Initial checkin of gRPC to third_party/

third_party/grpc/src/objective-c/RxLibrary/GRXImmediateWriter.h

+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * 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.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * 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
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#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