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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2016 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 package info | 5 package module |
6 | 6 |
7 import ( | 7 import ( |
8 "golang.org/x/net/context" | 8 "golang.org/x/net/context" |
9 ) | 9 ) |
10 | 10 |
11 type key int | 11 type key int |
12 | 12 |
13 var ( | 13 var ( |
14 » infoKey key | 14 » moduleKey key |
15 » infoFilterKey key = 1 | 15 » moduleFilterKey key = 1 |
16 ) | 16 ) |
17 | 17 |
18 // Factory is the function signature for factory methods compatible with | 18 // Factory is the function signature for factory methods compatible with |
19 // SetFactory. | 19 // SetFactory. |
20 type Factory func(context.Context) Interface | 20 type Factory func(context.Context) Interface |
21 | 21 |
22 // Filter is the function signature for a filter GI implementation. It | 22 // Filter is the function signature for a filter module implementation. It gets |
23 // gets the current GI implementation, and returns a new GI implementation | 23 // the current module implementation, and returns a new module implementation |
24 // backed by the one passed in. | 24 // backed by the one passed in. |
25 type Filter func(context.Context, Interface) Interface | 25 type Filter func(context.Context, Interface) Interface |
26 | 26 |
27 // getUnfiltered gets gets the Interface implementation from context without | 27 // getUnfiltered gets gets the Interface implementation from context without |
28 // any of the filters applied. | 28 // any of the filters applied. |
29 func getUnfiltered(c context.Context) Interface { | 29 func getUnfiltered(c context.Context) Interface { |
30 » if f, ok := c.Value(infoKey).(Factory); ok && f != nil { | 30 » if f, ok := c.Value(moduleKey).(Factory); ok && f != nil { |
31 return f(c) | 31 return f(c) |
32 } | 32 } |
33 return nil | 33 return nil |
34 } | 34 } |
35 | 35 |
36 // Get gets the Interface implementation from context. | 36 // Get gets the Interface implementation from context. |
37 func Get(c context.Context) Interface { | 37 func Get(c context.Context) Interface { |
38 ret := getUnfiltered(c) | 38 ret := getUnfiltered(c) |
39 if ret == nil { | 39 if ret == nil { |
40 return nil | 40 return nil |
41 } | 41 } |
42 for _, f := range getCurFilters(c) { | 42 for _, f := range getCurFilters(c) { |
43 ret = f(c, ret) | 43 ret = f(c, ret) |
44 } | 44 } |
45 return ret | 45 return ret |
46 } | 46 } |
47 | 47 |
48 // SetFactory sets the function to produce Interface instances, as returned | 48 // SetFactory sets the function to produce Interface instances, as returned |
49 // by the Get method. | 49 // by the Get method. |
50 func SetFactory(c context.Context, gif Factory) context.Context { | 50 func SetFactory(c context.Context, gif Factory) context.Context { |
51 » return context.WithValue(c, infoKey, gif) | 51 » return context.WithValue(c, moduleKey, gif) |
52 } | 52 } |
53 | 53 |
54 // Set sets the current Interface object in the context. Useful for testing | 54 // Set sets the current Interface object in the context. Useful for testing |
55 // with a quick mock. This is just a shorthand SetFactory invocation to set | 55 // with a quick mock. This is just a shorthand SetFactory invocation to set |
56 // a factory which always returns the same object. | 56 // a factory which always returns the same object. |
57 func Set(c context.Context, gi Interface) context.Context { | 57 func Set(c context.Context, gi Interface) context.Context { |
58 return SetFactory(c, func(context.Context) Interface { return gi }) | 58 return SetFactory(c, func(context.Context) Interface { return gi }) |
59 } | 59 } |
60 | 60 |
61 func getCurFilters(c context.Context) []Filter { | 61 func getCurFilters(c context.Context) []Filter { |
62 » curFiltsI := c.Value(infoFilterKey) | 62 » curFiltsI := c.Value(moduleFilterKey) |
63 if curFiltsI != nil { | 63 if curFiltsI != nil { |
64 return curFiltsI.([]Filter) | 64 return curFiltsI.([]Filter) |
65 } | 65 } |
66 return nil | 66 return nil |
67 } | 67 } |
68 | 68 |
69 // AddFilters adds Interface filters to the context. | 69 // AddFilters adds Interface filters to the context. |
70 func AddFilters(c context.Context, filts ...Filter) context.Context { | 70 func AddFilters(c context.Context, filts ...Filter) context.Context { |
71 if len(filts) == 0 { | 71 if len(filts) == 0 { |
72 return c | 72 return c |
73 } | 73 } |
74 cur := getCurFilters(c) | 74 cur := getCurFilters(c) |
75 newFilts := make([]Filter, 0, len(cur)+len(filts)) | 75 newFilts := make([]Filter, 0, len(cur)+len(filts)) |
76 newFilts = append(newFilts, getCurFilters(c)...) | 76 newFilts = append(newFilts, getCurFilters(c)...) |
77 newFilts = append(newFilts, filts...) | 77 newFilts = append(newFilts, filts...) |
78 » return context.WithValue(c, infoFilterKey, newFilts) | 78 » return context.WithValue(c, moduleFilterKey, newFilts) |
79 } | 79 } |
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