goldengine.java
Class GOLDParser

java.lang.Object

  |

  +--goldengine.java.GOLDParser

All Implemented Interfaces:

ActionConstants, GPMessageConstants, ParseResultConstants, RecordIDConstants, SymbolTypeConstants

public class GOLDParser

extends java.lang.Object

implements GPMessageConstants, SymbolTypeConstants, ActionConstants, RecordIDConstants, ParseResultConstants

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Source File: GenericParser.java
Author: Devin Cook, Matthew Hawkins
Description: The main parsing engine.
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Revision List

      Author          Version         Description
      ------          -------         -----------
      MPH             1.0             First Issue
      MPH             1.1             Added the TrimReductions property and required logic
      MPH             1.2             Fixed Comment bug to ignore all tokens

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IMPORT: java.io, java.util
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Fields inherited from interface goldengine.java.GPMessageConstants

gpMsgAccept, gpMsgCommentError, gpMsgInternalError, gpMsgLexicalError, gpMsgNotLoadedError, gpMsgReduction, gpMsgSyntaxError, gpMsgTokenRead

Fields inherited from interface goldengine.java.SymbolTypeConstants

symbolTypeCommentEnd, symbolTypeCommentLine, symbolTypeCommentStart, symbolTypeEnd, symbolTypeError, symbolTypeNonterminal, symbolTypeTerminal, symbolTypeWhitespace

Fields inherited from interface goldengine.java.ActionConstants

actionAccept, actionError, actionGoto, actionReduce, actionShift

Fields inherited from interface goldengine.java.RecordIDConstants

recordIdCharSets, recordIdComment, recordIdDFAStates, recordIdInitial, recordIdLRTables, recordIdParameters, recordIdRules, recordIdSymbols, recordIdTableCounts

Fields inherited from interface goldengine.java.ParseResultConstants

parseResultAccept, parseResultInternalError, parseResultReduceEliminated, parseResultReduceNormal, parseResultShift, parseResultSyntaxError

Constructor Summary

GOLDParser()
GOLDParser The constructor initiates some variables.

Method Summary

void	clear() clear This method clears every value in the parser engine.
void	closeFile() closeFile This method will close the source file.
int	currentLineNumber() currentLineNumber Returns the current source file line number.
Reduction	currentReduction() currentReduction This method will return the current reduction.
Token	currentToken() currentToken This method returns the current Token.
Token	getToken(int index) getToken If you require access to tokens in the stack before they are placed on the parse tree.
boolean	getTrimReductions() getTrimReductions #ver1.1# This method will get whether or not we should trim the reductions.
boolean	loadCompiledGrammar(java.lang.String fileName) loadCompiledGrammar This method will reset the GOLDParser engine before loading a new .cgt file into it.
boolean	openFile(java.lang.String fileName) openFile This method will open the source file for reading.
java.lang.String	parameter(java.lang.String name) parameter This method will return the value of a parameter that corresponds to the name passed in.
int	parse() parse Will parse a token.
Token	popInputToken() popInputToken This method should only be called if there is a lexical error and you need to pop an unexpected token out of the stack.
void	pushInputToken(Token theToken) pushInputToken This method should only be used if there is a syntax error.
void	reset() reset This method will reset the parser engine.
int	ruleTableCount() ruleTableCount This method returns the total number of rules in the rule table.
Rule	ruleTableEntry(int index) ruleTableEntry This method will return a Rule at the specified index.
void	setCurrentReduction(Reduction value) setCurrentReduction This method will set the current reduction to the one passed in.
void	setTrimReductions(boolean value) setTrimReductions #ver1.1# This method will set the whether or not the program should trim the reductions.
int	symbolTableCount() symbolTableCount This method returns the total number of symbols in the symbol table.
Symbol	symbolTableEntry(int index) symbolTableEntry This method will return a Symbol at the specified index.
int	tokenCount() tokenCount This method will return the number of tokens in the stack.

Methods inherited from class java.lang.Object

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

Constructor Detail

GOLDParser

public GOLDParser()

GOLDParser The constructor initiates some variables.

Method Detail

currentLineNumber

public int currentLineNumber()

currentLineNumber Returns the current source file line number.

Returns:

The current source file line number

closeFile

public void closeFile()
               throws ParserException

closeFile This method will close the source file.

