SignaturePrinter.java

package checkers.util.debug;

import java.io.PrintStream;
import java.lang.reflect.Constructor;
import java.util.Collections;
import java.util.List;

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import javax.lang.model.util.AbstractElementVisitor6;

import checkers.source.*;
import checkers.types.AnnotatedTypeFactory;
import checkers.types.AnnotatedTypeMirror;
import checkers.types.AnnotatedTypeMirror.*;

import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.util.AbstractTypeProcessor;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.processing.JavacProcessingEnvironment;
import com.sun.tools.javac.util.Context;

/**
 * Outputs the method signatures of a class with fully annotated types.
 *
 * The class determines the effective annotations for a checker in source or
 * the classfile.  Finding the effective annotations is useful for the
 * following purposes:
 *
 * <ol>
 * <li id="1">Debugging annotations in classfile</li>
 * <li id="2">Debugging the default annotations that are implicitly added
 *    by the checker</li>
 * </ol>
 *
 * <p>The class can be used in two possible ways, depending on the type file:
 *
 * <ol>
 * <li id="a">From source: the class is to be used as an annotation processor
 * when reading annotations from source.  It can be invoked via the command:
 * <p><code>javac -processor SignaturePrinter <java files> ...</code>
 *
 * <li id="b">From classfile: the class is to be used as an independent app
 * when reading annotations from classfile.  It can be invoked via the command:
 * <p><code>java SignaturePrinter <class name></code>
 *
 * </ol>
 *
 * By default, only the annotations explicitly written by the user are emitted.
 * To view the default and effective annotations in a class that are associated
 * with a checker, the fully qualified name of the checker needs to be passed
 * as '-Achecker=' argument, e.g.
 * <p><code>javac -processor SignaturePrinter
 *         -Achecker=checkers.nullness.NullnessChecker JavaFile.java</code>
 */
@SupportedSourceVersion(SourceVersion.RELEASE_7)
@SupportedAnnotationTypes("*")
@SupportedOptions("checker")
public class SignaturePrinter extends AbstractTypeProcessor {

    private SourceChecker checker;

    ///////// Initialization /////////////
    private void init(ProcessingEnvironment env, String checkerName) {
        if (checkerName != null) {
            try {
                Class<?> checkerClass = Class.forName(checkerName);
                Constructor<?> cons = checkerClass.getConstructor();
                checker = (SourceChecker)cons.newInstance();
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        } else {
            checker = new SourceChecker() {

                @Override
                protected SourceVisitor<?, ?> createSourceVisitor(
                        CompilationUnitTree root) {
                    return null;
                }

            };
        }
        checker.init(env);
    }

    @Override
    public void init(ProcessingEnvironment env) {
        super.init(env);
        String checkerName = env.getOptions().get("checker");
        init(env, checkerName);
    }

    @Override
    public void typeProcess(TypeElement element, TreePath p) {
        checker.currentPath = p;
        CompilationUnitTree root = p != null ? p.getCompilationUnit() : null;
        ElementPrinter printer = new ElementPrinter(checker.createFactory(root), System.out);
        printer.visit(element);
    }

    ////////// Printer //////////
    static class ElementPrinter extends AbstractElementVisitor6<Void, Void> {
        private final static String INDENTION = "    ";

        private PrintStream out;
        private String indent = "";
        private AnnotatedTypeFactory factory;

        public ElementPrinter(AnnotatedTypeFactory factory, PrintStream out) {
            this.factory = factory;
            this.out = out;
        }

        public void printTypeParams(List<? extends AnnotatedTypeVariable> params) {
            if (params.isEmpty())
                return;

            out.print("<");
            boolean isntFirst = false;
            for (AnnotatedTypeMirror param : params) {
                if (isntFirst)
                    out.print(", ");
                isntFirst = true;
                out.print(param);
            }
            out.print("> ");
        }

        public void printParameters(AnnotatedExecutableType type) {
            ExecutableElement elem = type.getElement();

            out.print("(");
            for (int i = 0; i < type.getParameterTypes().size(); ++i) {
                if (i != 0)
                    out.print(", ");
                printVariable(type.getParameterTypes().get(i),
                        elem.getParameters().get(i).getSimpleName());
            }
            out.print(")");
        }

        public void printThrows(AnnotatedExecutableType type) {
            if (type.getThrownTypes().isEmpty())
                return;

