-
Notifications
You must be signed in to change notification settings - Fork 0
/
reader.go
165 lines (142 loc) · 3.3 KB
/
reader.go
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
153
154
155
156
157
158
159
160
161
162
163
164
165
package chain
import (
"io"
)
// ReaderBuilder lets you build a chain of io.Readers
// in a more natural way
type ReaderBuilder struct {
r io.ReadCloser
err error
}
// ReadChain represents a common pattern in go packages.
// For examples, see:
// https://pkg.go.dev/compress/gzip#NewReader
//
// While this type only expects an io.Reader to be returned, it will
// detect if the result is a Closer and make sure the
// types Close function is run.
type ReadChain func(io.ReadCloser) (io.ReadCloser, error)
// ReadingFrom creates a new ReaderBuilder where the
// contents of the chain comes from the given io.Reader
//
// If r is an io.ReadCloser, the resulting Reader
// after building the chain will call r.Close for you
func ReadingFrom(r io.ReadCloser) *ReaderBuilder {
return &ReaderBuilder{r: r}
}
// Then adds the next ReadChain to the current builder chain
func (chain *ReaderBuilder) Then(next ReadChain) *ReaderBuilder {
if chain.err == nil {
r, err := next(chain.r)
if err != nil {
chain.r.Close()
chain.err = err
} else {
chain.r = r
}
}
return chain
}
// Finally adds the last ReadChain to the current builder chain,
// then builds it into an io.ReadCloser
func (chain *ReaderBuilder) Finally(next ReadChain) (io.ReadCloser, error) {
chain.Then(next)
return chain.r, chain.err
}
type ReadFSChain func(io.ReadCloser) (ReadFS, error)
type ReaderFSBuilder struct {
first *ReaderBuilder
fs ReadFSChain
after []ReadChain
}
func ReadingFromFS(fs ReadFS) *ReaderFSBuilder {
return &ReaderFSBuilder{
first: &ReaderBuilder{
r: io.NopCloser(nil),
},
fs: func(io.ReadCloser) (ReadFS, error) { return fs, nil },
after: nil,
}
}
func (chain *ReaderBuilder) AsFS(next ReadFSChain) *ReaderFSBuilder {
return &ReaderFSBuilder{
first: chain,
fs: next,
after: nil,
}
}
func (chain *ReaderFSBuilder) Open(name string) *ReaderBuilder {
fs, err := chain.build()
if err != nil {
return &ReaderBuilder{err: err}
}
r, err := fs.Open(name)
if err != nil {
fs.Close()
return &ReaderBuilder{err: err}
}
return &ReaderBuilder{r: ReadCloser2{
ReadCloser: r,
Closer: fs.fs,
}}
}
func (chain *ReaderFSBuilder) Then(next ReadChain) *ReaderFSBuilder {
chain.after = append(chain.after, next)
return chain
}
func (chain *ReaderFSBuilder) Finally(next ReadChain) (ReadFS, error) {
return chain.Then(next).build()
}
func (chain *ReaderFSBuilder) build() (*readFS, error) {
if chain.first.err != nil {
return nil, chain.first.err
}
fs, err := chain.fs(chain.first.r)
if err != nil {
return nil, err
}
return &readFS{
Closer: chain.first.r,
fs: fs,
after: chain.after,
}, nil
}
type readFS struct {
io.Closer
fs ReadFS
after []ReadChain
}
func (fs *readFS) Open(path string) (io.ReadCloser, error) {
r, err := fs.fs.Open(path)
if err != nil {
return nil, err
}
builder := ReadingFrom(r)
for _, then := range fs.after {
builder.Then(then)
}
if builder.err != nil {
return nil, builder.err
}
return builder.r, nil
}
type ReadFS interface {
Open(path string) (io.ReadCloser, error)
io.Closer
}
type ReadCloser2 struct {
io.ReadCloser
Closer io.Closer
}
func (wc ReadCloser2) Close() error {
err1 := wc.ReadCloser.Close()
err2 := wc.Closer.Close()
if err1 != nil {
return err1
}
return err2
}
type ReadCloser struct {
io.Reader
io.Closer
}