C++ example: ContinuousIntegerParser

The ContinuousIntegerParser example is a variation of BasicIntegerParser. Both examples parse integers from input strings. ContinuousIntegerParser uses Continuous load to read data.

Loading and using the example

Load the ContinuousIntegerParser example as follows.

=> CREATE LIBRARY ContinuousIntegerParserLib AS '/home/dbadmin/CIP.so';

=> CREATE PARSER ContinuousIntegerParser AS
LANGUAGE 'C++' NAME 'ContinuousIntegerParserFactory'
LIBRARY ContinuousIntegerParserLib;

Use it in the same way that you use BasicIntegerParser. See C++ example: BasicIntegerParser.

Implementation

ContinuousIntegerParser is a subclass of ContinuousUDParser. Subclasses of ContinuousUDParser place the processing logic in the run() method.

    virtual void run() {

        // This parser assumes a single-column input, and
        // a stream of ASCII integers split by non-numeric characters.
        size_t pos = 0;
        size_t reserved = cr.reserve(pos+1);
        while (!cr.isEof() || reserved == pos + 1) {
            while (reserved == pos + 1 && isdigit(*ptr(pos))) {
                pos++;
                reserved = cr.reserve(pos + 1);
            }

            std::string st(ptr(), pos);
            writer->setInt(0, strToInt(st));
            writer->next();

            while (reserved == pos + 1 && !isdigit(*ptr(pos))) {
                pos++;
                reserved = cr.reserve(pos + 1);
            }
            cr.seek(pos);
            pos = 0;
            reserved = cr.reserve(pos + 1);
        }
    }
};

For a more complex example of a ContinuousUDParser, see ExampleDelimitedParser in the examples. (See Downloading and running UDx example code.) ExampleDelimitedParser uses a chunker; see C++ example: delimited parser and chunker.