Represents a location with context in an ATN. The location is identified by the following values:

The current ATN state
The predicted alternative
The semantic context which must be true for this configuration to be enabled
The syntactic context, which is represented as a graph-structured stack whose path(s) lead to the root of the rule invocations leading to this state.

In addition to these values, ATNConfig stores several properties about paths taken to get to the location which were added over time to help with performance, correctness, and/or debugging.

getReachesIntoOuterContext(): Used to ensure semantic predicates are not evaluated in the wrong context.
hasPassedThroughNonGreedyDecision(): Used for enabling first-match-wins instead of longest-match-wins after crossing a non-greedy decision.
getLexerActionExecutor(): Used for tracking the lexer action(s) to execute should this instance be selected during lexing.
isPrecedenceFilterSuppressed(): A state variable for one of the dynamic disambiguation strategies employed by ParserATNSimulator#applyPrecedenceFilter.

Due to the use of a graph-structured stack, a single ATNConfig is capable of representing many individual ATN configurations which reached the same location in an ATN by following different paths.

PERF: To conserve memory, ATNConfig is split into several different concrete types. ATNConfig itself stores the minimum amount of information typically used to define an ATNConfig instance. Various derived types provide additional storage space for cases where a non-default value is used for some of the object properties. The ATNConfig#create and ATNConfig#transform methods automatically select the smallest concrete type capable of representing the unique information for any given ATNConfig.

Nested and Inner Type Summary

Modifier and Type	Class and Description
private static class	ATNConfig.ActionATNConfig This class was derived from `ATNConfig` purely as a memory optimization.
private static class	ATNConfig.ActionSemanticContextATNConfig This class was derived from `SemanticContextATNConfig` purely as a memory optimization.
private static class	ATNConfig.SemanticContextATNConfig This class was derived from `ATNConfig` purely as a memory optimization.

Field Summary

Modifier and Type	Field and Description
private int	altAndOuterContextDepth This is a bit-field currently containing the following values.
private PredictionContext	context The stack of invoking states leading to the rule/states associated with this config.
private final ATNState	state The ATN state associated with this configuration
private static final int	SUPPRESS_PRECEDENCE_FILTER This field stores the bit mask for implementing the `isPrecedenceFilterSuppressed` property as a bit within the existing `altAndOuterContextDepth` field.

Access	Constructor and Description
protected	ATNConfig(ATNState state, int alt, PredictionContext context)
protected	ATNConfig(ATNConfig c, ATNState state, PredictionContext context)

