org.antlr.v4.runtime.atn

Class Transition

java.lang.Object

org.antlr.v4.runtime.atn.Transition

Direct Known Subclasses:

AbstractPredicateTransition, ActionTransition, AtomTransition, EpsilonTransition, RangeTransition, RuleTransition, SetTransition, WildcardTransition

public abstract class Transition
extends java.lang.Object

An ATN transition between any two ATN states. Subclasses define atom, set, epsilon, action, predicate, rule transitions.

This is a one way link. It emanates from a state (usually via a list of transitions) and has a target state.

Since we never have to change the ATN transitions once we construct it, we can fix these transitions as specific classes. The DFA transitions on the other hand need to update the labels as it adds transitions to the states. We'll use the term Edge for the DFA to distinguish them from ATN transitions.

Field Summary

Fields

Modifier and Type	Field and Description
static int	ACTION
static int	ATOM
static int	EPSILON
static int	NOT_SET
static int	PRECEDENCE
static int	PREDICATE
static int	RANGE
static int	RULE
static java.util.List<java.lang.String>	serializationNames
static java.util.Map<java.lang.Class<? extends Transition>,java.lang.Integer>	serializationTypes
static int	SET
ATNState	target The target of this transition.
static int	WILDCARD

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Transition(ATNState target)

Method Summary

Methods

Modifier and Type	Method and Description
abstract int	getSerializationType()
boolean	isEpsilon() Determines if the transition is an "epsilon" transition.
IntervalSet	label()
abstract boolean	matches(int symbol, int minVocabSymbol, int maxVocabSymbol)

Methods inherited from class java.lang.Object

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

Field Detail

EPSILON

public static final int EPSILON

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Constant Field Values

RANGE

public static final int RANGE

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Constant Field Values

RULE

public static final int RULE

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Constant Field Values

PREDICATE

public static final int PREDICATE

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Constant Field Values

ATOM

public static final int ATOM

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Constant Field Values

ACTION

public static final int ACTION

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Constant Field Values

SET

public static final int SET

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Constant Field Values

NOT_SET

public static final int NOT_SET

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Constant Field Values

WILDCARD

public static final int WILDCARD

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Constant Field Values

PRECEDENCE

public static final int PRECEDENCE

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Constant Field Values

serializationNames

public static final java.util.List<java.lang.String> serializationNames

serializationTypes

public static final java.util.Map<java.lang.Class<? extends Transition>,java.lang.Integer> serializationTypes

target

public ATNState target

The target of this transition.

Constructor Detail

Transition

protected Transition(ATNState target)

Method Detail

getSerializationType

public abstract int getSerializationType()

isEpsilon

public boolean isEpsilon()

Determines if the transition is an "epsilon" transition.

The default implementation returns false.

Returns:

true if traversing this transition in the ATN does not consume an input symbol; otherwise, false if traversing this transition consumes (matches) an input symbol.

label

public IntervalSet label()

matches

public abstract boolean matches(int symbol,
              int minVocabSymbol,
              int maxVocabSymbol)