org.antlr.v4.runtime.atn

Class DecisionInfo

java.lang.Object

org.antlr.v4.runtime.atn.DecisionInfo

public class DecisionInfo
extends Object

This class contains profiling gathered for a particular decision.

Parsing performance in ANTLR 4 is heavily influenced by both static factors (e.g. the form of the rules in the grammar) and dynamic factors (e.g. the choice of input and the state of the DFA cache at the time profiling operations are started). For best results, gather and use aggregate statistics from a large sample of inputs representing the inputs expected in production before using the results to make changes in the grammar.

Since:

4.3

Field Summary

Fields

Modifier and Type	Field and Description
List<AmbiguityInfo>	ambiguities A collection of AmbiguityInfo instances describing the ambiguities encountered during LL prediction for this decision.
List<ContextSensitivityInfo>	contextSensitivities A collection of ContextSensitivityInfo instances describing the context sensitivities encountered during LL prediction for this decision.
int	decision The decision number, which is an index into ATN.decisionToState.
List<ErrorInfo>	errors A collection of ErrorInfo instances describing the parse errors identified during calls to ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) for this decision.
long	invocations The total number of times ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) was invoked for this decision.
long	LL_ATNTransitions The total number of ATN transitions required during LL prediction for this decision.
long	LL_DFATransitions The total number of DFA transitions required during LL prediction for this decision.
long	LL_Fallback Gets the total number of times SLL prediction completed in a conflict state, resulting in fallback to LL prediction.
long	LL_MaxLook Gets the maximum lookahead required for any single LL prediction to complete for this decision.
LookaheadEventInfo	LL_MaxLookEvent Gets the LookaheadEventInfo associated with the event where the LL_MaxLook value was set.
long	LL_MinLook Gets the minimum lookahead required for any single LL prediction to complete for this decision.
long	LL_TotalLook The sum of the lookahead required for LL prediction for this decision.
List<PredicateEvalInfo>	predicateEvals A collection of PredicateEvalInfo instances describing the results of evaluating individual predicates during prediction for this decision.
long	SLL_ATNTransitions The total number of ATN transitions required during SLL prediction for this decision.
long	SLL_DFATransitions The total number of DFA transitions required during SLL prediction for this decision.
long	SLL_MaxLook Gets the maximum lookahead required for any single SLL prediction to complete for this decision, by reaching a unique prediction, reaching an SLL conflict state, or encountering a syntax error.
LookaheadEventInfo	SLL_MaxLookEvent Gets the LookaheadEventInfo associated with the event where the SLL_MaxLook value was set.
long	SLL_MinLook Gets the minimum lookahead required for any single SLL prediction to complete for this decision, by reaching a unique prediction, reaching an SLL conflict state, or encountering a syntax error.
long	SLL_TotalLook The sum of the lookahead required for SLL prediction for this decision.
long	timeInPrediction The total time spent in ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) for this decision, in nanoseconds.

Constructor Summary

Constructors

Constructor and Description
DecisionInfo(int decision) Constructs a new instance of the DecisionInfo class to contain statistics for a particular decision.

Method Summary

Methods

Modifier and Type	Method and Description
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

decision

public final int decision

The decision number, which is an index into ATN.decisionToState.

invocations

public long invocations

The total number of times ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) was invoked for this decision.

timeInPrediction

public long timeInPrediction

The total time spent in ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) for this decision, in nanoseconds.

The value of this field contains the sum of differential results obtained by System.nanoTime(), and is not adjusted to compensate for JIT and/or garbage collection overhead. For best accuracy, use a modern JVM implementation that provides precise results from System.nanoTime(), and perform profiling in a separate process which is warmed up by parsing the input prior to profiling. If desired, call ATNSimulator.clearDFA() to reset the DFA cache to its initial state before starting the profiling measurement pass.

SLL_TotalLook

public long SLL_TotalLook

The sum of the lookahead required for SLL prediction for this decision. Note that SLL prediction is used before LL prediction for performance reasons even when PredictionMode.LL or PredictionMode.LL_EXACT_AMBIG_DETECTION is used.

SLL_MinLook

public long SLL_MinLook

Gets the minimum lookahead required for any single SLL prediction to complete for this decision, by reaching a unique prediction, reaching an SLL conflict state, or encountering a syntax error.

SLL_MaxLook

public long SLL_MaxLook

Gets the maximum lookahead required for any single SLL prediction to complete for this decision, by reaching a unique prediction, reaching an SLL conflict state, or encountering a syntax error.

SLL_MaxLookEvent

public LookaheadEventInfo SLL_MaxLookEvent

Gets the LookaheadEventInfo associated with the event where the SLL_MaxLook value was set.

LL_TotalLook

public long LL_TotalLook

The sum of the lookahead required for LL prediction for this decision. Note that LL prediction is only used when SLL prediction reaches a conflict state.

