1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*
*
* 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 "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 (^)())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
|
