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
|
/*-------------------------------------------------------------------------
*
* fstack.c--
* Fixed format stack definitions.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/lib/Attic/fstack.c,v 1.1.1.1 1996/07/09 06:21:28 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
#include "c.h"
#include "lib/fstack.h"
/*
* Internal function definitions
*/
/*
* FixedItemIsValid --
* True iff item is valid.
*/
#define FixedItemIsValid(item) PointerIsValid(item)
/*
* FixedStackGetItemBase --
* Returns base of enclosing structure.
*/
#define FixedStackGetItemBase(stack, item) \
((Pointer)((char *)(item) - (stack)->offset))
/*
* FixedStackGetItem --
* Returns item of given pointer to enclosing structure.
*/
#define FixedStackGetItem(stack, pointer) \
((FixedItem)((char *)(pointer) + (stack)->offset))
/*
* External functions
*/
/*
* FixedStackIsValid --
* True iff stack is valid.
*/
static bool
FixedStackIsValid(FixedStack stack)
{
return ((bool)PointerIsValid(stack));
}
void
FixedStackInit(FixedStack stack, Offset offset)
{
AssertArg(PointerIsValid(stack));
stack->top = NULL;
stack->offset = offset;
}
Pointer
FixedStackPop(FixedStack stack)
{
Pointer pointer;
AssertArg(FixedStackIsValid(stack));
if (!PointerIsValid(stack->top)) {
return (NULL);
}
pointer = FixedStackGetItemBase(stack, stack->top);
stack->top = stack->top->next;
return (pointer);
}
void
FixedStackPush(FixedStack stack, Pointer pointer)
{
FixedItem item = FixedStackGetItem(stack, pointer);
AssertArg(FixedStackIsValid(stack));
AssertArg(PointerIsValid(pointer));
item->next = stack->top;
stack->top = item;
}
/*
* FixedStackContains --
* True iff ordered stack contains given element.
*
* Note:
* This is inefficient. It is intended for debugging use only.
*
* Exceptions:
* BadArg if stack is invalid.
* BadArg if pointer is invalid.
*/
static bool
FixedStackContains(FixedStack stack, Pointer pointer)
{
FixedItem next;
FixedItem item;
AssertArg(FixedStackIsValid(stack));
AssertArg(PointerIsValid(pointer));
item = FixedStackGetItem(stack, pointer);
for (next = stack->top; FixedItemIsValid(next); next = next->next) {
if (next == item) {
return (true);
}
}
return (false);
}
Pointer
FixedStackGetTop(FixedStack stack)
{
AssertArg(FixedStackIsValid(stack));
if (!PointerIsValid(stack->top)) {
return (NULL);
}
return (FixedStackGetItemBase(stack, stack->top));
}
Pointer
FixedStackGetNext(FixedStack stack, Pointer pointer)
{
FixedItem item;
/* AssertArg(FixedStackIsValid(stack)); */
/* AssertArg(PointerIsValid(pointer)); */
AssertArg(FixedStackContains(stack, pointer));
item = FixedStackGetItem(stack, pointer)->next;
if (!PointerIsValid(item)) {
return (NULL);
}
return(FixedStackGetItemBase(stack, item));
}
|
