private Prediction predictionMove(Piece p, Board board)
{
Board virtualBoard = new Board(board);
// On créer le premier noeud
PredictionTree node = new PredictionTree(ABType.MAX, new Prediction(virtualBoard, p.color)); // Max car c'est les predictions du joueur
//Debug.Log(node);
int maxValue = alphaBeta(node, p, smart, int.MinValue, int.MaxValue);
//Debug.Log(node);
Prediction predi = null;
foreach (PredictionTree son in node.sons)
{
if (son.value == maxValue)
{
predi = son.prediction;
break;
}
}
//Debug.Log(predi.board);
//Debug.Log( "AlphaBeta : "+ predi.getAction(p));
// On cherche alors la meilleur prédiction
return(predi);
}
/// <summary>Recursively merges adjacent duplicate cases in prediction trees.
/// The tree is modified in-place, but in case a tree collapses to a single
/// alternative, the return value indicates which single alternative.</summary>
private PredictionTreeOrAlt SimplifyPredictionTree(PredictionTree tree)
{
for (int i = 0; i < tree.Children.Count; i++)
{
PredictionBranch pb = tree.Children[i];
if (pb.Sub.Tree != null)
{
pb.Sub = SimplifyPredictionTree(pb.Sub.Tree);
}
}
for (int i = tree.Children.Count - 1; i > 0; i--)
{
PredictionBranch a = tree.Children[i - 1], b = tree.Children[i];
if (a.Sub.Equals(b.Sub))
{
// Merge a and b
if (a.Set != null)
{
a.Set = a.Set.Union(b.Set);
}
a.CombineAndPredsWith(b.AndPreds);
tree.Children.RemoveAt(i);
}
}
if (tree.Children.Count == 1)
{
return(tree.Children[0].Sub);
}
return(tree);
}
/// <summary>
/// Visit(Alts) is the most important method in this class. It generates
/// all prediction code, which is the majority of the code in a parser.
/// </summary>
public override void Visit(Alts alts)
{
PredictionTree tree = alts.PredictionTree;
var timesUsed = new Dictionary <int, int>();
tree.CountTimesUsed(timesUsed);
GenerateCodeForAlts(alts, timesUsed, tree);
}
/// <summary>
/// Denotes an ambiguous context which identifies the current node as consistent within the ambiguity.
/// </summary>
/// <param name="ambiguityContext">
/// The <see cref="PredictionTree"/> which represents the ambiguous context, or the 'paths' from which the rule of the current node
/// was entered.</param>
/// <remarks>
/// A reduction on the rule of the node will take place, the ambiguous context needs identified so follow-based ambiguities can be isolated and handled.
/// </remarks>
public void DenoteReductionPoint(PredictionTree ambiguityContext, PredictionTree declarationContext)
{
var entry = new ProductionRuleProjectionReductionDetail {
Entrypoint = declarationContext, ReductionPoint = ambiguityContext
};
lock (this.steppedAmbiguityContexts)
this.steppedAmbiguityContexts.Add(entry);
AddRootReduction(declarationContext);
}
private PredictionTree GetFollowDPathSet(FiniteAutomataMultiTargetTransitionTable <GrammarVocabulary, Tuple <int, PredictionTreeBranch> > transitionTableResult, GrammarVocabulary transition, Dictionary <PredictionTreeBranch, int[]> epDepthLookup)
{
//var minMinDepth = (from deviationPath in transitionTableResult[transition]
// select deviationPath.Item2.MinDepth).Min();
//minDepth = minMinDepth;
//epDepthLookup = epDepthLookup.ToDictionary(dps => new PredictionTreeBranch(dps.Key.Skip(minMinDepth).ToList(), dps.Key.Depth - minMinDepth, minDepth: dps.Key.MinDepth - minMinDepth), dps => dps.Value);
var result = PredictionTree.GetPathSet(transition, epDepthLookup.Keys.ToList(), this, ProductionRuleProjectionType.FollowAmbiguity, PredictionDerivedFrom.LookAhead_FollowPrediction);
result.SetFollowEpsilonData(provider => epDepthLookup[provider]);
return(result);
}
/// <summary>Creates a new <see cref="PredictionTreeFollow"/> instance with the <paramref name="initialPaths"/>, and <paramref name="edgeNode"/> provided.</summary>
/// <param name="initialPaths">The <see cref="PredictionTree"/> built from the analysis of the incoming paths to a rule which are in an initial deadlock for disambiguation upon the rule entering the <paramref name="edgeNode"/>.</param>
/// <param name="edgeNode">The <see cref="PredictionTreeLeaf"/> which delineates the ambiguity.</param>
internal PredictionTreeFollow(PredictionTree initialPaths, PredictionTreeLeaf edgeNode)
{
this.initialPaths = initialPaths;
this.edgeNode = edgeNode;
/* *
* Initial variations are used to deconstruct the incoming states
* *
* Necessary because certain commonality groupings yield similarities
* that are only similar to the edgeNode, which means the transition
* sets are identical.
* *
* ToDo: Verify this claim.
* */
}
private LNode GenerateIfElseChain(PredictionTree tree, LNode[] branchCode, ref LNode laVar, MSet <int> switchCases)
{
// From the prediction table, generate a chain of if-else
// statements in reverse, starting with the final "else" clause.
