Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl.function.programming;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

import java.util.Map;

import javax.json.JsonObject;

import org.apache.commons.lang3.Range;

import org.apache.commons.lang3.StringUtils;

import org.gvsig.expressionevaluator.AttributeHandler;

import org.gvsig.expressionevaluator.Code;

import org.gvsig.expressionevaluator.Codes;

import org.gvsig.expressionevaluator.ExpressionBuilder;

import static org.gvsig.expressionevaluator.ExpressionBuilder.FUNCTION_GETATTR;

import org.gvsig.expressionevaluator.Formatter;

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

import org.gvsig.expressionevaluator.spi.JsonUtils;

import org.gvsig.tools.dynobject.DynObject;

import org.gvsig.tools.util.GetItemByKey;

import org.gvsig.tools.util.PropertiesSupport;

public class GetattrFunction extends AbstractFunction {

    public GetattrFunction() {

        super(

                Function.GROUP_PROGRAMMING, 

                FUNCTION_GETATTR, 

                Range.is(2),

                null,

                "GETATTR({{object}}, attribute_name_as_string)",

                null,

                null,

                true

        );

    }

    @Override

    public boolean allowConstantFolding() {

        return false;

    }

    @Override

    public Object call(Interpreter interpreter, Object[] args) throws Exception {

        Object obj = getObject(args, 0);

        String attrname = getStr(args,1);

        if( StringUtils.isBlank(attrname) ) {

            throw new NullPointerException("A attribute name was expected and a null was received");

        }

        if( obj==null ) {

            return null;

            //throw new NullPointerException("An object pointer was expected to access attribute "+attrname+" and a null was received");

        }

        Object value;

        if( obj instanceof DynObject && ((DynObject) obj).hasDynValue(attrname) ) {

            value = ((DynObject) obj).getDynValue(attrname);

        } else if( obj instanceof AttributeHandler ) {

            value = ((AttributeHandler) obj).get(attrname);

        } else if( obj instanceof GetItemByKey ) {

            value = ((GetItemByKey) obj).get(attrname);

        } else {

            Field field = this.getField(obj, attrname);

            if( field!=null ) {

                value = field.get(obj);

            } else {

                Method method = this.getMethod(obj, "get" + StringUtils.capitalize(attrname));

                if( method!=null ) {

                    value = method.invoke(obj);

                } else if( obj instanceof PropertiesSupport ) {

                    value = ((PropertiesSupport) obj).getProperty(attrname);

                } else if( obj instanceof JsonObject ) {

                    JsonObject jsonobj = ((JsonObject)obj);

                    value = JsonUtils.getitem(jsonobj, attrname);

                } else if( obj instanceof Map ) {

                    value = ((Map)obj).get(attrname);

                } else {

                    throw new NoSuchFieldException(attrname);

                }

            }

        }

        return value;

    }

    @Override

    public String toString(Codes args, Formatter<Code> formatter) {

        StringBuilder builder = new StringBuilder();

        Code arg0 = args.get(0);

        Code arg1 = args.get(1);

//        if( arg0 instanceof Code.Identifier && arg1 instanceof Code.Identifier ) {

//          builder.append(arg0.toString(formatter));

//          builder.append("->");

//          builder.append(arg1.toString());

//        } else 

        if( arg0 instanceof Code.Identifier && arg1 instanceof Code.Constant && ((Code.Constant)arg1).value() instanceof CharSequence ) {

          builder.append(arg0.toString(formatter));

          builder.append(".\"");

          builder.append(((Code.Constant)arg1).value().toString());

          builder.append("\"");

        } else {

          builder.append(this.name());

          builder.append("(");

          builder.append(arg0.toString(formatter));

          builder.append(", ");

          builder.append(arg1.toString(formatter));

          builder.append(")");

        }

        return builder.toString();

    }

    private Field getField(Object obj, String attrname) {

        Class<?> theClass = obj.getClass();

        try {

            Field field = theClass.getField(attrname);

            return field;

        } catch(NoSuchFieldException e) {

            return null;

        }

    }

    private Method getMethod(Object obj, String methodname) {

        Class<?> theClass = obj.getClass();

        try {

            Method method = theClass.getMethod(methodname);

            return method;

        } catch(NoSuchMethodException e) {

            return null;

        }

    }

    @Override

    public ExpressionBuilder.Value toValue(ExpressionBuilder builder, Codes parameters) {

        Code arg0 = parameters.get(0);

        Code arg1 = parameters.get(1);

        if( arg0 instanceof Code.Identifier && 

                arg1 instanceof Code.Constant && 

                ((Code.Constant)arg1).value() instanceof CharSequence ) {

            return builder.getattr(

                    ((Code.Identifier)arg0).name(), 

                    ((Code.Constant)arg1).value().toString()

            );

        }

        return builder.function(FUNCTION_GETATTR,arg0.toValue(), arg1.toValue());

    }

}