GRXImmediateWriter.h

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#import <Foundation/Foundation.h>

#import "GRXWriter.h"

// Utility to construct GRXWriter instances from values that are immediately available when
// required. The returned writers all support pausing and early termination.
//
// Unless the writeable callback pauses them or stops them early, these writers will do all their
// interactions with the writeable before the start method returns.
@interface GRXImmediateWriter : NSObject<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.
+ (id<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.
+ (id<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.
+ (id<GRXWriter>)writerWithContainer:(id<NSFastEnumeration>)container;

// Returns a writer that sends the passed value to its writeable and then finishes (releasing the
// value).
+ (id<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).
+ (id<GRXWriter>)writerWithError:(NSError *)error;

// Returns a writer that, as part of its start method, finishes immediately without sending any
// values to its writeable.
+ (id<GRXWriter>)emptyWriter;

@end