Heuristics

This gem allows you to define a set of conditions and test values against them. A typical simple example can look like this:

require 'chronic'
Heuristics.define(:field_tester) do
    assume_default :integer

    assume(:date) { Chronic.parse(value) }
    assume(:string) { value.instance_of? String }
    assume(:hash) { value.instance_of? Hash } 
end

Then you can use it like this

# Returns :string
Heuristics.test(:field_tester, 'abc')

# Returns :date
Heuristics.test(:field_tester, '23.09.1985')

Installation

Add this line to your application's Gemfile:

gem 'heuristics'

And then execute:

$ bundle

Or install it yourself as:

$ gem install heuristics

Usage

NOTE: Order matters. First assumption to return true for all conditions will be used. This means you should write your assumptions in the order from most specific to least specfic.

# Creates a new heuristic named :field_tester
Heuristics.define(:field_tester) do

  # Default value to return if no assumptions match
  assume_default :integer

  # Assummption with multiple conditions. Returns :hash_with_values
  # if all conditions return true
  assume(:hash_with_values) do
    value.instance_of? Hash
    value.keys.size > 0
  }

  # An assumption that will return :date if all conditions return true
  assume(:date) { Chronic.parse(value) != nil }

  # An assumption that will return :string if all conditions return true
  assume(:string) { value.instance_of? String }
end


# Test a value against heuristic named :field_tester
# First assumption to test true for all conditions will win
# Returns :hash_with_values in this case
Heuristics.test(:field_tester, {a: 1})

Test an array of value (Also shows of using heuristic without a name): Heuristics.define do

# Default value to return if no assumptions match
assume_default :set

assume(:date) { Chronic.parse(value) != nil }
assume(:string) { value.instance_of? String }
assume(:integer) { value.instance_of? Fixnum }

end

Heuristics.test([1,2,3,'23.09.85','1','2','3','4']) # returns :string

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request