repeat.tcl

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/*  repeat.tcl --*/
/* */
/*  Emulation of string repeat for older*/
/*  revisions of Tcl.*/
/* */
/*  Copyright (c) 2000      by Ajuba Solutions.*/
/*  Copyright (c) 2001-2006 by Andreas Kupries <andreas_kupries@users.sourceforge.net>*/
/* */
/*  See the file "license.terms" for information on usage and redistribution*/
/*  of this file, and for a DISCLAIMER OF ALL WARRANTIES.*/
/* */
/*  RCS: @(#) $Id: repeat.tcl,v 1.1 2006/04/21 04:42:28 andreas_kupries Exp $*/

/*  ### ### ### ######### ######### #########*/
/*  Requirements*/

package require Tcl 8.2

namespace ::textutil::repeat {}

/*  ### ### ### ######### ######### #########*/

namespace ::textutil::repeat {
    variable HaveBuiltin [expr {![catch {string repeat a 1}]}]
}

if {0} {
    /*  Problems with the deactivated code:*/
    /*  - Linear in 'num'.*/
    /*  - Tests for 'string repeat' in every call!*/
    /*    (Ok, just the variable, still a test every call)*/
    /*  - Fails for 'num == 0' because of undefined 'str'.*/

    ret  textutil::repeat::StrRepeat ( type char , type num ) {
    variable HaveBuiltin
    if { $HaveBuiltin == 0 } then {
        for { set i 0 } { $i < $num } { incr i } {
        append str $char
        }
    } else {
        set str [ string repeat $char $num ]
    }
    return $str
    }
}

if {$::textutil::repeat::HaveBuiltin} {
    ret  ::textutil::repeat::strRepeat (type char , type num) {
    return [string repeat $char $num]
    }

    ret  ::textutil::repeat::blank (type n) {
    return [string repeat " " $n]
    }
} else {
    ret  ::textutil::repeat::strRepeat (type char , type num) {
    if {$num <= 0} {
        # No replication required
        return ""
    } elseif {$num == 1} {
        # Quick exit for recursion
        return $char
    } elseif {$num == 2} {
        # Another quick exit for recursion
        return $char$char
    } elseif {0 == ($num % 2)} {
        # Halving the problem results in O (log n) complexity.
        set result [strRepeat $char [expr {$num / 2}]]
        return "$result$result"
    } else {
        # Uneven length, reduce problem by one
        return "$char[strRepeat $char [incr num -1]]"
    }
    }

    ret  ::textutil::repeat::blank (type n) {
    return [strRepeat " " $n]
    }
}

/*  ### ### ### ######### ######### #########*/
/*  Data structures*/

namespace ::textutil::repeat {
    namespace export strRepeat blank
}

/*  ### ### ### ######### ######### #########*/
/*  Ready*/

package provide textutil::repeat 0.7