GenericInflater.java

package org.holoeverywhere.internal;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.HashMap;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import android.content.Context;
import android.content.res.XmlResourceParser;
import android.util.AttributeSet;
import android.util.Xml;
import android.view.InflateException;

public abstract class GenericInflater<T, P extends GenericInflater.Parent<T>> {
    public interface Factory<T> {
        public T onCreateItem(String name, Context context, AttributeSet attrs);
    }

    private static class FactoryMerger<T> implements Factory<T> {
        private final Factory<T> mF1, mF2;

        FactoryMerger(Factory<T> f1, Factory<T> f2) {
            mF1 = f1;
            mF2 = f2;
        }

        @Override
        public T onCreateItem(String name, Context context, AttributeSet attrs) {
            T v = mF1.onCreateItem(name, context, attrs);
            if (v != null) {
                return v;
            }
            return mF2.onCreateItem(name, context, attrs);
        }
    }

    public interface Parent<T> {
        public void addItemFromInflater(T child);
    }

    protected static final HashMap<String, Constructor<?>> constructorMap = new HashMap<String, Constructor<?>>();
    protected static final Class<?>[] constructorSignature = new Class<?>[] {
            Context.class, AttributeSet.class
    };
    protected final Object[] constructorArgs = new Object[2];
    protected final Context context;
    private String defaultPackage;
    private Factory<T> factory;
    private boolean factorySet;

    protected GenericInflater(Context context) {
        this.context = context;
    }

    protected GenericInflater(GenericInflater<T, P> original, Context newContext) {
        context = newContext;
        factory = original.factory;
    }

    public abstract GenericInflater<T, P> cloneInContext(Context newContext);

    @SuppressWarnings("unchecked")
    public final T createItem(String name, String prefix, AttributeSet attrs)
            throws ClassNotFoundException, InflateException {
        Constructor<?> constructor = GenericInflater.constructorMap.get(name);

        try {
            if (constructor == null) {
                Class<?> clazz = context.getClassLoader().loadClass(
                        prefix != null ? prefix + name : name);
                constructor = findConstructor(clazz);
                GenericInflater.constructorMap.put(name, constructor);
            }
            Object[] args = constructorArgs;
            args[1] = attrs;
            return (T) constructor.newInstance(args);
        } catch (NoSuchMethodException e) {
            InflateException ie = new InflateException(
                    attrs.getPositionDescription() + ": Error inflating class "
                            + (prefix != null ? prefix + name : name));
            ie.initCause(e);
            throw ie;
        } catch (Exception e) {
            InflateException ie = new InflateException(
                    attrs.getPositionDescription() + ": Error inflating class "
                            + constructor.toString());
            ie.initCause(e);
            throw ie;
        }
    }

    private final T createItemFromTag(XmlPullParser parser, String name,
            AttributeSet attrs) {
        try {
            T item = factory == null ? null : factory.onCreateItem(name,
                    context, attrs);
            if (item == null) {
                if (name.indexOf('.') < 0) {
                    item = onCreateItem(name, attrs);
                } else {
                    item = createItem(name, null, attrs);
                }
            }
            return item;
        } catch (InflateException e) {
            throw e;
        } catch (ClassNotFoundException e) {
            InflateException ie = new InflateException(
                    attrs.getPositionDescription() + ": Error inflating class "
                            + name);
            ie.initCause(e);
            throw ie;
        } catch (Exception e) {
            InflateException ie = new InflateException(
                    attrs.getPositionDescription() + ": Error inflating class "
                            + name);
            ie.initCause(e);
            throw ie;
        }
    }

    protected Constructor<?> findConstructor(Class<?> clazz)
            throws NoSuchMethodException {
        return clazz.getConstructor(GenericInflater.constructorSignature);
    }

    public Context getContext() {
        return context;
    }

    public String getDefaultPackage() {
        return defaultPackage;
    }

    public final Factory<T> getFactory() {
        return factory;
    }

    public T inflate(int resource, P root) {
        return inflate(resource, root, root != null);
    }

    public T inflate(int resource, P root, boolean attachToRoot) {
        XmlResourceParser parser = getContext().getResources().getXml(resource);
        try {
            return inflate(parser, root, attachToRoot);
        } finally {
            parser.close();
        }
    }

    public T inflate(XmlPullParser parser, P root) {
        return inflate(parser, root, root != null);
    }

    @SuppressWarnings("unchecked")
    public T inflate(XmlPullParser parser, P root, boolean attachToRoot) {
        synchronized (constructorArgs) {
            final AttributeSet attrs = Xml.asAttributeSet(parser);
            constructorArgs[0] = context;
            T result = (T) root;
            try {
                int type;
                while ((type = parser.next()) != XmlPullParser.START_TAG
                        && type != XmlPullParser.END_DOCUMENT) {
                    ;
                }
                if (type != XmlPullParser.START_TAG) {
                    throw new InflateException(parser.getPositionDescription()
                            + ": No start tag found!");
                }
                T xmlRoot = createItemFromTag(parser, parser.getName(), attrs);
                result = (T) onMergeRoots(root, attachToRoot, (P) xmlRoot);
                rInflate(parser, result, attrs);
            } catch (InflateException e) {
                throw e;
            } catch (XmlPullParserException e) {
                InflateException ex = new InflateException(e.getMessage());
                ex.initCause(e);
                throw ex;
            } catch (IOException e) {
                InflateException ex = new InflateException(
                        parser.getPositionDescription() + ": " + e.getMessage());
                ex.initCause(e);
                throw ex;
            }
            return result;
        }
    }

    protected boolean onCreateCustomFromTag(XmlPullParser parser, T parent,
            final AttributeSet attrs) throws XmlPullParserException {
        return false;
    }

    protected T onCreateItem(String name, AttributeSet attrs)
            throws ClassNotFoundException {
        return createItem(name, defaultPackage, attrs);
    }

    protected P onMergeRoots(P givenRoot, boolean attachToGivenRoot, P xmlRoot) {
        return xmlRoot;
    }

    @SuppressWarnings("unchecked")
    private void rInflate(XmlPullParser parser, T parent,
            final AttributeSet attrs) throws XmlPullParserException,
            IOException {
        final int depth = parser.getDepth();
        int type;
        while (((type = parser.next()) != XmlPullParser.END_TAG || parser
                .getDepth() > depth) && type != XmlPullParser.END_DOCUMENT) {
            if (type != XmlPullParser.START_TAG) {
                continue;
            }
            if (onCreateCustomFromTag(parser, parent, attrs)) {
                continue;
            }
            String name = parser.getName();
            T item = createItemFromTag(parser, name, attrs);
            ((P) parent).addItemFromInflater(item);
            rInflate(parser, item, attrs);
        }
    }

    public void setDefaultPackage(String defaultPackage) {
        this.defaultPackage = defaultPackage;
    }

    public void setFactory(Factory<T> factory) {
        if (factorySet) {
            throw new IllegalStateException(
                    "A factory has already been set on this inflater");
        }
        if (factory == null) {
            throw new NullPointerException("Given factory can not be null");
        }
        factorySet = true;
        if (this.factory == null) {
            this.factory = factory;
        } else {
            this.factory = new FactoryMerger<T>(factory, this.factory);
        }
    }
}