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/**
 * 
 */
package com.feilong.lib.ognl;

import com.feilong.lib.ognl.enhance.UnsupportedCompilationException;

/**
 * Base class for types that compare values.
 */
public abstract class ComparisonExpression extends BooleanExpression{

    /**
     * 
     */
    private static final long serialVersionUID = 3946867623791689411L;

    public ComparisonExpression(int id){
        super(id);
    }

    public ComparisonExpression(OgnlParser p, int id){
        super(p, id);
    }

    public abstract String getComparisonFunction();

    @Override
    public String toGetSourceString(OgnlContext context,Object target){
        if (target == null){
            throw new UnsupportedCompilationException("Current target is null, can't compile.");
        }

        try{

            Object value = getValueBody(context, target);

            if (value != null && Boolean.class.isAssignableFrom(value.getClass())){
                _getterClass = Boolean.TYPE;
            }else if (value != null){
                _getterClass = value.getClass();
            }else{
                _getterClass = Boolean.TYPE;
            }

            // iterate over children to make numeric type detection work properly

            OgnlRuntime.getChildSource(context, target, _children[0]);
            OgnlRuntime.getChildSource(context, target, _children[1]);

            //            System.out.println("comparison expression currentType: " + context.getCurrentType() + " previousType: " + context.getPreviousType());

            boolean conversion = OgnlRuntime.shouldConvertNumericTypes(context);

            String result = conversion ? "(" + getComparisonFunction() + "( ($w) (" : "(";

            result += OgnlRuntime.getChildSource(context, target, _children[0], conversion) + " "
                            + (conversion ? "), ($w) " : getExpressionOperator(0)) + " "
                            + OgnlRuntime.getChildSource(context, target, _children[1], conversion);

            result += conversion ? ")" : "";

            context.setCurrentType(Boolean.TYPE);

            result += ")";

            return result;
        }catch (NullPointerException e){

            // expected to happen in some instances

            throw new UnsupportedCompilationException("evaluation resulted in null expression.");
        }catch (Throwable t){
            throw OgnlOps.castToRuntime(t);
        }
    }
}