This repository has been archived by the owner on Mar 8, 2021. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 5
/
scope_stack.go
98 lines (85 loc) · 2.7 KB
/
scope_stack.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
// Copyright 2017 Northern.tech AS
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package scopestack
import "fmt"
import "container/list"
import "runtime"
// A stack type that tries to verify that each push and pop happens in the same
// function.
type ScopeStack struct {
// The list of stack frames where Push() has been called.
stack list.List
// The depth at which the scope stack is. If you wrap ScopeStack in a
// different scoped object, add one to this so that the stack frame of
// the calling function of that object is considered. Otherwise the
// stack frame of the scoped object is checked which will always be
// different. If ScopeStack is used directly, this should be zero.
scopeDistance int
}
type scopeElement struct {
frame *uintptr
value interface{}
}
func NewScopeStack(scopeDistance int) *ScopeStack {
var ret ScopeStack
ret.scopeDistance = scopeDistance
return &ret
}
func (self *ScopeStack) Push(v interface{}) {
var frame *uintptr
pc, _, _, ok := runtime.Caller(self.scopeDistance + 1)
if !ok {
frame = nil
} else {
frame = new(uintptr)
*frame = pc
}
self.stack.PushBack(scopeElement{frame, v})
}
func (self *ScopeStack) Pop() interface{} {
var oldFrame *uintptr
var newFrame uintptr
lElement := self.stack.Back()
if lElement == nil {
panic("ScopeStack: Nothing to Pop()")
}
sElement := lElement.Value.(scopeElement)
value := sElement.value
oldFrame = sElement.frame
self.stack.Remove(lElement)
if oldFrame == nil {
// We cannot perform any checks in this case.
return value
}
pc, _, _, ok := runtime.Caller(self.scopeDistance + 1)
if !ok {
// We cannot perform any checks in this case.
return value
}
newFrame = pc
oldFunc := runtime.FuncForPC(*oldFrame)
newFunc := runtime.FuncForPC(newFrame)
if oldFunc.Entry() != newFunc.Entry() {
oldFile, oldLine := oldFunc.FileLine(*oldFrame)
newFile, newLine := newFunc.FileLine(newFrame)
msg := fmt.Sprintf("Unbalanced ScopeStack.Pop(). "+
"Push inside %s() at %s:%d does not balance "+
"with pop in %s() at %s:%d "+
"(Push and Pop have to be in the same function)",
oldFunc.Name(), oldFile, oldLine,
newFunc.Name(), newFile, newLine)
panic(msg)
}
return value
}