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-rw-r--r--libc/misc/search/tsearch.c190
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diff --git a/libc/misc/search/tsearch.c b/libc/misc/search/tsearch.c
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+/* Copyright (C) 1994 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA. */
+
+/*
+ * Tree search generalized from Knuth (6.2.2) Algorithm T just like
+ * the AT&T man page says.
+ *
+ * The node_t structure is for internal use only, lint doesn't grok it.
+ *
+ * Written by reading the System V Interface Definition, not the code.
+ *
+ * Totally public domain.
+ */
+/*LINTLIBRARY*/
+
+#include <search.h>
+#include <stdlib.h>
+
+/* This routine is not very bad. It makes many assumptions about
+ * the compiler. It assumpts that the first field in node must be
+ * the "key" field, which points to the datum. It is a very trick
+ * stuff. H.J.
+ */
+
+typedef struct node_t
+{
+ void *key;
+ struct node_t *left, *right;
+} node;
+
+#ifdef L_tsearch
+/* find or insert datum into search tree.
+char *key; key to be located
+register node **rootp; address of tree root
+int (*compar)(); ordering function
+*/
+
+void *tsearch(__const void *key, void **vrootp, __compar_fn_t compar)
+{
+ register node *q;
+ register node **rootp = (node **) vrootp;
+
+ if (rootp == (struct node_t **)0)
+ return ((struct node_t *)0);
+ while (*rootp != (struct node_t *)0) /* Knuth's T1: */
+ {
+ int r;
+
+ if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
+ return (*rootp); /* we found it! */
+ rootp = (r < 0) ?
+ &(*rootp)->left : /* T3: follow left branch */
+ &(*rootp)->right; /* T4: follow right branch */
+ }
+ q = (node *) malloc(sizeof(node)); /* T5: key not found */
+ if (q != (struct node_t *)0) /* make new node */
+ {
+ *rootp = q; /* link new node to old */
+ q->key = (void *)key; /* initialize new node */
+ q->left = q->right = (struct node_t *)0;
+ }
+ return (q);
+}
+#endif
+
+#ifdef L_tfind
+void *tfind(__const void *key, void * __const *vrootp, __compar_fn_t compar)
+{
+ register node **rootp = (node **) vrootp;
+
+ if (rootp == (struct node_t **)0)
+ return ((struct node_t *)0);
+ while (*rootp != (struct node_t *)0) /* Knuth's T1: */
+ {
+ int r;
+
+ if ((r = (*compar)(key, (*rootp)->key)) == 0) /* T2: */
+ return (*rootp); /* we found it! */
+ rootp = (r < 0) ?
+ &(*rootp)->left : /* T3: follow left branch */
+ &(*rootp)->right; /* T4: follow right branch */
+ }
+ return NULL;
+}
+#endif
+
+#ifdef L_tdelete
+/* delete node with given key
+char *key; key to be deleted
+register node **rootp; address of the root of tree
+int (*compar)(); comparison function
+*/
+void *tdelete(__const void *key, void ** vrootp, __compar_fn_t compar)
+{
+ node *p;
+ register node *q;
+ register node *r;
+ int cmp;
+ register node **rootp = (node **) vrootp;
+
+ if (rootp == (struct node_t **)0 || (p = *rootp) == (struct node_t *)0)
+ return ((struct node_t *)0);
+ while ((cmp = (*compar)(key, (*rootp)->key)) != 0)
+ {
+ p = *rootp;
+ rootp = (cmp < 0) ?
+ &(*rootp)->left : /* follow left branch */
+ &(*rootp)->right; /* follow right branch */
+ if (*rootp == (struct node_t *)0)
+ return ((struct node_t *)0); /* key not found */
+ }
+ r = (*rootp)->right; /* D1: */
+ if ((q = (*rootp)->left) == (struct node_t *)0) /* Left (struct node_t *)0? */
+ q = r;
+ else if (r != (struct node_t *)0) /* Right link is null? */
+ {
+ if (r->left == (struct node_t *)0) /* D2: Find successor */
+ {
+ r->left = q;
+ q = r;
+ }
+ else
+ { /* D3: Find (struct node_t *)0 link */
+ for (q = r->left; q->left != (struct node_t *)0; q = r->left)
+ r = q;
+ r->left = q->right;
+ q->left = (*rootp)->left;
+ q->right = (*rootp)->right;
+ }
+ }
+ free((struct node_t *) *rootp); /* D4: Free node */
+ *rootp = q; /* link parent to new node */
+ return(p);
+}
+#endif
+
+#ifdef L_twalk
+/* Walk the nodes of a tree
+register node *root; Root of the tree to be walked
+register void (*action)(); Function to be called at each node
+register int level;
+*/
+static void trecurse(__const void *vroot, __action_fn_t action, int level)
+{
+ register node *root = (node *) vroot;
+
+ if (root->left == (struct node_t *)0 && root->right == (struct node_t *)0)
+ (*action)(root, leaf, level);
+ else
+ {
+ (*action)(root, preorder, level);
+ if (root->left != (struct node_t *)0)
+ trecurse(root->left, action, level + 1);
+ (*action)(root, postorder, level);
+ if (root->right != (struct node_t *)0)
+ trecurse(root->right, action, level + 1);
+ (*action)(root, endorder, level);
+ }
+}
+
+/* void twalk(root, action) Walk the nodes of a tree
+node *root; Root of the tree to be walked
+void (*action)(); Function to be called at each node
+PTR
+*/
+void twalk(__const void *vroot, __action_fn_t action)
+{
+ register __const node *root = (node *) vroot;
+
+ if (root != (node *)0 && action != (__action_fn_t) 0)
+ trecurse(root, action, 0);
+}
+#endif
+
+/* tsearch.c ends here */