Collection

(Experimental) Functions to iterates over a list of elements, yielding each in turn to an iteratee function.

Table of Contents

collection::each()

Iterates over elements of collection and invokes iteratee for each element. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 2: Function missing arguments.
  • other exitcode returned by iteratee.

Output on stdout

  • Output of iteratee function.

Example

test_func(){
   printf "print value: %s\n" "$1"
   return 0
 }
arr1=("a b" "c d" "a" "d")
printf "%s\n" "${arr1[@]}" | collection::each "test_func"
collection::each "test_func"  < <(printf "%s\n" "${arr1[@]}") #alternative approach
#output
 print value: a b
 print value: c d
 print value: a
 print value: d

Example

# If other function from this library is already used to process the array.
# Then following method could be used to pass the array to the function.
out=("$(array::dedupe "${arr1[@]}")")
collection::each "test_func"  <<< "${out[@]}"

collection::every()

Checks if iteratee function returns truthy for all elements of collection. Iteration is stopped once predicate returns false. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 1: If iteratee function fails.
  • 2: Function missing arguments.

Example

arri=("1" "2" "3" "4")
printf "%s\n" "${arri[@]}" | collection::every "variable::is_numeric"

collection::filter()

Iterates over elements of array, returning all elements where iteratee returns true. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 2: Function missing arguments.

Output on stdout

  • array values matching the iteratee function.

Example

arri=("1" "2" "3" "a")
printf "%s\n" "${arri[@]}" | collection::filter "variable::is_numeric"
#output
1
2
3

collection::find()

Iterates over elements of collection, returning the first element where iteratee returns true. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 1: If no match found.
  • 2: Function missing arguments.

Output on stdout

  • first array value matching the iteratee function.

Example

arr=("1" "2" "3" "a")
check_a(){
    [[ "$1" = "a" ]]
}
printf "%s\n" "${arr[@]}" | collection::find "check_a"
#Output
a

collection::invoke()

Invokes the iteratee with each element passed as argument to the iteratee. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 2: Function missing arguments.
  • other exitcode returned by iteratee.

Output on stdout

  • Output from the iteratee function.

Example

opt=("-a" "-l")
printf "%s\n" "${opt[@]}" | collection::invoke "ls"

collection::map()

Creates an array of values by running each element in array through iteratee. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 2: Function missing arguments.
  • other exitcode returned by iteratee.

Output on stdout

  • Output result of iteratee on value.

Example

arri=("1" "2" "3")
add_one(){
  i=${1}
  i=$(( i + 1 ))
  printf "%s\n" "$i"
}
printf "%s\n" "${arri[@]}" | collection::map "add_one"

collection::reject()

The opposite of filter function; this method returns the elements of collection that iteratee does not return true. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If successful.
  • 2: Function missing arguments.

Output on stdout

  • array values not matching the iteratee function.

Example

arri=("1" "2" "3" "a")
printf "%s\n" "${arri[@]}" | collection::reject "variable::is_numeric"
#Ouput
a

See also

collection::some()

Checks if iteratee returns true for any element of the array. Input to the function can be a pipe output, here-string or file.

Arguments

  • $1 (string): Iteratee function.

Exit codes

  • 0: If match successful.
  • 1: If no match found.
  • 2: Function missing arguments.

Example

arr=("a" "b" "3" "a")
printf "%s\n" "${arr[@]}" | collection::reject "variable::is_numeric"