stdlib

#!/bin/bash

# Standard library functions to be included in other bash scripts
#
# (c) Copyright 2015 John Peach
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Maintainer: John Peach <john@jppeach.com>
#

# ChangeLog
# 1.0.0    Initial Release
# 1.1.0    Added quoted_array

# Sample code to load the library
#LIBLIST=('/usr/local/sbin/stdlib')
#for file in "${LIBLIST[@]}" ; do
#   [ -x "$file" ] && { source $file; }
#done


#####################################################################################################
# Functions
#####################################################################################################

# join an array and echo elements seperated by $1
# PARAMETERS:   $1      seperator
#               $2..    unknown number of parameters
# Examples:
# join , a "b c" d #a,b c,d
# join / var local tmp #var/local/tmp
# join , "${FOO[@]}" #a,b,c
function join { 
   local IFS="$1" 
   shift 
   echo "$*" 
}

# wrap single quotes around each element in an array and echo it out onto a single
# line.  This is useful for quoting filenames used for command line arguements
#
# PARAMETERS:  $1       name of array by reference
# Example:
# FILE_STRING=$(quoted_array FILE_LIST[@])   # note the lack of $ 
function quoted_array {
    local myarray=("${!1}")

    for x in "${myarray[@]}"; do
        echo -n "'$x' "
    done
}

# Determine if a name exists and it is a function.
# PARAMETERS:   $1       function name
#
# returns $ISFUNCTION_VALID if true, $ISFUNCTION_INVALID otherwise.  Check $?
# Examples:
# isFunction 'join'
# if [ $? -eq $ISFUNCTION_VALID ]; then
#   echo 'join is a fuction'
# fi
ISFUNCTION_VALID=1
ISFUNCTION_INVALID=0
function isFunction() {
   local funname="$1" 

   # make sure there is a fuction name
   [ -z "$funname" ] && { return $ISFUNCTION_INVALID; }

   # Make sure that it function
   if [ -n "$(type -t $funname)" ] && [ "$(type -t $funname)" == "function" ]; then
       return $ISFUNCTION_VALID
   else
       return $ISFUNCTION_INVALID
   fi
}

# Assert that the first parameter is not zero length
# if it is then print an error message in parameter $2
# to STDERR and exit the program. If there is no second
# parameter, call usage (if it is defined) and exit
# PARAMETERS:   $1      Tested to see if it is zero length
#               $2      Error message to print
#               $3      Error code to use if the program is to exit
function AssertNonZeroLen() {
    local test_value="$1" 
    local message="$2" 
    local err_code="$3" 

    if [ -z "$test_value" ] ; then
        if [ -n "$message" ] ; then
            ErrorMsg "$message" "$err_code"
        else
            # If usage is a defined function, call it.
            isFunction 'usage'
            local usage_exists=$?
            [ $usage_exists -eq $ISFUNCTION_VALID ] && { usage; }
        fi
        [ -z "$err_code" ] && {  exit $err_code; }
    fi
}

# Error Message
#
# Write an error message to STDERR.  If an error code is given then also exit with that code.
#
# Parameter:    $1      Error message
#               $2      if exists, it must be an exit code (0-255).  The program will exit
function ErrorMsg() { 
    local message="$1" 
    local err_code="$2" 

    >&2 echo "ERROR: $message"
    if [ -n "$err_code" ] ; then
        # Exit code was give, exit the program
        exit $err_code
    fi
}