/// <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);
}
/// <summary>
/// 用LR(0)分析法计算分析表
/// </summary>
/// <param name="grammar"></param>
/// <returns></returns>
public static void GetLR0ParsingMap(this RegulationList grammar,
out LRParsingMap map,
out LR0StateCollection stateCollection,
out LR0EdgeCollection edgeCollection, TextWriter writer)
{
// 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 LR0Item(decoratedGrammar[0], 0);
var firstState = new LR0State(firstItem);
firstState = decoratedGrammar.Closure(firstState);
stateCollection = new LR0StateCollection(firstState);
edgeCollection = new LR0EdgeCollection(stateCollection);
var queue = new Queue <LR0State>();
queue.Enqueue(firstState);
int lastOutputLength = 0;
int stateListCount = 1;
int queueCount = 1;
while (queue.Count > 0)
{
LR0State fromState = queue.Dequeue(); queueCount--;
int itemIndex = 0;
int itemCount = fromState.Count();
foreach (var item in fromState)
{
{
TextWriter currentWriter = Console.Out;
if (Console.Out != writer)
{
Console.SetOut(writer);
}
for (int i = 0; i < lastOutputLength; i++)
{
Console.Write('\u0008');
}
string output = string.Format("Calculating LR(0) State List: {0} <-- {1}, working on {2}/{3} ...",
stateListCount, queueCount, 1 + itemIndex++, itemCount);
Console.Write(output);
lastOutputLength = output.Length;
Console.SetOut(currentWriter);
}
TreeNodeType x = item.GetNodeNext2Dot();
if (x == null || x == decoratedEnd)
{
continue;
}
LR0State toState = decoratedGrammar.Goto(fromState, x);
if (stateCollection.TryInsert(toState))
{
queue.Enqueue(toState);
stateListCount++;
queueCount++;
var edge = new LR0Edge(fromState, x, toState);
edgeCollection.TryInsert(edge);
}
else
{
int index = stateCollection.IndexOf(toState);
toState = stateCollection[index];
var edge = new LR0Edge(fromState, x, toState);
edgeCollection.TryInsert(edge);
}
}
}
{
TextWriter currentWriter = Console.Out;
if (Console.Out != writer)
{
Console.SetOut(writer);
}
Console.WriteLine();
Console.SetOut(currentWriter);
}
map = new LRParsingMap();
foreach (var edge in edgeCollection)
{
int stateId = edge.From.ParsingMapIndex + 1; //stateCollection.IndexOf(edge.From) + 1;
int nextStateId = edge.To.ParsingMapIndex + 1; //stateCollection.IndexOf(edge.To) + 1;
if (edge.X.IsLeave)
{
map.SetAction(stateId, edge.X, new LR1ShiftInAction(nextStateId));
}
else
{
map.SetAction(stateId, edge.X, new LR1GotoAction(nextStateId));
}
}
var endItem = new LR0Item(decoratedRegulation, 1);
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 item in state)
{
if (item.GetNodeNext2Dot() == null)
{
List <TreeNodeType> allTreeNodeTypes = decoratedGrammar.GetAllTreeNodeLeaveTypes();
foreach (var treeNodeType in allTreeNodeTypes)
{
int stateId = state.ParsingMapIndex + 1;//stateCollection.IndexOf(state) + 1
map.SetAction(stateId, treeNodeType,
new LR1ReducitonAction(decoratedGrammar.IndexOf(item.Regulation)));
}
}
}
}
}