// Skip any branches that have been claimed for use in a switch()
LNode ifChain = null;
bool usedTest = false;
for (int i = tree.Children.Count - 1; i >= 0; i--)
{
if (switchCases.Contains(i))
{
continue;
}
if (ifChain == null)
{
ifChain = branchCode[i];
}
else
{
usedTest = true;
var branch = tree.Children[i];
LNode test;
if (tree.IsAssertionLevel)
{
test = GenerateTest(branch.AndPreds, tree.Lookahead, laVar);
}
else
{
var set = CGH.Optimize(branch.Set, branch.Covered);
test = CGH.GenerateTest(set, laVar);
}
LNode @if = F.Call(S.If, test, branchCode[i]);
if (!ifChain.IsIdWithoutPAttrs(S.Missing))
{
@if = @if.PlusArg(ifChain);
}
ifChain = @if;
}
}
if (!usedTest)
{
laVar = null; // unnecessary
}
return(ifChain);
}
private void AddRootReduction(PredictionTree entry)
{
var currentSet = new HashList <HashList <PredictionTreeLeaf> >();
lock (this.RootLeaf._rootAmbiguityContexts)
{
this.Compiler.DenoteReduction(this.Rule);
foreach (var path in entry)
{
var currentItem = new HashList <PredictionTreeLeaf>(path.Skip(path.MinDepth).Take(path.Depth - (path.MinDepth - 1)));
currentSet.Add(currentItem);
}
this.RootLeaf._rootAmbiguityContexts.Add(currentSet);
this.RootLeaf._predictionReductions.Add(entry);
}
}
private Prediction predictionMove(Piece p, Board board)
{
Board virtualBoard = new Board(board);
Tuple <int, Prediction> find = data.Find(virtualBoard, p.position);
// On n'a pas trouvé dans la base un déplacement
Prediction result = find.Item2;
if (find.Item1 == -1)
{
// On créer le premier noeud
PredictionTree node = new PredictionTree(ABType.MAX, new Prediction(virtualBoard, p.color)); // Max car c'est les predictions du joueur
//Debug.Log(node);
int maxValue = alphaBeta(node, p, smart, int.MinValue, int.MaxValue);
//Debug.Log(node);
Prediction predi = null;
foreach (PredictionTree son in node.sons)
{
if (son.value == maxValue)
{
predi = son.prediction;
break;
}
}
//Debug.Log(predi.board);
//Debug.Log("Compute:" + predi.getAction(p));
// On sauvegarde le prédicat dans la base de données
data.Add(predi, p.color, virtualBoard, p.position);
result = predi;
}
else
{
Debug.Log("Database:" + result.getAction(p));
}
// On cherche alors la meilleur prédiction
return(result);
}
// Syteme de calcul alpha beta
// La valeur smart le nombre de prédiction que l'on réalise
// la piece fournit en paramètre est la piece qui réalise l
private int alphaBeta(PredictionTree node, Piece p, int smart, int alpha, int beta)/* alpha et toujours inférieur à beta*/
{
if (!node.isNode())
{
//Debug.Log("C'est une feuille");
return(node.value);
}
else if (node.type == ABType.MIN) // Noeud de type Min
{
int v = int.MaxValue;
foreach (PredictionTree son in node.getSons(p.color, p.id, (smart == 0)))
{
v = Math.Min(v, alphaBeta(son, p, smart, alpha, beta));
node.value = v;
if (alpha >= v)
{
return(v);
}
beta = Math.Min(beta, v);
}
return(v);
}
else // Noeud de type Max
{
int v = int.MinValue;
foreach (PredictionTree son in node.getSons(p.color, p.id)) // On parcours tous les mins
{
v = Math.Max(v, alphaBeta(son, p, smart - 1, alpha, beta));
node.value = v;
if (v >= beta)
{
return(v);
}
alpha = Math.Max(alpha, v);
}
return(v);
}
}
// GENERATED CODE EXAMPLE: The methods in this region generate
// the for(;;) loop in this example and everything inside it, except
// the calls to Match() which are generated by Visit(TerminalPred).
// The generated code uses "goto" and "match" blocks in some cases
// to avoid code duplication. This occurs when the matching code
// requires multiple statements AND appears more than once in the
// prediction tree. Otherwise, matching is done "inline" during
// prediction. We generate a for(;;) loop for (...)*, and in certain
// cases, we generates a do...while(false) loop for (...)?.
//
// rule Foo @{ (('a'|'A') 'A')* 'a'..'z' 'a'..'z' };
// public void Foo()
// {
// int la0, la1;
// for (;;) {
// la0 = LA(0);
// if (la0 == 'a') {
// la1 = LA(1);
// if (la1 == 'A')
// goto match1;
// else
// break;
// } else if (la0 == 'A')
// goto match1;
// else
// break;
// match1:
// {
// Match('A', 'a');
// Match('A');
// }
// }
// MatchRange('a', 'z');
// MatchRange('a', 'z');
// }
private void GenerateCodeForAlts(Alts alts, Dictionary<int, int> timesUsed, PredictionTree tree)
{
bool needError = LLPG.NeedsErrorBranch(tree, alts);
if (!needError && alts.ErrorBranch != null)
LLPG.Output(Warning, alts, "The error branch will not be used because the other alternatives are exhaustive (cover all cases)");
bool userDefinedError = needError && alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value;
// Generate matching code for each arm. the "string" in each pair
// becomes non-null if the matching code for that branch needs to be
// split out (separated) from the prediction tree because it appears
// multiple times in the tree. The string is the goto-label name.
