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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 "GRXImmediateWriter.h"
#import "NSEnumerator+GRXUtil.h"
@implementation GRXImmediateWriter {
NSEnumerator *_enumerator;
NSError *_errorOrNil;
id<GRXWriteable> _writeable;
}
@synthesize state = _state;
- (instancetype)init {
return [self initWithEnumerator:nil error:nil]; // results in an empty writer.
}
// Designated initializer
- (instancetype)initWithEnumerator:(NSEnumerator *)enumerator error:(NSError *)errorOrNil {
if (((self = [super init]))) {
_enumerator = enumerator;
_errorOrNil = errorOrNil;
_state = GRXWriterStateNotStarted;
}
return self;
}
#pragma mark Convenience constructors
+ (instancetype)writerWithEnumerator:(NSEnumerator *)enumerator error:(NSError *)errorOrNil {
return [[self alloc] initWithEnumerator:enumerator error:errorOrNil];
}
+ (GRXWriter *)writerWithEnumerator:(NSEnumerator *)enumerator {
return [self writerWithEnumerator:enumerator error:nil];
}
+ (GRXWriter *)writerWithValueSupplier:(id (^)(void))block {
return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithValueSupplier:block]];
}
+ (GRXWriter *)writerWithContainer:(id<NSFastEnumeration>)container {
return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithContainer:container]];
;
}
+ (GRXWriter *)writerWithValue:(id)value {
return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithSingleValue:value]];
}
+ (GRXWriter *)writerWithError:(NSError *)error {
return [self writerWithEnumerator:nil error:error];
}
+ (GRXWriter *)emptyWriter {
return [self writerWithEnumerator:nil error:nil];
}
#pragma mark Conformance with GRXWriter
// Most of the complexity in this implementation is the result of supporting pause and resumption of
// the GRXWriter. It's an important feature for instances of GRXWriter that are backed by a
// container (which may be huge), or by a NSEnumerator (which may even be infinite).
- (void)writeUntilPausedOrStopped {
id value;
while (value = [_enumerator nextObject]) {
[_writeable writeValue:value];
// If the writeable has a reference to us, it might change our state to paused or finished.
if (_state == GRXWriterStatePaused || _state == GRXWriterStateFinished) {
return;
}
}
[self finishWithError:_errorOrNil];
}
- (void)startWithWriteable:(id<GRXWriteable>)writeable {
_state = GRXWriterStateStarted;
_writeable = writeable;
[self writeUntilPausedOrStopped];
}
- (void)finishWithError:(NSError *)errorOrNil {
_state = GRXWriterStateFinished;
_enumerator = nil;
_errorOrNil = nil;
id<GRXWriteable> writeable = _writeable;
_writeable = nil;
[writeable writesFinishedWithError:errorOrNil];
}
- (void)setState:(GRXWriterState)newState {
// Manual transitions are only allowed from the started or paused states.
if (_state == GRXWriterStateNotStarted || _state == GRXWriterStateFinished) {
return;
}
switch (newState) {
case GRXWriterStateFinished:
_state = newState;
_enumerator = nil;
_errorOrNil = nil;
// Per GRXWriter's contract, setting the state to Finished manually
// means one doesn't wish the writeable to be messaged anymore.
_writeable = nil;
return;
case GRXWriterStatePaused:
_state = newState;
return;
case GRXWriterStateStarted:
if (_state == GRXWriterStatePaused) {
_state = newState;
[self writeUntilPausedOrStopped];
}
return;
case GRXWriterStateNotStarted:
return;
}
}
@end
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