1# repeat.tcl --
2#
3#	Emulation of string repeat for older
4#	revisions of Tcl.
5#
6# Copyright (c) 2000      by Ajuba Solutions.
7# Copyright (c) 2001-2006 by Andreas Kupries <andreas_kupries@users.sourceforge.net>
8#
9# See the file "license.terms" for information on usage and redistribution
10# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
11#
12# RCS: @(#) $Id: repeat.tcl,v 1.1 2006/04/21 04:42:28 andreas_kupries Exp $
13
14# ### ### ### ######### ######### #########
15## Requirements
16
17package require Tcl 8.2
18
19namespace eval ::textutil::repeat {}
20
21# ### ### ### ######### ######### #########
22
23namespace eval ::textutil::repeat {
24    variable HaveBuiltin [expr {![catch {string repeat a 1}]}]
25}
26
27if {0} {
28    # Problems with the deactivated code:
29    # - Linear in 'num'.
30    # - Tests for 'string repeat' in every call!
31    #   (Ok, just the variable, still a test every call)
32    # - Fails for 'num == 0' because of undefined 'str'.
33
34    proc textutil::repeat::StrRepeat { char num } {
35	variable HaveBuiltin
36	if { $HaveBuiltin == 0 } then {
37	    for { set i 0 } { $i < $num } { incr i } {
38		append str $char
39	    }
40	} else {
41	    set str [ string repeat $char $num ]
42	}
43	return $str
44    }
45}
46
47if {$::textutil::repeat::HaveBuiltin} {
48    proc ::textutil::repeat::strRepeat {char num} {
49	return [string repeat $char $num]
50    }
51
52    proc ::textutil::repeat::blank {n} {
53	return [string repeat " " $n]
54    }
55} else {
56    proc ::textutil::repeat::strRepeat {char num} {
57	if {$num <= 0} {
58	    # No replication required
59	    return ""
60	} elseif {$num == 1} {
61	    # Quick exit for recursion
62	    return $char
63	} elseif {$num == 2} {
64	    # Another quick exit for recursion
65	    return $char$char
66	} elseif {0 == ($num % 2)} {
67	    # Halving the problem results in O (log n) complexity.
68	    set result [strRepeat $char [expr {$num / 2}]]
69	    return "$result$result"
70	} else {
71	    # Uneven length, reduce problem by one
72	    return "$char[strRepeat $char [incr num -1]]"
73	}
74    }
75
76    proc ::textutil::repeat::blank {n} {
77	return [strRepeat " " $n]
78    }
79}
80
81# ### ### ### ######### ######### #########
82## Data structures
83
84namespace eval ::textutil::repeat {
85    namespace export strRepeat blank
86}
87
88# ### ### ### ######### ######### #########
89## Ready
90
91package provide textutil::repeat 0.7
92