Pair<LNode, string>[] matchingCode = new Pair<LNode, string>[alts.Arms.Count + (userDefinedError ? 1 : 0)];
MSet<int> unreachable = new MSet<int>();
int separateCount = 0;
for (int i = 0; i < alts.Arms.Count; i++) {
if (!timesUsed.ContainsKey(i)) {
unreachable.Add(i);
continue;
}
var codeForThisArm = new WList<LNode>();
VisitWithNewTarget(alts.Arms[i], codeForThisArm);
matchingCode[i].A = F.Braces(codeForThisArm.ToVList());
if (timesUsed[i] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A)) {
separateCount++;
matchingCode[i].B = alts.Arms[i].ChooseGotoLabel()
?? "match" + (i + 1).ToString();
}
}
// Add matching code for the error branch, if present. Note: the
// default error branch, which is produced by IPGCodeGenHelper.
// ErrorBranch() is handled differently: default error code can
// differ at each error point in the prediction tree. Therefore
// we generate it later, on-demand.
if (userDefinedError) {
int i = alts.Arms.Count;
var errorHandler = new WList<LNode>();
VisitWithNewTarget(alts.ErrorBranch, errorHandler);
matchingCode[i].A = F.Braces(errorHandler.ToVList());
if (timesUsed[ErrorAlt] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A)) {
matchingCode[i].B = "error";
separateCount++;
}
}
// Print unreachability warnings
if (unreachable.Count == 1)
LLPG.Output(Warning, alts, string.Format("Branch {{{0}}} is unreachable.", alts.AltName(unreachable.First())));
else if (unreachable.Count > 1)
LLPG.Output(Warning, alts, string.Format("Branches {{{0}}} are unreachable.", unreachable.Select(i => alts.AltName(i)).Join(", ")));
if (!timesUsed.ContainsKey(ExitAlt) && alts.Mode != LoopMode.None)
LLPG.Output(Warning, alts, "Infinite loop. The exit branch is unreachable.");
Symbol loopType = null;
// Choose a loop type for (...)* or (...)?:
if (alts.Mode == LoopMode.Star)
loopType = S.For;
else if (alts.Mode == LoopMode.Opt) {
if (alts.HasErrorBranch(LLPG) || alts.NonExitDefaultArmRequested())
loopType = S.DoWhile;
}
// If the code for an arm is nontrivial and appears multiple times
// in the prediction table, it will have to be split out into a
// labeled block and reached via "goto". I'd rather just do a goto
// from inside one "if" statement to inside another, but in C#
// (unlike in CIL, and unlike in C) that is prohibited :(
DeduplicateLabels(matchingCode);
var extraMatching = GenerateExtraMatchingCode(matchingCode, separateCount, ref loopType);
if (separateCount != 0)
loopType = loopType ?? S.DoWhile;
Symbol breakMode = loopType; // used to request a "goto" label in addition to the loop
LNode code = GeneratePredictionTreeCode(tree, matchingCode, ref breakMode);
// Add break/continue between prediction tree and extra matching code,
// if necessary.
if (extraMatching.Count != 0 && CodeGenHelperBase.EndMayBeReachable(code)) {
loopType = loopType ?? S.DoWhile;
extraMatching.Insert(0, GetContinueStmt(loopType));
}
if (!extraMatching.IsEmpty)
code = LNode.MergeLists(code, F.Braces(extraMatching), S.Braces);
if (loopType == S.For) {
// (...)* => for (;;) {}
code = F.Call(S.For, F.List(), F.Missing, F.List(), code);
} else if (loopType == S.DoWhile) {
// (...)? becomes "do {...} while(false);" IF the exit branch is NOT the default.
// If the exit branch is the default, then no loop and no "break" is needed.
code = F.Call(S.DoWhile, code, F.@false);
}
if (breakMode != loopType && breakMode != null) {
// Add "stop:" label (plus extra ";" for C# compatibility, in
// case the label ends the block in which it is located.)
var stopLabel = F.Call(S.Label, F.Id(breakMode))
.PlusTrailingTrivia(F.Trivia(S.TriviaRawText, ";"));
code = LNode.MergeLists(code, stopLabel, S.Braces);
}
int oldCount = _target.Count;
_target.SpliceAdd(code, S.Braces);
// Add comment before code
if (LLPG.AddComments) {
var pos = alts.Basis.Range.Start;
var comment = F.Trivia(S.TriviaSLComment, string.Format(" Line {0}: {1}", pos.Line, alts.ToString()));
if (_target.Count > oldCount)
_target[oldCount] = _target[oldCount].PlusAttr(comment);
}
}
/// <summary>Recursively merges adjacent duplicate cases in prediction trees.
/// The tree is modified in-place, but in case a tree collapses to a single
/// alternative, the return value indicates which single alternative.</summary>
private PredictionTreeOrAlt SimplifyPredictionTree(PredictionTree tree)
{
for (int i = 0; i < tree.Children.Count; i++) {
PredictionBranch pb = tree.Children[i];
if (pb.Sub.Tree != null)
pb.Sub = SimplifyPredictionTree(pb.Sub.Tree);
}
for (int i = tree.Children.Count-1; i > 0; i--) {
PredictionBranch a = tree.Children[i-1], b = tree.Children[i];
if (a.Sub.Equals(b.Sub))
{
// Merge a and b
if (a.Set != null)
a.Set = a.Set.Union(b.Set);
a.CombineAndPredsWith(b.AndPreds);
tree.Children.RemoveAt(i);
}
}
if (tree.Children.Count == 1)
return tree.Children[0].Sub;
return tree;
}
/// <summary>
/// Denotes an ambiguous context which identifies the current node as consistent within the ambiguity.
/// </summary>
/// <param name="ambiguityContext">
/// The <see cref="PredictionTree"/> which represents the ambiguous context, or the 'paths' from which the rule of the current node
/// was entered.</param>
/// <remarks>
/// A reduction on the rule of the node will take place, the ambiguous context needs identified so follow-based ambiguities can be isolated and handled.
