A simple iterator facility is provided to allow, for example, iterating over the set of program symbols without having to first construct a list of all of them. A useful contribution would be to add support for SRFI 41 and SRFI 45.
<gdb:iterator>object is constructed with the
make-iteratorprocedure. It takes three arguments: the object to be iterated over, an object to record the progress of the iteration, and a procedure to return the next element in the iteration, or an implementation chosen value to denote the end of iteration.
By convention, end of iteration is marked with
(end-of-iteration), and may be tested with the
end-of-iteration?predicate. The result of
(end-of-iteration)is chosen so that it is not otherwise used by the
(gdb)module. If you are using
<gdb:iterator>in your own code it is your responsibility to maintain this invariant.
A trivial example for illustration's sake:(use-modules (gdb iterator)) (define my-list (list 1 2 3)) (define iter (make-iterator my-list my-list (lambda (iter) (let ((l (iterator-progress iter))) (if (eq? l '()) (end-of-iteration) (begin (set-iterator-progress! iter (cdr l)) (car l)))))))
Here is a slightly more realistic example, which computes a list of all the functions in
my-global-block.(use-modules (gdb iterator)) (define this-sal (find-pc-line (frame-pc (selected-frame)))) (define this-symtab (sal-symtab this-sal)) (define this-global-block (symtab-global-block this-symtab)) (define syms-iter (make-block-symbols-iterator this-global-block)) (define functions (iterator-filter symbol-function? syms-iter))
#tif object is a
<gdb:iterator>object. Otherwise return
Return the first argument that was passed to
make-iterator. This is the object being iterated over.
Set the object tracking iteration progress.
Invoke the procedure that was the third argument to
make-iterator, passing it one argument, the
<gdb:iterator>object. The result is either the next element in the iteration, or an end marker as implemented by the
next!procedure. By convention the end marker is the result of
#tif object is the end of iteration marker. Otherwise return
These functions are provided by the
(gdb iterator) module to
assist in using iterators.
<gdb:iterator>object that will iterate over list.
Return the list of objects obtained by applying proc to the object pointed to by iterator and to each subsequent object.
Apply proc to each element pointed to by iterator. The result is unspecified.
Return the list of elements pointed to by iterator that satisfy pred.