framework.src.org.checkerframework.common.util.debug.TreePrinter Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of checker Show documentation

The Checker Framework enhances Java’s type system to make it more powerful and useful. This lets software developers detect and prevent errors in their Java programs. The Checker Framework includes compiler plug-ins ("checkers") that find bugs or verify their absence. It also permits you to write your own compiler plug-ins.

There is a newer version: 3.42.0

Show newest version

package org.checkerframework.common.util.debug;

import com.sun.source.util.TreePath;
import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
import com.sun.tools.javac.tree.Pretty;

import java.io.IOException;
import java.io.StringWriter;

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.TypeElement;

import org.checkerframework.javacutil.AbstractTypeProcessor;

/**
 * A utility class for pretty-printing the AST of a program.
 *
 * 
 * The class is actually an annotation processor; in order to use it, invoke the
 * compiler on the source file(s) for which you wish to view the AST of the program.
 * You may also wish to use the {@code -proc:only} javac option to
 * stop compilation after annotation processing.  (But, in general
 * {@code -proc:only} causes type annotation processors not to be run.)
 *
 * 

 * A simple main method is also provided. Put jsr308-all.jar on the bootclasspath
 * and you can invoke this tool as:
 *
 *   java org.checkerframework.common.util.debug.TreePrinter *.java
 *
 * TODO: is there an environment variable for the bootclasspath?
 *
 * 
 * The visitor simply uses the javac Pretty visitor to output a nicely formatted
 * version of the AST.
 *
 * TODO: I couldn't find a way to display the result of Pretty, therefore I wrote
 * this simple class. If there already was a way, please let me know.
 *
 * TODO: what I really want is something like SignaturePrinter, but for the whole
 * source of the program, that is, for each type in the program use the factory
 * to determine the defaulted annotations on the type.
 *
 * @see org.checkerframework.common.util.debug.TreeDebug
 */
@SupportedAnnotationTypes("*")
@SupportedSourceVersion(SourceVersion.RELEASE_8)
public class TreePrinter extends AbstractTypeProcessor {
    @Override
    public void typeProcess(TypeElement element, TreePath tree) {
        final StringWriter out = new StringWriter();
        final Pretty pretty = new Pretty(out, true);

        try {
            pretty.printUnit((JCCompilationUnit) tree.getCompilationUnit(), null);
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println(out.toString());
    }

    public static void main(String[] args) throws Exception {
        String[] newArgs = new String[args.length + 3];
        newArgs[0] = "-processor";
        newArgs[1] = "org.checkerframework.common.util.debug.TreePrinter";
        newArgs[2] = "-proc:only";
        System.arraycopy(args, 0, newArgs, 3, args.length);
        com.sun.tools.javac.Main.compile(newArgs);
    }
}