org.antlr.v4.runtime

Class ParserRuleContext

java.lang.Object

org.antlr.v4.runtime.RuleContext

org.antlr.v4.runtime.ParserRuleContext

All Implemented Interfaces:

ParseTree, RuleNode, SyntaxTree, Tree

Direct Known Subclasses:

InterpreterRuleContext, RuleContextWithAltNum

public class ParserRuleContext
extends RuleContext

A rule invocation record for parsing. Contains all of the information about the current rule not stored in the RuleContext. It handles parse tree children list, Any ATN state tracing, and the default values available for rule invocations: start, stop, rule index, current alt number. Subclasses made for each rule and grammar track the parameters, return values, locals, and labels specific to that rule. These are the objects that are returned from rules. Note text is not an actual field of a rule return value; it is computed from start and stop using the input stream's toString() method. I could add a ctor to this so that we can pass in and store the input stream, but I'm not sure we want to do that. It would seem to be undefined to get the .text property anyway if the rule matches tokens from multiple input streams. I do not use getters for fields of objects that are used simply to group values such as this aggregate. The getters/setters are there to satisfy the superclass interface.

Field Summary

Fields

Modifier and Type	Field and Description
List<ParseTree>	children If we are debugging or building a parse tree for a visitor, we need to track all of the tokens and rule invocations associated with this rule's context.
RecognitionException	exception The exception that forced this rule to return.
Token	start For debugging/tracing purposes, we want to track all of the nodes in the ATN traversed by the parser for a particular rule.
Token	stop For debugging/tracing purposes, we want to track all of the nodes in the ATN traversed by the parser for a particular rule.

Fields inherited from class org.antlr.v4.runtime.RuleContext

invokingState, parent

Constructor Summary

Constructors

Constructor and Description
ParserRuleContext()
ParserRuleContext(ParserRuleContext parent, int invokingStateNumber)

Method Summary

Modifier and Type	Method and Description
<T extends ParseTree> T	addAnyChild(T t) Add a parse tree node to this as a child.
void	addChild(RuleContext ruleInvocation)
void	addChild(TerminalNode t) Add a token leaf node child.
TerminalNode	addChild(Token matchedToken) Deprecated.
ErrorNode	addErrorNode(ErrorNode errorNode) Add an error node child.
ErrorNode	addErrorNode(Token badToken) Deprecated.
void	copyFrom(ParserRuleContext ctx) COPY a ctx (I'm deliberately not using copy constructor) to avoid confusion with creating node with parent.
static ParserRuleContext	emptyContext()
void	enterRule(ParseTreeListener listener)
void	exitRule(ParseTreeListener listener)
<T extends ParseTree> T	getChild(Class<? extends T> ctxType, int i)
ParseTree	getChild(int i) If there are children, get the ith value indexed from 0.
int	getChildCount() How many children are there? If there is none, then this node represents a leaf node.
ParserRuleContext	getParent() The parent of this node.
<T extends ParserRuleContext> T	getRuleContext(Class<? extends T> ctxType, int i)
<T extends ParserRuleContext> List<? extends T>	getRuleContexts(Class<? extends T> ctxType)
Interval	getSourceInterval() Return an Interval indicating the index in the TokenStream of the first and last token associated with this subtree.
Token	getStart() Get the initial token in this context.
Token	getStop() Get the final token in this context.
TerminalNode	getToken(int ttype, int i)
List<? extends TerminalNode>	getTokens(int ttype)
void	removeLastChild() Used by enterOuterAlt to toss out a RuleContext previously added as we entered a rule.
String	toInfoString(Parser recognizer) Used for rule context info debugging during parse-time, not so much for ATN debugging

Methods inherited from class org.antlr.v4.runtime.RuleContext

accept, depth, getAltNumber, getChildContext, getPayload, getRuleContext, getRuleIndex, getText, isEmpty, setAltNumber, setParent, toString, toString, toString, toString, toString, toStringTree, toStringTree, toStringTree

Methods inherited from class java.lang.Object

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

Field Detail

children

public List<ParseTree> children

If we are debugging or building a parse tree for a visitor, we need to track all of the tokens and rule invocations associated with this rule's context. This is empty for parsing w/o tree constr. operation because we don't the need to track the details about how we parse this rule.

start

public Token start

For debugging/tracing purposes, we want to track all of the nodes in the ATN traversed by the parser for a particular rule. This list indicates the sequence of ATN nodes used to match the elements of the children list. This list does not include ATN nodes and other rules used to match rule invocations. It traces the rule invocation node itself but nothing inside that other rule's ATN submachine. There is NOT a one-to-one correspondence between the children and states list. There are typically many nodes in the ATN traversed for each element in the children list. For example, for a rule invocation there is the invoking state and the following state. The parser setState() method updates field s and adds it to this list if we are debugging/tracing. This does not trace states visited during prediction.

stop

public Token stop

For debugging/tracing purposes, we want to track all of the nodes in the ATN traversed by the parser for a particular rule. This list indicates the sequence of ATN nodes used to match the elements of the children list. This list does not include ATN nodes and other rules used to match rule invocations. It traces the rule invocation node itself but nothing inside that other rule's ATN submachine. There is NOT a one-to-one correspondence between the children and states list. There are typically many nodes in the ATN traversed for each element in the children list. For example, for a rule invocation there is the invoking state and the following state. The parser setState() method updates field s and adds it to this list if we are debugging/tracing. This does not trace states visited during prediction.

exception

public RecognitionException exception

The exception that forced this rule to return. If the rule successfully completed, this is null.

