Package org.antlr.v4.runtime.atn

Class SemanticContext.PrecedencePredicate

java.lang.Object

org.antlr.v4.runtime.atn.SemanticContext

org.antlr.v4.runtime.atn.SemanticContext.PrecedencePredicate

All Implemented Interfaces:

Comparable<SemanticContext.PrecedencePredicate>

Enclosing class:

SemanticContext

public static class SemanticContext.PrecedencePredicate
extends SemanticContext
implements Comparable<SemanticContext.PrecedencePredicate>

Nested Class Summary

Nested classes/interfaces inherited from class org.antlr.v4.runtime.atn.SemanticContext

SemanticContext.AND, SemanticContext.Empty, SemanticContext.Operator, SemanticContext.OR, SemanticContext.PrecedencePredicate, SemanticContext.Predicate

Field Summary

Fields

Modifier and Type	Field	Description
int	precedence

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PrecedencePredicate()
	PrecedencePredicate(int precedence)

Method Summary

Modifier and Type	Method	Description
int	compareTo(SemanticContext.PrecedencePredicate o)
boolean	equals(Object obj)
boolean	eval(Recognizer<?,?> parser, RuleContext parserCallStack)	For context independent predicates, we evaluate them without a local context (i.e., null context).
SemanticContext	evalPrecedence(Recognizer<?,?> parser, RuleContext parserCallStack)	Evaluate the precedence predicates for the context and reduce the result.
int	hashCode()
String	toString()

Methods inherited from class org.antlr.v4.runtime.atn.SemanticContext

and, or

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

precedence

public final int precedence

Constructor Detail

PrecedencePredicate

protected PrecedencePredicate()

PrecedencePredicate

public PrecedencePredicate(int precedence)

Method Detail

eval

public boolean eval(Recognizer<?,?> parser,
                    RuleContext parserCallStack)

Description copied from class: SemanticContext

For context independent predicates, we evaluate them without a local context (i.e., null context). That way, we can evaluate them without having to create proper rule-specific context during prediction (as opposed to the parser, which creates them naturally). In a practical sense, this avoids a cast exception from RuleContext to myruleContext.

For context dependent predicates, we must pass in a local context so that references such as $arg evaluate properly as _localctx.arg. We only capture context dependent predicates in the context in which we begin prediction, so we passed in the outer context here in case of context dependent predicate evaluation.

Specified by:

eval in class SemanticContext

evalPrecedence

public SemanticContext evalPrecedence(Recognizer<?,?> parser,
                                      RuleContext parserCallStack)

Description copied from class: SemanticContext

Evaluate the precedence predicates for the context and reduce the result.

Overrides:

evalPrecedence in class SemanticContext

Parameters:

parser - The parser instance.

Returns:

The simplified semantic context after precedence predicates are evaluated, which will be one of the following values.

• SemanticContext.Empty.Instance: if the predicate simplifies to true after precedence predicates are evaluated.
• null: if the predicate simplifies to false after precedence predicates are evaluated.
• this: if the semantic context is not changed as a result of precedence predicate evaluation.
• A non-null SemanticContext: the new simplified semantic context after precedence predicates are evaluated.

compareTo

public int compareTo(SemanticContext.PrecedencePredicate o)

Specified by:

compareTo in interface Comparable<SemanticContext.PrecedencePredicate>

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object