LL_MinLook

public long LL_MinLook

Gets the minimum lookahead required for any single LL prediction to complete for this decision. An LL prediction completes when the algorithm reaches a unique prediction, a conflict state (for PredictionMode.LL, an ambiguity state (for PredictionMode.LL_EXACT_AMBIG_DETECTION, or a syntax error.

LL_MaxLook

public long LL_MaxLook

Gets the maximum lookahead required for any single LL prediction to complete for this decision. An LL prediction completes when the algorithm reaches a unique prediction, a conflict state (for PredictionMode.LL, an ambiguity state (for PredictionMode.LL_EXACT_AMBIG_DETECTION, or a syntax error.

LL_MaxLookEvent

public LookaheadEventInfo LL_MaxLookEvent

Gets the LookaheadEventInfo associated with the event where the LL_MaxLook value was set.

contextSensitivities

public final List<ContextSensitivityInfo> contextSensitivities

A collection of ContextSensitivityInfo instances describing the context sensitivities encountered during LL prediction for this decision.

See Also:

ContextSensitivityInfo

errors

public final List<ErrorInfo> errors

A collection of ErrorInfo instances describing the parse errors identified during calls to ParserATNSimulator.adaptivePredict(org.antlr.v4.runtime.TokenStream, int, org.antlr.v4.runtime.ParserRuleContext) for this decision.

See Also:

ErrorInfo

ambiguities

public final List<AmbiguityInfo> ambiguities

A collection of AmbiguityInfo instances describing the ambiguities encountered during LL prediction for this decision.

See Also:

AmbiguityInfo

predicateEvals

public final List<PredicateEvalInfo> predicateEvals

A collection of PredicateEvalInfo instances describing the results of evaluating individual predicates during prediction for this decision.

See Also:

PredicateEvalInfo

SLL_ATNTransitions

public long SLL_ATNTransitions

The total number of ATN transitions required during SLL prediction for this decision. An ATN transition is determined by the number of times the DFA does not contain an edge that is required for prediction, resulting in on-the-fly computation of that edge.

If DFA caching of SLL transitions is employed by the implementation, ATN computation may cache the computed edge for efficient lookup during future parsing of this decision. Otherwise, the SLL parsing algorithm will use ATN transitions exclusively.

See Also:

SLL_ATNTransitions, ParserATNSimulator.computeTargetState(org.antlr.v4.runtime.dfa.DFA, org.antlr.v4.runtime.dfa.DFAState, int), LexerATNSimulator.computeTargetState(org.antlr.v4.runtime.CharStream, org.antlr.v4.runtime.dfa.DFAState, int)

SLL_DFATransitions

public long SLL_DFATransitions

The total number of DFA transitions required during SLL prediction for this decision.

If the ATN simulator implementation does not use DFA caching for SLL transitions, this value will be 0.

See Also:

ParserATNSimulator.getExistingTargetState(org.antlr.v4.runtime.dfa.DFAState, int), LexerATNSimulator.getExistingTargetState(org.antlr.v4.runtime.dfa.DFAState, int)

LL_Fallback

public long LL_Fallback

Gets the total number of times SLL prediction completed in a conflict state, resulting in fallback to LL prediction.

Note that this value is not related to whether or not PredictionMode.SLL may be used successfully with a particular grammar. If the ambiguity resolution algorithm applied to the SLL conflicts for this decision produce the same result as LL prediction for this decision, PredictionMode.SLL would produce the same overall parsing result as PredictionMode.LL.

LL_ATNTransitions

public long LL_ATNTransitions

The total number of ATN transitions required during LL prediction for this decision. An ATN transition is determined by the number of times the DFA does not contain an edge that is required for prediction, resulting in on-the-fly computation of that edge.

If DFA caching of LL transitions is employed by the implementation, ATN computation may cache the computed edge for efficient lookup during future parsing of this decision. Otherwise, the LL parsing algorithm will use ATN transitions exclusively.

See Also:

LL_DFATransitions, ParserATNSimulator.computeTargetState(org.antlr.v4.runtime.dfa.DFA, org.antlr.v4.runtime.dfa.DFAState, int), LexerATNSimulator.computeTargetState(org.antlr.v4.runtime.CharStream, org.antlr.v4.runtime.dfa.DFAState, int)

LL_DFATransitions

public long LL_DFATransitions

The total number of DFA transitions required during LL prediction for this decision.

If the ATN simulator implementation does not use DFA caching for LL transitions, this value will be 0.

See Also:

ParserATNSimulator.getExistingTargetState(org.antlr.v4.runtime.dfa.DFAState, int), LexerATNSimulator.getExistingTargetState(org.antlr.v4.runtime.dfa.DFAState, int)

Constructor Detail

DecisionInfo

public DecisionInfo(int decision)

Constructs a new instance of the DecisionInfo class to contain statistics for a particular decision.

Parameters:

decision - The decision number

Method Detail

toString

public String toString()

Overrides:

toString in class Object