http://codebrawl.com/contests/key-value-stores

README.textile

KeyValue

KeyValue is a simple key value store written in Ruby for Codebrawl #9. It provides programmatic and command line access to the store. The data is persisted as JSON, serialized to a file.

Programmatic access:

require "key_value"

kv = KeyValue.new

kv.set("foo", "bar") # => "bar"
kv.get("foo") # => "bar"
kv.keys # => ["foo"]
kv.delete("foo") # => "bar"

CLI access:

$ ./key_value.rb get [key]
$ ./key_value.rb set [key] [value]
$ ./key_value.rb keys
$ ./key_value.rb delete [key]

key_value.rb

#!/usr/bin/env ruby -w
# encoding: utf-8

require "json"

class KeyValue
  FILE = "#{ENV['HOME']}/.keyvalue"

  def initialize
    begin
      @data = JSON.parse(File.read(FILE))
    rescue Errno::ENOENT, JSON::ParserError
      @data = {}
    end
  end

  def get(key)
    @data[key.to_s]
  end

  def set(key, value)
    @data[key.to_s] = value
    save
    value
  end

  def keys
    @data.keys
  end

  def delete(key)
    value = @data.delete(key.to_s)
    save
    value
  end

  private

  def save
    File.open(FILE, "w") { |f| f.write(JSON.generate(@data)) }
  end
end

if $0 == __FILE__
  method, key, value = *ARGV
  method ||= ""
  kv = KeyValue.new

  result = case method.to_sym
  when :get
    kv.get(key)
  when :set
    kv.set(key, value)
  when :keys
    kv.keys
  when :delete
    kv.delete(key)
  else
    <<-eos
Usage:

./key_value.rb get [key]
./key_value.rb set [key] [value]
./key_value.rb keys
./key_value.rb delete [key]
eos
  end

  puts result if result
end