Why does echo not return the same thing as without-CodePudding

I have the following case:

regex: $'\[OK\][[:space:]] ([[:alnum:]_] )\.([[:alnum:]_] )([^[]*)'

text:

[OK] AAA.BBBBBB
aaabbbcccdddfffed
asdadadadadadsada
[OK] CCC.KKKKKKK
some text here
[OK] OKO.II

if I am using this site

Now... If I will have the following code:

var_test=()
while [[ $text =~ $regex ]]; do
  var_test =("${BASH_REMATCH[@]:1}")
  text=${text#*"${BASH_REMATCH[0]}"}
done
declare -p var_test

I will have the correct output:

declare -a var_test=([0]="AAA" [1]="BBBBBB" [2]=$'\naaabbbcccdddfffed\nasdadadadadadsada\n' [3]="CCC" [4]="KKKKKKK" [5]=$'\nsome text here\n' [6]="OKO" [7]="II" [8]="")

But once I will convert it into a function like this:

function split_by_regex {
  regex=$1
  text=$2
  groups=()
  while [[ $text =~ $regex ]]; do
    groups =("${BASH_REMATCH[@]:1}")
    text=${text#*"${BASH_REMATCH[0]}"}
  done
  echo "${groups[@]}"
}

res=($(split_by_regex "$regex" "$text"))
declare -p res

I will get the wrong output:

declare -a res=([0]="AAA" [1]="BBBBBB" [2]="aaabbbcccdddfffed" [3]="asdadadadadadsada" [4]="CCC" [5]="KKKKKKK" [6]="some" [7]="text" [8]="here" [9]="OKO" [10]="II")

After some debug all it the error looks like it comes from the echo "${groups[@]}" because if I will check the groups within the function it looks as it should, but after I get the result from the function is not.

Sorry if this is an obvious question, but I am new to bash and shell scripting and I am trying to figure it out.

CodePudding user response：

Returning arrays from functions is tricky because whitespaces will, as you have noticed, be used to split the values in the array - and will therefore not be preserved.

I suggest using a nameref instead.

function split_by_regex {
  local -n groups=$1   # -n makes `groups` a reference to `res`
  local regex=$2
  local text=$3
  while [[ $text =~ $regex ]]; do
    groups =("${BASH_REMATCH[@]:1}")
    text=${text#*"${BASH_REMATCH[0]}"}
  done
}

declare -a res                       # declare `res` as an array
split_by_regex res "$regex" "$text"  # pass in `res` as a parameter
declare -p res                       # prints the expected result

CodePudding user response：

Another approach is to declare the array outside of the function, If the work flow/requirements will allow it, something like:

regex=$'\[OK\][[:space:]] ([[:alnum:]_] )\.([[:alnum:]_] )([^[]*)'

text='[OK] AAA.BBBBBB
aaabbbcccdddfffed
asdadadadadadsada
[OK] CCC.KKKKKKK
some text here
[OK] OKO.II'

#: `declare -a groups` will work as well
#: Declare it outside of the function
groups=()

function split_by_regex {
  local regex=$1
  local text=$2
  while [[ "$text" =~ $regex ]]; do
    groups =("${BASH_REMATCH[@]:1}")
    text=${text#*"${BASH_REMATCH[0]}"}
  done
}

split_by_regex "$regex" "$text"

#: Now one can access/process the array `groups` outside of the function.
declare -p groups

Without nameref, the above code is an alternative.