View Source erlfdb_iterator behaviour (erlfdb v0.3.4)

A generic iterator behaviour, useful for streaming results from the database.

Summary

Types

iterator()

result()

state()

Callbacks

handle_call/3

handle_next/1

handle_stop/1

Functions

call(Iterator, Call)

Executes a handle_call on the iterator.

module_state/1

Identifies the module and the specific state of the iterator implementation.

new(Module, State)

Creates an iterator.

next/1

Progresses the iterator one step.

pipeline(List)

Runs all iterators to completion.

run(Iterator)

Runs the iterator to completion.

stop/1

Stops the iterator.

Types

iterator()

-type iterator() :: {module(), state()}.

result()

-type result() :: term().

state()

-type state() :: term().

Callbacks

handle_call/3

(optional)

-callback handle_call(term(), term(), state()) -> {reply, term(), state()}.

handle_next/1

-callback handle_next(state()) ->
                         {cont, [result()], state()} | {halt, [result()], state()} | {halt, state()}.

handle_stop/1

-callback handle_stop(state()) -> ok.

Functions

call(Iterator, Call)

-spec call(iterator(), term()) -> {term(), iterator()}.

Executes a handle_call on the iterator.

module_state/1

-spec module_state(iterator()) -> {module(), state()}.

Identifies the module and the specific state of the iterator implementation.

new(Module, State)

-spec new(module(), state()) -> iterator().

Creates an iterator.

next/1

-spec next(iterator()) ->
              {cont, [result()], iterator()} | {halt, [result()], iterator()} | {halt, iterator()}.

Progresses the iterator one step.

pipeline(List)

-spec pipeline([iterator()]) -> [{[result()], iterator()}].

Runs all iterators to completion.

Caller must call stop/1 to terminate the iterators.

run(Iterator)

-spec run(iterator()) -> {[result()], iterator()}.

Runs the iterator to completion.

Returns the list of results and the state of the iterator.

Caller must call stop/1 to terminate the iterator.

stop/1

-spec stop(iterator()) -> ok.

Stops the iterator.