# GraphBuilder

[![Build History][2]][1]

[1]: http://travis-ci.org/tracksun/graph_builder
[2]: https://secure.travis-ci.org/tracksun/graph_builder.png?branch=master


DSL to build directed graphs

## Installation

Add this line to your application's Gemfile:

    gem 'graph_builder'

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install graph_builder

## Usage

GraphBuilder provides a DSL to build a graph of arbritary objects.

The objects must implement 

    link_to( other ) 

which must implement a link between self and other.


### Examples:

#### A simple chain: a → b → c

    GraphBuilder::Builder.build do |builder|
       builder.add a 
       builder.add b 
       builder.add c 
    end

#### A simple branch: a → b, a → c

    GraphBuilder::Builder.build do |builder|
       builder.add a  
       builder.branch do 
         builder.add b 
         builder.add c 
       end
    end

#### Diamond shaped graph: a → l → b,  a → r → b

    GraphBuilder::Builder.build do |builder|
       builder.add a  
       builder.branch do 
         builder.add l 
         builder.add r 
       end
       builder.add b  
    end

#### Diamond with chains: a →  l1 → l2 → b, a →  r1 → r2 → r3 → b 

    GraphBuilder::Builder.build do |builder|
       builder.add a  
       builder.branch do 
         builder.chain do 
           builder.add l1
           builder.add l2
         end
         builder.chain do 
           builder.add r1
           builder.add r2
           builder.add r3
         end
       end
       builder.add b  
    end

### Implemention of #link_to 

graph_builder comes with the module GraphBuilder::Linkable which implements

    # links self to other
    link_to( other ) 

    # returns an array of objects self is linked to
    linked_to

    # returns an array of pairs [ [ self, other1 ], [ self, other2 ], ... ]
    # for linked objects other1,  other2, ...
    links
    

## Contributing

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