File: sbs.sh
   1 #!/bin/sh
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright © 2020-2025 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the “Software”), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 # sbs [column count...] [filepaths...]
  27 #
  28 # Side-By-Side lays out lines read from all inputs given into several columns,
  29 # separating them with a special symbol. If no named inputs are given, lines
  30 # are read from the standard input, instead of files.
  31 #
  32 # If a column-count isn't given, the script tries to find the most columns
  33 # which can fit a reasonable width-limit; when even a single column can't fit
  34 # that limit, it simply emits all lines, which is the same as using 1 column.
  35 
  36 
  37 case "$1" in
  38     -h|--h|-help|--help)
  39         awk '/^# +sbs /, /^$/ { gsub(/^# ?/, ""); print }' "$0"
  40         exit 0
  41     ;;
  42 esac
  43 
  44 num_columns=0
  45 if [ "$(echo "$1" | grep -E '^[+-]?[0-9]+$' 2> /dev/null)" ]; then
  46     num_columns="$1"
  47     shift
  48 fi
  49 
  50 # allow loading lines from multiple files, ensuring no lines are accidentally
  51 # joined across inputs
  52 awk 1 "$@" |
  53 
  54 # ignore leading UTF-8 BOMs (byte-order marks) and trailing carriage-returns:
  55 # the latter in particular will ruin side-by-side output
  56 sed 's-^\xef\xbb\xbf--; s-\r$--' |
  57 
  58 # before laying out lines side-by-side, expand all tabs, using 4 as the
  59 # tabstop width
  60 expand -t 4 |
  61 
  62 # lay lines into side-by-side columns
  63 awk -v num_columns="${num_columns}" '
  64 BEGIN {
  65     sep = " █"
  66     sep_width = width(sep)
  67     total_max_width = 79
  68     max_auto_cols = 26
  69 
  70     # num_columns = 0
  71     # detect a leading number, and use it as the max-number of columns
  72     if (ARGV[1] + 0 != 0) {
  73         num_columns = ARGV[1] + 0
  74         delete ARGV[1]
  75     }
  76 }
  77 
  78 # remember all lines; carriage-returns are already removed
  79 { lines[NR] = $0 }
  80 
  81 # width counts items in the string given, ignoring ANSI-style sequences
  82 function width(s) {
  83     gsub(/\x1b\[[0-9;]*[A-Za-z]/, "", s)
  84     return length(s)
  85 }
  86 
  87 # pick a line using a row-column pair as an index
  88 function pick(lines, height, row, col) {
  89     return lines[(col - 1) * height + row]
  90 }
  91 
  92 # see if a list of lines can fit the number of columns given exactly
  93 function fits(lines, line_count, num_cols, height, max_widths, i, j, w, l) {
  94     height = ceil(line_count / num_cols)
  95 
  96     # prevent too many empty columns
  97     if (height * num_cols - line_count >= height) {
  98         return 0
  99     }
 100 
 101     for (i = 1; i <= height; i++) {
 102         for (j = 1; j <= num_cols; j++) {
 103             w = width(pick(lines, height, i, j))
 104             if (w > total_max_width) return 0
 105             if (max_widths[j] < w) max_widths[j] = w
 106         }
 107     }
 108 
 109     for (i = 1; i <= height; i++) {
 110         w = 0
 111 
 112         for (j = 1; j <= num_cols; j++) {
 113             if (j > 1) w += sep_width
 114 
 115             l = pick(lines, height, i, j)
 116             if (j > 1 && l != "") w++
 117 
 118             w += width(l)
 119 
 120             if (j < num_cols) {
 121                 pad = max_widths[j] - width(l)
 122                 if (pad > 0) {
 123                     if (l == "") pad++
 124                     w += pad
 125                 }
 126             }
 127 
 128             if (w > total_max_width) return 0
 129         }
 130     }
 131 
 132     return 1
 133 }
 134 
 135 # auto-detect an appropriate column-count for the list of lines given
 136 function find_max_fit(lines, num_columns) {
 137     if (!fits(lines, NR, 1)) {
 138         return 1
 139     }
 140 
 141     for (num_columns = max_auto_cols; num_columns >= 2; num_columns--) {
 142         if (fits(lines, NR, num_columns)) {
 143             return num_columns
 144         }
 145     }
 146     return 1
 147 }
 148 
 149 # round up non-integers
 150 function ceil(n) {
 151     return (n % 1) ? n - (n % 1) + 1 : n
 152 }
 153 
 154 END {
 155     # prevent errors when input has no lines
 156     if (NR < 1) exit
 157 
 158     # auto-fit when given a non-positive count, or when not given a count
 159     if (num_columns < 1) num_columns = find_max_fit(lines)
 160 
 161     # prevent column-count from exceeding the number of input lines
 162     if (num_columns > NR) num_columns = NR
 163 
 164     # emit a single column as lines, quitting right away
 165     if (num_columns < 2) {
 166         for (i = 1; i <= NR; i++) print lines[i]
 167         exit
 168     }
 169 
 170     # prevent a trailing empty column
 171     num_lines = ceil(NR / num_columns)
 172     if (num_lines * num_columns - NR >= num_lines) {
 173         num_columns--
 174     }
 175 
 176     num_lines = ceil(NR / num_columns)
 177     for (i = 1; i <= num_lines; i++) {
 178         for (j = 1; j <= num_columns; j++) {
 179             w = width(pick(lines, num_lines, i, j))
 180             if (max_widths[j] < w) max_widths[j] = w
 181         }
 182     }
 183 
 184     widest = 0
 185     for (i in max_widths) {
 186         if (widest < max_widths[i]) widest = max_widths[i]
 187     }
 188 
 189     # emit lines side by side
 190     for (i = 1; i <= num_lines; i++) {
 191         for (j = 1; j <= num_columns; j++) {
 192             l = pick(lines, num_lines, i, j)
 193 
 194             if (j > 1) {
 195                 printf "%s", sep
 196                 if (j != num_columns || l != "") printf " "
 197             }
 198 
 199             printf "%s", l
 200 
 201             if (j < num_columns) {
 202                 pad = max_widths[j] - width(l)
 203                 if (pad > 0) printf "%*s", pad, ""
 204             }
 205         }
 206 
 207         print ""
 208     }
 209 }
 210 ' |
 211 
 212 # view the result interactively
 213 less -JMKiCRS