Package org.antlr.tool

Class Interpreter

java.lang.Object

org.antlr.tool.Interpreter

All Implemented Interfaces:

TokenSource

public class Interpreter
extends Object
implements TokenSource

The recognition interpreter/engine for grammars. Separated out of Grammar as it's related, but technically not a Grammar function. You create an interpreter for a grammar and an input stream. This object can act as a TokenSource so that you can hook up two grammars (via a CommonTokenStream) to lex/parse. Being a token source only makes sense for a lexer grammar of course.

Field Summary

Fields

Modifier and Type	Field	Description
protected Grammar	grammar
protected IntStream	input

Constructor Summary

Constructors

Constructor	Description
Interpreter(Grammar grammar, IntStream input)

Method Summary

Modifier and Type	Method	Description
String	getSourceName()	Where are you getting tokens from? normally the implication will simply ask lexers input stream.
Token	nextToken()	Return a Token object from your input stream (usually a CharStream).
ParseTree	parse(String startRule)
ParseTree	parse(String startRule, List visitedStates)
void	parse(String startRule, DebugEventListener actions, List visitedStates)
protected void	parseEngine(String startRule, NFAState start, NFAState stop, IntStream input, Stack ruleInvocationStack, DebugEventListener actions, List visitedStates)	Fill a list of all NFA states visited during the parse
int	predict(DFA dfa)	Given an input stream, return the unique alternative predicted by matching the input.
void	reportScanError(RecognitionException re)
CommonToken	scan(String startRule)
CommonToken	scan(String startRule, List visitedStates)
void	scan(String startRule, DebugEventListener actions, List visitedStates)	For a given input char stream, try to match against the NFA starting at startRule.

Methods inherited from class java.lang.Object

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

Field Detail

grammar

protected Grammar grammar

input

protected IntStream input

Constructor Detail

Interpreter

public Interpreter(Grammar grammar,
                   IntStream input)

Method Detail

nextToken

public Token nextToken()

Description copied from interface: TokenSource

Return a Token object from your input stream (usually a CharStream). Do not fail/return upon lexing error; keep chewing on the characters until you get a good one; errors are not passed through to the parser.

Specified by:

nextToken in interface TokenSource

scan

public void scan(String startRule,
                 DebugEventListener actions,
                 List visitedStates)
          throws RecognitionException

For a given input char stream, try to match against the NFA starting at startRule. This is a deterministic parse even though it is using an NFA because it uses DFAs at each decision point to predict which alternative will succeed. This is exactly what the generated parser will do. This only does lexer grammars. Return the token type associated with the final rule end state.

Throws:

RecognitionException

scan

public CommonToken scan(String startRule)
                 throws RecognitionException

Throws:

RecognitionException

scan

public CommonToken scan(String startRule,
                        List visitedStates)
                 throws RecognitionException

Throws:

RecognitionException

parse

public void parse(String startRule,
                  DebugEventListener actions,
                  List visitedStates)
           throws RecognitionException

Throws:

RecognitionException

parse

public ParseTree parse(String startRule)
                throws RecognitionException

Throws:

RecognitionException

parse

public ParseTree parse(String startRule,
                       List visitedStates)
                throws RecognitionException

Throws:

RecognitionException

parseEngine

protected void parseEngine(String startRule,
                           NFAState start,
                           NFAState stop,
                           IntStream input,
                           Stack ruleInvocationStack,
                           DebugEventListener actions,
                           List visitedStates)
                    throws RecognitionException

Fill a list of all NFA states visited during the parse

Throws:

RecognitionException

predict

public int predict(DFA dfa)

Given an input stream, return the unique alternative predicted by matching the input. Upon error, return NFA.INVALID_ALT_NUMBER The first symbol of lookahead is presumed to be primed; that is, input.lookahead(1) must point at the input symbol you want to start predicting with.

reportScanError

public void reportScanError(RecognitionException re)

getSourceName

public String getSourceName()

Description copied from interface: TokenSource

Where are you getting tokens from? normally the implication will simply ask lexers input stream.

Specified by:

getSourceName in interface TokenSource