• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1/*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *     http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19#import "GRXImmediateWriter.h"
20
21#import "NSEnumerator+GRXUtil.h"
22
23@implementation GRXImmediateWriter {
24  NSEnumerator *_enumerator;
25  NSError *_errorOrNil;
26  id<GRXWriteable> _writeable;
27}
28
29@synthesize state = _state;
30
31- (instancetype)init {
32  return [self initWithEnumerator:nil error:nil];  // results in an empty writer.
33}
34
35// Designated initializer
36- (instancetype)initWithEnumerator:(NSEnumerator *)enumerator error:(NSError *)errorOrNil {
37  if (((self = [super init]))) {
38    _enumerator = enumerator;
39    _errorOrNil = errorOrNil;
40    _state = GRXWriterStateNotStarted;
41  }
42  return self;
43}
44
45#pragma mark Convenience constructors
46
47+ (instancetype)writerWithEnumerator:(NSEnumerator *)enumerator error:(NSError *)errorOrNil {
48  return [[self alloc] initWithEnumerator:enumerator error:errorOrNil];
49}
50
51+ (GRXWriter *)writerWithEnumerator:(NSEnumerator *)enumerator {
52  return [self writerWithEnumerator:enumerator error:nil];
53}
54
55+ (GRXWriter *)writerWithValueSupplier:(id (^)(void))block {
56  return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithValueSupplier:block]];
57}
58
59+ (GRXWriter *)writerWithContainer:(id<NSFastEnumeration>)container {
60  return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithContainer:container]];
61  ;
62}
63
64+ (GRXWriter *)writerWithValue:(id)value {
65  return [self writerWithEnumerator:[NSEnumerator grx_enumeratorWithSingleValue:value]];
66}
67
68+ (GRXWriter *)writerWithError:(NSError *)error {
69  return [self writerWithEnumerator:nil error:error];
70}
71
72+ (GRXWriter *)emptyWriter {
73  return [self writerWithEnumerator:nil error:nil];
74}
75
76#pragma mark Conformance with GRXWriter
77
78// Most of the complexity in this implementation is the result of supporting pause and resumption of
79// the GRXWriter. It's an important feature for instances of GRXWriter that are backed by a
80// container (which may be huge), or by a NSEnumerator (which may even be infinite).
81
82- (void)writeUntilPausedOrStopped {
83  id value;
84  while (value = [_enumerator nextObject]) {
85    [_writeable writeValue:value];
86    // If the writeable has a reference to us, it might change our state to paused or finished.
87    if (_state == GRXWriterStatePaused || _state == GRXWriterStateFinished) {
88      return;
89    }
90  }
91  [self finishWithError:_errorOrNil];
92}
93
94- (void)startWithWriteable:(id<GRXWriteable>)writeable {
95  _state = GRXWriterStateStarted;
96  _writeable = writeable;
97  [self writeUntilPausedOrStopped];
98}
99
100- (void)finishWithError:(NSError *)errorOrNil {
101  _state = GRXWriterStateFinished;
102  _enumerator = nil;
103  _errorOrNil = nil;
104  id<GRXWriteable> writeable = _writeable;
105  _writeable = nil;
106  [writeable writesFinishedWithError:errorOrNil];
107}
108
109- (void)setState:(GRXWriterState)newState {
110  // Manual transitions are only allowed from the started or paused states.
111  if (_state == GRXWriterStateNotStarted || _state == GRXWriterStateFinished) {
112    return;
113  }
114
115  switch (newState) {
116    case GRXWriterStateFinished:
117      _state = newState;
118      _enumerator = nil;
119      _errorOrNil = nil;
120      // Per GRXWriter's contract, setting the state to Finished manually
121      // means one doesn't wish the writeable to be messaged anymore.
122      _writeable = nil;
123      return;
124    case GRXWriterStatePaused:
125      _state = newState;
126      return;
127    case GRXWriterStateStarted:
128      if (_state == GRXWriterStatePaused) {
129        _state = newState;
130        [self writeUntilPausedOrStopped];
131      }
132      return;
133    case GRXWriterStateNotStarted:
134      return;
135  }
136}
137
138@end
139