https://github.com/jruby/jruby/jruby-core: JRuby is the effort to recreate the Ruby (https://www.ruby-lang.org) interpreter in Java. (JRuby)
  • headius
  • enebo
  • wmeissner
  • BanzaiMan
  • mkristian 
BEGIN LICENSE BLOCK *****
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package org.jruby.javasupport;

import org.jruby.IncludedModuleWrapper;
import org.jruby.MetaClass;
import org.jruby.Ruby;
import org.jruby.RubyBoolean;
import org.jruby.RubyClass;
import org.jruby.RubyModule;
import org.jruby.RubyString;
import org.jruby.RubySymbol;
import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.exceptions.RaiseException;
import org.jruby.internal.runtime.methods.DynamicMethod;
import org.jruby.internal.runtime.methods.NullMethod;
import org.jruby.runtime.*;
import org.jruby.runtime.builtin.IRubyObject;
import org.jruby.util.ClassProvider;
import org.jruby.util.TypeConverter;

import static org.jruby.runtime.Visibility.PRIVATE;


A "thin" Java package wrapper (for the runtime to see them as Ruby objects).

Author:kares
Since:9K
@notepreviously JavaPackageModuleTemplate in Ruby code
/**
 * A "thin" Java package wrapper (for the runtime to see them as Ruby objects).
 *
 * @since 9K
 * @note previously <code>JavaPackageModuleTemplate</code> in Ruby code
 * @author kares
 */
@JRubyClass(name="Java::JavaPackage", parent="Module")
public class JavaPackage extends RubyModule {

    static RubyModule createJavaPackageClass(final Ruby runtime, final RubyModule Java) {
        RubyClass superClass = new BlankSlateWrapper(runtime, runtime.getModule(), runtime.getKernel());
        RubyClass JavaPackage = RubyClass.newClass(runtime, superClass);
        JavaPackage.setMetaClass(runtime.getModule());
        JavaPackage.setAllocator(ObjectAllocator.NOT_ALLOCATABLE_ALLOCATOR);
        ((MetaClass) JavaPackage.makeMetaClass(superClass)).setAttached(JavaPackage);

        JavaPackage.setBaseName("JavaPackage");

        JavaPackage.setParent(Java);
        Java.setConstant("JavaPackage", JavaPackage); // Java::JavaPackage
        // JavaPackage.setReifiedClass(JavaPackage.class);

        JavaPackage.defineAnnotatedMethods(JavaPackage.class);
        return JavaPackage;
    }

    static RubyModule newPackage(Ruby runtime, CharSequence name, RubyModule parent) {
        final JavaPackage pkgModule = new JavaPackage(runtime, name);
        // intentionally do NOT set pkgModule.setParent(parent);

        // this is where we'll get connected when classes are opened using
        // package module syntax.
        pkgModule.addClassProvider( JavaClassProvider.INSTANCE );
        return pkgModule;
    }

    static CharSequence buildPackageName(final RubyModule parentPackage, final String name) {
        return ((JavaPackage) parentPackage).packageRelativeName(name);
    }

    final String packageName;

    private JavaPackage(final Ruby runtime, final CharSequence packageName) {
        super(runtime, runtime.getJavaSupport().getJavaPackageClass());
        this.packageName = packageName.toString();
    }

    // NOTE: name is Ruby name not pkg.name ~ maybe it should be just like with JavaClass?

    @JRubyMethod(name = "package_name", alias = "to_s")
    public RubyString package_name() {
        return getRuntime().newString(packageName);
    }

    @Override
    public RubyString to_s() { return package_name(); }

    @Override
    @JRubyMethod
    public IRubyObject inspect() {
        return getRuntime().newString(getName()); // super.to_s()
    }

    @Override
    @JRubyMethod(name = "===")
    public RubyBoolean op_eqq(ThreadContext context, IRubyObject obj) {
        // maybe we could handle java.lang === java.lang.reflect as well ?
        return context.runtime.newBoolean(obj == this || isInstance(obj));
    }

    @JRubyMethod(name = "const_missing", required = 1)
    public IRubyObject const_missing(final ThreadContext context, final IRubyObject name) {
        return relativeJavaClassOrPackage(context, name, false);
    }

