org.antlr.v4.runtime

Class RuleContext

java.lang.Object

org.antlr.v4.runtime.RuleContext

All Implemented Interfaces:

ParseTree, RuleNode, SyntaxTree, Tree

Direct Known Subclasses:

ParserRuleContext

public class RuleContext
extends Object
implements RuleNode

A rule context is a record of a single rule invocation. It knows which context invoked it, if any. If there is no parent context, then naturally the invoking state is not valid. The parent link provides a chain upwards from the current rule invocation to the root of the invocation tree, forming a stack. We actually carry no information about the rule associated with this context (except when parsing). We keep only the state number of the invoking state from the ATN submachine that invoked this. Contrast this with the s pointer inside ParserRuleContext that tracks the current state being "executed" for the current rule. The parent contexts are useful for computing lookahead sets and getting error information. These objects are used during parsing and prediction. For the special case of parsers and tree parsers, we use the subclass ParserRuleContext.

See Also:

ParserRuleContext

Field Summary

Fields

Modifier and Type	Field and Description
static ParserRuleContext	EMPTY
int	invokingState What state invoked the rule associated with this context? The "return address" is the followState of invokingState If parent is null, this should be -1.
RuleContext	parent What context invoked this rule?

Constructor Summary

Constructors

Constructor and Description
RuleContext()
RuleContext(RuleContext parent, int invokingState)

Method Summary

Methods

Modifier and Type	Method and Description
<T> T	accept(ParseTreeVisitor<? extends T> visitor) The ParseTreeVisitor needs a double dispatch method
int	depth()
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.
RuleContext	getParent() The parent of this node.
RuleContext	getPayload() This method returns whatever object represents the data at this note.
RuleContext	getRuleContext()
int	getRuleIndex()
Interval	getSourceInterval() Return an interval indicating the index in the TokenStream of the first and last token associated with this subtree.
String	getText() Return the combined text of all child nodes.
void	inspect(Parser parser) Call this method to view a parse tree in a dialog box visually.
boolean	isEmpty() A context is empty if there is no invoking state; meaning nobody call current context.
void	save(Parser parser, String fileName) Save this tree in a postscript file
void	save(Parser parser, String fileName, String fontName, int fontSize) Save this tree in a postscript file using a particular font name and size
String	toString()
String	toString(List<String> ruleNames)
String	toString(List<String> ruleNames, RuleContext stop)
String	toString(Recognizer<?,?> recog)
String	toString(Recognizer<?,?> recog, RuleContext stop)
String	toStringTree() Print out a whole tree, not just a node, in LISP format (root child1 ..
String	toStringTree(List<String> ruleNames) Print out a whole tree, not just a node, in LISP format (root child1 ..
String	toStringTree(Parser recog) Print out a whole tree, not just a node, in LISP format (root child1 ..

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final ParserRuleContext EMPTY

parent

public RuleContext parent

What context invoked this rule?

invokingState

public int invokingState

What state invoked the rule associated with this context? The "return address" is the followState of invokingState If parent is null, this should be -1.

Constructor Detail

RuleContext

public RuleContext()

RuleContext

public RuleContext(RuleContext parent,
           int invokingState)

Method Detail

depth

public int depth()

isEmpty

public boolean isEmpty()

A context is empty if there is no invoking state; meaning nobody call current context.

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.

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

Specified by:

getSourceInterval in interface SyntaxTree

getRuleContext

public RuleContext getRuleContext()

Specified by:

getRuleContext in interface RuleNode

getParent

public RuleContext 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 Tree

getPayload

public RuleContext getPayload()

Description copied from interface: Tree

This method returns whatever object represents the data at this note. For example, for parse trees, the payload can be a Token representing a leaf node or a RuleContext object representing a rule invocation. For abstract syntax trees (ASTs), this is a Token object.

Specified by:

getPayload in interface Tree

getText

public String getText()

Return the combined text of all child nodes. This method only considers tokens which have been added to the parse tree.

Since tokens on hidden channels (e.g. whitespace or comments) are not added to the parse trees, they will not appear in the output of this method.

Specified by:

getText in interface ParseTree

getRuleIndex

public int getRuleIndex()

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

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

accept

public <T> T accept(ParseTreeVisitor<? extends T> visitor)

Description copied from interface: ParseTree

The ParseTreeVisitor needs a double dispatch method

Specified by:

accept in interface ParseTree

inspect

public void inspect(Parser parser)

Call this method to view a parse tree in a dialog box visually.

save

public void save(Parser parser,
        String fileName)
          throws IOException,
                 PrintException

Save this tree in a postscript file

Throws:

IOException

PrintException

save

public void save(Parser parser,
        String fileName,
        String fontName,
        int fontSize)
          throws IOException

Save this tree in a postscript file using a particular font name and size

Throws:

IOException

toStringTree

public String toStringTree(@Nullable
                  Parser recog)

Print out a whole tree, not just a node, in LISP format (root child1 .. childN). Print just a node if this is a leaf. We have to know the recognizer so we can get rule names.

Specified by:

toStringTree in interface ParseTree

toStringTree

public String toStringTree(@Nullable
                  List<String> ruleNames)

Print out a whole tree, not just a node, in LISP format (root child1 .. childN). Print just a node if this is a leaf.

toStringTree

public String toStringTree()

Description copied from interface: Tree

Print out a whole tree, not just a node, in LISP format (root child1 .. childN). Print just a node if this is a leaf.

Specified by:

toStringTree in interface Tree

toString

public String toString()

Overrides:

toString in class Object

toString

public final String toString(@Nullable
              Recognizer<?,?> recog)

toString

public final String toString(@Nullable
              List<String> ruleNames)

toString

public String toString(@Nullable
              Recognizer<?,?> recog,
              @Nullable
              RuleContext stop)

toString

public String toString(@Nullable
              List<String> ruleNames,
              @Nullable
              RuleContext stop)