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
|
/*++
/* NAME
/* tok_pool 3
/* SUMMARY
/* maintain pool of unused token structures
/* PACKAGE
/* unproto
/* SYNOPSIS
/* #include "token.h"
/*
/* struct token *tok_alloc()
/*
/* void tok_free(t)
/* struct token *t;
/* DESCRIPTION
/* tok_alloc() and tok_free() maintain a pool of unused token
/* structures.
/*
/* tok_alloc() takes the first free token structure from the pool
/* or allocates a new one if the pool is empty.
/*
/* tok_free() adds a (possibly composite) token structure to the pool.
/* BUGS
/* The pool never shrinks.
/* AUTHOR(S)
/* Wietse Venema
/* Eindhoven University of Technology
/* Department of Mathematics and Computer Science
/* Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
/* LAST MODIFICATION
/* 92/01/15 21:53:04
/* VERSION/RELEASE
/* 1.2
/*--*/
static char pool_sccsid[] = "@(#) tok_pool.c 1.2 92/01/15 21:53:04";
/* C library */
extern char *malloc();
/* Application-specific stuff */
#include "token.h"
#include "vstring.h"
#include "error.h"
#define TOKLEN 5 /* initial string buffer length */
struct token *tok_pool = 0; /* free token pool */
/* tok_alloc - allocate token structure from pool or heap */
struct token *tok_alloc()
{
register struct token *t;
if (tok_pool) { /* re-use an old one */
t = tok_pool;
tok_pool = t->next;
} else { /* create a new one */
if ((t = (struct token *) malloc(sizeof(struct token))) == 0
|| (t->vstr = vs_alloc(TOKLEN)) == 0)
fatal("out of memory");
}
t->next = t->head = t->tail = 0;
#ifdef DEBUG
strcpy(t->vstr->str, "BUSY");
#endif
return (t);
}
/* tok_free - return (possibly composite) token to pool of free tokens */
void tok_free(t)
register struct token *t;
{
#ifdef DEBUG
/* Check if we are freeing free token */
register struct token *p;
for (p = tok_pool; p; p = p->next)
if (p == t)
fatal("freeing free token");
#endif
/* Free neighbours and subordinates first */
if (t->next)
tok_free(t->next);
if (t->head)
tok_free(t->head);
/* Free self */
t->next = tok_pool;
t->head = t->tail = 0;
tok_pool = t;
#ifdef DEBUG
strcpy(t->vstr->str, "FREE");
#endif
}
|