/// </remarks>
public void DenoteReductionPoint(PredictionTree ambiguityContext)
{
lock (this.ambiguityContexts)
this.ambiguityContexts.Add(ambiguityContext);
AddRootReduction(ambiguityContext);
}
/// <summary>Extends each level of the prediction tree so that it has
/// total coverage. For example, a typicaly prediction tree might have
/// branches for 'a'..'z' and '0..'9'; this method will add coverage for
/// all other possible inputs. It does this either by adding an error
/// branch, or by extending the set handled by the default branch of
/// each level.</summary>
private void AddElseCases(Alts alts, PredictionTree tree)
{
foreach (var branch in tree.Children)
if (branch.Sub.Tree != null)
AddElseCases(alts, branch.Sub.Tree);
if (tree.IsAssertionLevel) {
tree.Children.Last.AndPreds.Clear();
tree.Children.Last.AndPreds.Add(Set<AndPred>.Empty);
} else if (!tree.TotalCoverage.ContainsEverything) {
var rest = tree.TotalCoverage.Inverted();
if (alts.HasErrorBranch(LLPG))
tree.Children.Add(new PredictionBranch(rest, new PredictionTreeOrAlt { Alt = ErrorAlt }, tree.TotalCoverage));
else {
// No error branch, so use default arm
#if false
// First try: this tends to produce less intuitive code. Neither
// version is objectively better; sometimes this version gives
// faster code and sometimes the other version gives faster code.
int defaultArm = alts.DefaultArmInt();
foreach (PredictionBranch branch in tree.Children)
if (branch.Sub.Tree == null && branch.Sub.Alt == defaultArm) {
branch.Set = branch.Set.Union(rest);
goto done;
}
if (alts.DefaultArm != null)
tree.Children.Add(new PredictionBranch(rest, defaultArm, tree.TotalCoverage));
else
tree.Children.Last.Set = tree.Children.Last.Set.Union(rest);
done:;
#else
PredictionBranch last = tree.Children.Last;
if (alts.DefaultArm != null && (last.Sub.Tree != null || last.Sub.Alt != alts.DefaultArm.Value))
tree.Children.Add(new PredictionBranch(rest, alts.DefaultArm.Value, tree.TotalCoverage));
else
last.Set = last.Set.Union(rest);
#endif
}
}
}
internal MultikeyedDictionary <GrammarVocabulary, int, List <Tuple <Tuple <int[], PredictionTree>[], int[]> > > ObtainTerminalAmbiguities(
Dictionary <SyntacticalDFAState, PredictionTreeLeaf> fullSeries,
ControlledDictionary <IOilexerGrammarProductionRuleEntry, SyntacticalDFARootState> ruleDFAs,
Dictionary <IOilexerGrammarProductionRuleEntry, GrammarVocabulary> ruleLookup,
GrammarSymbolSet grammarSymbols)
{
if (!this.Veins.DFAOriginState.IsEdge)
{
return(new MultikeyedDictionary <GrammarVocabulary, int, List <Tuple <Tuple <int[], PredictionTree>[], int[]> > >());
}
var tempDictionary = new MultikeyedDictionary <PredictionTreeBranch, GrammarVocabulary, Tuple <int[], PredictionTree> >();
var rootNode = fullSeries[ruleDFAs[this.Rule]];
var currentIncoming = new List <PredictionTreeBranch>(rootNode.incoming);
var reductions = rootNode.PointsOfReduction.ToArray();
if (reductions.Length > 0)
{
}
var totalIncoming = new HashSet <PredictionTreeBranch>();
Dictionary <PredictionTree, PredictionTree> uniqueSet = new Dictionary <PredictionTree, PredictionTree>();
foreach (var path in currentIncoming)
{
var transitionTableResult = new FiniteAutomataMultiTargetTransitionTable <GrammarVocabulary, Tuple <int, PredictionTreeBranch> >();
var masterPathChop = new PredictionTreeBranch(path.Take(path.Depth).Concat(new[] { this }).ToArray(), path.Depth, false, false);
masterPathChop.SetDeviations(path.GetDeviationsUpTo(path.Depth));
ObtainTerminalAmbiguitiesOnPath(masterPathChop, fullSeries, ruleDFAs, ruleLookup, transitionTableResult, grammarSymbols);
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * \
* Construct the sequence of Path->Grammar->PathSets based *
* off of the table provided by the ObtainTerminalAmbiguitiesOnPath. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * **/
foreach (var transition in transitionTableResult.Keys)
{
var epDepthLookup =
(from entry in transitionTableResult[transition]
group entry.Item1 by entry.Item2).ToDictionary(k => k.Key, v => v.ToArray());
//int minDepth;
//var uniqueCurrent = GetUniqueDPathSet(uniqueSet, transitionTableResult, transition, epDepthLookup);
//var subPath = new PredictionTreeBranch(path.Skip(minDepth).ToList(), path.Depth - minDepth, minDepth: path.MinDepth);
tempDictionary.TryAdd(path, transition, Tuple.Create((from epDepth in transitionTableResult[transition]
select epDepth.Item1).ToArray(), GetFollowDPathSet(transitionTableResult, transition, epDepthLookup)));
}
}
var regrouping = (from ksvp in tempDictionary
group new { Path = ksvp.Keys.Key1, Set = ksvp.Value } by ksvp.Keys.Key2).ToDictionary(k => k.Key, v => v.ToArray());
/*
* foreach (var pathSet in from key in regrouping.Keys
* let value = regrouping[key]
* from r in value
* select r.Set)
* pathSet.Item2.FixAllPaths();//*/
var comparisons = (from key in regrouping.Keys
let value = regrouping[key]
let kRewrite = from r in value
select r.Set
let commonalities = PredictionTree.GetCompoundRightSideSimilarities(kRewrite)
