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| 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 package datastore |
| 6 |
| 7 import ( |
| 8 "golang.org/x/net/context" |
| 9 ) |
| 10 |
| 11 type key int |
| 12 |
| 13 var ( |
| 14 rawDatastoreKey key |
| 15 rawDatastoreFilterKey key = 1 |
| 16 ) |
| 17 |
| 18 // RawFactory is the function signature for factory methods compatible with |
| 19 // SetRawFactory. |
| 20 type RawFactory func(context.Context) RawInterface |
| 21 |
| 22 // RawFilter is the function signature for a filter RDS implementation. It |
| 23 // gets the current RDS implementation, and returns a new RDS implementation |
| 24 // backed by the one passed in. |
| 25 type RawFilter func(context.Context, RawInterface) RawInterface |
| 26 |
| 27 // getUnfiltered gets gets the RawInterface implementation from context without |
| 28 // any of the filters applied. |
| 29 func getUnfiltered(c context.Context) RawInterface { |
| 30 if f, ok := c.Value(rawDatastoreKey).(RawFactory); ok && f != nil { |
| 31 return f(c) |
| 32 } |
| 33 return nil |
| 34 } |
| 35 |
| 36 // GetRaw gets the RawInterface implementation from context. |
| 37 func GetRaw(c context.Context) RawInterface { |
| 38 ret := getUnfiltered(c) |
| 39 if ret == nil { |
| 40 return nil |
| 41 } |
| 42 for _, f := range getCurFilters(c) { |
| 43 ret = f(c, ret) |
| 44 } |
| 45 return applyCheckFilter(c, ret) |
| 46 } |
| 47 |
| 48 // Get gets the Interface implementation from context. |
| 49 func Get(c context.Context) Interface { |
| 50 return &datastoreImpl{GetRaw(c)} |
| 51 } |
| 52 |
| 53 // SetRawFactory sets the function to produce Datastore instances, as returned b
y |
| 54 // the GetRaw method. |
| 55 func SetRawFactory(c context.Context, rdsf RawFactory) context.Context { |
| 56 return context.WithValue(c, rawDatastoreKey, rdsf) |
| 57 } |
| 58 |
| 59 // SetRaw sets the current Datastore object in the context. Useful for testing w
ith |
| 60 // a quick mock. This is just a shorthand SetRawFactory invocation to set a fact
ory |
| 61 // which always returns the same object. |
| 62 func SetRaw(c context.Context, rds RawInterface) context.Context { |
| 63 return SetRawFactory(c, func(context.Context) RawInterface { return rds
}) |
| 64 } |
| 65 |
| 66 func getCurFilters(c context.Context) []RawFilter { |
| 67 curFiltsI := c.Value(rawDatastoreFilterKey) |
| 68 if curFiltsI != nil { |
| 69 return curFiltsI.([]RawFilter) |
| 70 } |
| 71 return nil |
| 72 } |
| 73 |
| 74 // AddRawFilters adds RawInterface filters to the context. |
| 75 func AddRawFilters(c context.Context, filts ...RawFilter) context.Context { |
| 76 if len(filts) == 0 { |
| 77 return c |
| 78 } |
| 79 cur := getCurFilters(c) |
| 80 newFilts := make([]RawFilter, 0, len(cur)+len(filts)) |
| 81 newFilts = append(newFilts, getCurFilters(c)...) |
| 82 newFilts = append(newFilts, filts...) |
| 83 return context.WithValue(c, rawDatastoreFilterKey, newFilts) |
| 84 } |
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