Application: gvSIG desktop

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

import java.util.Iterator;

import java.util.List;

import java.util.logging.Level;

import java.util.logging.Logger;

import org.apache.commons.lang3.Range;

import org.apache.commons.lang3.StringUtils;

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

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

import org.gvsig.tools.ToolsLocator;

import org.gvsig.tools.dataTypes.DataTypes;

import org.gvsig.tools.dataTypes.Coercion;

import org.gvsig.tools.dataTypes.CoercionException;

import org.gvsig.tools.util.GetItem;

import org.gvsig.tools.util.Size;

public class ToStrFunction extends AbstractFunction {

    @SuppressWarnings("OverridableMethodCallInConstructor")

    public ToStrFunction() {

        super(GROUP_CONVERSION, FUNCTION_TOSTR, Range.is(1));

        this.addAlias("STR");

        this.addAlias("toString");

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

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

        Object obj = this.getObject(args, 0);

        StringBuilder builder = new StringBuilder(); 

        join(builder, obj, ", ");

        return builder.toString();

    }

    private void join(StringBuilder builder, Object obj, String separator) {

        Coercion toStr = ToolsLocator.getDataTypesManager().getCoercion(DataTypes.STRING);

        if( obj instanceof Iterable ) {

            builder.append("[");

            join(builder, ((Iterable) obj).iterator(), separator);

            builder.append("]");

        } else if( obj instanceof GetItem && obj instanceof Size ) {

            Iterator it = new Iterator() {

                int i=0;

                @Override

                public boolean hasNext() {

                    return i<((Size)obj).size();

                }

                @Override

                public Object next() {

                    return ((GetItem)obj).get(i++);

                }

            };

            builder.append("[");

            join(builder, ((Iterable) obj).iterator(), separator);

            builder.append("]");

        } else {

            try {

                Object value = toStr.coerce(obj);

                builder.append(value);

            } catch (CoercionException ex) {

                builder.append(obj);

            }

        }

    }

    private void join(StringBuilder builder, Iterator it, String separator) {

        boolean needseparator = false;

        while( it.hasNext() ) {

            if( needseparator ) {

                builder.append(separator);

            } else {

                needseparator = true;

            }

            Object item = it.next();

            join(builder, item, separator);

        }

    }

}