/*
 *
 * Copyright 2015, Google Inc.
 * All rights reserved.
 *
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 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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#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 (^)())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