Constructor Detail

ParserRuleContext

public ParserRuleContext()

ParserRuleContext

public ParserRuleContext(@Nullable
                         ParserRuleContext parent,
                         int invokingStateNumber)

Method Detail

emptyContext

public static ParserRuleContext emptyContext()

copyFrom

public void copyFrom(ParserRuleContext ctx)

COPY a ctx (I'm deliberately not using copy constructor) to avoid confusion with creating node with parent. Does not copy children (except error leaves).

This is used in the generated parser code to flip a generic XContext node for rule X to a YContext for alt label Y. In that sense, it is not really a generic copy function.

If we do an error sync() at start of a rule, we might add error nodes to the generic XContext so this function must copy those nodes to the YContext as well else they are lost!

enterRule

public void enterRule(ParseTreeListener listener)

exitRule

public void exitRule(ParseTreeListener listener)

addAnyChild

public <T extends ParseTree> T addAnyChild(T t)

Add a parse tree node to this as a child. Works for internal and leaf nodes. Does not set parent link; other add methods must do that. Other addChild methods call this. We cannot set the parent pointer of the incoming node because the existing interfaces do not have a setParent() method and I don't want to break backward compatibility for this.

Since:

4.7

addChild

public void addChild(RuleContext ruleInvocation)

addChild

public void addChild(TerminalNode t)

Add a token leaf node child.

addErrorNode

public ErrorNode addErrorNode(ErrorNode errorNode)

Add an error node child.

Since:

4.7

addChild

@Deprecated
public TerminalNode addChild(Token matchedToken)

Deprecated.

Add a child to this node based upon matchedToken. It creates a TerminalNodeImpl rather than using Parser.createTerminalNode(ParserRuleContext, Token). I'm leaving this in for compatibility but the parser doesn't use this anymore.

addErrorNode

@Deprecated
public ErrorNode addErrorNode(Token badToken)

Deprecated.

Add a child to this node based upon badToken. It creates a ErrorNodeImpl rather than using Parser.createErrorNode(ParserRuleContext, Token). I'm leaving this in for compatibility but the parser doesn't use this anymore.

removeLastChild

public void removeLastChild()

Used by enterOuterAlt to toss out a RuleContext previously added as we entered a rule. If we have # label, we will need to remove generic ruleContext object.

getParent

public ParserRuleContext getParent()

Description copied from interface: Tree

The parent of this node. If the return value is null, then this node is the root of the tree.

Specified by:

getParent in interface ParseTree

Specified by:

getParent in interface RuleNode

Specified by:

getParent in interface Tree

Overrides:

getParent in class RuleContext

getChild

public ParseTree getChild(int i)

Description copied from interface: Tree

If there are children, get the ith value indexed from 0.

Specified by:

getChild in interface ParseTree

Specified by:

getChild in interface Tree

Overrides:

getChild in class RuleContext

getChild

public <T extends ParseTree> T getChild(Class<? extends T> ctxType,
                                        int i)

getToken

public TerminalNode getToken(int ttype,
                             int i)

getTokens

public List<? extends TerminalNode> getTokens(int ttype)

getRuleContext

public <T extends ParserRuleContext> T getRuleContext(Class<? extends T> ctxType,
                                                      int i)

getRuleContexts

public <T extends ParserRuleContext> List<? extends T> getRuleContexts(Class<? extends T> ctxType)

getChildCount

public int getChildCount()

Description copied from interface: Tree

How many children are there? If there is none, then this node represents a leaf node.

Specified by:

getChildCount in interface Tree

Overrides:

getChildCount in class RuleContext

getSourceInterval

public Interval getSourceInterval()

Description copied from interface: SyntaxTree

Return an Interval indicating the index in the TokenStream of the first and last token associated with this subtree. If this node is a leaf, then the interval represents a single token and has interval i..i for token index i.

An interval of i..i-1 indicates an empty interval at position i in the input stream, where 0 <= i <= the size of the input token stream. Currently, the code base can only have i=0..n-1 but in concept one could have an empty interval after EOF.

If source interval is unknown, this returns Interval.INVALID.

As a weird special case, the source interval for rules matched after EOF is unspecified.

Specified by:

getSourceInterval in interface SyntaxTree

Overrides:

getSourceInterval in class RuleContext

getStart

public Token getStart()

Get the initial token in this context. Note that the range from start to stop is inclusive, so for rules that do not consume anything (for example, zero length or error productions) this token may exceed stop.

getStop

public Token getStop()

Get the final token in this context. Note that the range from start to stop is inclusive, so for rules that do not consume anything (for example, zero length or error productions) this token may precede start.

toInfoString

public String toInfoString(Parser recognizer)

Used for rule context info debugging during parse-time, not so much for ATN debugging