Method Summary

Modifier and Type	Method and Description
public ATNConfig	appendContext(int context, PredictionContextCache contextCache)
public ATNConfig	appendContext(PredictionContext context, PredictionContextCache contextCache)
private static boolean	checkNonGreedyDecision(ATNConfig source, ATNState target)
public final ATNConfig	clone() Overrides java.lang.Object.clone. Creates and returns a copy of this object.
public boolean	Returns: `true` if this configuration contains `subconfig`; otherwise, `false`. contains(ATNConfig The sub configuration. subconfig) Determines if this `ATNConfig` fully contains another `ATNConfig`.
public static ATNConfig	create(ATNState state, int alt, PredictionContext context)
public static ATNConfig	create(ATNState state, int alt, PredictionContext context, SemanticContext semanticContext)
public static ATNConfig	create(ATNState state, int alt, PredictionContext context, SemanticContext semanticContext, LexerActionExecutor lexerActionExecutor)
public boolean	equals(Object the reference object with which to compare. o) Overrides java.lang.Object.equals. An ATN configuration is equal to another if both have the same state, they predict the same alternative, and syntactic/semantic contexts are the same.
public boolean	equals(ATNConfig other)
public final int	getAlt() What alt (or lexer rule) is predicted by this configuration
public final PredictionContext	getContext()
public LexerActionExecutor	getLexerActionExecutor()
public final int	getOuterContextDepth() We cannot execute predicates dependent upon local context unless we know for sure we are in the correct context.
public final boolean	getReachesIntoOuterContext()
public SemanticContext	getSemanticContext()
public final ATNState	getState() Gets the ATN state associated with this configuration
public int	hashCode() Overrides java.lang.Object.hashCode. Returns a hash code value for the object.
public boolean	hasPassedThroughNonGreedyDecision()
public final boolean	isPrecedenceFilterSuppressed()
public void	setContext(PredictionContext context)
public void	setOuterContextDepth(int outerContextDepth)
public final void	setPrecedenceFilterSuppressed(boolean value)
public String	Returns: A Graphviz graph representing the current `ATNConfig`. toDotString() Returns a graphical representation of the current `ATNConfig` in Graphviz format.
public String	toString() Overrides java.lang.Object.toString. Returns a string representation of the object.
public String	toString(Recognizer<?, ?> recog, boolean showAlt)
public String	toString(Recognizer<?, ?> recog, boolean showAlt, boolean showContext)
public final ATNConfig	transform(ATNState state, boolean checkNonGreedy)
public final ATNConfig	transform(ATNState state, SemanticContext semanticContext, boolean checkNonGreedy)
public final ATNConfig	transform(ATNState state, PredictionContext context, boolean checkNonGreedy)
public final ATNConfig	transform(ATNState state, LexerActionExecutor lexerActionExecutor, boolean checkNonGreedy)
private ATNConfig	transform(ATNState state, PredictionContext context, SemanticContext semanticContext, boolean checkNonGreedy, LexerActionExecutor lexerActionExecutor)

Inherited from java.lang.Object:: finalize getClass notify notifyAll wait wait wait

Field Detail

altAndOuterContextDepth	back to summary
private int altAndOuterContextDepth This is a bit-field currently containing the following values. 0x00FFFFFF: Alternative 0x7F000000: Outer context depth 0x80000000: Suppress precedence filter

altAndOuterContextDepth

back to summary

private int altAndOuterContextDepth

This is a bit-field currently containing the following values.

0x00FFFFFF: Alternative
0x7F000000: Outer context depth
0x80000000: Suppress precedence filter

context	back to summary
private PredictionContext context The stack of invoking states leading to the rule/states associated with this config. We track only those contexts pushed during execution of the ATN simulator. Annotations @NotNull

state	back to summary
private final ATNState state The ATN state associated with this configuration Annotations @NotNull

SUPPRESS_PRECEDENCE_FILTER	back to summary
private static final int SUPPRESS_PRECEDENCE_FILTER This field stores the bit mask for implementing the `isPrecedenceFilterSuppressed` property as a bit within the existing `altAndOuterContextDepth` field.

Constructor Detail

ATNConfig	back to summary
protected ATNConfig(ATNState state, int alt, PredictionContext context)

ATNConfig	back to summary
protected ATNConfig(ATNConfig c, ATNState state, PredictionContext context)

Method Detail

appendContext	back to summary
public ATNConfig appendContext(int context, PredictionContextCache contextCache)

appendContext	back to summary
public ATNConfig appendContext(PredictionContext context, PredictionContextCache contextCache)

checkNonGreedyDecision	back to summary
private static boolean checkNonGreedyDecision(ATNConfig source, ATNState target)

clone back to summary

clone	back to summary
public final ATNConfig clone() Overrides java.lang.Object.clone. Doc from java.lang.Object.clone. Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object `x`, the expression: x.clone() != x will be true, and that the expression: x.clone().getClass() == x.getClass() will be `true`, but these are not absolute requirements. While it is typically the case that: x.clone().equals(x) will be `true`, this is not an absolute requirement. By convention, the returned object should be obtained by calling `super.clone`. If a class and all of its superclasses (except `Object`) obey this convention, it will be the case that `x.clone().getClass() == x.getClass()`. By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by `super.clone` before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by `super.clone` need to be modified. Returns:ATNConfig a clone of this instance. Annotations @Override

public final ATNConfig clone()

Overrides java.lang.Object.clone.

