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
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file implements the Mapping data structure.
package main
import (
"fmt"
"io"
"os"
pathutil "path"
"sort"
"strings"
)
// A Mapping object maps relative paths (e.g. from URLs)
// to absolute paths (of the file system) and vice versa.
//
// A Mapping object consists of a list of individual mappings
// of the form: prefix -> path which are interpreted as follows:
// A relative path of the form prefix/tail is to be mapped to
// the absolute path/tail, if that absolute path exists in the file
// system. Given a Mapping object, a relative path is mapped to an
// absolute path by trying each of the individual mappings in order,
// until a valid mapping is found. For instance, for the mapping:
//
// user -> /home/user
// public -> /home/user/public
// public -> /home/build/public
//
// the relative paths below are mapped to absolute paths as follows:
//
// user/foo -> /home/user/foo
// public/net/rpc/file1.go -> /home/user/public/net/rpc/file1.go
//
// If there is no /home/user/public/net/rpc/file2.go, the next public
// mapping entry is used to map the relative path to:
//
// public/net/rpc/file2.go -> /home/build/public/net/rpc/file2.go
//
// (assuming that file exists).
//
// Each individual mapping also has a RWValue associated with it that
// may be used to store mapping-specific information. See the Iterate
// method.
//
type Mapping struct {
list []mapping
prefixes []string // lazily computed from list
}
type mapping struct {
prefix, path string
value *RWValue
}
// Init initializes the Mapping from a list of ':'-separated
// paths. Empty paths are ignored; relative paths are assumed
// to be relative to the current working directory and converted
// to absolute paths. For each path of the form:
//
// dirname/localname
//
// a mapping
//
// localname -> path
//
// is added to the Mapping object, in the order of occurrence.
// For instance, the argument:
//
// /home/user:/home/build/public
//
// leads to the following mapping:
//
// user -> /home/user
// public -> /home/build/public
//
func (m *Mapping) Init(paths string) {
pathlist := canonicalizePaths(strings.Split(paths, ":", -1), nil)
list := make([]mapping, len(pathlist))
// create mapping list
for i, path := range pathlist {
_, prefix := pathutil.Split(path)
list[i] = mapping{prefix, path, new(RWValue)}
}
m.list = list
}
// IsEmpty returns true if there are no mappings specified.
func (m *Mapping) IsEmpty() bool { return len(m.list) == 0 }
// PrefixList returns a list of all prefixes, with duplicates removed.
// For instance, for the mapping:
//
// user -> /home/user
// public -> /home/user/public
// public -> /home/build/public
//
// the prefix list is:
//
// user, public
//
func (m *Mapping) PrefixList() []string {
// compute the list lazily
if m.prefixes == nil {
list := make([]string, len(m.list))
// populate list
for i, e := range m.list {
list[i] = e.prefix
}
// sort the list and remove duplicate entries
sort.SortStrings(list)
i := 0
prev := ""
for _, path := range list {
if path != prev {
list[i] = path
i++
prev = path
}
}
m.prefixes = list[0:i]
}
return m.prefixes
}
// Fprint prints the mapping.
func (m *Mapping) Fprint(w io.Writer) {
for _, e := range m.list {
fmt.Fprintf(w, "\t%s -> %s\n", e.prefix, e.path)
}
}
func splitFirst(path string) (head, tail string) {
i := strings.Index(path, "/")
if i > 0 {
// 0 < i < len(path)
return path[0:i], path[i+1:]
}
return "", path
}
// ToAbsolute maps a relative path to an absolute path using the Mapping
// specified by the receiver. If the path cannot be mapped, the empty
// string is returned.
//
func (m *Mapping) ToAbsolute(path string) string {
prefix, tail := splitFirst(path)
for _, e := range m.list {
switch {
case e.prefix == prefix:
// use tail
case e.prefix == "":
tail = path
default:
continue // no match
}
abspath := pathutil.Join(e.path, tail)
if _, err := os.Stat(abspath); err == nil {
return abspath
}
}
return "" // no match
}
// ToRelative maps an absolute path to a relative path using the Mapping
// specified by the receiver. If the path cannot be mapped, the empty
// string is returned.
//
func (m *Mapping) ToRelative(path string) string {
for _, e := range m.list {
if strings.HasPrefix(path, e.path) {
// /absolute/prefix/foo -> prefix/foo
return pathutil.Join(e.prefix, path[len(e.path):]) // Join will remove a trailing '/'
}
}
return "" // no match
}
// Iterate calls f for each path and RWValue in the mapping (in uspecified order)
// until f returns false.
//
func (m *Mapping) Iterate(f func(path string, value *RWValue) bool) {
for _, e := range m.list {
if !f(e.path, e.value) {
return
}
}
}
|
