GNU libmicrohttpd  0.9.76
tsearch.c
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1 /*
2  * Tree search generalized from Knuth (6.2.2) Algorithm T just like
3  * the AT&T man page says.
4  *
5  * The node_t structure is for internal use only, lint doesn't grok it.
6  *
7  * Written by reading the System V Interface Definition, not the code.
8  *
9  * Totally public domain.
10  */
11 
12 #include "mhd_options.h"
13 #include "tsearch.h"
14 #ifdef HAVE_STDDEF_H
15 #include <stddef.h>
16 #endif /* HAVE_STDDEF_H */
17 #ifdef HAVE_STDLIB_H
18 #include <stdlib.h>
19 #endif /* HAVE_STDLIB_H */
20 
21 
22 typedef struct node
23 {
24  const void *key;
25  struct node *llink;
26  struct node *rlink;
28 
29 
30 /* $NetBSD: tsearch.c,v 1.5 2005/11/29 03:12:00 christos Exp $ */
31 /* find or insert datum into search tree */
32 void *
33 tsearch (const void *vkey, /* key to be located */
34  void **vrootp, /* address of tree root */
35  int (*compar)(const void *, const void *))
36 {
37  node_t *q;
38  node_t **rootp = (node_t **) vrootp;
39 
40  if (NULL == rootp)
41  return NULL;
42 
43  while (*rootp != NULL)
44  { /* Knuth's T1: */
45  int r;
46 
47  if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
48  return *rootp; /* we found it! */
49 
50  rootp = (r < 0) ?
51  &(*rootp)->llink : /* T3: follow left branch */
52  &(*rootp)->rlink; /* T4: follow right branch */
53  }
54 
55  q = malloc (sizeof(node_t)); /* T5: key not found */
56  if (q)
57  { /* make new node */
58  *rootp = q; /* link new node to old */
59  q->key = vkey; /* initialize new node */
60  q->llink = q->rlink = NULL;
61  }
62  return q;
63 }
64 
65 
66 /* $NetBSD: tfind.c,v 1.5 2005/03/23 08:16:53 kleink Exp $ */
67 /* find a node, or return NULL */
68 void *
69 tfind (const void *vkey, /* key to be found */
70  void *const *vrootp, /* address of the tree root */
71  int (*compar)(const void *, const void *))
72 {
73  node_t *const *rootp = (node_t *const*) vrootp;
74 
75  if (NULL == rootp)
76  return NULL;
77 
78  while (*rootp != NULL)
79  { /* T1: */
80  int r;
81 
82  if ((r = (*compar)(vkey, (*rootp)->key)) == 0) /* T2: */
83  return *rootp; /* key found */
84  rootp = (r < 0) ?
85  &(*rootp)->llink : /* T3: follow left branch */
86  &(*rootp)->rlink; /* T4: follow right branch */
87  }
88  return NULL;
89 }
90 
91 
92 /* $NetBSD: tdelete.c,v 1.2 1999/09/16 11:45:37 lukem Exp $ */
93 /*
94  * delete node with given key
95  *
96  * vkey: key to be deleted
97  * vrootp: address of the root of the tree
98  * compar: function to carry out node comparisons
99  */
100 void *
101 tdelete (const void *__restrict vkey,
102  void **__restrict vrootp,
103  int (*compar)(const void *, const void *))
104 {
105  node_t **rootp = (node_t **) vrootp;
106  node_t *p;
107  node_t *q;
108  node_t *r;
109  int cmp;
110 
111  if ((rootp == NULL) || ((p = *rootp) == NULL))
112  return NULL;
113 
114  while ((cmp = (*compar)(vkey, (*rootp)->key)) != 0)
115  {
116  p = *rootp;
117  rootp = (cmp < 0) ?
118  &(*rootp)->llink : /* follow llink branch */
119  &(*rootp)->rlink; /* follow rlink branch */
120  if (*rootp == NULL)
121  return NULL; /* key not found */
122  }
123  r = (*rootp)->rlink; /* D1: */
124  if ((q = (*rootp)->llink) == NULL) /* Left NULL? */
125  {
126  q = r;
127  }
128  else if (r != NULL)
129  { /* Right link is NULL? */
130  if (r->llink == NULL)
131  { /* D2: Find successor */
132  r->llink = q;
133  q = r;
134  }
135  else
136  { /* D3: Find NULL link */
137  for (q = r->llink; q->llink != NULL; q = r->llink)
138  r = q;
139  r->llink = q->rlink;
140  q->llink = (*rootp)->llink;
141  q->rlink = (*rootp)->rlink;
142  }
143  }
144  free (*rootp); /* D4: Free node */
145  *rootp = q; /* link parent to new node */
146  return p;
147 }
148 
149 
150 /* end of tsearch.c */
#define NULL
Definition: reason_phrase.c:30
void * tsearch(const void *vkey, void **vrootp, int(*compar)(const void *, const void *))
Definition: tsearch.c:27
struct node node_t
void * tfind(const void *vkey, void *const *vrootp, int(*compar)(const void *, const void *))
Definition: tsearch.c:63
void * tdelete(const void *__restrict vkey, void **__restrict vrootp, int(*compar)(const void *, const void *))
Definition: tsearch.c:95
additional automatic macros for MHD_config.h