select new { Commonalities = commonalities, Transition = key }).ToDictionary(k => k.Transition, v => v.Commonalities);
var resultDictionary = new MultikeyedDictionary <GrammarVocabulary, int, List <Tuple <Tuple <int[], PredictionTree>[], int[]> > >();
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * \
* Once we're done, we need to rebuild the paths with the MinDepth set to *
* their current Depth. This is to ensure that it the PathSets don't try *
* to reduce more than necessary. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Then we take that set and perform a right-hand-side comparison between *
* the elements. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* This will be used later to reduce the walking necessary to isolate the *
* proper machine to use to disambiguate the look-ahead. *
\ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * **/
foreach (var comparison in comparisons.Keys)
{
var comparisonElements = comparisons[comparison];
foreach (var memberCount in comparisonElements.Keys)
{
var comparisonElement = comparisonElements[memberCount];
resultDictionary.Add(comparison, memberCount, comparisonElement);
}
}
return(resultDictionary);
}
void ScanTree(PredictionTree tree, Alts alts, DList <Prematched> path)
{
int oldCount = path.Count;
while (path.Count <= tree.Lookahead)
{
path.Add(new Prematched {
Terminals = Anything
});
}
Prematched pm = path.Last;
if (tree.IsAssertionLevel)
{
foreach (PredictionBranch b in tree.Children)
{
var old = pm.AndPreds.Clone();
var verified = Enumerable.Aggregate(b.AndPreds, (set1, set2) => (set1.Union(set2))); // usually empty if more than one
pm.AndPreds.UnionWith(verified);
if (b.Sub.Tree != null)
{
ScanTree(b.Sub.Tree, alts, path);
}
else
{
Debug.Assert(b.Sub.Alt != ErrorAlt);
if (b.Sub.Alt == ExitAlt)
{
_apply.ApplyPrematchData(alts.Next, path);
}
else
{
_apply.ApplyPrematchData(alts.Arms[b.Sub.Alt], path);
}
}
pm.AndPreds = old;
}
}
else // !IsAssertionLevel (terminal-matching level)
{
bool needErrorBranch = LLPG.NeedsErrorBranch(tree, alts);
for (int i = 0; i < tree.Children.Count; i++)
{
PredictionBranch b = tree.Children[i];
IPGTerminalSet set = b.Set;
if (!needErrorBranch && i + 1 == tree.Children.Count)
{
// Add all the default cases
set = set.Union(tree.TotalCoverage.Inverted());
}
pm.Terminals = set;
if (b.Sub.Tree != null)
{
ScanTree(b.Sub.Tree, alts, path);
}
else
{
if (b.Sub.Alt == ExitAlt)
{
_apply.ApplyPrematchData(alts.Next, path);
}
else if (b.Sub.Alt != ErrorAlt)
{
_apply.ApplyPrematchData(alts.Arms[b.Sub.Alt], path);
}
}
}
path.PopLast();
}
path.Resize(oldCount);
}
protected LNode GeneratePredictionTreeCode(PredictionTree tree, Pair <LNode, string>[] matchingCode, ref Symbol haveLoop)
{
var braces = F.Braces();
Debug.Assert(tree.Children.Count >= 1);
var alts = (Alts)_currentPred;
if (tree.Children.Count == 1)
{
return(GetPredictionSubtreeCode(tree.Children[0], matchingCode, ref haveLoop));
}
// From the prediction table, we can generate either an if-else chain:
//
// if (la0 >= '0' && la0 <= '7') sub_tree_1();
// else if (la0 == '-') sub_tree_2();
// else break;
//
// or a switch statement:
//
// switch(la0) {
// case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7':
// sub_tree_1();
// break;
// case '-':
// sub_tree_2();
// break;
// default:
// goto breakfor;
// }
//
// Assertion levels always need an if-else chain; lookahead levels
// consider the complexity of switch vs if and decide which is most
// appropriate. Generally "if" is slower, but a switch may require
// too many labels since it doesn't support ranges like "la0 >= 'a'
// && la0 <= 'z'".
//
// This class makes if-else chains directly (using IPGTerminalSet.
// GenerateTest() to generate the test expressions), but the code
// generation helper (CGH) is used to generate switch statements
// because the required code may be more complex.
//
// We may or may not be generating code inside a for(;;) loop. If we
// decide to generate a switch() statement, one of the branches will
// usually need to break out of the for loop, but "break" can only
// break out of the switch(). In that case, add "stop:" after the
// switch() and use "goto stop" instead of "break".
WList <LNode> block = new WList <LNode>();
LNode laVar = null;
MSet <int> switchCases = new MSet <int>();
IPGTerminalSet[] branchSets = null;
bool should = false;
if (tree.UsesLA())
{
laVar = F.Id("la" + tree.Lookahead.ToString());
if (!tree.IsAssertionLevel)
{
IPGTerminalSet covered = CGH.EmptySet;
branchSets = tree.Children.Select(branch => {
var set = branch.Set.Subtract(covered);
covered = covered.Union(branch.Set);
return(set);
}).ToArray();
should = CGH.ShouldGenerateSwitch(branchSets, switchCases, tree.Children.Last.IsErrorBranch);
if (!should)
{
switchCases.Clear();
}
else if (should && haveLoop == S.For)
{
// Can't "break" out of the for-loop when there is a nested switch,
haveLoop = GSymbol.Get(NextStopLabel()); // so use "goto stop".
