SLR 分析表构建：C# 代码实现及优化

public class SLRNode { public string Left; public string Right; public SLRNode(string Left, string Right) { this.Left = Left; this.Right = Right; } } //项目集类 public class SLRitemsets { public List Container = new List(100); //记录项目在项目集合中的序号 }

//DFA结点 public struct DFA { public int from; public char symbol; public int to; public DFA(int from, char symbol, int to) { this.from = from; this.symbol = symbol; this.to = to; } } public class Table { public bool error;//是否为ERROR public char type;//结点类型 public int id;//数值 public Table() { this.error = true; } public Table(char type, int id) { this.type = type; this.id = id; this.error = false; } } public DFA[] dfa = new DFA[100]; public int Pindex = 0; //dfa数组指针 public Table[][] SLRAna;//分析表 public Analyze Jz; public bool Success = false; public List SLRproNum = new List(50);//产生式 列表 public List SLRobjNum = new List(50);//项目 列表 public List proitemset = new List(100);//项目集合 public List Gy_obj = new List(50);//归约项目序号集合 public List Gy_itemset = new List(50);//含有归约项目的集合的序号 的集合 public List Nchar = new List(50);//非终结符集合 public List Echar = new List(50);//终结符集合

    public List<char>[] Follow; //每个非终结符的follow集合

    public string RStr = '';
    public string RStr_obitemset = '';//输出返回
    public string RStr_DFA = '';
    public string RStr_ANA = '';

public Table[][] GET_ANA() { SLRAnaly(); RStr_ANA += '\r\nSLR0分析表:\r\n '; int i; for (i = 0; i < Echar.Count; i++) { RStr_ANA += Echar[i].ToString() + ' '; } for (i = 0; i < Nchar.Count; i++) { RStr_ANA += Nchar[i].ToString() + ' '; } RStr_ANA += '\r\n'; for (i = 0; i < proitemset.Count; i++) { RStr_ANA += i.ToString() + ' '; for (int j = 0; j < Echar.Count + Nchar.Count; j++) {

                if (SLRAna[i][j].error)
                {
                    RStr_ANA += '  ' + '    ';
                }
                else if (i == 1 && j == Echar.Count - 1)
                {
                    RStr_ANA += 'AC' + '    ';
                }
                else if (SLRAna[i][j].type != 'N')
                {
                    RStr_ANA += SLRAna[i][j].type.ToString() + SLRAna[i][j].id.ToString() + '    ';
                }
                else
                    RStr_ANA += SLRAna[i][j].id.ToString() + '    ';
            }
            RStr_ANA += '\r\n';
        }

        return SLRAna;

    }

public void SLRAnaly() { Table tnode = new Table();

        SLRAna = new Table[proitemset.Count][];
        for (int i = 0; i < proitemset.Count; i++)
            SLRAna[i] = new Table[Echar.Count + Nchar.Count];

        for (int i = 0; i < proitemset.Count; i++)//初始化 赋予ERROR属性
            for (int j = 0; j < Echar.Count + Nchar.Count; j++)//为终结符加r状态 
                SLRAna[i][j] = tnode;

        tnode = new Table('A', 0);
        SLRAna[1][FindID(Echar, '#')] = tnode;//项目集1必定是接受项目   构建[1][#]:acc的情况 先直接赋值好 dfa里没有

        for (int i = 0; i < Gy_itemset.Count; i++)
        {
            SLRNode item = SLRobjNum[proitemset[Gy_itemset[i]].Container[0]];
            char left = item.Left[0];
            List<char> follow = GetFollow(left);
            foreach (char c in follow)
            {
                int CID = FindID(Echar, c);
                Table tnode = new Table('r', Find_pro(item));
                if (c == '#')
                {
                    for (int k = 0; k < Echar.Count; k++)
                    {
                        SLRAna[Gy_itemset[i]][k] = tnode;
                    }
                }
                else
                {
                    SLRAna[Gy_itemset[i]][CID] = tnode;
                }
            }
        }

        for (int i = 0; i < Pindex; i++)
        {
            if (isFinalsymbol(dfa[i].symbol))//symbol为非终结符  添加状态N
            {
                int CID = FindID(Nchar, dfa[i].symbol);
                SLRAna[dfa[i].from][CID + Echar.Count] = new Table('N', dfa[i].to);
            }
            else //不是归约项目 添加状态S
            {
                int CID = FindID(Echar, dfa[i].symbol);
                SLRAna[dfa[i].from][CID] = new Table('S', dfa[i].to);
            }
        }
    }

public List GetFollow(char c) { List follow = new List(); if (c == 'E') follow.Add('#'); foreach (SLRNode node in SLRproNum) { int index = node.Right.IndexOf(c); if (index != -1 && index < node.Right.Length - 1) { char next = node.Right[index + 1]; if (isFinalsymbol(next)) follow.Add(next); else { List first = GetFirst(next); if (first.Contains('#')) { first.Remove('#'); follow.AddRange(first); follow.AddRange(GetFollow(node.Left[0])); } else { follow.AddRange(first); } } } else if (index != -1 && index == node.Right.Length - 1) { follow.AddRange(GetFollow(node.Left[0])); } } follow = follow.Distinct().ToList(); return follow; }

    public List<char> GetFirst(char c)
    {
        List<char> first = new List<char>();
        if (isFinalsymbol(c))
            first.Add(c);
        else
        {
            foreach (SLRNode node in SLRproNum)
            {
                if (node.Left[0] == c)
                {
                    if (node.Right[0] == c)
                        continue;
                    else if (isFinalsymbol(node.Right[0]))
                        first.Add(node.Right[0]);
                    else
                    {
                        List<char> subFirst = GetFirst(node.Right[0]);
                        if (subFirst.Contains('#'))
                        {
                            subFirst.Remove('#');
                            first.AddRange(subFirst);
                            first.AddRange(GetFirst(node.Right[1]));
                        }
                        else
                        {
                            first.AddRange(subFirst);
                        }
                    }
                }
            }
        }
        first = first.Distinct().ToList();
        return first;
    }