    @JRubyMethod(name = "const_get", required = 1)
    public final IRubyObject const_get(final ThreadContext context, final IRubyObject name) {
        // skip constant validation and do not inherit or include object
        IRubyObject constant = getConstantNoConstMissing(name.toString(), false, false);
        if ( constant != null ) return constant;
        return relativeJavaClassOrPackage(context, name, false); // e.g. javax.const_get(:script)
    }

    @JRubyMethod(name = "const_get", required = 2)
    public final IRubyObject const_get(final ThreadContext context,
        final IRubyObject name, final IRubyObject inherit) {
        IRubyObject constant = getConstantNoConstMissing(name.toString(), inherit.isTrue(), false);
        if ( constant != null ) return constant;
        return relativeJavaClassOrPackage(context, name, false);
    }

    @Override // so that e.g. java::util gets stored as expected
    public final IRubyObject storeConstant(String name, IRubyObject value) {
        // skip constant name validation
        assert value != null : "value is null";

        ensureConstantsSettable();
        return constantTableStore(name, value);
    }

    @Override // skip constant name assert
    public final boolean hasConstant(String name) {
        return constantTableContains(name);
    }

    @Override // skip constant name assert
    public final IRubyObject fetchConstant(String name, boolean includePrivate) {
        ConstantEntry entry = constantEntryFetch(name);
        if (entry == null) return null;
        if (entry.hidden && !includePrivate) {
            throw getRuntime().newNameError("private constant " + getName() + "::" + name + " referenced", name);
        }
        return entry.value;
    }

    @Override // skip constant name assert
    public final IRubyObject deleteConstant(String name) {
        assert name != null : "name is null";
        ensureConstantsSettable();
        return constantTableRemove(name);
    }

    final CharSequence packageRelativeName(final CharSequence name) {
        final int length = packageName.length();
        final StringBuilder fullName = new StringBuilder(length + 1 + name.length());
        // packageName.length() > 0 ? package + '.' + name : name;
        fullName.append(packageName);
        if ( length > 0 ) fullName.append('.');
        return fullName.append(name);
    }

    private RubyModule relativeJavaClassOrPackage(final ThreadContext context,
        final IRubyObject name, final boolean cacheMethod) {
        return Java.getProxyOrPackageUnderPackage(context, this, name.toString(), cacheMethod);
    }

    RubyModule relativeJavaProxyClass(final Ruby runtime, final IRubyObject name) {
        final String fullName = packageRelativeName( name.toString() ).toString();
        final JavaClass javaClass = JavaClass.forNameVerbose(runtime, fullName);
        return Java.getProxyClass(runtime, javaClass);
    }

    @JRubyMethod(name = "respond_to?")
    public IRubyObject respond_to_p(final ThreadContext context, IRubyObject name) {
        return respond_to(context, name, false);
    }

    @JRubyMethod(name = "respond_to?")
    public IRubyObject respond_to_p(final ThreadContext context, IRubyObject name, IRubyObject includePrivate) {
        return respond_to(context, name, includePrivate.isTrue());
    }

    private IRubyObject respond_to(final ThreadContext context, IRubyObject mname, final boolean includePrivate) {
        RubySymbol name = TypeConverter.checkID(mname);

        if (getMetaClass().respondsToMethod(name.idString(), !includePrivate)) return context.tru;
        /*
        if ( ( name = BlankSlateWrapper.handlesMethod(name) ) != null ) {
            RubyBoolean bound = checkMetaClassBoundMethod(context, name, includePrivate);
            if ( bound != null ) return bound;
            return context.fals; // un-bound (removed) method
        }
        */

