Hash map / dictionary / associative array implementation for bash

bash-hash-map.sh

#!/bin/bash
# Bash hash-map which works in Bash 3.

# WARNING: this code is useless and you should not use it. See the comments.

# Hashing function from Adam Katz: https://stackoverflow.com/a/12945518
ht() {
  local h=0 i
  for (( i=0; i < ${#1}; i++ )); do
    let "h=( (h<<5) - h ) + $(printf %d \'${1:$i:1})"
    let "h |= h"
  done
  printf "$h"
}

# Hash map functions
# (collisions are handled)

map=()

function put {
  local hash="$(ht "$1")"
  map["$hash"]="$1=$2"
}

function get {
  local hash="$(ht "$1")"
  local value=""
  for item in "${map[@]}"; do
    if [ "${item%%=*}" == "$1" ]; then
      value="${item#*=}"
      break
    fi
  done
  echo "$value"
}

function contains_key {
  local hash="$(ht "$1")"
  local result="false"
  for item in "${map[@]}"; do
    if [ "${item%%=*}" == "$1" ]; then
      result="true"
      break
    fi
  done
  echo "$result"
}

# Example usage

put "key1" "value1"
put "key2" "value2"

value1=$(get "key1")
value2=$(get "key2")

echo "key1: $value1"
echo "key2: $value2"

contains_key_result1=$(contains_key "key1")
contains_key_result2=$(contains_key "key3")

echo "key1 exists: $contains_key_result1"
echo "key3 exists: $contains_key_result2"

Lol yes you are correct, this is a truly awful solution and nobody should use it.

My first impulse is to remove this gist but I think I am going to leave it up here to serve as a warning to others. It's incredibly embarrassing that a veteran software developer like me, with bash Git repos with hundreds of stars, could have made such an elementary mistake. The way this happened is quite simple. I trusted the output from a GPT large language model after running the code but without taking a few moments to properly read it. If I had done so instead of breathlessly posting the link on Stackoverflow I would have come to the same conclusion you did and not had my ass handed to me in public. This has been a very valuable lesson. In future I will be much more wary of the output from these GPTs.

Adam thank you for taking the time to comment on and utterly destroy this implementation, you have done me a great service.