Doc from java.lang.Object.clone.

Creates and returns a copy of this object. The precise meaning of "copy" may depend on the class of the object. The general intent is that, for any object x, the expression:

x.clone() != x

will be true, and that the expression:

x.clone().getClass() == x.getClass()

will be true, but these are not absolute requirements. While it is typically the case that:

x.clone().equals(x)

will be true, this is not an absolute requirement.

By convention, the returned object should be obtained by calling super.clone. If a class and all of its superclasses (except Object) obey this convention, it will be the case that x.clone().getClass() == x.getClass().

By convention, the object returned by this method should be independent of this object (which is being cloned). To achieve this independence, it may be necessary to modify one or more fields of the object returned by super.clone before returning it. Typically, this means copying any mutable objects that comprise the internal "deep structure" of the object being cloned and replacing the references to these objects with references to the copies. If a class contains only primitive fields or references to immutable objects, then it is usually the case that no fields in the object returned by super.clone need to be modified.

Returns:ATNConfig

a clone of this instance.

Annotations

@Override

contains back to summary

contains	back to summary
public boolean contains(ATNConfig subconfig) Determines if this `ATNConfig` fully contains another `ATNConfig`. An ATN configuration represents a position (including context) in an ATN during parsing. Since `ATNConfig` stores the context as a graph, a single `ATNConfig` instance is capable of representing many ATN configurations which are all in the same "location" but have different contexts. These `ATNConfig` instances are again merged when they are added to an `ATNConfigSet`. This method supports `ATNConfigSet#contains` by evaluating whether a particular `ATNConfig` contains all of the ATN configurations represented by another `ATNConfig`. An `ATNConfig` a contains another `ATNConfig` b if all of the following conditions are met: The configurations are in the same state (`getState()`) The configurations predict the same alternative (`getAlt()`) The semantic context of a implies the semantic context of b (this method performs a weaker equality check) Joining the prediction contexts of a and b results in the prediction context of a This method implements a conservative approximation of containment. As a result, when this method returns {code true} it is known that parsing from `subconfig` can only recognize a subset of the inputs which can be recognized starting at the current `ATNConfig`. However, due to the imprecise evaluation of implication for the semantic contexts, no assumptions can be made about the relationship between the configurations when this method returns `false`. Parameters subconfig:ATNConfig The sub configuration. Returns:boolean `true` if this configuration contains `subconfig`; otherwise, `false`.

public boolean contains(ATNConfig subconfig)

Determines if this ATNConfig fully contains another ATNConfig.

An ATN configuration represents a position (including context) in an ATN during parsing. Since ATNConfig stores the context as a graph, a single ATNConfig instance is capable of representing many ATN configurations which are all in the same "location" but have different contexts. These ATNConfig instances are again merged when they are added to an ATNConfigSet. This method supports ATNConfigSet#contains by evaluating whether a particular ATNConfig contains all of the ATN configurations represented by another ATNConfig.

An ATNConfig a contains another ATNConfig b if all of the following conditions are met:

The configurations are in the same state (getState())
The configurations predict the same alternative (getAlt())
The semantic context of a implies the semantic context of b (this method performs a weaker equality check)
Joining the prediction contexts of a and b results in the prediction context of a

This method implements a conservative approximation of containment. As a result, when this method returns {code true} it is known that parsing from subconfig can only recognize a subset of the inputs which can be recognized starting at the current ATNConfig. However, due to the imprecise evaluation of implication for the semantic contexts, no assumptions can be made about the relationship between the configurations when this method returns false.

Parameters

subconfig:ATNConfig: The sub configuration.

