)
          {
            isNullable = true;
            break;
          }
        }
      }

      return (bool)isNullable;
    }
  }
}