marf.nlp.Parsing
Class Parser

java.lang.Object
  marf.nlp.Parsing.Parser

public class Parser
extends java.lang.Object

Generic Language Parser.

$Id: Parser.java,v 1.25 2008/01/03 03:21:57 mokhov Exp $

Since:

0.3.0.2

Version:

$Revision: 1.25 $

Author:

Serguei Mokhov, mokhov@cs.concordia.ca

Field Summary

protected boolean	bErrorsPresent Fact, indicating that there are syntax errors.
protected java.util.Stack	oBracketStack Stack for checking mismatched brackets.
private GrammarCompiler	oGrammarCompiler Grammar Compiler.
private LexicalAnalyzer	oLexer An instance of Lexical Analyzer.
private java.util.Stack	oStack Stack needed for Transition State Parsing Algorithm.
protected java.util.Vector	oSyntaxErrors A list of Syntax Errors so far.
private TransitionTable	oTT Transitional Table for Transition State Parsing Algorithm.
private static SymbolTable	soSymTab Global Scope Symbol Table.

Constructor Summary

Parser(java.lang.String[] argv)
Constructor with command-line arguments.

Method Summary

boolean	areErrorsPresent() Allows to query the fact that there were lexical or syntax errors or not.
GrammarCompiler	getGrammarCompiler() Allows querying for the grammar compiler used.
LexicalAnalyzer	getLexer() Allows querying for the instance of the lexer.
static java.lang.String	getMARFSourceCodeRevision() Retrieves class' revision.
java.util.Stack	getStack() Allows querying for the current stack.
static SymbolTable	getSymbolTable() Allows querying for the current symbol table.
java.util.Vector	getSyntaxErrors() Allows querying for the recorded syntax errors that were found.
TransitionTable	getTransitionTable() Allows querying for the current transition table.
private void	inverseMultiplePush(NonTerminal poNonTerminal, Token poToken) Pushes multiple tokens on a RHS of a rule into the stack in the reverse order.
boolean	parse() Implements State Transition Algorithm for top-down table-driven predictive parser.
Token	popBracket() Pops a bracket-type token from the stack.
void	pushBracket(Token poToken) Pushes bracket-type token onto the bracket stack.
void	setErrorsPresent(boolean pbErrorsPresent) Allows externally setting the fact that there were errors.
void	setGrammarCompiler(GrammarCompiler poGrammarCompiler) Allows setting a new grammar compiler to use.
void	setLexer(LexicalAnalyzer poLexer) Allows setting a new lexer for scanning.
static void	setSymbolTable(SymbolTable poSymTab) Allows setting a new symbol table.
void	setTransitionTable(TransitionTable poTT) Allows setting a new transition table.
private void	skipErrors() Error recovery function.
private void	stackDump() Performs textual stack dump.

Methods inherited from class java.lang.Object

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

Field Detail

oTT

private TransitionTable oTT

Transitional Table for Transition State Parsing Algorithm.

oLexer

private LexicalAnalyzer oLexer

An instance of Lexical Analyzer.

soSymTab

private static SymbolTable soSymTab

Global Scope Symbol Table.

oGrammarCompiler

private GrammarCompiler oGrammarCompiler

Grammar Compiler. Needed to compile source grammar file if TT does not exist.

oStack

private java.util.Stack oStack

Stack needed for Transition State Parsing Algorithm.

oSyntaxErrors

protected java.util.Vector oSyntaxErrors

A list of Syntax Errors so far.

bErrorsPresent

protected boolean bErrorsPresent

Fact, indicating that there are syntax errors.

oBracketStack

protected java.util.Stack oBracketStack

Stack for checking mismatched brackets.

Constructor Detail

Parser

public Parser(java.lang.String[] argv)
       throws CompilerError

Constructor with command-line arguments.

Parameters:

argv - the command-line arguments

Throws:

CompilerError - if there are problems initializing a lexer or a transition table

Method Detail

pushBracket

public void pushBracket(Token poToken)

Pushes bracket-type token onto the bracket stack. Used for further validation of matching brackets, parentheses, and braces.

Parameters:

poToken - the bracket-type token

popBracket

public Token popBracket()

Pops a bracket-type token from the stack.

Returns:

the top bracket-type token

parse

public boolean parse()
              throws SyntaxError,
                     LexicalError

Implements State Transition Algorithm for top-down table-driven predictive parser.

Returns:

true if the parse was successful

Throws:

SyntaxError - if a parsed statement for some reason does not conform the grammar

LexicalError - if an invalid token read off the source character stream

skipErrors

private void skipErrors()
                 throws LexicalError

Error recovery function. Skips syntax errors until next valid symbol in TT.

Throws:

LexicalError - if invalid token is encounterd

inverseMultiplePush

private void inverseMultiplePush(NonTerminal poNonTerminal,
                                 Token poToken)

Pushes multiple tokens on a RHS of a rule into the stack in the reverse order.

Parameters:

poNonTerminal - non-terminal to recover the corresponding rule

poToken - token to recover the corresponding rule

stackDump

private void stackDump()

Performs textual stack dump.

getSymbolTable

public static SymbolTable getSymbolTable()

Allows querying for the current symbol table.

Returns:

the reference to the contained symbol table

Since:

0.3.0.5

setSymbolTable

public static void setSymbolTable(SymbolTable poSymTab)

Allows setting a new symbol table.

Parameters:

poSymTab - the global symbol table to set

Since:

0.3.0.5

areErrorsPresent

public boolean areErrorsPresent()

Allows to query the fact that there were lexical or syntax errors or not.

Returns:

true if there were errors in parsing

Since:

0.3.0.5

setErrorsPresent

public void setErrorsPresent(boolean pbErrorsPresent)

Allows externally setting the fact that there were errors.

Parameters:

pbErrorsPresent - the new value of the flag

Since:

0.3.0.5

getLexer

public LexicalAnalyzer getLexer()

Allows querying for the instance of the lexer.

Returns:

the reference to the lexer used

Since:

0.3.0.5

setLexer

public void setLexer(LexicalAnalyzer poLexer)

Allows setting a new lexer for scanning.

Parameters:

poLexer - the new lexer to be used

Since:

0.3.0.5

getGrammarCompiler

public GrammarCompiler getGrammarCompiler()

Allows querying for the grammar compiler used.

Returns:

the reference to the contained grammar compiler

Since:

0.3.0.5

setGrammarCompiler

public void setGrammarCompiler(GrammarCompiler poGrammarCompiler)

Allows setting a new grammar compiler to use.

Parameters:

poGrammarCompiler - the new grammar compiler

Since:

0.3.0.5

getStack

public java.util.Stack getStack()

Allows querying for the current stack.

Returns:

the current stack data structure

Since:

0.3.0.5

getTransitionTable

public TransitionTable getTransitionTable()

Allows querying for the current transition table.

Returns:

the current transition table data structure

Since:

0.3.0.5

setTransitionTable

public void setTransitionTable(TransitionTable poTT)

Allows setting a new transition table.

Parameters:

poTT - the new transition table data structure to set

Since:

0.3.0.5

getSyntaxErrors

public java.util.Vector getSyntaxErrors()

Allows querying for the recorded syntax errors that were found.

Returns:

the collection of syntax errors

Since:

0.3.0.5

getMARFSourceCodeRevision

public static java.lang.String getMARFSourceCodeRevision()

Retrieves class' revision.

Returns:

revision string