Examples with ParseTreeWalker org.antlr.v4.runtime.tree.ParseTreeWalker used on opensource projects

Example 6 with ParseTreeWalker

use of org.antlr.v4.runtime.tree.ParseTreeWalker in project incubator-systemml by apache.

the class DMLParserWrapper method doParse.

/**
	 * This function is supposed to be called directly only from DmlSyntacticValidator when it encounters 'import'
	 * @param fileName script file name
	 * @param dmlScript script file contents
	 * @param sourceNamespace namespace from source statement
	 * @param argVals script arguments
	 * @return dml program, or null if at least one error
	 * @throws ParseException if ParseException occurs
	 */
public DMLProgram doParse(String fileName, String dmlScript, String sourceNamespace, Map<String, String> argVals) throws ParseException {
    DMLProgram dmlPgm = null;
    ANTLRInputStream in;
    try {
        if (dmlScript == null) {
            dmlScript = readDMLScript(fileName, LOG);
        }
        InputStream stream = new ByteArrayInputStream(dmlScript.getBytes());
        in = new ANTLRInputStream(stream);
    } catch (FileNotFoundException e) {
        throw new ParseException("Cannot find file/resource: " + fileName, e);
    } catch (IOException e) {
        throw new ParseException("Cannot open file: " + fileName, e);
    } catch (LanguageException e) {
        throw new ParseException(e.getMessage(), e);
    }
    ProgramrootContext ast = null;
    CustomErrorListener errorListener = new CustomErrorListener();
    try {
        DmlLexer lexer = new DmlLexer(in);
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        DmlParser antlr4Parser = new DmlParser(tokens);
        // For now no optimization, since it is not able to parse integer value. 
        boolean tryOptimizedParsing = false;
        if (tryOptimizedParsing) {
            // Try faster and simpler SLL
            antlr4Parser.getInterpreter().setPredictionMode(PredictionMode.SLL);
            antlr4Parser.removeErrorListeners();
            antlr4Parser.setErrorHandler(new BailErrorStrategy());
            try {
                ast = antlr4Parser.programroot();
            // If successful, no need to try out full LL(*) ... SLL was enough
            } catch (ParseCancellationException ex) {
                // Error occurred, so now try full LL(*) for better error messages
                tokens.reset();
                antlr4Parser.reset();
                if (fileName != null) {
                    errorListener.setCurrentFileName(fileName);
                } else {
                    errorListener.setCurrentFileName("MAIN_SCRIPT");
                }
                // Set our custom error listener
                antlr4Parser.addErrorListener(errorListener);
                antlr4Parser.setErrorHandler(new DefaultErrorStrategy());
                antlr4Parser.getInterpreter().setPredictionMode(PredictionMode.LL);
                ast = antlr4Parser.programroot();
            }
        } else {
            // Set our custom error listener
            antlr4Parser.removeErrorListeners();
            antlr4Parser.addErrorListener(errorListener);
            errorListener.setCurrentFileName(fileName);
            // Now do the parsing
            ast = antlr4Parser.programroot();
        }
    } catch (Exception e) {
        throw new ParseException("ERROR: Cannot parse the program:" + fileName, e);
    }
    // Now convert the parse tree into DMLProgram
    // Do syntactic validation while converting 
    ParseTree tree = ast;
    // And also do syntactic validation
    ParseTreeWalker walker = new ParseTreeWalker();
    // Get list of function definitions which take precedence over built-in functions if same name
    DmlPreprocessor prep = new DmlPreprocessor(errorListener);
    walker.walk(prep, tree);
    // Syntactic validation
    DmlSyntacticValidator validator = new DmlSyntacticValidator(errorListener, argVals, sourceNamespace, prep.getFunctionDefs());
    walker.walk(validator, tree);
    errorListener.unsetCurrentFileName();
    this.parseIssues = errorListener.getParseIssues();
    this.atLeastOneWarning = errorListener.isAtLeastOneWarning();
    this.atLeastOneError = errorListener.isAtLeastOneError();
    if (atLeastOneError) {
        throw new ParseException(parseIssues, dmlScript);
    }
    if (atLeastOneWarning) {
        LOG.warn(CustomErrorListener.generateParseIssuesMessage(dmlScript, parseIssues));
    }
    dmlPgm = createDMLProgram(ast, sourceNamespace);
    return dmlPgm;
}