        //if ( ! (mname instanceof RubySymbol) ) mname = context.runtime.newSymbol(name);
        //IRubyObject respond = Helpers.invoke(context, this, "respond_to_missing?", mname, context.runtime.newBoolean(includePrivate));
        //return context.runtime.newBoolean(respond.isTrue());

        return context.nil; // NOTE: this is wrong - should be true but compatibility first, for now
    }

    private RubyBoolean checkMetaClassBoundMethod(final ThreadContext context, final String name, final boolean includePrivate) {
        // getMetaClass().isMethodBound(name, !includePrivate, true)
        DynamicMethod method = getMetaClass().searchMethod(name);
        if ( ! method.isUndefined() && ! method.isNotImplemented() ) {
            if ( ! includePrivate && method.getVisibility() == PRIVATE ) {
                return context.fals;
            }
            return context.tru;
        }
        return null;
    }

    @JRubyMethod(name = "respond_to_missing?")
    public IRubyObject respond_to_missing_p(final ThreadContext context, IRubyObject name) {
        return respond_to_missing(context, name, false);
    }

    @JRubyMethod(name = "respond_to_missing?")
    public IRubyObject respond_to_missing_p(final ThreadContext context, IRubyObject name, IRubyObject includePrivate) {
        return respond_to_missing(context, name, includePrivate.isTrue());
    }

    private RubyBoolean respond_to_missing(final ThreadContext context, IRubyObject mname, final boolean includePrivate) {
        return context.runtime.newBoolean(BlankSlateWrapper.handlesMethod(TypeConverter.checkID(mname).idString()) == null);
    }

    @JRubyMethod(name = "method_missing")
    public IRubyObject method_missing(ThreadContext context, final IRubyObject name) {
        // NOTE: getProxyOrPackageUnderPackage binds the (cached) method for us
        return Java.getProxyOrPackageUnderPackage(context, this, name.toString(), true);
    }

    @JRubyMethod(name = "method_missing", rest = true)
    public IRubyObject method_missing(ThreadContext context, final IRubyObject[] args) {
        if (args.length > 1) {
            throw packageMethodArgumentMismatch(context.runtime, this, args[0].toString(), args.length - 1);
        }
        return method_missing(context, args[0]);
    }
    
    static RaiseException packageMethodArgumentMismatch(final Ruby runtime, final RubyModule pkg,
        final String method, final int argsLength) {
        String packageName = ((JavaPackage) pkg).packageName;
        return runtime.newArgumentError(
                "Java package '" + packageName + "' does not have a method `" +
                        method + "' with " + argsLength + (argsLength == 1 ? " argument" : " arguments")
        );
    }

    public final boolean isAvailable() {
        // may be null if no package information is available from the archive or codebase
        return Package.getPackage(packageName) != null;
    }

    @JRubyMethod(name = "available?")
    public IRubyObject available_p(ThreadContext context) {
        return context.runtime.newBoolean(isAvailable());
    }

    @JRubyMethod(name = "sealed?")
    public IRubyObject sealed_p(ThreadContext context) {
        final Package pkg = Package.getPackage(packageName);
        if ( pkg == null ) return context.nil;
        return context.runtime.newBoolean(pkg.isSealed());
    }

    @Override
    @SuppressWarnings("unchecked")
    public <T> T toJava(Class<T> target) {
        if ( target.isAssignableFrom( Package.class ) ) {
            return target.cast(Package.getPackage(packageName));
        }
        return super.toJava(target);
    }

    private static class JavaClassProvider implements ClassProvider {

        static final JavaClassProvider INSTANCE = new JavaClassProvider();

        public RubyClass defineClassUnder(RubyModule pkg, String name, RubyClass superClazz) {
            // shouldn't happen, but if a superclass is specified, it's not ours
            if ( superClazz != null ) return null;

            final String subPackageName = JavaPackage.buildPackageName(pkg, name).toString();

            final Ruby runtime = pkg.getRuntime();
            JavaClass javaClass = JavaClass.forNameVerbose(runtime, subPackageName);
            return (RubyClass) Java.getProxyClass(runtime, javaClass);
        }

        public RubyModule defineModuleUnder(RubyModule pkg, String name) {
            final String subPackageName = JavaPackage.buildPackageName(pkg, name).toString();

            final Ruby runtime = pkg.getRuntime();
            JavaClass javaClass = JavaClass.forNameVerbose(runtime, subPackageName);
            return Java.getInterfaceModule(runtime, javaClass);
        }

    }

    
This special module wrapper is used by the Java "package modules" in order to
simulate a blank slate. Only a certain subset of method names will carry
through to searching the superclass, with all others returning null and
triggering the method_missing call needed to handle lazy Java package
discovery.
Because this is in the hierarchy, it does mean any methods that are not Java
packages or otherwise defined on the Java::JavaPackage will
be inaccessible.

