/// <summary>
/// 从一个LR(1)状态跳转到另一个LR(1)状态
/// </summary>
/// <param name="from"></param>
/// <param name="x"></param>
/// <param name="to"></param>
public LALR1Edge(LALR1State from, TreeNodeType x, LALR1State to)
: base(GetUniqueString)
{
this.From = from;
this.X = x;
this.To = to;
}
/// <summary>
/// LR(1)的Goto操作。
/// 将圆点移到所有LR(1)项中的符号<paramref name="x"/>之后。
/// </summary>
/// <param name="list"></param>
/// <param name="state"></param>
/// <param name="x">一个文法符号，终结点或非终结点。</param>
/// <param name="firstList"></param>
/// <returns></returns>
static LALR1State Goto(this RegulationList list, LALR1State state, TreeNodeType x, Dictionary <TreeNodeType, bool> nullableDict, FIRSTCollection firstList = null)
{
var toState = new LALR1State();
foreach (var group in state.GetGroups())
{
TreeNodeType nextNode = group.Item1.GetNodeNext2Dot();
if (nextNode == x)
{
toState.TryInsert(
new LR0Item(group.Item1.Regulation, group.Item1.DotPosition + 1),
group.Item2);
}
}
return(Closure(list, toState, nullableDict, firstList));
}
/// <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 LALR1State Closure(this RegulationList grammar, LALR1State 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>
/// 用LALR(1)分析法计算分析表
/// </summary>
/// <param name="grammar"></param>
/// <returns></returns>
public static void GetLALR1ParsingMap(this RegulationList grammar,
out LRParsingMap map,
out LALR1StateCollection stateCollection,
out LALR1EdgeCollection 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 LALR1State(firstItem);
Dictionary <TreeNodeType, bool> nullableDict;
decoratedGrammar.GetNullableDict(out nullableDict);
FIRSTCollection firstCollection;
decoratedGrammar.GetFirstCollection(out firstCollection, nullableDict);
firstState = decoratedGrammar.Closure(firstState, nullableDict, firstCollection);
stateCollection = new LALR1StateCollection(firstState);
edgeCollection = new LALR1EdgeCollection(stateCollection);
var queue = new Queue <LALR1State>();
queue.Enqueue(firstState);
int lastOutputLength = 0;
int stateListCount = 1;
int queueCount = 1;
while (queue.Count > 0)
{
LALR1State 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 LALR(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;
}
LALR1State 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 LALR1Edge(fromState, x, toState);
edgeCollection.TryInsert(edge);
}
else
{
int index = stateCollection.IndexOf(toState);
toState = stateCollection[index];
var edge = new LALR1Edge(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)));
}
}
}
}
