bool
casereader_read (struct casereader *reader, struct ccase *c)
{
- if (reader->case_cnt != 0 && reader->class->read (reader, reader->aux, c))
+ if (reader->case_cnt != 0)
{
- assert (case_get_value_cnt (c) >= reader->value_cnt);
+ /* ->read may use casereader_swap to replace itself by
+ another reader and then delegate to that reader by
+ recursively calling casereader_read. Currently only
+ lazy_casereader does this and, with luck, nothing else
+ ever will.
+
+ To allow this to work, however, we must decrement
+ case_cnt before calling ->read. If we decremented
+ case_cnt after calling ->read, then this would actually
+ drop two cases from case_cnt instead of one, and we'd
+ lose the last case in the casereader. */
if (reader->case_cnt != CASENUMBER_MAX)
reader->case_cnt--;
- return true;
- }
- else
- {
- reader->case_cnt = 0;
- case_nullify (c);
- return false;
+ if (reader->class->read (reader, reader->aux, c))
+ {
+ assert (case_get_value_cnt (c) >= reader->value_cnt);
+ return true;
+ }
}
+ reader->case_cnt = 0;
+ case_nullify (c);
+ return false;
}
/* Destroys READER.