            out.print(" throws ");

            boolean isntFirst = false;
            for (AnnotatedTypeMirror thrown : type.getThrownTypes()) {
                if (isntFirst)
                    out.print(", ");
                isntFirst = true;
                out.print(thrown);
            }
        }
        public void printVariable(AnnotatedTypeMirror type, Name name, boolean isVarArg) {
            out.print(type);
            if (isVarArg)
                out.println("...");
            out.print(' ');
            out.print(name);
        }

        public void printVariable(AnnotatedTypeMirror type, Name name) {
            printVariable(type, name, false);
        }

        public void printType(AnnotatedTypeMirror type) {
            out.print(type);
            out.print(' ');
        }

        public void printName(CharSequence name) {
            out.print(name);
        }

        @Override
        public Void visitExecutable(ExecutableElement e, Void p) {
            out.print(indent);

            AnnotatedExecutableType type = factory.getAnnotatedType(e);
            printTypeParams(type.getTypeVariables());
            if (e.getKind() != ElementKind.CONSTRUCTOR) {
                printType(type.getReturnType());
            }
            printName(e.getSimpleName());
            printParameters(type);
            printThrows(type);
            out.println(';');

            return null;
        }

        @Override
        public Void visitPackage(PackageElement e, Void p) {
            throw new IllegalArgumentException("Cannot process packages");
        }

        private String typeIdentifier(TypeElement e) {
            switch (e.getKind()) {
            case INTERFACE: return "interface";
            case CLASS: return "class";
            case ANNOTATION_TYPE: return "@interface";
            case ENUM: return "enum";
            default:
                throw new IllegalArgumentException("Not a type element: " + e.getKind());
            }
        }

        @Override
        public Void visitType(TypeElement e, Void p) {
            String prevIndent = indent;

                out.print(indent);
                out.print(typeIdentifier(e));
                out.print(' ');
                out.print(e.getSimpleName());
                out.print(' ');
                AnnotatedDeclaredType dt = factory.getAnnotatedType(e);
                printSupers(dt);
                out.println("{");

                indent += INDENTION;

                for (Element enclosed : e.getEnclosedElements())
                    this.visit(enclosed);

                indent = prevIndent;
                out.print(indent);
                out.println("}");

                return null;
        }

        private void printSupers(AnnotatedDeclaredType dt) {
            if (dt.directSuperTypes().isEmpty())
                return;

            out.print("extends ");

            boolean isntFirst = false;
            for (AnnotatedDeclaredType st : dt.directSuperTypes()) {
                if (isntFirst)
                    out.print(", ");
                isntFirst = true;
                out.print(st);
            }
            out.print(' ');
        }

        @Override
        public Void visitTypeParameter(TypeParameterElement e, Void p) {
            throw new IllegalStateException("Shouldn't visit any type parameters");
        }

        @Override
        public Void visitVariable(VariableElement e, Void p) {
            if (!e.getKind().isField())
                throw new IllegalStateException("can only process fields, received " + e.getKind());

            out.print(indent);
            AnnotatedTypeMirror type = factory.getAnnotatedType(e);
            this.printVariable(type, e.getSimpleName());
            out.println(';');

            return null;
        }

    }

    public static void printUsage() {
        System.out.println("   Usage: java SignaturePrinter [-Achecker=<checkerName>] classname");
    }

    private static final String CHECKER_ARG = "-Achecker=";

    public static void main(String[] args) {
        if (!(args.length == 1 && !args[0].startsWith(CHECKER_ARG))
            && !(args.length == 2 && args[0].startsWith(CHECKER_ARG))) {
            printUsage();
            return;
        }

        // process arguments
        String checkerName = "";
        if (args[0].startsWith(CHECKER_ARG))
            checkerName = args[0].substring(CHECKER_ARG.length());

        // Setup compiler environment
        Context context = new Context();
        JavacProcessingEnvironment env = new JavacProcessingEnvironment(context, Collections.<Processor>emptyList());
        SignaturePrinter printer = new SignaturePrinter();
        printer.init(env, checkerName);

        String className = args[args.length - 1];
        TypeElement elem = env.getElementUtils().getTypeElement(className);
        if (elem == null) {
            System.err.println("Couldn't find class: " + className);
            return;
        }

        printer.typeProcess(elem, null);
    }
}