}
}
}
LNode[] branchCode = new LNode[tree.Children.Count];
for (int i = 0; i < tree.Children.Count; i++)
{
if (tree.Children[i].IsErrorBranch)
{
if (_recognizerMode)
{
branchCode[i] = F.Call(S.Return, F.False);
}
else if (alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value)
{
Debug.Assert(matchingCode.Length == alts.Arms.Count + 1);
branchCode[i] = matchingCode[alts.Arms.Count].A;
}
else
{
branchCode[i] = CGH.ErrorBranch(tree.TotalCoverage, tree.Lookahead);
}
}
else
{
branchCode[i] = GetPredictionSubtreeCode(tree.Children[i], matchingCode, ref haveLoop);
}
}
var code = GenerateIfElseChain(tree, branchCode, ref laVar, switchCases);
if (laVar != null)
{
block.Insert(0, F.Assign(laVar, CGH.LA(tree.Lookahead)));
_laVarsNeeded |= 1ul << tree.Lookahead;
}
else if (should)
{
laVar = CGH.LA(tree.Lookahead);
}
if (should)
{
Debug.Assert(switchCases.Count != 0);
code = CGH.GenerateSwitch(branchSets, branchCode, switchCases, code ?? F.Missing, laVar);
}
block.Add(code);
return(F.Braces(block.ToVList()));
}
// GENERATED CODE EXAMPLE: The methods in this region generate
// the for(;;) loop in this example and everything inside it, except
// the calls to Match() which are generated by Visit(TerminalPred).
// The generated code uses "goto" and "match" blocks in some cases
// to avoid code duplication. This occurs when the matching code
// requires multiple statements AND appears more than once in the
// prediction tree. Otherwise, matching is done "inline" during
// prediction. We generate a for(;;) loop for (...)*, and in certain
// cases, we generates a do...while(false) loop for (...)?.
//
// rule Foo @{ (('a'|'A') 'A')* 'a'..'z' 'a'..'z' };
// public void Foo()
// {
// int la0, la1;
// for (;;) {
// la0 = LA(0);
// if (la0 == 'a') {
// la1 = LA(1);
// if (la1 == 'A')
// goto match1;
// else
// break;
// } else if (la0 == 'A')
// goto match1;
// else
// break;
// match1:
// {
// Match('A', 'a');
// Match('A');
// }
// }
// MatchRange('a', 'z');
// MatchRange('a', 'z');
// }
private void GenerateCodeForAlts(Alts alts, Dictionary <int, int> timesUsed, PredictionTree tree)
{
bool needError = LLPG.NeedsErrorBranch(tree, alts);
if (!needError && alts.ErrorBranch != null)
{
LLPG.Output(Warning, alts, "The error branch will not be used because the other alternatives are exhaustive (cover all cases)");
}
bool userDefinedError = needError && !_recognizerMode && alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value;
// Generate matching code for each arm. the "string" in each pair
// becomes non-null if the matching code for that branch needs to be
// split out (separated) from the prediction tree because it appears
// multiple times in the tree. The string is the goto-label name.
Pair <LNode, string>[] matchingCode = new Pair <LNode, string> [alts.Arms.Count + (userDefinedError ? 1: 0)];
MSet <int> unreachable = new MSet <int>();
int separateCount = 0;
for (int i = 0; i < alts.Arms.Count; i++)
{
if (!timesUsed.ContainsKey(i))
{
unreachable.Add(i);
continue;
}
var codeForThisArm = new WList <LNode>();
VisitWithNewTarget(alts.Arms[i], codeForThisArm);
matchingCode[i].A = F.Braces(codeForThisArm.ToVList());
if (timesUsed[i] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A))
{
separateCount++;
matchingCode[i].B = alts.Arms[i].ChooseGotoLabel()
?? "match" + (i + 1).ToString();
}
}
// Add matching code for the error branch, if present. Note: the
// default error branch, which is produced by IPGCodeGenHelper.
// ErrorBranch() is handled differently: default error code can
// differ at each error point in the prediction tree. Therefore
// we generate it later, on-demand.
if (userDefinedError)
{
int i = alts.Arms.Count;
var errorHandler = new WList <LNode>();
VisitWithNewTarget(alts.ErrorBranch, errorHandler);
matchingCode[i].A = F.Braces(errorHandler.ToVList());
if (timesUsed[ErrorAlt] > 1 && !SimpleEnoughToRepeat(matchingCode[i].A))
{
matchingCode[i].B = "error";
separateCount++;
}
}
// Print unreachability warnings
if (unreachable.Count == 1)
{
LLPG.Output(Warning, alts, string.Format("Branch {{{0}}} is unreachable.", alts.AltName(unreachable.First())));
}
else if (unreachable.Count > 1)
{
LLPG.Output(Warning, alts, string.Format("Branches {{{0}}} are unreachable.", unreachable.Select(i => alts.AltName(i)).Join(", ")));
}
if (!timesUsed.ContainsKey(ExitAlt) && alts.Mode != LoopMode.None)
{
LLPG.Output(Warning, alts, "Infinite loop. The exit branch is unreachable.");
}
Symbol loopType = null;
// Choose a loop type for (...)* or (...)?:
if (alts.Mode == LoopMode.Star)
{
loopType = S.For;
}
else if (alts.Mode == LoopMode.Opt)
{
if (alts.HasErrorBranch(LLPG) || alts.NonExitDefaultArmRequested())
{
loopType = S.DoWhile;
}
}
// If the code for an arm is nontrivial and appears multiple times
// in the prediction table, it will have to be split out into a
// labeled block and reached via "goto". I'd rather just do a goto
// from inside one "if" statement to inside another, but in C#
// (unlike in CIL, and unlike in C) that is prohibited :(
DeduplicateLabels(matchingCode);
var extraMatching = GenerateExtraMatchingCode(matchingCode, separateCount, ref loopType);
if (separateCount != 0)
{
loopType = loopType ?? S.DoWhile;
}
Symbol breakMode = loopType; // used to request a "goto" label in addition to the loop
LNode code = GeneratePredictionTreeCode(tree, matchingCode, ref breakMode);
// Add break/continue between prediction tree and extra matching code,
// if necessary.
