string_pad_get.cpp (Beispielprogramm)

/** 
* UDF string_pad_get(int4) -> char(1)
* Gets a character at index from the pad "stringpad". 
* The pad must be created first by using string_pad_create.
* 
* argument1 = index at which to return the character
* 
* returns = the character at index
* 
* throws error if the spu pad "stringpad" is not found or if index 
* is out of range.
* 
* COMPILATION:
* nzudxcompile UDX_StringPadGet.cpp -o /tmp/test/UDX_StringPadGet.o
* 
* REGISTRATION:
* CREATE OR REPLACE FUNCTION string_pad_get (int4)
* RETURNS char(1)
* LANGUAGE CPP
* PARAMETER STYLE NPSGENERIC NOT FENCED
* CALLED ON NULL INPUT
* NOT DETERMINISTIC
* EXTERNAL CLASS NAME 'StringPadGet'
* EXTERNAL HOST OBJECT '/tmp/test/UDX_StringPadGet.o_x86'
* EXTERNAL SPU OBJECT '/tmp/test/UDX_StringPadGet.o_spu10';
* 
* -->Do not register any spu-pad related UDFs as 'deterministic'
* 
* USAGE:
* CREATE TABLE one_dslice(c1 int4);
* INSERT INTO one_dslice VALUES(1);
* SELECT string_pad_create(10, 'netezza') FROM one_dslice;
* SELECT string_pad_get(1) FROM one_dslice;
* 
* Copyright (c) 2007-2010 Netezza Corporation, an IBM Company
* All rights reserved.
*/


#include "udxinc.h"
#include <string.h>

using namespace nz::udx;

struct Root
{
 char* data;
 int size;
};

class StringPadGet: public Udf
{
private:

public:
  static Udf* instantiate();
  virtual ReturnValue evaluate()
  {

    if(isArgNull(0))
    {
      throwUdxException("must not accept null arguments.");
    }
    if(argType(0)!=UDX_INT32)
    {
      throwUdxException("1st argument must be int4 (int32).");
    }
    CPad* pad = getPad("stringpad");
    Root *ro = (Root*) pad->getRootObject(sizeof(Root));
    if(!ro)
    {
      throwUdxException("Pad does not exist");
    }
    else
    {
      int index = int32Arg(0);
      if(index<0||index>=ro->size)
      {
        throwUdxException("Index out of bounds");
      }
      StringReturn *ret = stringReturnInfo();
      ret->size=1;
      ret->data[0]=ro->data[index];
      NZ_UDX_RETURN_STRING(ret); 
    }
  }
};

Udf* StringPadGet::instantiate()
{
    return new StringPadGet;
}