org.antlr.v4.runtime.atn.DecisionInfo Maven / Gradle / Ivy
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/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.runtime.atn;
import java.util.ArrayList;
import java.util.List;
/**
* 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
*/
public class DecisionInfo {
/**
* The decision number, which is an index into {@link ATN#decisionToState}.
*/
public final int decision;
/**
* The total number of times {@link ParserATNSimulator#adaptivePredict} was
* invoked for this decision.
*/
public long invocations;
/**
* The total time spent in {@link ParserATNSimulator#adaptivePredict} for
* this decision, in nanoseconds.
*
*
* The value of this field contains the sum of differential results obtained
* by {@link 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
* {@link System#nanoTime()}, and perform profiling in a separate process
* which is warmed up by parsing the input prior to profiling. If desired,
* call {@link ATNSimulator#clearDFA} to reset the DFA cache to its initial
* state before starting the profiling measurement pass.
*/
public long timeInPrediction;
/**
* 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 {@link PredictionMode#LL} or
* {@link PredictionMode#LL_EXACT_AMBIG_DETECTION} is used.
*/
public long SLL_TotalLook;
/**
* 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.
*/
public long SLL_MinLook;
/**
* 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.
*/
public long SLL_MaxLook;
/**
* Gets the {@link LookaheadEventInfo} associated with the event where the
* {@link #SLL_MaxLook} value was set.
*/
public LookaheadEventInfo SLL_MaxLookEvent;
/**
* 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.
*/
public long LL_TotalLook;
/**
* 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
* {@link PredictionMode#LL}, an ambiguity state (for
* {@link PredictionMode#LL_EXACT_AMBIG_DETECTION}, or a syntax error.
*/
public long LL_MinLook;
/**
* 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
* {@link PredictionMode#LL}, an ambiguity state (for
* {@link PredictionMode#LL_EXACT_AMBIG_DETECTION}, or a syntax error.
*/
public long LL_MaxLook;
/**
* Gets the {@link LookaheadEventInfo} associated with the event where the
* {@link #LL_MaxLook} value was set.
*/
public LookaheadEventInfo LL_MaxLookEvent;
/**
* A collection of {@link ContextSensitivityInfo} instances describing the
* context sensitivities encountered during LL prediction for this decision.
*
* @see ContextSensitivityInfo
*/
public final List contextSensitivities = new ArrayList();
/**
* A collection of {@link ErrorInfo} instances describing the parse errors
* identified during calls to {@link ParserATNSimulator#adaptivePredict} for
* this decision.
*
* @see ErrorInfo
*/
public final List errors = new ArrayList();
/**
* A collection of {@link AmbiguityInfo} instances describing the
* ambiguities encountered during LL prediction for this decision.
*
* @see AmbiguityInfo
*/
public final List ambiguities = new ArrayList();
/**
* A collection of {@link PredicateEvalInfo} instances describing the
* results of evaluating individual predicates during prediction for this
* decision.
*
* @see PredicateEvalInfo
*/
public final List predicateEvals = new ArrayList();
/**
* 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 #SLL_ATNTransitions
* @see ParserATNSimulator#computeTargetState
* @see LexerATNSimulator#computeTargetState
*/
public long SLL_ATNTransitions;
/**
* 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 ParserATNSimulator#getExistingTargetState
* @see LexerATNSimulator#getExistingTargetState
*/
public long SLL_DFATransitions;
/**
* 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
* {@link 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, {@link PredictionMode#SLL} would produce the same overall
* parsing result as {@link PredictionMode#LL}.
*/
public long LL_Fallback;
/**
* 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 #LL_DFATransitions
* @see ParserATNSimulator#computeTargetState
* @see LexerATNSimulator#computeTargetState
*/
public long LL_ATNTransitions;
/**
* 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 ParserATNSimulator#getExistingTargetState
* @see LexerATNSimulator#getExistingTargetState
*/
public long LL_DFATransitions;
/**
* Constructs a new instance of the {@link DecisionInfo} class to contain
* statistics for a particular decision.
*
* @param decision The decision number
*/
public DecisionInfo(int decision) {
this.decision = decision;
}
@Override
public String toString() {
return "{" +
"decision=" + decision +
", contextSensitivities=" + contextSensitivities.size() +
", errors=" + errors.size() +
", ambiguities=" + ambiguities.size() +
", SLL_lookahead=" + SLL_TotalLook +
", SLL_ATNTransitions=" + SLL_ATNTransitions +
", SLL_DFATransitions=" + SLL_DFATransitions +
", LL_Fallback=" + LL_Fallback +
", LL_lookahead=" + LL_TotalLook +
", LL_ATNTransitions=" + LL_ATNTransitions +
'}';
}
}