if (extraMatching.Count != 0 && CodeGenHelperBase.EndMayBeReachable(code))
{
loopType = loopType ?? S.DoWhile;
extraMatching.Insert(0, GetContinueStmt(loopType));
}
if (!extraMatching.IsEmpty)
{
code = LNode.MergeLists(code, F.Braces(extraMatching), S.Braces);
}
if (loopType == S.For)
{
// (...)* => for (;;) {}
code = F.Call(S.For, F.List(), F.Missing, F.List(), code);
}
else if (loopType == S.DoWhile)
{
// (...)? becomes "do {...} while(false);" IF the exit branch is NOT the default.
// If the exit branch is the default, then no loop and no "break" is needed.
code = F.Call(S.DoWhile, code, F.@false);
}
if (breakMode != loopType && breakMode != null)
{
// Add "stop:" label (plus extra ";" for C# compatibility, in
// case the label ends the block in which it is located.)
var stopLabel = F.Call(S.Label, F.Id(breakMode))
.PlusTrailingTrivia(F.Trivia(S.TriviaRawText, ";"));
code = LNode.MergeLists(code, stopLabel, S.Braces);
}
int oldCount = _target.Count;
_target.SpliceAdd(code, S.Braces);
// Add comment before code
if (LLPG.AddComments)
{
var pos = alts.Basis.Range.Start;
var comment = F.Trivia(S.TriviaSLComment, string.Format(" Line {0}: {1}", pos.Line, alts.ToString()));
if (_target.Count > oldCount)
{
_target[oldCount] = _target[oldCount].PlusAttr(comment);
}
}
}
void ScanTree(PredictionTree tree, Alts alts, DList<Prematched> path)
{
int oldCount = path.Count;
while (path.Count <= tree.Lookahead)
path.Add(new Prematched { Terminals = Anything });
Prematched pm = path.Last;
if (tree.IsAssertionLevel)
{
foreach (PredictionBranch b in tree.Children)
{
var old = pm.AndPreds.Clone();
var verified = Enumerable.Aggregate(b.AndPreds, (set1, set2) => (set1.Union(set2))); // usually empty if more than one
pm.AndPreds.UnionWith(verified);
if (b.Sub.Tree != null) {
ScanTree(b.Sub.Tree, alts, path);
} else {
Debug.Assert(b.Sub.Alt != ErrorAlt);
if (b.Sub.Alt == ExitAlt)
_apply.ApplyPrematchData(alts.Next, path);
else
_apply.ApplyPrematchData(alts.Arms[b.Sub.Alt], path);
}
pm.AndPreds = old;
}
}
else // !IsAssertionLevel (terminal-matching level)
{
bool needErrorBranch = LLPG.NeedsErrorBranch(tree, alts);
for (int i = 0; i < tree.Children.Count; i++) {
PredictionBranch b = tree.Children[i];
IPGTerminalSet set = b.Set;
if (!needErrorBranch && i + 1 == tree.Children.Count)
// Add all the default cases
set = set.Union(tree.TotalCoverage.Inverted());
pm.Terminals = set;
if (b.Sub.Tree != null) {
ScanTree(b.Sub.Tree, alts, path);
} else {
if (b.Sub.Alt == ExitAlt)
_apply.ApplyPrematchData(alts.Next, path);
else if (b.Sub.Alt != ErrorAlt)
_apply.ApplyPrematchData(alts.Arms[b.Sub.Alt], path);
}
}
path.PopLast();
}
path.Resize(oldCount);
}
public void addSon(PredictionTree son)
{
sons.Add(son);
}
protected LNode GeneratePredictionTreeCode(PredictionTree tree, Pair<LNode, string>[] matchingCode, ref Symbol haveLoop)
{
var braces = F.Braces();
Debug.Assert(tree.Children.Count >= 1);
var alts = (Alts)_currentPred;
if (tree.Children.Count == 1)
return GetPredictionSubtreeCode(tree.Children[0], matchingCode, ref haveLoop);
// From the prediction table, we can generate either an if-else chain:
//
// if (la0 >= '0' && la0 <= '7') sub_tree_1();
// else if (la0 == '-') sub_tree_2();
// else break;
//
// or a switch statement:
//
// switch(la0) {
// case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7':
// sub_tree_1();
// break;
// case '-':
// sub_tree_2();
// break;
// default:
// goto breakfor;
// }
//
// Assertion levels always need an if-else chain; lookahead levels
// consider the complexity of switch vs if and decide which is most
// appropriate. Generally "if" is slower, but a switch may require
// too many labels since it doesn't support ranges like "la0 >= 'a'
// && la0 <= 'z'".
//
// This class makes if-else chains directly (using IPGTerminalSet.
// GenerateTest() to generate the test expressions), but the code
// snippet generator (CSG) is used to generate switch statements
// because the required code may be more complex.