Returns:boolean

true if this configuration contains subconfig; otherwise, false.

create	back to summary
public static ATNConfig create(ATNState state, int alt, PredictionContext context)

create	back to summary
public static ATNConfig create(ATNState state, int alt, PredictionContext context, SemanticContext semanticContext)

create	back to summary
public static ATNConfig create(ATNState state, int alt, PredictionContext context, SemanticContext semanticContext, LexerActionExecutor lexerActionExecutor)

equals back to summary

equals	back to summary
public boolean equals(Object o) Overrides java.lang.Object.equals. An ATN configuration is equal to another if both have the same state, they predict the same alternative, and syntactic/semantic contexts are the same. Parameters o:Object Doc from java.lang.Object.equals. the reference object with which to compare. Returns:boolean Doc from java.lang.Object.equals. `true` if this object is the same as the obj argument; `false` otherwise. Annotations @Override

public boolean equals(Object o)

Overrides java.lang.Object.equals.

An ATN configuration is equal to another if both have the same state, they predict the same alternative, and syntactic/semantic contexts are the same.

Parameters

o:Object

Doc from java.lang.Object.equals.

the reference object with which to compare.

Returns:boolean

Doc from java.lang.Object.equals.

true if this object is the same as the obj argument; false otherwise.

Annotations

@Override

equals	back to summary
public boolean equals(ATNConfig other)

getAlt	back to summary
public final int getAlt() What alt (or lexer rule) is predicted by this configuration

getContext	back to summary
public final PredictionContext getContext() Annotations @NotNull

getLexerActionExecutor	back to summary
public LexerActionExecutor getLexerActionExecutor() Annotations @Nullable

getOuterContextDepth	back to summary
public final int getOuterContextDepth() We cannot execute predicates dependent upon local context unless we know for sure we are in the correct context. Because there is no way to do this efficiently, we simply cannot evaluate dependent predicates unless we are in the rule that initially invokes the ATN simulator. closure() tracks the depth of how far we dip into the outer context: depth > 0. Note that it may not be totally accurate depth since I don't ever decrement. TODO: make it a boolean then

getOuterContextDepth

back to summary

public final int getOuterContextDepth()

We cannot execute predicates dependent upon local context unless we know for sure we are in the correct context. Because there is no way to do this efficiently, we simply cannot evaluate dependent predicates unless we are in the rule that initially invokes the ATN simulator.

closure() tracks the depth of how far we dip into the outer context: depth > 0. Note that it may not be totally accurate depth since I don't ever decrement. TODO: make it a boolean then

getReachesIntoOuterContext	back to summary
public final boolean getReachesIntoOuterContext()

getSemanticContext	back to summary
public SemanticContext getSemanticContext() Annotations @NotNull

getState	back to summary
public final ATNState getState() Gets the ATN state associated with this configuration Annotations @NotNull

getState

back to summary

public final ATNState getState()

Gets the ATN state associated with this configuration

Annotations

@NotNull

hashCode back to summary

hashCode	back to summary
public int hashCode() Overrides java.lang.Object.hashCode. Doc from java.lang.Object.hashCode. Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by `java.util.HashMap`. The general contract of `hashCode` is: Whenever it is invoked on the same object more than once during an execution of a Java application, the `hashCode` method must consistently return the same integer, provided no information used in `equals` comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. If two objects are equal according to the `equals` method, then calling the `hashCode` method on each of the two objects must produce the same integer result. It is not required that if two objects are unequal according to the `equals` method, then calling the `hashCode` method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables. Returns:int a hash code value for this object. Annotations @Override

public int hashCode()

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

Returns:int

a hash code value for this object.

Annotations

@Override

hasPassedThroughNonGreedyDecision	back to summary
public boolean hasPassedThroughNonGreedyDecision()

isPrecedenceFilterSuppressed	back to summary
public final boolean isPrecedenceFilterSuppressed()

setContext	back to summary
public void setContext(PredictionContext context)

setOuterContextDepth	back to summary
public void setOuterContextDepth(int outerContextDepth)

setPrecedenceFilterSuppressed	back to summary
public final void setPrecedenceFilterSuppressed(boolean value)

toDotString back to summary

toDotString	back to summary
public String toDotString() Returns a graphical representation of the current `ATNConfig` in Graphviz format. The graph can be stored to a .dot file and then rendered to an image using Graphviz. Returns:String A Graphviz graph representing the current `ATNConfig`. See Also http://www.graphviz.org/

public String toDotString()

Returns a graphical representation of the current ATNConfig in Graphviz format. The graph can be stored to a .dot file and then rendered to an image using Graphviz.

