[−][src]Module sophia::triple::stream
A triple source produces triples, and may also fail in the process.
The trait TripleSource
provides an API similar to (a subset of) the Iterator API,
with methods such as for_each_triple and try_for_each_triple.
Rationale (or Why not simply use Iterator?)
The Iterator trait is designed in such a way that items must live at least as long as the iterator itself.
This assumption may be too strong in some situations.
For example,
consider a parser using 3 buffers to store the subject, predicate,
and object of the triples it parses.
Each time it extracts a triple from the data,
it yields it (as 3 references to its internal buffers)
to the closure passed to for_each_triple.
Then, it reuses the buffers to store the data for the next triple,
and yields the new triple, as 3 references to the same buffers.
Such a parser can not implement Iterator,
because, once yielded by the iterator's next method,
an item is free to live during further iterations.
In particular, it can be stored in a vector,
and still be alive when the next method is called again
(consider for example the Iterator::collect method).
Because many parsers (as well as other triple sources) will be implemented in a manner similar to that described above, we have to provide a trait with weaker assumptions on the lifetime of the yielded triples.
The alternative would be to wrap such parsers with a layer that would copy the data from internal buffers to fresh buffers for each triples, but we do not want to impose that cost on all implementations — especially when many consumers will be happy with short-lived references.
Structs
| FilterMapSource | The result of
|
| FilterMapSourceIterator | An iterator over the result of
|
| FilterSource | The result of
|
| MapSource | The result of
|
| MapSourceIterator | An iterator over the result of
|
Enums
| StreamError | A error that is raised by functions that move fallible |
Traits
| AsTripleSource | A utility extension trait for converting any iterator of |
| SinkResult | Extension trait for |
| SourceResult | Extension trait for |
| TripleSource | A triple source produces triples, and may also fail in the process. |
Type Definitions
| AsInfallibleSource | |
| StreamResult | Convenient type alias |
| TSTerm | Type alias for referencing the |