Class: Latinum::Collection

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/latinum/collection.rb

Overview

Aggregates a set of resources, typically used for summing values to compute a total.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(names = Set.new) ⇒ Collection

Initialize the collection with a given set of resource names.



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# File 'lib/latinum/collection.rb', line 15

def initialize(names = Set.new)
  @names = names
  @resources = Hash.new {|hash, key| @names << key; BigDecimal(0)}
end

Instance Attribute Details

#names ⇒ Object

All resource names which have been added to the collection. e.g. ‘[’NZD’, ‘USD’]‘.



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# File 'lib/latinum/collection.rb', line 23

def names
  @names
end

#resources ⇒ Object (readonly)

Keeps track of all added resources.



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# File 'lib/latinum/collection.rb', line 27

def resources
  @resources
end

Instance Method Details

#-(other) ⇒ Object

Subtract something from this collection.



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# File 'lib/latinum/collection.rb', line 54

def - other
  self << -other
end

#-@ ⇒ Object

Allow negation of all values within the collection.



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# File 'lib/latinum/collection.rb', line 60

def -@
  collection = self.class.new
  
  @resources.each do |key, value|
    collection.resources[key] = -value
  end
  
  return collection
end

#<<(object) ⇒ Object Also known as: +

Add a resource, an array of resources, or another collection into this one.



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# File 'lib/latinum/collection.rb', line 37

def <<(object)
  case object
  when Resource
    add(object)
  when Array
    object.each { |resource| add(resource) }
  when Collection
    object.resources.each { |name, amount| @resources[name] += amount }
  end
  
  return self
end

#[](key) ⇒ Object 



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# File 'lib/latinum/collection.rb', line 75

def [] key
  if amount = @resources[key]
    Resource.new(@resources[key], key)
  end
end

#[]=(key, amount) ⇒ Object

Set the amount for the specified resource name.



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# File 'lib/latinum/collection.rb', line 84

def []= key, amount
  @resources[key] = amount
end

#add(resource) ⇒ Object

Add a resource into the totals.



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# File 'lib/latinum/collection.rb', line 31

def add(resource)
  @resources[resource.name] += resource.amount
end

#compact ⇒ Object

Generate a new collection but ignore zero values.



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# File 'lib/latinum/collection.rb', line 113

def compact
  collection = self.class.new
  
  @resources.each do |key, value|
    unless value.zero?
      collection.resources[key] = value
    end
  end
  
  return collection
end

#each ⇒ Object

Iterates over all the resources.



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# File 'lib/latinum/collection.rb', line 91

def each
  return to_enum(:each) unless block_given?
  
  @resources.each do |key, value|
    yield Resource.new(value, key)
  end
end

#empty? ⇒ Boolean

Whether the collection is empty.

Returns:

  • (Boolean) 


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# File 'lib/latinum/collection.rb', line 101

def empty?
  @resources.empty?
end

#include?(key) ⇒ Boolean

Whether the collection contains the specified resource (may be zero).

Returns:

  • (Boolean) 


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# File 'lib/latinum/collection.rb', line 107

def include?(key)
  @resources.include?(key)
end

#key?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/latinum/collection.rb', line 70

def key?(name)
  @resources.key?(name)
end

#to_s ⇒ Object

A human readable representation of the collection. e.g. ‘“5.0 NZD; 10.0 USD”`



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# File 'lib/latinum/collection.rb', line 128

def to_s
  @resources.map{|name, amount| "#{amount.to_s('F')} #{name}"}.join("; ")
end