//
// We may or may not be generating code inside a for(;;) loop. If we
// decide to generate a switch() statement, one of the branches will
// usually need to break out of the for loop, but "break" can only
// break out of the switch(). In that case, add "stop:" after the
// switch() and use "goto stop" instead of "break".
WList<LNode> block = new WList<LNode>();
LNode laVar = null;
MSet<int> switchCases = new MSet<int>();
IPGTerminalSet[] branchSets = null;
bool should = false;
if (tree.UsesLA()) {
laVar = F.Id("la" + tree.Lookahead.ToString());
if (!tree.IsAssertionLevel) {
IPGTerminalSet covered = CGH.EmptySet;
branchSets = tree.Children.Select(branch => {
var set = branch.Set.Subtract(covered);
covered = covered.Union(branch.Set);
return set;
}).ToArray();
should = CGH.ShouldGenerateSwitch(branchSets, switchCases, tree.Children.Last.IsErrorBranch);
if (!should)
switchCases.Clear();
else if (should && haveLoop == S.For)
// Can't "break" out of the for-loop when there is a nested switch,
haveLoop = GSymbol.Get(NextStopLabel()); // so use "goto stop".
}
}
LNode[] branchCode = new LNode[tree.Children.Count];
for (int i = 0; i < tree.Children.Count; i++)
if (tree.Children[i].IsErrorBranch) {
if (alts.ErrorBranch != null && alts.ErrorBranch != DefaultErrorBranch.Value) {
Debug.Assert(matchingCode.Length == alts.Arms.Count + 1);
branchCode[i] = matchingCode[alts.Arms.Count].A;
} else
branchCode[i] = CGH.ErrorBranch(tree.TotalCoverage, tree.Lookahead);
} else
branchCode[i] = GetPredictionSubtreeCode(tree.Children[i], matchingCode, ref haveLoop);
var code = GenerateIfElseChain(tree, branchCode, ref laVar, switchCases);
if (laVar != null) {
block.Insert(0, F.Assign(laVar, CGH.LA(tree.Lookahead)));
_laVarsNeeded |= 1ul << tree.Lookahead;
} else if (should)
laVar = CGH.LA(tree.Lookahead);
if (should) {
Debug.Assert(switchCases.Count != 0);
code = CGH.GenerateSwitch(branchSets, switchCases, branchCode, code, laVar);
}
block.Add(code);
return F.Braces(block.ToVList());
}
private LNode GenerateIfElseChain(PredictionTree tree, LNode[] branchCode, ref LNode laVar, MSet<int> switchCases)
{
// From the prediction table, generate a chain of if-else
// statements in reverse, starting with the final "else" clause.
// Skip any branches that have been claimed for use in a switch()
LNode ifChain = null;
bool usedTest = false;
for (int i = tree.Children.Count - 1; i >= 0; i--) {
if (switchCases.Contains(i))
continue;
if (ifChain == null)
ifChain = branchCode[i];
else {
usedTest = true;
var branch = tree.Children[i];
LNode test;
if (tree.IsAssertionLevel)
test = GenerateTest(branch.AndPreds, tree.Lookahead, laVar);
else {
var set = CGH.Optimize(branch.Set, branch.Covered);
test = CGH.GenerateTest(set, laVar);
}
LNode @if = F.Call(S.If, test, branchCode[i]);
if (!ifChain.IsIdWithoutPAttrs(S.Missing))
@if = @if.PlusArg(ifChain);
ifChain = @if;
}
}
if (!usedTest)
laVar = null; // unnecessary
return ifChain;
}
/// <summary>Extends each level of the prediction tree so that it has
/// total coverage. For example, a typicaly prediction tree might have
/// branches for 'a'..'z' and '0..'9'; this method will add coverage for
/// all other possible inputs. It does this either by adding an error
/// branch, or by extending the set handled by the default branch of
/// each level.</summary>
private void AddElseCases(Alts alts, PredictionTree tree)
{
foreach (var branch in tree.Children)
{
if (branch.Sub.Tree != null)
{
AddElseCases(alts, branch.Sub.Tree);
}
}
if (tree.IsAssertionLevel)
{
tree.Children.Last.AndPreds.Clear();
tree.Children.Last.AndPreds.Add(Set <AndPred> .Empty);
}
else if (!tree.TotalCoverage.ContainsEverything)
{
var rest = tree.TotalCoverage.Inverted();
if (alts.HasErrorBranch(LLPG))
{
tree.Children.Add(new PredictionBranch(rest, new PredictionTreeOrAlt {
Alt = ErrorAlt
}, tree.TotalCoverage));
}
else
{
// No error branch, so use default arm
#if false
// First try: this tends to produce less intuitive code. Neither
// version is objectively better; sometimes this version gives
// faster code and sometimes the other version gives faster code.
int defaultArm = alts.DefaultArmInt();
foreach (PredictionBranch branch in tree.Children)
{
if (branch.Sub.Tree == null && branch.Sub.Alt == defaultArm)
{
branch.Set = branch.Set.Union(rest);
goto done;
}
}
if (alts.DefaultArm != null)
{
tree.Children.Add(new PredictionBranch(rest, defaultArm, tree.TotalCoverage));
}
else
{
tree.Children.Last.Set = tree.Children.Last.Set.Union(rest);
}
done :;
#else
PredictionBranch last = tree.Children.Last;
if (alts.DefaultArm != null && (last.Sub.Tree != null || last.Sub.Alt != alts.DefaultArm.Value))
{
tree.Children.Add(new PredictionBranch(rest, alts.DefaultArm.Value, tree.TotalCoverage));
}
else
{
last.Set = last.Set.Union(rest);
}
#endif
}
}
}