Package org.antlr.v4.runtime
Class ParserInterpreter
java.lang.Object
org.antlr.v4.runtime.Recognizer<Token,ParserATNSimulator>
org.antlr.v4.runtime.Parser
org.antlr.v4.runtime.ParserInterpreter
- Direct Known Subclasses:
GrammarParserInterpreter
A parser simulator that mimics what ANTLR's generated
parser code does. A ParserATNSimulator is used to make
predictions via adaptivePredict but this class moves a pointer through the
ATN to simulate parsing. ParserATNSimulator just
makes us efficient rather than having to backtrack, for example.
This properly creates parse trees even for left recursive rules.
We rely on the left recursive rule invocation and special predicate
transitions to make left recursive rules work.
See TestParserInterpreter for examples.
-
Nested Class Summary
Nested classes/interfaces inherited from class org.antlr.v4.runtime.Parser
Parser.TraceListener, Parser.TrimToSizeListener
-
Field Summary
FieldsModifier and TypeFieldDescriptionprotected final Deque
<Pair<ParserRuleContext, Integer>> This stack corresponds to the _parentctx, _parentState pair of locals that would exist on call stack frames with a recursive descent parser; in the generated function for a left-recursive rule you'd see: private EContext e(int _p) throws RecognitionException { ParserRuleContext _parentctx = _ctx; // Pair.a int _parentState = getState(); // Pair.b ...protected final ATN
protected final DFA[]
protected final String
protected int
We need a map from (decision,inputIndex)->forced alt for computing ambiguous parse trees.protected int
protected int
protected boolean
protected InterpreterRuleContext
What is the current context when we override a decisions? This tells us what the root of the parse tree is when using override for an ambiguity/lookahead check.protected InterpreterRuleContext
protected final String[]
protected final PredictionContextCache
protected final String[]
Deprecated.Fields inherited from class org.antlr.v4.runtime.Parser
_buildParseTrees, _ctx, _errHandler, _input, _parseListeners, _precedenceStack, _syntaxErrors, matchedEOF
Fields inherited from class org.antlr.v4.runtime.Recognizer
_interp, EOF
-
Constructor Summary
ConstructorsConstructorDescriptionParserInterpreter
(String grammarFileName, Collection<String> tokenNames, Collection<String> ruleNames, ATN atn, TokenStream input) Deprecated.ParserInterpreter
(String grammarFileName, Vocabulary vocabulary, Collection<String> ruleNames, ATN atn, TokenStream input) -
Method Summary
Modifier and TypeMethodDescriptionvoid
addDecisionOverride
(int decision, int tokenIndex, int forcedAlt) Override this parser interpreters normal decision-making process at a particular decision and input token index.protected InterpreterRuleContext
createInterpreterRuleContext
(ParserRuleContext parent, int invokingStateNumber, int ruleIndex) Provide simple "factory" for InterpreterRuleContext's.void
enterRecursionRule
(ParserRuleContext localctx, int state, int ruleIndex, int precedence) getATN()
Get theATN
used by the recognizer for prediction.protected ATNState
For debugging and other purposes, might want the grammar name.Return the root of the parse, which can be useful if the parser bails out.String[]
String[]
Deprecated.Get the vocabulary used by the recognizer.parse
(int startRuleIndex) Begin parsing at startRuleIndexprotected void
Rely on the error handler for this parser but, if no tokens are consumed to recover, add an error node.protected Token
void
reset()
reset the parser's stateprotected int
Method visitDecisionState() is called when the interpreter reaches a decision state (instance of DecisionState).protected void
protected void
Methods inherited from class org.antlr.v4.runtime.Parser
addContextToParseTree, addParseListener, compileParseTreePattern, compileParseTreePattern, consume, createErrorNode, createTerminalNode, dumpDFA, enterOuterAlt, enterRecursionRule, enterRule, exitRule, getATNWithBypassAlts, getBuildParseTree, getContext, getCurrentToken, getDFAStrings, getErrorHandler, getExpectedTokens, getExpectedTokensWithinCurrentRule, getInputStream, getInvokingContext, getNumberOfSyntaxErrors, getParseInfo, getParseListeners, getPrecedence, getRuleContext, getRuleIndex, getRuleInvocationStack, getRuleInvocationStack, getSourceName, getTokenFactory, getTokenStream, getTrimParseTree, inContext, isExpectedToken, isMatchedEOF, isTrace, match, matchWildcard, notifyErrorListeners, notifyErrorListeners, precpred, pushNewRecursionContext, removeParseListener, removeParseListeners, setBuildParseTree, setContext, setErrorHandler, setInputStream, setProfile, setTokenFactory, setTokenStream, setTrace, setTrimParseTree, triggerEnterRuleEvent, triggerExitRuleEvent, unrollRecursionContexts
Methods inherited from class org.antlr.v4.runtime.Recognizer
action, addErrorListener, getErrorHeader, getErrorListenerDispatch, getErrorListeners, getInterpreter, getRuleIndexMap, getSerializedATN, getState, getTokenErrorDisplay, getTokenType, getTokenTypeMap, removeErrorListener, removeErrorListeners, sempred, setInterpreter, setState
-
Field Details
-
grammarFileName
-
atn
-
decisionToDFA
-
tokenNames
Deprecated. -
ruleNames
-
_parentContextStack
This stack corresponds to the _parentctx, _parentState pair of locals that would exist on call stack frames with a recursive descent parser; in the generated function for a left-recursive rule you'd see: private EContext e(int _p) throws RecognitionException { ParserRuleContext _parentctx = _ctx; // Pair.a int _parentState = getState(); // Pair.b ... } Those values are used to create new recursive rule invocation contexts associated with left operand of an alt like "expr '*' expr". -
