3.2.2.1 Example 1: prototyped arrays of even-length arrays

 

As a first example, consider a matrix of reals given as an array of arrays³. In this case, the prototype consists of a common meta operator whose value is MP_CopProtoArray and whose number-of-arguments field is non-zero. The common meta operator has a prototype annotation specifying the type of each argument to the MP_CopProtoArray operator. Notice again, that the number-of-arguments field of the meta operator specifies the number of data values that appear at data communication time and not the number of arguments that follow the meta operator within the prototype tree. Figure 5 gives prototyped and non-prototyped versions side-by-side for comparison.

  

Figure 5: An array of even-lengths arrays

The top-level operator on line 1 specifies an array with 2 arguments. The prototype annotation starting on line 2 specifies the element type of the top-level array to be a 3 element array (line 3). So each element of the array from line 1 is another array. The meta operator on line 3 also has a prototype (lines 4 - 5) specifying that the elements of each subarray is an IMP_Real32. Note that the meta operator on line 3 does not have any actual arguments within the prototype tree. The number-of-arguments field specifies the number of arguments to expect in the prototyped data tree that follows.