org.antlr.v4.runtime.atn

Class PredictionContext

java.lang.Object

org.antlr.v4.runtime.atn.PredictionContext

All Implemented Interfaces:

Comparable<PredictionContext>, Iterable<SingletonPredictionContext>

Direct Known Subclasses:

ArrayPredictionContext, SingletonPredictionContext

public abstract class PredictionContext
extends Object
implements Iterable<SingletonPredictionContext>, Comparable<PredictionContext>

Field Summary

Fields

Modifier and Type	Field and Description
int	cachedHashCode
static EmptyPredictionContext	EMPTY Represents $ in local ctx prediction, which means wildcard.
static int	EMPTY_RETURN_STATE Represents $ in an array in full ctx mode, when $ doesn't mean wildcard: $ + x = [$,x].
static int	globalNodeCount
int	id

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PredictionContext(int cachedHashCode)

Method Summary

Methods

Modifier and Type	Method and Description
protected static int	calculateHashCode(int parentHashCode, int returnStateHashCode)
protected static void	combineCommonParents(PredictionContext[] parents) make pass over all M parents; merge any equals() ones
int	compareTo(PredictionContext o)
static PredictionContext	fromRuleContext(ATN atn, RuleContext outerContext) Convert a RuleContext tree to a PredictionContext graph.
static void	getAllContextNodes_(PredictionContext context, List<PredictionContext> nodes, Map<PredictionContext,PredictionContext> visited)
static List<PredictionContext>	getAllContextNodes(PredictionContext context)
static PredictionContext	getCachedContext(PredictionContext context, PredictionContextCache contextCache, IdentityHashMap<PredictionContext,PredictionContext> visited)
abstract PredictionContext	getParent(int index)
abstract int	getReturnState(int index)
boolean	hasEmptyPath()
int	hashCode()
boolean	isEmpty() This means only the EMPTY context is in set
abstract Iterator<SingletonPredictionContext>	iterator()
static PredictionContext	merge(PredictionContext a, PredictionContext b, boolean rootIsWildcard, DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache) Two contexts conflict() if they are equals() or one is a stack suffix of the other.
static PredictionContext	mergeArrays(ArrayPredictionContext a, ArrayPredictionContext b, boolean rootIsWildcard, DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache)
static PredictionContext	mergeRoot(SingletonPredictionContext a, SingletonPredictionContext b, boolean rootIsWildcard) Handle case where at least one of a or b is $ (EMPTY)
static PredictionContext	mergeSingletons(SingletonPredictionContext a, SingletonPredictionContext b, boolean rootIsWildcard, DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache)
abstract int	size()
static String	toDOTString(PredictionContext context)
String	toString(Recognizer<?,?> recog)
String	toString(Recognizer<?,?> recog, RuleContext stop)
String[]	toStrings(Recognizer<?,?> recognizer, int currentState)
String[]	toStrings(Recognizer<?,?> recognizer, PredictionContext stop, int currentState)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY

public static final EmptyPredictionContext EMPTY

Represents $ in local ctx prediction, which means wildcard. *+x = *.

EMPTY_RETURN_STATE

public static final int EMPTY_RETURN_STATE

Represents $ in an array in full ctx mode, when $ doesn't mean wildcard: $ + x = [$,x]. Here, $ = EMPTY_RETURN_STATE.

See Also:

Constant Field Values

globalNodeCount

public static int globalNodeCount

id

public final int id

cachedHashCode

public final int cachedHashCode

Constructor Detail

PredictionContext

protected PredictionContext(int cachedHashCode)

Method Detail

fromRuleContext

public static PredictionContext fromRuleContext(@NotNull
                                ATN atn,
                                RuleContext outerContext)

Convert a RuleContext tree to a PredictionContext graph. Return EMPTY if outerContext is empty or null.

iterator

public abstract Iterator<SingletonPredictionContext> iterator()

Specified by:

iterator in interface Iterable<SingletonPredictionContext>

size

public abstract int size()

getParent

public abstract PredictionContext getParent(int index)

getReturnState

public abstract int getReturnState(int index)

isEmpty

public boolean isEmpty()

This means only the EMPTY context is in set

hasEmptyPath

public boolean hasEmptyPath()

compareTo

public int compareTo(PredictionContext o)

Specified by:

compareTo in interface Comparable<PredictionContext>

hashCode

public int hashCode()

Overrides:

hashCode in class Object

calculateHashCode

protected static int calculateHashCode(int parentHashCode,
                    int returnStateHashCode)

merge

public static PredictionContext merge(PredictionContext a,
                      PredictionContext b,
                      boolean rootIsWildcard,
                      DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache)

Two contexts conflict() if they are equals() or one is a stack suffix of the other. For example, contexts [21 12 $] and [21 9 $] do not conflict, but [21 $] and [21 12 $] do conflict. Note that I should probably not show the $ in this case. There is a dummy node for each stack that just means empty; $ is a marker that's all. This is used in relation to checking conflicts associated with a single NFA state's configurations within a single DFA state. If there are configurations s and t within a DFA state such that s.state=t.state && s.alt != t.alt && s.ctx conflicts t.ctx then the DFA state predicts more than a single alt--it's nondeterministic. Two contexts conflict if they are the same or if one is a suffix of the other. When comparing contexts, if one context has a stack and the other does not then they should be considered the same context. The only way for an NFA state p to have an empty context and a nonempty context is the case when closure falls off end of rule without a call stack and re-enters the rule with a context. This resolves the issue I discussed with Sriram Srinivasan Feb 28, 2005 about not terminating fast enough upon nondeterminism. UPDATE FOR GRAPH STACK; no suffix

mergeSingletons

public static PredictionContext mergeSingletons(SingletonPredictionContext a,
                                SingletonPredictionContext b,
                                boolean rootIsWildcard,
                                DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache)

mergeRoot

public static PredictionContext mergeRoot(SingletonPredictionContext a,
                          SingletonPredictionContext b,
                          boolean rootIsWildcard)

Handle case where at least one of a or b is $ (EMPTY)

mergeArrays

public static PredictionContext mergeArrays(ArrayPredictionContext a,
                            ArrayPredictionContext b,
                            boolean rootIsWildcard,
                            DoubleKeyMap<PredictionContext,PredictionContext,PredictionContext> mergeCache)

combineCommonParents

protected static void combineCommonParents(PredictionContext[] parents)

make pass over all M parents; merge any equals() ones

toDOTString

public static String toDOTString(PredictionContext context)

getCachedContext

public static PredictionContext getCachedContext(@NotNull
                                 PredictionContext context,
                                 @NotNull
                                 PredictionContextCache contextCache,
                                 @NotNull
                                 IdentityHashMap<PredictionContext,PredictionContext> visited)

getAllContextNodes

public static List<PredictionContext> getAllContextNodes(PredictionContext context)

getAllContextNodes_

public static void getAllContextNodes_(PredictionContext context,
                       List<PredictionContext> nodes,
                       Map<PredictionContext,PredictionContext> visited)

toString

public String toString(@Nullable
              Recognizer<?,?> recog)

toString

public String toString(@Nullable
              Recognizer<?,?> recog,
              RuleContext stop)

toStrings

public String[] toStrings(Recognizer<?,?> recognizer,
                 int currentState)

toStrings

public String[] toStrings(Recognizer<?,?> recognizer,
                 PredictionContext stop,
                 int currentState)