CupParser.java

package polyglot.frontend;

import java.io.*;
import polyglot.ast.*;
import polyglot.util.*;

/**
 * A parser implemented with a Cup generated-parser.
 */
public class CupParser implements Parser
{
    java_cup.runtime.lr_parser grm;
    Source source;
    ErrorQueue eq;

    public CupParser(java_cup.runtime.lr_parser grm, Source source, ErrorQueue eq) {
	this.grm = grm;
	this.source = source;
       	this.eq = eq;
    }

    public Node parse() {
	try {
	    java_cup.runtime.Symbol sym = grm.parse();

	    if (sym != null && sym.value instanceof Node) {
		SourceFile sf = (SourceFile) sym.value;
                return sf.source(source);
	    }

	    eq.enqueue(ErrorInfo.SYNTAX_ERROR, "Unable to parse " +
		source.name() + ".");
	}
	catch (IOException e) {
	    eq.enqueue(ErrorInfo.IO_ERROR, e.getMessage());
	}
	catch (RuntimeException e) {
	    // Let the Compiler catch and report it.
	    throw e;
	}
	catch (Exception e) {
	    // Used by cup to indicate a non-recoverable error.
	    if (e.getMessage() != null) {
	        eq.enqueue(ErrorInfo.SYNTAX_ERROR, e.getMessage());
	    }
	}

	return null;
    }

    public String toString() {
	return "CupParser(" + grm.getClass().getName() + ")";
    }
}