Пример #1
0
        /// <summary>
        /// 计算文法的所有单个的结点的FIRST
        /// </summary>
        /// <param name="grammar"></param>
        /// <param name="nullableDict"></param>
        /// <returns></returns>
        private static void GetFirstCollection4Node(
            this RegulationList grammar,
            out FIRSTCollection firstCollection,
            Dictionary <TreeNodeType, bool> nullableDict = null)
        {
            // 初始化FIRST
            firstCollection = new FIRSTCollection();
            // 初始化非叶结点的FIRST
            foreach (var item in grammar.GetAllTreeNodeNonLeaveTypes())
            {
                if (nullableDict[item])
                {
                    firstCollection.TryInsert(new FIRST(item, TreeNodeType.NullNode));
                }
                else
                {
                    firstCollection.TryInsert(new FIRST(item));
                }
            }
            // 初始化叶结点的FIRST(叶结点的FIRST实际上已经完工)
            foreach (var item in grammar.GetAllTreeNodeLeaveTypes())
            {
                firstCollection.TryInsert(new FIRST(item, item));
            }

            bool changed = false;

            do
            {
                changed = false;
                foreach (var regulation in grammar)
                {
                    FIRST first          = FindFirst(firstCollection, regulation.Left);
                    int   rightPartCount = regulation.RightPart.Count();
                    for (int checkCount = 0; checkCount < rightPartCount; checkCount++)
                    {
                        // 如果前面checkCount个结点都可为null,
                        // 就说明RightPart[checkCount]的FIRST是此regulation.Left的FIRST的一部分。
                        if (Nullable(regulation.RightPart, 0, checkCount, nullableDict))
                        {
                            FIRST refFirst = FindFirst(firstCollection, regulation.RightNode(checkCount));
                            if (refFirst == null)
                            {
                                throw new Exception("algorithm error!");
                            }
                            if (refFirst != first)
                            {
                                foreach (var value in refFirst.Values)
                                {
                                    if (value != TreeNodeType.NullNode)
                                    {
                                        changed = first.TryInsert(value) || changed;
                                    }
                                }
                            }
                        }
                    }
                }
            } while (changed);
        }
Пример #2
0
        private static string GetUniqueString(HashCache cache)
        {
            FIRST obj = cache as FIRST;

            return(obj.Dump());
            //StringBuilder builder = new StringBuilder();
            //{
            //    builder.Append("FIRST( ");

            //    int count = obj.target.Count;
            //    for (int i = 0; i < count; i++)
            //    {
            //        builder.Append(obj.target[i].Nickname);
            //        if (i + 1 < count)
            //        { builder.Append(" "); }
            //    }
            //    if (count == 0)
            //    { builder.Append("ε "); }

            //    builder.Append(" ) = ");
            //}
            //{
            //    builder.Append("【 ");
            //    int count = obj.values.Count;
            //    for (int i = 0; i < count; i++)
            //    {
            //        builder.Append(obj.values[i].Nickname);
            //        if (i + 1 < count)
            //        { builder.Append(" "); }
            //    }
            //    builder.Append(" 】");
            //}
            //return builder.ToString();
        }
Пример #3
0
        /// <summary>
        /// 计算文法的各个RightPart的FIRST集
        /// </summary>
        /// <param name="grammar"></param>
        /// <param name="nullableDict"></param>
        /// <param name="firstList4Node"></param>
        /// <returns></returns>
        private static void GetFirstCollection4Regulation(
            this RegulationList grammar,
            out FIRSTCollection firstCollection,
            Dictionary <TreeNodeType, bool> nullableDict = null, FIRSTCollection firstList4Node = null)
        {
            // 初始化FIRST集
            firstCollection = new FIRSTCollection();
            foreach (var regulation in grammar)
            {
                firstCollection.TryInsert(new FIRST(regulation.RightPart));
            }

            bool changed = false;

            do
            {
                changed = false;
                foreach (var first in firstCollection)
                {
                    int count = first.Target.Count();
                    for (int i = 0; i < count; i++)
                    {
                        // 如果前i个结点都可为null,就说明下一个结点(first.Target[i])的FIRST是此RightPart的FIRST的一部分
                        if (Nullable(first.Target, 0, i, nullableDict))
                        {
                            // 找到下一个结点的FIRST
                            FIRST refFirst = FindFirst(firstList4Node, first.GetNode(i));
                            foreach (var value in refFirst.Values)
                            {
                                if (value != TreeNodeType.NullNode)
                                {
                                    changed = first.TryInsert(value) || changed;
                                }
                            }
                        }
                    }
                    {
                        // 如果RightPart的全部结点都可为null,就说明此RightPart的FIRST包含"null"结点。
                        if (Nullable(first.Target, 0, first.Target.Count(), nullableDict))
                        {
                            changed = first.TryInsert(TreeNodeType.NullNode) || changed;
                        }
                    }
                }
            } while (changed);
        }
        /// <summary>
        /// LR(1)的Closure操作。
        /// 补全一个状态。
        /// </summary>
        /// <param name="grammar"></param>
        /// <param name="state"></param>
        /// <returns></returns>
        static SmallerLR1State Closure(this RegulationList grammar, SmallerLR1State state,
                                       Dictionary <TreeNodeType, bool> nullableDict = null, FIRSTCollection firstCollection = null)
        {
            if (nullableDict == null)
            {
                grammar.GetNullableDict(out nullableDict);
            }
            if (firstCollection == null)
            {
                grammar.GetFirstCollection(out firstCollection, nullableDict);
            }

