PD tsearch as reqd by xpg; by esr

1 files changed, 125 insertions, 0 deletions

diff --git a/lib/libc/stdlib/tsearch.c b/lib/libc/stdlib/tsearch.c
new file mode 100644
index 00000000000..defa8a30060
--- /dev/null
+++ b/lib/libc/stdlib/tsearch.c
@@ -0,0 +1,125 @@
+/*
+ * 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>
+
+typedef struct node_t {
+    char	  *key;
+    struct node_t *left, *right;
+} node;
+
+/* find or insert datum into search tree */
+void *
+tsearch(vkey, vrootp, compar)
+	const void 	*vkey;		/* key to be located */
+	void		**vrootp;	/* address of tree root */
+	int		(*compar) __P((const void *, const void *));
+{
+    register node *q;
+    char *key = (char *)vkey;
+    node **rootp = (node **)vrootp;
+
+    if (rootp == (struct node_t **)0)
+	return ((void *)0);
+    while (*rootp != (struct node_t *)0) {	/* Knuth's T1: */
+	int r;
+
+	if ((r = (*compar)(key, (*rootp)->key)) == 0)	/* T2: */
+	    return ((void *)*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 = key;			/* initialize new node */
+	q->left = q->right = (struct node_t *)0;
+    }
+    return ((void *)q);
+}
+
+/* delete node with given key */
+void *
+tdelete(vkey, vrootp, compar)
+	const void	*vkey;		/* key to be deleted */
+	void		**vrootp;	/* address of the root of tree */
+	int		(*compar) __P((const void *, const void *));
+{
+    node **rootp = (node **)vrootp;
+    char *key = (char *)vkey;
+    node *p;
+    register node *q;
+    register node *r;
+    int cmp;
+
+    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 ((void *)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);
+}
+
+/* Walk the nodes of a tree */
+static void
+trecurse(root, action, level)
+	register node	*root;		/* Root of the tree to be walked */
+	register void	(*action)();	/* Function to be called at each node */
+	register int	level;
+{
+    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);
+    }
+}
+
+/* Walk the nodes of a tree */
+void
+twalk(vroot, action)
+	const void	*vroot;		/* Root of the tree to be walked */
+	void		(*action) __P((const void *, VISIT, int));
+{
+    node *root = (node *)vroot;
+
+    if (root != (node *)0 && action != (void(*)())0)
+	trecurse(root, action, 0);
+}