Package org.antlr.v4.runtime.atn

Class ReachComputation

java.lang.Object

org.antlr.v4.runtime.atn.ReachComputation

final class ReachComputation
extends Object

Package-private reach / target-state engine for adaptive LL(*) prediction.

Owns the retained reach and intermediate ATNConfigSets plus the ReachConfigSource view used by a single ParserATNSimulator.computeTargetState(org.antlr.v4.runtime.dfa.DFA, org.antlr.v4.runtime.dfa.DFAState, org.antlr.v4.runtime.ParserRuleContext, int, boolean, org.antlr.v4.runtime.atn.PredictionContextCache) invocation. Extracted so ParserATNSimulator stays focused on adaptivePredict / DFA orchestration while allocation and release policy for edge computation live in one place.

Ownership: one instance per ParserATNSimulator. A simulator is used by one parser thread at a time during prediction, so retained scratch is not shared across threads. Each computeTargetState(org.antlr.v4.runtime.dfa.DFA, org.antlr.v4.runtime.dfa.DFAState, org.antlr.v4.runtime.ParserRuleContext, int, boolean, org.antlr.v4.runtime.atn.PredictionContextCache) binds scratch inside try/finally and always releases after the edge is cloned into the DFA.

Not part of any public or protected API.

Field Summary

Fields

Modifier and Type	Field	Description
private final RetainedConfigSet	retainedIntermediate
private final RetainedConfigSet	retainedReach	Retained reach / intermediate sets.
private final ReachConfigSource	retainedReachConfigs	Retained config view.
private final ParserATNSimulator	simulator

Constructor Summary

Constructors

Constructor	Description
ReachComputation(ParserATNSimulator simulator)

Method Summary

Modifier and Type	Method	Description
(package private) Tuple2<DFAState,ParserRuleContext>	computeTargetState(DFA dfa, DFAState s, ParserRuleContext remainingGlobalContext, int t, boolean useContext, PredictionContextCache contextCache)	Compute a target state for an edge in the DFA, and attempt to add the computed state and corresponding edge to the DFA.
private Tuple2<DFAState,ParserRuleContext>	finishTargetEdge(DFA dfa, DFAState s, int t, IntegerList contextElements, ATNConfigSet edgeConfigs, ParserRuleContext remainingGlobalContext, PredictionContextCache contextCache)	Install a DFA edge for the computed config set, or ATNSimulator.ERROR if empty.
(package private) ReachConfigSource	retainedReachConfigs()	Retained config source after construction.

Methods inherited from class java.lang.Object

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

Field Details

simulator

@NotNull
private final ParserATNSimulator simulator

retainedReach

private final RetainedConfigSet retainedReach

Retained reach / intermediate sets. RetainedConfigSet.obtain(int) always returns empty; RetainedConfigSet.release() runs in finally after each edge.

retainedIntermediate

private final RetainedConfigSet retainedIntermediate

retainedReachConfigs

private final ReachConfigSource retainedReachConfigs

Retained config view. ReachConfigSource.reset(org.antlr.v4.runtime.atn.ATNConfigSet) binds the source set; ReachConfigSource.release() runs in finally so the full-context rewrite list keeps capacity across predictions.

Constructor Details

ReachComputation

ReachComputation(@NotNull
 ParserATNSimulator simulator)

Method Details

retainedReachConfigs

@NotNull
ReachConfigSource retainedReachConfigs()

Retained config source after construction. Same-package tests may observe rewrite-list identity across full-context edges.

computeTargetState

@NotNull
Tuple2<DFAState,ParserRuleContext> computeTargetState(@NotNull
 DFA dfa,
 @NotNull
 DFAState s,
 ParserRuleContext remainingGlobalContext,
 int t,
 boolean useContext,
 PredictionContextCache contextCache)

Compute a target state for an edge in the DFA, and attempt to add the computed state and corresponding edge to the DFA.

Returns:

The computed target DFA state for the given input symbol t. If t does not lead to a valid DFA state, this method returns ATNSimulator.ERROR.

finishTargetEdge

@NotNull
private Tuple2<DFAState,ParserRuleContext> finishTargetEdge(@NotNull
 DFA dfa,
 @NotNull
 DFAState s,
 int t,
 @Nullable
 IntegerList contextElements,
 @NotNull
 ATNConfigSet edgeConfigs,
 ParserRuleContext remainingGlobalContext,
 PredictionContextCache contextCache)

Install a DFA edge for the computed config set, or ATNSimulator.ERROR if empty.