overrideDecision
protected int overrideDecisionWe need a map from (decision,inputIndex)->forced alt for computing ambiguous parse trees. For now, we allow exactly one override. -
overrideDecisionInputIndex
protected int overrideDecisionInputIndex -
overrideDecisionAlt
protected int overrideDecisionAlt -
overrideDecisionReached
protected boolean overrideDecisionReached -
overrideDecisionRoot
What is the current context when we override a decisions? This tells us what the root of the parse tree is when using override for an ambiguity/lookahead check. -
rootContext
-
-
Constructor Details
-
ParserInterpreter
@Deprecated public ParserInterpreter(String grammarFileName, Collection<String> tokenNames, Collection<String> ruleNames, ATN atn, TokenStream input) Deprecated. -
ParserInterpreter
public ParserInterpreter(String grammarFileName, Vocabulary vocabulary, Collection<String> ruleNames, ATN atn, TokenStream input)
-
-
Method Details
-
reset
public void reset()Description copied from class:Parser
reset the parser's state -
getATN
Description copied from class:Recognizer
Get theATN
used by the recognizer for prediction.- Specified by:
getATN
in classRecognizer<Token,
ParserATNSimulator> - Returns:
- The
ATN
used by the recognizer for prediction.
-
getTokenNames
Deprecated.Description copied from class:Recognizer
Used to print out token names like ID during debugging and error reporting. The generated parsers implement a method that overrides this to point to their String[] tokenNames.- Specified by:
getTokenNames
in classRecognizer<Token,
ParserATNSimulator>
-
getVocabulary
Description copied from class:Recognizer
Get the vocabulary used by the recognizer.- Overrides:
getVocabulary
in classRecognizer<Token,
ParserATNSimulator> - Returns:
- A
Vocabulary
instance providing information about the vocabulary used by the grammar.
-
getRuleNames
- Specified by:
getRuleNames
in classRecognizer<Token,
ParserATNSimulator>
-
getGrammarFileName
Description copied from class:Recognizer
For debugging and other purposes, might want the grammar name. Have ANTLR generate an implementation for this method.- Specified by:
getGrammarFileName
in classRecognizer<Token,
ParserATNSimulator>
-
parse
Begin parsing at startRuleIndex -
enterRecursionRule
public void enterRecursionRule(ParserRuleContext localctx, int state, int ruleIndex, int precedence) - Overrides:
enterRecursionRule
in classParser
-
getATNState
-
visitState
-
visitDecisionState
Method visitDecisionState() is called when the interpreter reaches a decision state (instance of DecisionState). It gives an opportunity for subclasses to track interesting things. -
createInterpreterRuleContext
protected InterpreterRuleContext createInterpreterRuleContext(ParserRuleContext parent, int invokingStateNumber, int ruleIndex) Provide simple "factory" for InterpreterRuleContext's.- Since:
- 4.5.1
-
visitRuleStopState
-
addDecisionOverride
public void addDecisionOverride(int decision, int tokenIndex, int forcedAlt) Override this parser interpreters normal decision-making process at a particular decision and input token index. Instead of allowing the adaptive prediction mechanism to choose the first alternative within a block that leads to a successful parse, force it to take the alternative, 1..n for n alternatives. As an implementation limitation right now, you can only specify one override. This is sufficient to allow construction of different parse trees for ambiguous input. It means re-parsing the entire input in general because you're never sure where an ambiguous sequence would live in the various parse trees. For example, in one interpretation, an ambiguous input sequence would be matched completely in expression but in another it could match all the way back to the root. s : e '!'? ; e : ID | ID '!' ; Here, x! can be matched as (s (e ID) !) or (s (e ID !)). In the first case, the ambiguous sequence is fully contained only by the root. In the second case, the ambiguous sequences fully contained within just e, as in: (e ID !). Rather than trying to optimize this and make some intelligent decisions for optimization purposes, I settled on just re-parsing the whole input and then using {link Trees#getRootOfSubtreeEnclosingRegion} to find the minimal subtree that contains the ambiguous sequence. I originally tried to record the call stack at the point the parser detected and ambiguity but left recursive rules create a parse tree stack that does not reflect the actual call stack. That impedance mismatch was enough to make it it challenging to restart the parser at a deeply nested rule invocation. Only parser interpreters can override decisions so as to avoid inserting override checking code in the critical ALL(*) prediction execution path.- Since:
- 4.5.1
-
getOverrideDecisionRoot
-
recover
Rely on the error handler for this parser but, if no tokens are consumed to recover, add an error node. Otherwise, nothing is seen in the parse tree. -
recoverInline
-
getRootContext
Return the root of the parse, which can be useful if the parser bails out. You still can access the top node. Note that, because of the way left recursive rules add children, it's possible that the root will not have any children if the start rule immediately called and left recursive rule that fails.- Since:
- 4.5.1
-
ParserInterpreter(String, Vocabulary, Collection, ATN, TokenStream)
instead.