/// <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);
        }
Example #2
0
        public static void GetFollowCollection(
            this RegulationList grammar,
            out FOLLOWCollection followCollection,
            Dictionary <TreeNodeType, bool> nullableDict = null,
            FIRSTCollection firstCollection = null)
        {
            if (nullableDict == null)
            {
                grammar.GetNullableDict(out nullableDict);
            }
            if (firstCollection == null)
            {
                grammar.GetFirstCollection(out firstCollection, nullableDict);
            }

            FIRSTCollection firstList4Node;

            grammar.GetFirstCollection4Node(out firstList4Node, nullableDict);
            FIRSTCollection firstList4Regulation;

            grammar.GetFirstCollection4Regulation(out firstList4Regulation, nullableDict, firstList4Node);
            grammar.DoGetFollowList(out followCollection, nullableDict, firstList4Node);
        }
        /// <summary>
        /// 用LR(1)分析法计算分析表
        /// </summary>
        /// <param name="grammar"></param>
        /// <returns></returns>
        public static void GetLR1ParsingMap(this RegulationList grammar,
                                            out LRParsingMap map,
                                            out LR1StateCollection stateCollection,
                                            out LR1EdgeCollection edgeCollection, TextWriter originalOut)
        {
            // 给文法添加一个辅助的开始产生式 S' -> S $
            // 如何添加一个外来的结点类型?用Enum是无法做到的。
            var decoratedS          = new TreeNodeType("__S2", "S'", "<S'>");
            var decoratedEnd        = TreeNodeType.endOfTokenListNode;
            var decoratedRegulation = new Regulation(
                decoratedS, grammar[0].Left, decoratedEnd);
            var decoratedGrammar = new RegulationList(decoratedRegulation);

            decoratedGrammar.AddRange(grammar);
            // 初始化T为{ Closure(S' -> S $) }
            var firstItem  = new LR1Item(decoratedGrammar[0], 0, decoratedEnd);
            var firstState = new SmallerLR1State(firstItem);
            Dictionary <TreeNodeType, bool> nullableDict;

            decoratedGrammar.GetNullableDict(out nullableDict);
            FIRSTCollection firstCollection;

            decoratedGrammar.GetFirstCollection(out firstCollection, nullableDict);
            firstState      = decoratedGrammar.Closure(firstState, nullableDict, firstCollection);
            stateCollection = new LR1StateCollection(firstState);
            edgeCollection  = new LR1EdgeCollection(stateCollection);
            var queue = new Queue <SmallerLR1State>();

            queue.Enqueue(firstState);
            int lastOutputLength = 0;
            int stateListCount   = 1;
            int queueCount       = 1;

            while (queue.Count > 0)
            {
                SmallerLR1State fromState  = queue.Dequeue(); queueCount--;
                int             itemIndex  = 0;
                int             groupCount = fromState.GroupCount;
                foreach (var group in fromState.GetGroups())
                {
                    {
                        TextWriter currentWriter = Console.Out;
                        if (Console.Out != originalOut)
                        {
                            Console.SetOut(originalOut);
                        }
                        for (int i = 0; i < lastOutputLength; i++)
                        {
                            Console.Write('\u0008');
                        }
                        string output = string.Format("Calculating LR(1) State List: {0} <-- {1}, working on group {2}/{3} ...",
                                                      stateListCount, queueCount, 1 + itemIndex++, groupCount);
                        Console.Write(output);
                        lastOutputLength = output.Length;
                        Console.SetOut(currentWriter);
                    }
                    TreeNodeType x = group.Item1.GetNodeNext2Dot();
                    if (x == null || x == decoratedEnd)
                    {
                        continue;
                    }
                    SmallerLR1State toState = decoratedGrammar.Goto(fromState, x, nullableDict, firstCollection);
                    if (stateCollection.TryInsert(toState))//融入组织之中吧
                    {
                        int index = stateCollection.IndexOf(toState);
                        toState = stateCollection[index];
                        queue.Enqueue(toState);
                        stateListCount++;
                        queueCount++;
                        var edge = new LR1Edge(fromState, x, toState);
                        edgeCollection.TryInsert(edge);
                    }
                    else
                    {
                        int index = stateCollection.IndexOf(toState);
                        toState = stateCollection[index];
                        var edge = new LR1Edge(fromState, x, toState);
                        edgeCollection.TryInsert(edge);
                    }
                }
            }
            {
                TextWriter currentWriter = Console.Out;
                if (Console.Out != originalOut)
                {
                    Console.SetOut(originalOut);
                }
                Console.WriteLine();
                Console.SetOut(currentWriter);
            }

            map = new LRParsingMap();
            foreach (var edge in edgeCollection)
            {
                if (edge.X.IsLeave)
                {
                    int stateId = edge.From.ParsingMapIndex + 1; // stateCollection.IndexOf(edge.From) + 1;
                    int gotoId  = edge.To.ParsingMapIndex + 1;   //stateCollection.IndexOf(edge.To) + 1
                    map.SetAction(stateId, edge.X, new LR1ShiftInAction(gotoId));
                }
                else
                {
                    int stateId = edge.From.ParsingMapIndex + 1; // stateCollection.IndexOf(edge.From) + 1;
                    int gotoId  = edge.To.ParsingMapIndex + 1;   //stateCollection.IndexOf(edge.To) + 1
                    map.SetAction(stateId, edge.X, new LR1GotoAction(gotoId));
                }
            }
            // TODO: not implemented
            var endItem = new LR1Item(decoratedRegulation, 1, decoratedEnd);

            foreach (var state in stateCollection)
            {
                if (state.Contains(endItem))
                {
                    int stateId = state.ParsingMapIndex + 1;// stateCollection.IndexOf(state) + 1;
                    map.SetAction(stateId, decoratedEnd, new LR1AceptAction());
                }
                foreach (var LR1Item in state)
                {
                    if (LR1Item.GetNodeNext2Dot() == null)
                    {
                        int stateId = state.ParsingMapIndex + 1;// stateCollection.IndexOf(state) + 1;
                        map.SetAction(stateId, LR1Item.LookAheadNodeType,
                                      new LR1ReducitonAction(decoratedGrammar.IndexOf(LR1Item.Regulation)));
                    }
                }
            }
        }