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Annotation of 43BSD/contrib/icon/src/cmd/parens.icn, revision 1.1

1.1     ! root        1: #      PARENS(1)
        !             2: #
        !             3: #      Produce parenthesis-balanced strings
        !             4: #
        !             5: #      Ralph E. Griswold
        !             6: #
        !             7: #      Last modified 8/11/84
        !             8: #
        !             9: 
        !            10: global r, k, lp, rp
        !            11: 
        !            12: procedure main(a)
        !            13:    local string, i, s, bound, limit, varying
        !            14:    bound := limit := 10                        # default bound and limit
        !            15:    lp := "("                           # default left paren
        !            16:    rp := ")"                           # default right paren
        !            17:    i := 0
        !            18:    while s := a[i +:= 1] do
        !            19:       if s[1] == "-" then
        !            20:          case s of {
        !            21:             "-b":   bound := integer(a[i +:= 1]) | Usage()     # bound
        !            22:             "-n":   limit := integer(a[i +:= 1]) | Usage()     # total number
        !            23:             "-l":   lp := a[i +:= 1] | Usage()                 # left paren
        !            24:             "-r":   rp := a[i +:= 1] | Usage()                 # right paren
        !            25:             "-v":   varying := 1                               # varying length
        !            26:             default: Usage()
        !            27:             }
        !            28:    every 1 to limit do {
        !            29:       if \varying then k := 2 * ?bound else k := 2 * bound
        !            30:       string := ""
        !            31:       r := 0
        !            32:       while k ~= r do {
        !            33:          if r = 0 then string ||:= Open()
        !            34:          else if ?0 < probClose()
        !            35:             then string ||:= Close() else string ||:= Open()
        !            36:          }
        !            37:       while k > 0 do string ||:= Close()
        !            38:       write(string)
        !            39:       }
        !            40: end
        !            41: 
        !            42: procedure Open()
        !            43:    r +:= 1
        !            44:    k -:= 1
        !            45:    return lp
        !            46: end
        !            47: 
        !            48: procedure Close()
        !            49:    r -:= 1
        !            50:    k -:= 1
        !            51:    return rp
        !            52: end
        !            53: 
        !            54: procedure probClose()
        !            55:    return ((r * (r + k + 2)) / (2.0 * k * (r + 1)))
        !            56: end
        !            57: 
        !            58: procedure Usage()
        !            59:    stop("usage: parens [-n i -b i -l s -r s]")
        !            60: end

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