examples/scripts.noah/string.bash

   1 # string.bash --- bash emulation of string(3) library routines
   2 # Author: Noah Friedman <friedman@prep.ai.mit.edu>
   3 # Created: 1992-07-01
   4 # Last modified: 1993-09-29
   5 # Public domain
   6
   7 # Conversion to bash v2 syntax done by Chet Ramey
   8
   9 # Commentary:
  10 # Code:
  11
  12 #:docstring strcat:
  13 # Usage: strcat s1 s2
  14 #
  15 # Strcat appends the value of variable s2 to variable s1.
  16 #
  17 # Example:
  18 #    a="foo"
  19 #    b="bar"
  20 #    strcat a b
  21 #    echo $a
  22 #    => foobar
  23 #
  24 #:end docstring:
  25
  26 ###;;;autoload
  27 function strcat ()
  28 {
  29     local s1_val s2_val
  30
  31     s1_val=${!1}                        # indirect variable expansion
  32     s2_val=${!2}
  33     eval "$1"=\'"${s1_val}${s2_val}"\'
  34 }
  35
  36 #:docstring strncat:
  37 # Usage: strncat s1 s2 $n
  38 #
  39 # Line strcat, but strncat appends a maximum of n characters from the value
  40 # of variable s2.  It copies fewer if the value of variabl s2 is shorter
  41 # than n characters.  Echoes result on stdout.
  42 #
  43 # Example:
  44 #    a=foo
  45 #    b=barbaz
  46 #    strncat a b 3
  47 #    echo $a
  48 #    => foobar
  49 #
  50 #:end docstring:
  51
  52 ###;;;autoload
  53 function strncat ()
  54 {
  55     local s1="$1"
  56     local s2="$2"
  57     local -i n="$3"
  58     local s1_val s2_val
  59
  60     s1_val=${!s1}                       # indirect variable expansion
  61     s2_val=${!s2}
  62
  63     if [ ${#s2_val} -gt ${n} ]; then
  64        s2_val=${s2_val:0:$n}            # substring extraction
  65     fi
  66
  67     eval "$s1"=\'"${s1_val}${s2_val}"\'
  68 }
  69
  70 #:docstring strcmp:
  71 # Usage: strcmp $s1 $s2
  72 #
  73 # Strcmp compares its arguments and returns an integer less than, equal to,
  74 # or greater than zero, depending on whether string s1 is lexicographically
  75 # less than, equal to, or greater than string s2.
  76 #:end docstring:
  77
  78 ###;;;autoload
  79 function strcmp ()
  80 {
  81     [ "$1" = "$2" ] && return 0
  82
  83     [ "${1}" '<' "${2}" ] > /dev/null && return -1
  84
  85     return 1
  86 }
  87
  88 #:docstring strncmp:
  89 # Usage: strncmp $s1 $s2 $n
  90 #
  91 # Like strcmp, but makes the comparison by examining a maximum of n
  92 # characters (n less than or equal to zero yields equality).
  93 #:end docstring:
  94
  95 ###;;;autoload
  96 function strncmp ()
  97 {
  98     if [ -z "${3}" ] || [ "${3}" -le "0" ]; then
  99        return 0
 100     fi
 101
 102     if [ ${3} -ge ${#1} ] && [ ${3} -ge ${#2} ]; then
 103        strcmp "$1" "$2"
 104        return $?
 105     else
 106        s1=${1:0:$3}
 107        s2=${2:0:$3}
 108        strcmp $s1 $s2
 109        return $?
 110     fi
 111 }
 112
 113 #:docstring strlen:
 114 # Usage: strlen s
 115 #
 116 # Strlen returns the number of characters in string literal s.
 117 #:end docstring:
 118
 119 ###;;;autoload
 120 function strlen ()
 121 {
 122     eval echo "\${#${1}}"
 123 }
 124
 125 #:docstring strspn:
 126 # Usage: strspn $s1 $s2
 127 #
 128 # Strspn returns the length of the maximum initial segment of string s1,
 129 # which consists entirely of characters from string s2.
 130 #:end docstring:
 131
 132 ###;;;autoload
 133 function strspn ()
 134 {
 135     # Unsetting IFS allows whitespace to be handled as normal chars.
 136     local IFS=
 137     local result="${1%%[!${2}]*}"
 138
 139     echo ${#result}
 140 }
 141
 142 #:docstring strcspn:
 143 # Usage: strcspn $s1 $s2
 144 #
 145 # Strcspn returns the length of the maximum initial segment of string s1,
 146 # which consists entirely of characters not from string s2.
 147 #:end docstring:
 148
 149 ###;;;autoload
 150 function strcspn ()
 151 {
 152     # Unsetting IFS allows whitspace to be handled as normal chars.
 153     local IFS=
 154     local result="${1%%[${2}]*}"
 155
 156     echo ${#result}
 157 }
 158
 159 #:docstring strstr:
 160 # Usage: strstr s1 s2
 161 #
 162 # Strstr echoes a substring starting at the first occurrence of string s2 in
 163 # string s1, or nothing if s2 does not occur in the string.  If s2 points to
 164 # a string of zero length, strstr echoes s1.
 165 #:end docstring:
 166
 167 ###;;;autoload
 168 function strstr ()
 169 {
 170     # if s2 points to a string of zero length, strstr echoes s1
 171     [ ${#2} -eq 0 ] && { echo "$1" ; return 0; }
 172
 173     # strstr echoes nothing if s2 does not occur in s1
 174     case "$1" in
 175     *$2*) ;;
 176     *) return 1;;
 177     esac
 178
 179     # use the pattern matching code to strip off the match and everything
 180     # following it
 181     first=${1/$2*/}
 182
 183     # then strip off the first unmatched portion of the string
 184     echo "${1##$first}"
 185 }
 186
 187 #:docstring strtok:
 188 # Usage: strtok s1 s2
 189 #
 190 # Strtok considers the string s1 to consist of a sequence of zero or more
 191 # text tokens separated by spans of one or more characters from the
 192 # separator string s2.  The first call (with a non-empty string s1
 193 # specified) echoes a string consisting of the first token on stdout. The
 194 # function keeps track of its position in the string s1 between separate
 195 # calls, so that subsequent calls made with the first argument an empty
 196 # string will work through the string immediately following that token.  In
 197 # this way subsequent calls will work through the string s1 until no tokens
 198 # remain.  The separator string s2 may be different from call to call.
 199 # When no token remains in s1, an empty value is echoed on stdout.
 200 #:end docstring:
 201
 202 ###;;;autoload
 203 function strtok ()
 204 {
 205  :
 206 }
 207
 208 #:docstring strtrunc:
 209 # Usage: strtrunc $n $s1 {$s2} {$...}
 210 #
 211 # Used by many functions like strncmp to truncate arguments for comparison.
 212 # Echoes the first n characters of each string s1 s2 ... on stdout.
 213 #:end docstring:
 214
 215 ###;;;autoload
 216 function strtrunc ()
 217 {
 218     n=$1 ; shift
 219     for z; do
 220         echo "${z:0:$n}"
 221     done
 222 }
 223
 224 provide string
 225
 226 # string.bash ends here