/**
     * This special module wrapper is used by the Java "package modules" in order to
     * simulate a blank slate. Only a certain subset of method names will carry
     * through to searching the superclass, with all others returning null and
     * triggering the method_missing call needed to handle lazy Java package
     * discovery.
     *
     * Because this is in the hierarchy, it does mean any methods that are not Java
     * packages or otherwise defined on the <code>Java::JavaPackage</code> will
     * be inaccessible.
     */
    static final class BlankSlateWrapper extends IncludedModuleWrapper {

        BlankSlateWrapper(Ruby runtime, RubyClass superClass, RubyModule delegate) {
            super(runtime, superClass, delegate);
        }

        @Override
        protected DynamicMethod searchMethodCommon(String id) {
            // this module is special and only searches itself;
            if ("superclass".equals(id)) {
                return new MethodValue(id, superClass); // JavaPackage.superclass
            }
            return (id = handlesMethod(id)) != null ? superClass.searchMethodInner(id) : NullMethod.INSTANCE;
        }

        private static class MethodValue extends DynamicMethod {

            private final IRubyObject value;

            MethodValue(final String name, final IRubyObject value) {
                super(name);
                this.value = value;
            }

            public final IRubyObject call(ThreadContext context, IRubyObject self, RubyModule clazz, String name, IRubyObject[] args, Block block) {
                return call(context, self, clazz, name);
            }

            @Override
            public IRubyObject call(ThreadContext context, IRubyObject self, RubyModule klazz, String name) {
                return value;
            }

            @Override
            public DynamicMethod dup() {
                try {
                    return (DynamicMethod) super.clone();
                }
                catch (CloneNotSupportedException ex) {
                    throw new AssertionError(ex);
                }
            }

            @Override
            public Arity getArity() { return Arity.NO_ARGUMENTS; }

        }
        private static String handlesMethod(final String name) {
            // FIXME: We should consider pure-bytelist search here.
            switch (name) {
                case "class" : case "singleton_class" : return name;
                case "object_id" : case "name" : return name;
                // these are handled already at the JavaPackage.class :
                // case "const_get" : case "const_missing" : case "method_missing" :
                case "const_set" : return name;
                case "inspect" : case "to_s" : return name;
                // these are handled bellow in switch (name.charAt(0))
                // case "__method__" : case "__send__" : case "__id__" :

                //case "require" : case "load" :
                case "throw" : case "catch" : //case "fail" : case "raise" :
                //case "exit" : case "at_exit" :
                    return name;

                case "singleton_method_added" :
                // JavaPackageModuleTemplate handled "singleton_method_added"
                case "singleton_method_undefined" :
                case "singleton_method_removed" :
                case "define_singleton_method" :
                    return name;

                // NOTE: these should maybe get re-thought and deprecated (for now due compatibility)
                case "__constants__" : return "constants";
                case "__methods__" : return "methods";
            }

            final int last = name.length() - 1;
            if ( last >= 0 ) {
                switch (name.charAt(last)) {
                    case '?' : case '!' : case '=' :
                        return name;
                }
                switch (name.charAt(0)) {
                    case '<' : case '>' : case '=' : // e.g. ==
                        return name;
                    case '_' : // e.g. __send__
                        if ( last > 0 && name.charAt(1) == '_' ) {
                            return name;
                        }
                }
            }

            //if ( last >= 5 && (
            //       name.indexOf("method") >= 0 || // method, instance_methods, singleton_methods ...
            //       name.indexOf("variable") >= 0 || // class_variables, class_variable_get, instance_variables ...
            //       name.indexOf("constant") >= 0 ) ) { // constants, :public_constant, :private_constant
            //    return true;
            //}

            return null;
        }

        @Override
        public void addSubclass(RubyClass subclass) { /* noop */ }

    }

}