AbstractSyntaxAnalyser.java

/**
 *
 * (Abstract) Syntax analyser for exercise course 312.
 * 
 * This class has been provided to students
 *
 * @Author: Roger Garside, John Mariani, John Vidler, Paul Rayson
 *
 *
 **/

import java.io.* ;

public abstract class AbstractSyntaxAnalyser
{
	/** The lexical analyser to process input using. */
	LexicalAnalyser lex ;
	/** A cache of the token to be processed next. */
	Token nextToken ;
	/** A code generator, descendant of AbstractGenerate. */
	Generate myGenerate = null;

	/** Begin processing the first (top level) token.*/
	public abstract void _statementPart_() throws IOException, CompilationException;

	/** Accept a token based on context.  Requires implementation. */
	public abstract void acceptTerminal(int symbol) throws IOException, CompilationException;

	/** Parses the given PrintStream with this instance's LexicalAnalyser.
		
	  @param ps The PrintStream object to read tokens from.
	  @throws IOException in the event that the PrintStream object can no longer read.
	*/
	public void parse( PrintStream ps ) throws IOException
	{
		myGenerate = new Generate();
		try {
			nextToken = lex.getNextToken() ;
			_statementPart_() ;
			acceptTerminal(Token.eofSymbol) ;
			myGenerate.reportSuccess() ;
		}
		catch( CompilationException ex )
		{
			ps.println( "Compilation Exception" );
			ps.println( ex.toTraceString() );
		}
	} // end of method parse
} // end of class AbstractSyntaxAnalyser