Package org.jruby.platform

Source Code of org.jruby.platform.Errno$FakeConstant

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* Version: CPL 1.0/GPL 2.0/LGPL 2.1
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* License Version 1.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
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* Copyright (C) 2008 JRuby project
*
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package org.jruby.platform;

import com.kenai.constantine.Constant;
import com.kenai.constantine.ConstantSet;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import org.jruby.IErrno;

/**
* Holds the platform specific errno values.
*/
public final class Errno {
    private static final Collection<Constant> constants = getConstants();
   
    private static final Collection<Constant> getConstants() {
        ConstantSet c = ConstantSet.getConstantSet("Errno");
        if (c != null) {
            return c;
        }
        return getConstantsFromFields(IErrno.class);
    }
    public static Collection<Constant> values() {
        return constants;
    }

    private static final class FakeConstant implements Constant {
        private final String name;
        private final int value;
        FakeConstant(String name, int value) {
            this.name = name;
            this.value = value;
        }
        public int value() {
            return value;
        }

        public String name() {
            return name;
        }
       
    }
   
    /**
     * Loads the errno values from a static field called 'CONSTANTS' in the class.
     * @param errnoClass The class to load errno constants from.
     * @return A map of errno name to errno value.
     */
    private static Collection<Constant> getConstantsFromFields(Class errnoClass) {
        Field[] fields = errnoClass.getFields();
        List<Constant> c = new ArrayList<Constant>(fields.length);
        for (int i = 0; i < fields.length; ++i) {
            try {
                c.add(new FakeConstant(fields[i].getName(), fields[i].getInt(errnoClass)));
            } catch (IllegalAccessException ex) {
                throw new RuntimeException("Non public constant in " + errnoClass.getName(), ex);
            }
        }
        return Collections.unmodifiableCollection(c);
    }
}
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