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/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#import <Foundation/Foundation.h>
#import "GRXWriter.h"
/**
* Utility to construct GRXWriter instances from values that are immediately available when
* required.
*
* Thread-safety:
*
* An object of this class shouldn't be messaged concurrently by more than one thread. It will start
* messaging the writeable before |startWithWriteable:| returns, in the same thread. That is the
* only place where the writer can be paused or stopped prematurely.
*
* If a paused writer of this class is resumed, it will start messaging the writeable, in the same
* thread, before |setState:| returns. Because the object can't be legally accessed concurrently,
* that's the only place where it can be paused again (or stopped).
*/
@interface GRXImmediateWriter : GRXWriter
/**
* Returns a writer that pulls values from the passed NSEnumerator instance and pushes them to
* its writeable. The NSEnumerator is released when it finishes.
*/
+ (GRXWriter *)writerWithEnumerator:(NSEnumerator *)enumerator;
/**
* Returns a writer that pushes to its writeable the successive values returned by the passed
* block. When the block first returns nil, it is released.
*/
+ (GRXWriter *)writerWithValueSupplier:(id (^)(void))block;
/**
* Returns a writer that iterates over the values of the passed container and pushes them to
* its writeable. The container is released when the iteration is over.
*
* Note that the usual speed gain of NSFastEnumeration over NSEnumerator results from not having to
* call one method per element. Because GRXWriteable instances accept values one by one, that speed
* gain doesn't happen here.
*/
+ (GRXWriter *)writerWithContainer:(id<NSFastEnumeration>)container;
/**
* Returns a writer that sends the passed value to its writeable and then finishes (releasing the
* value).
*/
+ (GRXWriter *)writerWithValue:(id)value;
/**
* Returns a writer that, as part of its start method, sends the passed error to the writeable
* (then releasing the error).
*/
+ (GRXWriter *)writerWithError:(NSError *)error;
/**
* Returns a writer that, as part of its start method, finishes immediately without sending any
* values to its writeable.
*/
+ (GRXWriter *)emptyWriter;
@end
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