What is Big, Red, and Eats Rocks?

This question has often vexed me since my childhood, ``What's big, red, and eats rocks?'' As anyone who grew up with the excellent children's book Big Red Rock Eater knows, a big red rock eater is big red and eats rocks. ( Sometimes the most complicated questions have the simplest answers. ) So what does this have to do with GAT much less the GATAdvertService?

We will next create a command line program, which we will christen brre, pronounced like ``brie'' and whose letters are an abbreviation for the phrase ``Big Red Rock Eater.'' This program given an set of key/value pairs will print out the POSIX paths of all the various advertisables which fit the description created by the passed key/value paris. For example, one could call brre as follows

% brre size=big color=red diet=rocks

The program would then respond with a list of POSIX paths which might look like this

/Users/MrBigRedRockEater
/Users/MrsBigRedRockEater

In addition these command line arguments can also contain POSIX regular expressions as values, see Appendix for the details of what a POSIX regular expression is. For example, one might also use brre as follows

% brre size=big color=r* diet=rocks

which might yield the results

/Users/MrsBigRotRockEater
/Users/MrBigRedRockEater
/Users/MrsBigRedRockEater

The full code for the command line tool brre is as follows

#include <stdio.h>
#include <string.h>
#include "GAT.h"

int main( int argc, char *argv[] )
{
    int count;
    char *key;
    char *value;
    int returnValue;
    GATTable table;
    GATResult result;
    GATContext context;
    GATList_String strings;
    GATAdvertService advertService;
    GATList_String_Iterator currentIterator;
    
    /* Set result to a memory failure */
    result = GAT_MEMORYFAILURE;
  
    /* Create GATTable */
    table = GATTable_Create();
    
    /* Check GATTable creation */
    if( NULL != table )
    {
      /* Loop over command line arguments */
      for( count = 1; count < argc; count++ )
      {
        /* Obtain key */
        key = strtok( argv[count], "=" );
        
        /* Obtain value */
        if( NULL != key )
          value = strtok( NULL, "=" );
        
        /* Place key and value in GATTable */
        if( (NULL != key) && (NULL != value) )
          result = GATTable_Add_String( table, key, value );
          
        /* Print out error */
         if( (NULL == key) || (NULL == value) || GAT_FAILED( result ) )
           printf( "Error parsing command line argument: %s\n", argv[count] );
      }
      
      /* Set result to a memory failure */
      result = GAT_MEMORYFAILURE;
      
      /* Create GATContext */
      context = GATContext_Create();
      
      /* Check GATContext creation */
      if( NULL != context )
      {
        /* Create GATAdvertService */
        advertService = GATAdvertService_Create( context, NULL );
        
        /* Check GATAdvertService creation */
        if( NULL != advertService )
        {
          /* Find Advertisables */
          result = GATAdvertService_Find( advertService, table, strings );
          
          /* Check Success of Last Call */
          if( GAT_SUCCEEDED( result ) )
          {
            /* Obtain Beginning GATList_String_Iterator */
            currentIterator = GATList_String_Begin( strings );
            
            /* Loop over strings */
            while( currentIterator != GATList_String_End( strings ) )
            {
              /* Print out POSIX path */
              printf( "%s\n", GATList_String_Get( currentIterator ) );
              
              /* Increment currentIterator */
              currentIterator = GATList_String_Next( currentIterator );
            }
            
            /* Destroy GATList_String */
            GATList_String_Destroy( &strings );
          }
        
          /* Destroy GATAdvertService */
          GATAdvertService_Destroy( &advertService );
        }
      
        /* Destroy GATContext */
        GATContext_Destroy( &context );
      }
      
      /* Destroy GATTable */
      GATTable_Destroy( &table );
    }
    
    /* Set returnValue and print error message */
    returnValue = 0;
    if( GAT_FAILED( result ) )
    {
      returnValue = 1;
      
      printf( "There was an error in execution of brre\n" );
    }
    
    /* Return to OS */
    return returnValue;
}