Throws:

ParserException - The engine parser should deal with a problem with closing the source file.

currentToken

public Token currentToken()

currentToken This method returns the current Token. The current token is the last token read by "retrieveToken".

Returns:

The current Token.

popInputToken

public Token popInputToken()

popInputToken This method should only be called if there is a lexical error and you need to pop an unexpected token out of the stack.

Returns:

The token at the top of the stack.

pushInputToken

public void pushInputToken(Token theToken)

pushInputToken This method should only be used if there is a syntax error. It will push a Token onto the top of the stack so that the parser might have a chance of finding an correctly typed token.

Parameters:

theToken - A token to push onto the stack.

getToken

public Token getToken(int index)

getToken If you require access to tokens in the stack before they are placed on the parse tree. Enter an index number and the Token will be returned, if and only if the index number is valid.

Parameters:

index - The index number.

Returns:

The Token at the index specified.

currentReduction

public Reduction currentReduction()

currentReduction This method will return the current reduction. This will only happen if the parsing engine has performed a reduction. If it has, then the reduction passed back will be the last one performed.

Returns:

The last Reduction performed.

setCurrentReduction

public void setCurrentReduction(Reduction value)

setCurrentReduction This method will set the current reduction to the one passed in.

Parameters:

value - The new Reduction to set as the current one.

setTrimReductions

public void setTrimReductions(boolean value)

setTrimReductions #ver1.1# This method will set the whether or not the program should trim the reductions.

Parameters:

value - True if we should trim reductions, false if not.

getTrimReductions

public boolean getTrimReductions()

getTrimReductions #ver1.1# This method will get whether or not we should trim the reductions.

Returns:

True if we should trim reductions, false if not.

parameter

public java.lang.String parameter(java.lang.String name)

parameter This method will return the value of a parameter that corresponds to the name passed in.

Parameters:

name - The name of the variable.

Returns:

The value of the variable.

symbolTableCount

public int symbolTableCount()

symbolTableCount This method returns the total number of symbols in the symbol table.

Returns:

The number of symbols in the table.

ruleTableCount

public int ruleTableCount()

ruleTableCount This method returns the total number of rules in the rule table.

Returns:

The number of rules in the table.

symbolTableEntry

public Symbol symbolTableEntry(int index)

symbolTableEntry This method will return a Symbol at the specified index.

Parameters:

index - The index number in the table.

Returns:

The Symbol at the specified index.

ruleTableEntry

public Rule ruleTableEntry(int index)

ruleTableEntry This method will return a Rule at the specified index.

Parameters:

index - The index number in the table.

Returns:

The Rule at the specified index.

tokenCount

public int tokenCount()

tokenCount This method will return the number of tokens in the stack.

Returns:

The number of tokens in the stack.

loadCompiledGrammar

public boolean loadCompiledGrammar(java.lang.String fileName)
                            throws ParserException

loadCompiledGrammar This method will reset the GOLDParser engine before loading a new .cgt file into it.

Parameters:

fileName - The absolute path of the .cgt file to load.

Returns:

True if the .cgt was loaded, false if not.

Throws:

ParserException - If there was a stream access problem with the file.

openFile

public boolean openFile(java.lang.String fileName)
                 throws ParserException

openFile This method will open the source file for reading. It will also reset all information from previous source files.

Parameters:

fileName - The absolute path to the source file.

Returns:

True if the file was successfully opened, false if not.

Throws:

ParserException - If there was a problem opening the file.

clear

public void clear()

clear This method clears every value in the parser engine.

reset

public void reset()

reset This method will reset the parser engine. It initalises the Error and Type End symbols, and then clears all the stacks of any tokens.

parse

public int parse()
          throws ParserException

parse Will parse a token. 1. If the tables are not setup then report GPM_NotLoadedError
2. If parser is in comment mode then read tokens until a recognized one is found and report it
3. Otherwise, parser normal
a. If there are no tokens on the stack 1) Read one and trap error 2) End function with GPM_TokenRead b. Otherwise, call ParseToken with the top of the stack. 1) If success, then Pop the value 2) Loop if the token was shifted (nothing to report)

Returns:

The result of one parse of the source file. The integer could be one of the constants defined in the interface GPMessageConstants.

Throws:

ParserException - This is thrown if there are any problems reading information from the source file.