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org.stringtemplate.v4.misc.ObjectModelAdaptor Maven / Gradle / Ivy

/*
 * [The "BSD license"]
 *  Copyright (c) 2011 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.stringtemplate.v4.misc;

import org.stringtemplate.v4.Interpreter;
import org.stringtemplate.v4.ModelAdaptor;
import org.stringtemplate.v4.ST;

import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

public class ObjectModelAdaptor implements ModelAdaptor {
    protected static final Member INVALID_MEMBER;
    static {
        Member invalidMember;
        try {
            invalidMember = ObjectModelAdaptor.class.getDeclaredField("INVALID_MEMBER");
        } catch (NoSuchFieldException ex) {
            invalidMember = null;
        } catch (SecurityException ex) {
            invalidMember = null;
        }

        INVALID_MEMBER = invalidMember;
    }

    protected static final Map, Map> membersCache =
        new HashMap, Map>();

    @Override
    public synchronized Object getProperty(Interpreter interp, ST self, T model, Object property, String propertyName)
        throws STNoSuchPropertyException
    {
        if (model == null) {
            throw new NullPointerException("o");
        }

        Class c = model.getClass();

        if ( property==null ) {
            return throwNoSuchProperty(c, propertyName, null);
        }

        Member member = findMember(c, propertyName);
        if ( member!=null ) {
            try {
                if (member instanceof Method) {
                    return ((Method)member).invoke(model);
                }
                else if (member instanceof Field) {
                    return ((Field)member).get(model);
                }
            }
            catch (Exception e) {
                throwNoSuchProperty(c, propertyName, e);
            }
        }

        return throwNoSuchProperty(c, propertyName, null);
    }

    protected static Member findMember(Class clazz, String memberName) {
        if (clazz == null) {
            throw new NullPointerException("clazz");
        }
        if (memberName == null) {
            throw new NullPointerException("memberName");
        }

        synchronized (membersCache) {
            Map members = membersCache.get(clazz);
            Member member;
            if (members != null) {
                member = members.get(memberName);
                if (member != null) {
                    return member != INVALID_MEMBER ? member : null;
                }
            }
            else {
                members = new HashMap();
                membersCache.put(clazz, members);
            }

            // try getXXX and isXXX properties, look up using reflection
            String methodSuffix = Character.toUpperCase(memberName.charAt(0)) +
                memberName.substring(1, memberName.length());
            
            member = tryGetMethod(clazz, "get" + methodSuffix);
            if (member == null) {
                member = tryGetMethod(clazz, "is" + methodSuffix);
                if (member == null) {
                    member = tryGetMethod(clazz, "has" + methodSuffix);
                }
            }

            if (member == null) {
                // try for a visible field
                member = tryGetField(clazz, memberName);
            }

            members.put(memberName, member != null ? member : INVALID_MEMBER);
            return member;
        }
    }

    protected static Method tryGetMethod(Class clazz, String methodName) {
        try {
            Method method = clazz.getMethod(methodName);
            if (method != null) {
                method.setAccessible(true);
            }

            return method;
        } catch (Exception ex) {
        }

        return null;
    }

    protected static Field tryGetField(Class clazz, String fieldName) {
        try {
            Field field = clazz.getField(fieldName);
            if (field != null) {
                field.setAccessible(true);
            }

            return field;
        } catch (Exception ex) {
        }

        return null;
    }

    protected Object throwNoSuchProperty(Class clazz, String propertyName, Exception cause) {
        throw new STNoSuchPropertyException(cause, null, clazz.getName() + "." + propertyName);
    }
}