Bds.java 文件源码

/**
 * Create an AST from a program (using ANTLR lexer & parser)
 * Returns null if error
 * Use 'alreadyIncluded' to keep track of from 'include' statements
 */
public static ParseTree createAst(File file, boolean debug, Set<String> alreadyIncluded) {
    alreadyIncluded.add(Gpr.getCanonicalFileName(file));
    String fileName = file.toString();
    String filePath = fileName;

    BigDataScriptLexer lexer = null;
    BigDataScriptParser parser = null;

    try {
        filePath = file.getCanonicalPath();

        // Input stream
        if (!Gpr.canRead(filePath)) {
            CompilerMessages.get().addError("Can't read file '" + filePath + "'");
            return null;
        }

        // Create a CharStream that reads from standard input
        ANTLRFileStream input = new ANTLRFileStream(fileName);

        //---
        // Lexer: Create a lexer that feeds off of input CharStream
        //---
        lexer = new BigDataScriptLexer(input) {
            @Override
            public void recover(LexerNoViableAltException e) {
                throw new RuntimeException(e); // Bail out
            }
        };

        //---
        // Parser
        //---
        CommonTokenStream tokens = new CommonTokenStream(lexer);
        parser = new BigDataScriptParser(tokens);

        // Parser error handling
        parser.setErrorHandler(new CompileErrorStrategy()); // Bail out with exception if errors in parser
        parser.addErrorListener(new CompilerErrorListener()); // Catch some other error messages that 'CompileErrorStrategy' fails to catch

        // Begin parsing at main rule
        ParseTree tree = parser.programUnit();

        // Error loading file?
        if (tree == null) {
            System.err.println("Can't parse file '" + filePath + "'");
            return null;
        }

        // Show main nodes
        if (debug) {
            Timer.showStdErr("AST:");
            for (int childNum = 0; childNum < tree.getChildCount(); childNum++) {
                Tree child = tree.getChild(childNum);
                System.err.println("\t\tChild " + childNum + ":\t" + child + "\tTree:'" + child.toStringTree() + "'");
            }
        }

        // Included files
        boolean resolveIncludePending = true;
        while (resolveIncludePending)
            resolveIncludePending = resolveIncludes(tree, debug, alreadyIncluded);

        return tree;
    } catch (Exception e) {
        String msg = e.getMessage();
        CompilerMessages.get().addError("Could not compile " + filePath //
                + (msg != null ? " :" + e.getMessage() : "") //
        );
        return null;
    }
}