Returns:String: A Graphviz graph representing the current ATNConfig.
See Also: http://www.graphviz.org/

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Doc from java.lang.Object.toString. Returns a string representation of the object. Returns:String a string representation of the object. Annotations @Override

toString

back to summary

public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object.

Returns:String

a string representation of the object.

Annotations

@Override

toString	back to summary
public String toString(Recognizer<?, ?> recog, boolean showAlt)

toString	back to summary
public String toString(Recognizer<?, ?> recog, boolean showAlt, boolean showContext)

transform	back to summary
public final ATNConfig transform(ATNState state, boolean checkNonGreedy)

transform	back to summary
public final ATNConfig transform(ATNState state, SemanticContext semanticContext, boolean checkNonGreedy)

transform	back to summary
public final ATNConfig transform(ATNState state, PredictionContext context, boolean checkNonGreedy)

transform	back to summary
public final ATNConfig transform(ATNState state, LexerActionExecutor lexerActionExecutor, boolean checkNonGreedy)

transform	back to summary
private ATNConfig transform(ATNState state, PredictionContext context, SemanticContext semanticContext, boolean checkNonGreedy, LexerActionExecutor lexerActionExecutor)

org.antlr.v4.runtime.atn back to summary

private Class ATNConfig.ActionATNConfig

Class Inheritance

extends ATNConfig

java.lang.Object
org.antlr.v4.runtime.atn.ATNConfig
org.antlr.v4.runtime.atn.ATNConfig.ActionATNConfig

This class was derived from ATNConfig purely as a memory optimization. It allows for the creation of an ATNConfig with a lexer action.

See the ATNConfig documentation for more information about conserving memory through the use of several concrete types.

Field Summary

Modifier and Type	Field and Description
private final LexerActionExecutor	lexerActionExecutor
private final boolean	passedThroughNonGreedyDecision

Constructor Summary

Access	Constructor and Description
public	ActionATNConfig(LexerActionExecutor lexerActionExecutor, ATNState state, int alt, PredictionContext context, boolean passedThroughNonGreedyDecision)
protected	ActionATNConfig(LexerActionExecutor lexerActionExecutor, ATNConfig c, ATNState state, PredictionContext context, boolean passedThroughNonGreedyDecision)

Method Summary

Modifier and Type	Method and Description
public LexerActionExecutor	getLexerActionExecutor() Overrides org.antlr.v4.runtime.atn.ATNConfig.getLexerActionExecutor.
public boolean	hasPassedThroughNonGreedyDecision() Overrides org.antlr.v4.runtime.atn.ATNConfig.hasPassedThroughNonGreedyDecision.

Field Detail

lexerActionExecutor	back to summary
private final LexerActionExecutor lexerActionExecutor

passedThroughNonGreedyDecision	back to summary
private final boolean passedThroughNonGreedyDecision

Constructor Detail

ActionATNConfig	back to summary
public ActionATNConfig(LexerActionExecutor lexerActionExecutor, ATNState state, int alt, PredictionContext context, boolean passedThroughNonGreedyDecision)

ActionATNConfig	back to summary
protected ActionATNConfig(LexerActionExecutor lexerActionExecutor, ATNConfig c, ATNState state, PredictionContext context, boolean passedThroughNonGreedyDecision)

Method Detail

getLexerActionExecutor	back to summary
public LexerActionExecutor getLexerActionExecutor() Overrides org.antlr.v4.runtime.atn.ATNConfig.getLexerActionExecutor. Annotations @Override

getLexerActionExecutor

back to summary

public LexerActionExecutor getLexerActionExecutor()

Overrides org.antlr.v4.runtime.atn.ATNConfig.getLexerActionExecutor.

