Soroban

Soroban is a calculating engine that understands Excel formulas.

Getting Started

> sudo gem install soroban

Example Usage

require 'soroban'

s = Soroban::Sheet.new()

s.A1 = 2
s.set('B1:B5', [1,2,3,4,5])
s.C1 = "=SUM(B1:B5) + A1 ^ 3"
s.C2 = "=IF(C1>25,'Large','Tiny')"

puts s.C1             # => 23

s.bind(:input, :A1)
s.bind(:output, :C2)

puts s.output         # => "Tiny"

s.input = 3

puts s.output         # => "Large"
puts s.C1             # => 42

Persistence

Soroban formulas are strings that begin with the = symbol. It is therefore easy to persist them, which is mighty handy if you need to parse an Excel spreadsheet, rip out formulas, store everything to a database and then perform calculations based on user input.

Soroban makes this easy, as it can tell you which cells you need to add to make it possible to do the calculations you want, and it can iterate over all the cells you've defined, so you can easily rip them out for persistence.

s.F1 = "= E1 + SUM(D1:D5)"

s.missing             # => [:E1, :D1, :D2, :D3, :D4, :D5]

s.E1 = "= D1 ^ D2"
s.set("D1:D5", [1,2,3,4,5])

s.missing             # => []

s.cells               # => {"F1"=>"= E1 + SUM(D1:D5)", "E1"=>"= D1 ^ D2", "D1"=>"1", "D2"=>"2", "D3"=>"3", "D4"=>"4", "D5"=>"5"}

This means parsing a file can be done as follows.

Add the cells that correspond to inputs and outputs
Add the cells reported by missing (and continue to do so until it's empty)
Persist the hash returned by cells

Iteration

Note that cells returns the label of the cell along with its raw contents. If you want to iterate over cell values (including computed values of formulas), then use walk.

s.set('D1:D5', [1,2,3,4,5])
s.walk('D1:D5').reduce(:+)    # => 15

Functions

Soroban implements some Excel functions, but you may find that you need more than those. In that case, it's easy to add more.

Soroban::functions            # => ["MIN", "VLOOKUP", "AND", "MAX", "OR", "NOT", "IF", "AVERAGE", "SUM"] 

Soroban::define :FOO => lambda { |lo, hi|
  raise ArgumentError if lo > hi
  rand(hi-lo) + lo
}

s.g = "=FOO(10, 20)"

puts s.g              # => 17

Contributing to Soroban

Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
Fork the project.
Start a feature/bugfix branch.
Commit and push until you are happy with your contribution.
Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.