            Queue <LR1Item> queue = new Queue <LR1Item>();

            foreach (var item in state)
            {
                queue.Enqueue(item);
            }
            while (queue.Count > 0)
            {
                LR1Item      item = queue.Dequeue();
                TreeNodeType node = item.GetNodeNext2Dot();
                if (node == null || node.IsLeave)
                {
                    continue;
                }

                List <TreeNodeType> betaZ     = item.GetBetaZ();
                FIRST             first       = grammar.GetFirst(firstCollection, nullableDict, betaZ);
                List <Regulation> regulations = grammar.GetRegulations(node);
                foreach (var regulation in regulations)
                {
                    foreach (var value in first.Values)
                    {
                        LR1Item newItem = new LR1Item(regulation, 0, value);
                        if (state.TryInsert(newItem))
                        {
                            queue.Enqueue(newItem);
                        }
                    }
                }
            }

            return(state);
        }
        /// <summary>
        /// 根据文法和已经计算的所有结点的FIRST集,计算任意一个结点串的FIRST。
        /// </summary>
        /// <param name="grammar"></param>
        /// <param name="firstList4Node"></param>
        /// <param name="target"></param>
        /// <returns></returns>
        private static FIRST GetFirst(this RegulationList grammar, FIRSTCollection firstList4Node, Dictionary <TreeNodeType, bool> nullableDict, List <TreeNodeType> target)
        {
            // 初始化FIRST集
            FIRST first = new FIRST(target);

            bool changed = false;

            do
            {
                changed = false;
                int count = first.Target.Count();
                for (int checkCount = 0; checkCount < count; checkCount++)
                {
                    // 如果前i个结点都可为null,就说明下一个结点(first.Target[i])的FIRST是此RightPart的FIRST的一部分
                    if (Nullable(first.Target, 0, checkCount, nullableDict))
                    {
                        // 找到下一个结点的FIRST
                        FIRST refFirst = FindFirst(firstList4Node, first.GetNode(checkCount));
                        foreach (var value in refFirst.Values)
                        {
                            if (value != TreeNodeType.NullNode)
                            {
                                changed = first.TryInsert(value) || changed;
                            }
                        }
                    }
                }
                {
                    // 如果RightPart的全部结点都可为null,就说明此RightPart的FIRST包含"null"结点。
                    if (Nullable(first.Target, 0, first.Target.Count(), nullableDict))
                    {
                        //throw new Exception("如果是在LR1分析器生成工具的设计时走到此处,说明代码有问题。");
                        if (!first.Values.Contains(TreeNodeType.NullNode))
                        {
                            changed = first.TryInsert(TreeNodeType.NullNode) || changed;
                        }
                    }
                }
            } while (changed);

            return(first);
        }
Пример #6
0
        /// <summary>
        /// 计算文法的FOLLOW集
        /// </summary>
        /// <param name="grammar"></param>
        /// <param name="nullableDict"></param>
        /// <param name="firstList4Node"></param>
        /// <returns></returns>
        private static void DoGetFollowList(
            this RegulationList grammar,
            out FOLLOWCollection followCollection,
            Dictionary <TreeNodeType, bool> nullableDict, FIRSTCollection firstList4Node)
        {
            // 初始化Follow list
            followCollection = new FOLLOWCollection();
            foreach (var item in grammar.GetAllTreeNodeNonLeaveTypes())
            {
                followCollection.TryInsert(new FOLLOW(item));
            }

            // 迭代到不动点
            bool changed = false;

            do
            {
                changed = false;
                foreach (var regulation in grammar)
                {
                    int count = regulation.RightPart.Count();
                    for (int index = 0; index < count; index++)
                    {
                        // 准备为target添加follow元素
                        TreeNodeType target = regulation.RightNode(index);
                        if (target.IsLeave)
                        {
                            continue;
                        }                                                     // 叶结点没有follow
                        FOLLOW follow = FindFollow(followCollection, target); // 找到follow对象
                        for (int checkCount = 0; checkCount < count - (index + 1); checkCount++)
                        {
                            if (Nullable(regulation.RightPart, index + 1, checkCount, nullableDict))
                            {
                                // nullable之后的FIRST是target的follow的一部分
                                FIRST first = FindFirst(
                                    firstList4Node, regulation.RightNode(index + 1 + checkCount));
                                foreach (var value in first.Values)
                                {
                                    if (value != TreeNodeType.NullNode)
                                    {
                                        changed = follow.TryInsert(value) || changed;
                                    }
                                }
                            }
                        }
                        {
                            // 如果target之后的全部结点都是nullable,说明此regulation.Left的folow也是target的一部分。
                            if (Nullable(regulation.RightPart, index + 1, count - (index + 1), nullableDict))
                            {
                                // 找到此regulation.Left的folow
                                FOLLOW refFollow = FindFollow(followCollection, regulation.Left);
                                if (refFollow != follow)
                                {
                                    foreach (var item in refFollow.Values)
                                    {
                                        changed = follow.TryInsert(item) || changed;
                                    }
                                }
                            }
                        }
                    }
                }
            } while (changed);
        }