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/****************************************************************************
 * author: Daniel Leybovich
 *
 * COMPILE:
 *
 *  $ g++ -D HAVE_LONG_INT_64 -I /opt/vertica/sdk/include -Wall \
 *  > -shared -Wno-unused-value -fPIC -o Cast.so Cast.cpp /opt/vertica/sdk/include/Vertica.cpp
 *
 ****************************************************************************/

/****************************************************************************
 *
 * daniel=> drop librARY castlib cascade;
 * ROLLBACK 3855:  Library "castlib" does not exist
 *
 * daniel=> CREATE LIBRARY CastLib AS '/tmp/Cast.so';
 * CREATE LIBRARY
 *
 * daniel=> CREATE FUNCTION int2str AS LANGUAGE 'C++' NAME 'CastFactory' LIBRARY CastLib;
 * CREATE FUNCTION
 *
 * daniel=> select int2str(2345);
 *        int2str
 * ---------------------
 *  2345 -*- append -*-
 * (1 row)
 *
 ****************************************************************************/
#include <string>
#include "Vertica.h"

using namespace Vertica;

class Cast : public ScalarFunction
{
    public:

        virtual void processBlock(ServerInterface &srvInterface, BlockReader &argReader, BlockWriter &resWriter) {
            try {
                if (argReader.getNumCols() != 1) {
                    vt_report_error(0, "Function only accept 1 arguments, but %zu provided", argReader.getNumCols());
                }

                // data type containers
                std::stringstream stream;
                std::string aString;

                do {

                    // get integer
                    stream << argReader.getIntRef(0);

                    // convert to string
                    stream >> aString;

                    // append to a string
                    aString.append(" -*- append -*-");

                    // write a result as VARCHAR
                    resWriter.getStringRef().copy(aString);

                    // process next
                    resWriter.next();

                } while (argReader.next());

            } catch(std::exception& e) {
                vt_report_error(0, "Exception while processing block: [%s]", e.what());
            }
        }
};

class CastFactory : public ScalarFunctionFactory {

    virtual ScalarFunction *createScalarFunction(ServerInterface &interface) {
        return vt_createFuncObject<Cast>(interface.allocator);
    }

    virtual void getPrototype(ServerInterface &interface, ColumnTypes &argTypes, ColumnTypes &returnType) {
        argTypes.addInt();
        returnType.addVarchar();
    }

    virtual void getReturnType(ServerInterface &srvInterface, const SizedColumnTypes &argTypes, SizedColumnTypes &returnType) {
        returnType.addVarchar(80);
    }

};

RegisterFactory(CastFactory);