org.antlr.runtime.tree
Class TreeParser

java.lang.Object
  org.antlr.runtime.BaseRecognizer
      org.antlr.runtime.tree.TreeParser

Direct Known Subclasses:

DebugTreeParser, TreeFilter, TreeRewriter

public class TreeParser
extends BaseRecognizer

A parser for a stream of tree nodes. "tree grammars" result in a subclass of this. All the error reporting and recovery is shared with Parser via the BaseRecognizer superclass.

Field Summary

static int	DOWN
protected TreeNodeStream	input
static int	UP

Fields inherited from class org.antlr.runtime.BaseRecognizer

DEFAULT_TOKEN_CHANNEL, HIDDEN, INITIAL_FOLLOW_STACK_SIZE, MEMO_RULE_FAILED, MEMO_RULE_UNKNOWN, NEXT_TOKEN_RULE_NAME, state

Constructor Summary

TreeParser(TreeNodeStream input)

TreeParser(TreeNodeStream input, RecognizerSharedState state)

Method Summary

protected static Object	getAncestor(TreeAdaptor adaptor, String[] tokenNames, Object t, String goal) Helper for static inContext
protected Object	getCurrentInputSymbol(IntStream input) Match needs to return the current input symbol, which gets put into the label for the associated token ref; e.g., x=ID.
String	getErrorHeader(RecognitionException e) Prefix error message with the grammar name because message is always intended for the programmer because the parser built the input tree not the user.
String	getErrorMessage(RecognitionException e, String[] tokenNames) Tree parsers parse nodes they usually have a token object as payload.
protected Object	getMissingSymbol(IntStream input, RecognitionException e, int expectedTokenType, BitSet follow) Conjure up a missing token during error recovery.
String	getSourceName()
TreeNodeStream	getTreeNodeStream()
boolean	inContext(String context) Check if current node in input has a context.
static boolean	inContext(TreeAdaptor adaptor, String[] tokenNames, Object t, String context) The worker for inContext.
void	matchAny(IntStream ignore) Match '.' in tree parser has special meaning.
protected Object	recoverFromMismatchedToken(IntStream input, int ttype, BitSet follow) We have DOWN/UP nodes in the stream that have no line info; override.
void	reset() reset the parser's state; subclasses must rewinds the input stream
void	setTreeNodeStream(TreeNodeStream input) Set the input stream
void	traceIn(String ruleName, int ruleIndex)
void	traceOut(String ruleName, int ruleIndex)

Methods inherited from class org.antlr.runtime.BaseRecognizer

alreadyParsedRule, beginResync, combineFollows, computeContextSensitiveRuleFOLLOW, computeErrorRecoverySet, consumeUntil, consumeUntil, displayRecognitionError, emitErrorMessage, endResync, failed, getBacktrackingLevel, getGrammarFileName, getNumberOfSyntaxErrors, getRuleInvocationStack, getRuleInvocationStack, getRuleMemoization, getRuleMemoizationCacheSize, getTokenErrorDisplay, getTokenNames, match, memoize, mismatchIsMissingToken, mismatchIsUnwantedToken, pushFollow, recover, recoverFromMismatchedSet, reportError, setBacktrackingLevel, toStrings, traceIn, traceOut

Methods inherited from class java.lang.Object

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

Field Detail

DOWN

public static final int DOWN

See Also:

Constant Field Values

UP

public static final int UP

See Also:

Constant Field Values

input

protected TreeNodeStream input

Constructor Detail

TreeParser

public TreeParser(TreeNodeStream input)

TreeParser

public TreeParser(TreeNodeStream input,
                  RecognizerSharedState state)

Method Detail

reset

public void reset()

Description copied from class: BaseRecognizer

reset the parser's state; subclasses must rewinds the input stream

Overrides:

reset in class BaseRecognizer

setTreeNodeStream

public void setTreeNodeStream(TreeNodeStream input)

Set the input stream

getTreeNodeStream

public TreeNodeStream getTreeNodeStream()

getSourceName

public String getSourceName()

Specified by:

getSourceName in class BaseRecognizer

getCurrentInputSymbol

protected Object getCurrentInputSymbol(IntStream input)

Description copied from class: BaseRecognizer

Match needs to return the current input symbol, which gets put into the label for the associated token ref; e.g., x=ID. Token and tree parsers need to return different objects. Rather than test for input stream type or change the IntStream interface, I use a simple method to ask the recognizer to tell me what the current input symbol is. This is ignored for lexers.

Overrides:

getCurrentInputSymbol in class BaseRecognizer

getMissingSymbol

protected Object getMissingSymbol(IntStream input,
                                  RecognitionException e,
                                  int expectedTokenType,
                                  BitSet follow)

Description copied from class: BaseRecognizer

Conjure up a missing token during error recovery. The recognizer attempts to recover from single missing symbols. But, actions might refer to that missing symbol. For example, x=ID {f($x);}. The action clearly assumes that there has been an identifier matched previously and that $x points at that token. If that token is missing, but the next token in the stream is what we want we assume that this token is missing and we keep going. Because we have to return some token to replace the missing token, we have to conjure one up. This method gives the user control over the tokens returned for missing tokens. Mostly, you will want to create something special for identifier tokens. For literals such as '{' and ',', the default action in the parser or tree parser works. It simply creates a CommonToken of the appropriate type. The text will be the token. If you change what tokens must be created by the lexer, override this method to create the appropriate tokens.

Overrides:

getMissingSymbol in class BaseRecognizer

matchAny

public void matchAny(IntStream ignore)

Match '.' in tree parser has special meaning. Skip node or entire tree if node has children. If children, scan until corresponding UP node.

Overrides:

matchAny in class BaseRecognizer

recoverFromMismatchedToken

protected Object recoverFromMismatchedToken(IntStream input,
                                            int ttype,
                                            BitSet follow)
                                     throws RecognitionException

We have DOWN/UP nodes in the stream that have no line info; override. plus we want to alter the exception type. Don't try to recover from tree parser errors inline...

Overrides:

recoverFromMismatchedToken in class BaseRecognizer

Throws:

RecognitionException

getErrorHeader

public String getErrorHeader(RecognitionException e)

Prefix error message with the grammar name because message is always intended for the programmer because the parser built the input tree not the user.

Overrides:

getErrorHeader in class BaseRecognizer

getErrorMessage

public String getErrorMessage(RecognitionException e,
                              String[] tokenNames)

Tree parsers parse nodes they usually have a token object as payload. Set the exception token and do the default behavior.

Overrides:

getErrorMessage in class BaseRecognizer

inContext

public boolean inContext(String context)

Check if current node in input has a context. Context means sequence of nodes towards root of tree. For example, you might say context is "MULT" which means my parent must be MULT. "CLASS VARDEF" says current node must be child of a VARDEF and whose parent is a CLASS node. You can use "..." to mean zero-or-more nodes. "METHOD ... VARDEF" means my parent is VARDEF and somewhere above that is a METHOD node. The first node in the context is not necessarily the root. The context matcher stops matching and returns true when it runs out of context. There is no way to force the first node to be the root.

inContext

public static boolean inContext(TreeAdaptor adaptor,
                                String[] tokenNames,
                                Object t,
                                String context)

The worker for inContext. It's static and full of parameters for testing purposes.

getAncestor

protected static Object getAncestor(TreeAdaptor adaptor,
                                    String[] tokenNames,
                                    Object t,
                                    String goal)

Helper for static inContext

traceIn

public void traceIn(String ruleName,
                    int ruleIndex)

traceOut

public void traceOut(String ruleName,
                     int ruleIndex)