Annotations

@Override

hasPassedThroughNonGreedyDecision

back to summary

public boolean hasPassedThroughNonGreedyDecision()

Overrides org.antlr.v4.runtime.atn.ATNConfig.hasPassedThroughNonGreedyDecision.

Annotations

@Override

org.antlr.v4.runtime.atn back to summary

private Class ATNConfig.ActionSemanticContextATNConfig

Class Inheritance

extends SemanticContextATNConfig

java.lang.Object
org.antlr.v4.runtime.atn.ATNConfig
org.antlr.v4.runtime.atn.ATNConfig.SemanticContextATNConfig
org.antlr.v4.runtime.atn.ATNConfig.ActionSemanticContextATNConfig

This class was derived from SemanticContextATNConfig purely as a memory optimization. It allows for the creation of an ATNConfig with both a lexer action and a non-default semantic context.

See the ATNConfig documentation for more information about conserving memory through the use of several concrete types.

Field Summary

Modifier and Type	Field and Description
private final LexerActionExecutor	lexerActionExecutor
private final boolean	passedThroughNonGreedyDecision

Constructor Summary

Access	Constructor and Description
public	ActionSemanticContextATNConfig(LexerActionExecutor lexerActionExecutor, SemanticContext semanticContext, ATNState state, int alt, PredictionContext context, boolean passedThroughNonGreedyDecision)
public	ActionSemanticContextATNConfig(LexerActionExecutor lexerActionExecutor, SemanticContext semanticContext, ATNConfig c, ATNState state, PredictionContext context, boolean passedThroughNonGreedyDecision)

Method Summary

Modifier and Type	Method and Description
public LexerActionExecutor	getLexerActionExecutor() Overrides org.antlr.v4.runtime.atn.ATNConfig.getLexerActionExecutor.
public boolean	hasPassedThroughNonGreedyDecision() Overrides org.antlr.v4.runtime.atn.ATNConfig.hasPassedThroughNonGreedyDecision.

Inherited from org.antlr.v4.runtime.atn.ATNConfig.SemanticContextATNConfig:: getSemanticContext

Field Detail

lexerActionExecutor	back to summary
private final LexerActionExecutor lexerActionExecutor

passedThroughNonGreedyDecision	back to summary
private final boolean passedThroughNonGreedyDecision

Constructor Detail

ActionSemanticContextATNConfig	back to summary
public ActionSemanticContextATNConfig(LexerActionExecutor lexerActionExecutor, SemanticContext semanticContext, ATNState state, int alt, PredictionContext context, boolean passedThroughNonGreedyDecision)

ActionSemanticContextATNConfig	back to summary
public ActionSemanticContextATNConfig(LexerActionExecutor lexerActionExecutor, SemanticContext semanticContext, ATNConfig c, ATNState state, PredictionContext context, boolean passedThroughNonGreedyDecision)

Method Detail

getLexerActionExecutor

back to summary

public LexerActionExecutor getLexerActionExecutor()

Overrides org.antlr.v4.runtime.atn.ATNConfig.getLexerActionExecutor.

Annotations

@Override

hasPassedThroughNonGreedyDecision

back to summary

public boolean hasPassedThroughNonGreedyDecision()

Overrides org.antlr.v4.runtime.atn.ATNConfig.hasPassedThroughNonGreedyDecision.

Annotations

@Override

public Class ATNConfig

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class ATNConfig.ActionATNConfig

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class ATNConfig.ActionSemanticContextATNConfig

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

private Class ATNConfig.SemanticContextATNConfig

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

Access	Constructor and Description
public	SemanticContextATNConfig(SemanticContext semanticContext, ATNState state, int alt, PredictionContext context)
public	SemanticContextATNConfig(SemanticContext semanticContext, ATNConfig c, ATNState state, PredictionContext context)