stdlib/FreeBSD/tsearch.3

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   2 .\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
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  27 .\"     OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp
  28 .\" $FreeBSD: src/lib/libc/stdlib/tsearch.3,v 1.12 2002/12/19 09:40:24 ru Exp $
  29 .\"
  30 .Dd June 15, 1997
  31 .Dt TSEARCH 3
  32 .Os
  33 .Sh NAME
  34 .Nm tsearch , tfind , tdelete , twalk
  35 .Nd manipulate binary search trees
  36 .Sh SYNOPSIS
  37 .In search.h
  38 .Ft void *
  39 .Fn tdelete "const void * restrict key" "void ** restrict rootp" "int (*compar) (const void *, const void *)"
  40 .Ft void *
  41 .Fn tfind "const void *key" "void * const *rootp" "int (*compar) (const void *, const void *)"
  42 .Ft void *
  43 .Fn tsearch "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"
  44 .Ft void
  45 .Fn twalk "const void *root" "void (*compar) (const void *, VISIT, int)"
  46 .Sh DESCRIPTION
  47 The
  48 .Fn tdelete ,
  49 .Fn tfind ,
  50 .Fn tsearch ,
  51 and
  52 .Fn twalk
  53 functions manage binary search trees based on algorithms T and D
  54 from Knuth (6.2.2).  The comparison function passed in by
  55 the user has the same style of return values as
  56 .Xr strcmp 3 .
  57 .Pp
  58 The
  59 .Fn tfind
  60 function
  61 searches for the datum matched by the argument
  62 .Fa key
  63 in the binary tree rooted at
  64 .Fa rootp ,
  65 returning a pointer to the datum if it is found and NULL
  66 if it is not.
  67 .Pp
  68 The
  69 .Fn tsearch
  70 function
  71 is identical to
  72 .Fn tfind
  73 except that if no match is found,
  74 .Fa key
  75 is inserted into the tree and a pointer to it is returned.  If
  76 .Fa rootp
  77 points to a NULL value a new binary search tree is created.
  78 .Pp
  79 The
  80 .Fn tdelete
  81 function
  82 deletes a node from the specified binary search tree and returns
  83 a pointer to the parent of the node to be deleted.
  84 It takes the same arguments as
  85 .Fn tfind
  86 and
  87 .Fn tsearch .
  88 If the node to be deleted is the root of the binary search tree,
  89 .Fa rootp
  90 will be adjusted.
  91 .Pp
  92 The
  93 .Fn twalk
  94 function
  95 walks the binary search tree rooted in
  96 .Fa root
  97 and calls the function
  98 .Fa action
  99 on each node.
 100 The
 101 .Fa action
 102 function
 103 is called with three arguments: a pointer to the current node,
 104 a value from the enum
 105 .Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"
 106 specifying the traversal type, and a node level (where level
 107 zero is the root of the tree).
 108 .Sh SEE ALSO
 109 .Xr bsearch 3 ,
 110 .Xr hsearch 3 ,
 111 .Xr lsearch 3
 112 .Sh RETURN VALUES
 113 The
 114 .Fn tsearch
 115 function returns NULL if allocation of a new node fails (usually
 116 due to a lack of free memory).
 117 .Pp
 118 The
 119 .Fn tfind ,
 120 .Fn tsearch ,
 121 and
 122 .Fn tdelete
 123 functions
 124 return NULL if
 125 .Fa rootp
 126 is NULL or the datum cannot be found.
 127 .Pp
 128 The
 129 .Fn twalk
 130 function returns no value.