unitproc/bkt-insertStr

   1 #!/usr/bin/env bash
   2 # Desc: Insert string into provided string
   3
   4 yell() { echo "$0: $*" >&2; }
   5 die() { yell "$*"; exit 111; }
   6 must() { "$@" || die "cannot $*"; }
   7 insertStr() {
   8     # Desc: Inserts a string into another string at a specified position.
   9     # Input: arg1: str   str_rec  String to receive insertion
  10     #        arg2: int   pos      Insertion position (0 = append to front)
  11     #        arg3: str   str_ins  String to be inserted
  12     # Output: stdout:    Combined string
  13     # Version: 0.0.2
  14     # Depends: BK-2020-03: yell(), die(), must()
  15     # Ref/Attrib: * BK-2020-03: https://gitlab.com/baltakatei/baltakatei-exdev/
  16     #             * Cooper, Mendel. “Advanced Bash-Scripting Guide: Manipulating Strings”. tldp.org https://tldp.org/LDP/abs/html/string-manipulation.html
  17
  18     local str_rec pos str_ins re len_str_rec;
  19     local pfx_pos_start pfx_len pfx;
  20     local sfx_pos_start sfx_len sfx;
  21
  22     # Check args
  23     if [[ $# -ne 3 ]]; then
  24         yell "ERROR:Invalid argument count:$#";
  25         return 1; fi;
  26     re='^[0-9]+$';
  27     if [[ ! "$2" =~ $re ]]; then
  28         yell "ERROR:Not an int:$2";
  29         return 1; fi;
  30     str_rec="$1";
  31     pos="$2";
  32     str_ins="$3";
  33
  34     # Calculate string stats
  35     len_str_rec="${#str_rec}";
  36
  37     # Form prefix
  38     pfx_pos_start="0";
  39     pfx_len="$pos";
  40     pfx="${str_rec:$pfx_pos_start:$pfx_len}";
  41
  42     # Form suffix
  43     sfx_pos_start="$(( pos ))";
  44     sfx_len="$(( len_str_rec - pos ))";
  45     sfx="${str_rec:$sfx_pos_start:$sfx_len}";
  46
  47     # Print output to stdout
  48     printf "%s%s%s\n" "$pfx" "$str_ins" "$sfx";
  49 }; # Insert string provided at indicated position via stdout
  50
  51
  52 # Tests
  53 printf "\"%s\" should read \"foobarbaz\"\n" "$(insertStr "foobaz" 3 "bar";)";
  54
  55 insertStr "foobaz" 0 "bar";
  56 insertStr "foobaz" 1 "bar";
  57 insertStr "foobaz" 2 "bar";
  58 insertStr "foobaz" 3 "bar";
  59 insertStr "foobaz" 4 "bar";
  60 insertStr "foobaz" 5 "bar";
  61 insertStr "foobaz" 6 "bar";
  62 insertStr "foobaz" 7 "bar";
  63 insertStr "foobaz" 999 "bar";