Class: Ruleby::Core::MultiHash

Inherits:
Object
  • Object
show all
Defined in:
lib/core/utils.rb

Overview

This class is used when we need to have a Hash where keys and values are mapped many-to-many. This class allows for quick access of both key and value. It is similar to Multimap in C++ standard lib. This thing is a mess (and barely works). It needs to be refactored.

Instance Method Summary collapse

Constructor Details

#initialize(key = nil, values = []) ⇒ MultiHash

Returns a new instance of MultiHash.



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# File 'lib/core/utils.rb', line 171

def initialize(key=nil, values=[])
  @i = 0
  clear
  if key
    @keys = {key => []} 
    values.each do |v|
      xref = generate_xref()
      xref_list = @keys[key]
      xref_list.push xref
      @keys[key] = xref_list
      @values = {xref => v}
      @backward_hash = {xref => [key]}
    end
  end
end

Instance Method Details

#+(dh) ⇒ Object 



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# File 'lib/core/utils.rb', line 234

def +(dh)
  # TODO this can be faster
  new_dh = dh.dup
  dh.concat self.dup
  return new_dh
end

#==(dh) ⇒ Object 



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# File 'lib/core/utils.rb', line 485

def ==(dh)
  # TODO need to implement this
  return super
end

#add(ids, val) ⇒ Object 



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# File 'lib/core/utils.rb', line 241

def add(ids,val)
  xref = generate_xref()      
  ids.each do |id|
    xref_list = @keys[id]
    xref_list = [] if xref_list == @keys.default
    xref_list.push xref             
    @keys[id] = xref_list  
  end       
  @values[xref] = val    
  @backward_hash[xref] = ids
end

#add_uniq(ids, val) ⇒ Object

DEPRECATED WARN this method adds a value to the MultiHash only if it is unique. It can be a fairly costly operation, and should be avoided. We only implemented this as part of a hack to get things working early on.



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# File 'lib/core/utils.rb', line 257

def add_uniq(ids,val)
  xref = generate_xref()
  exist_list = []
  ids.each do |id|
    xref_list = @keys[id]
    if xref_list != @keys.default           
      xref_list.each do |existing_xref|  
        existing_val = @values[existing_xref] 
        if existing_val 
          if val == existing_val                        
            xref = existing_xref 
            exist_list.push id
            break
          end
        else
          # HACK there shouldn't be any xrefs like this in the
          # hash to being with.  Why are they there?
          xref_list.delete(existing_xref)
          @keys[id] = xref_list
        end
      end         
    end             
  end   
  add_list = ids - exist_list   
  add_list.each do |id|
    xref_list = @keys[id]
    xref_list = [] if xref_list == @keys.default
    xref_list.push xref             
    @keys[id] = xref_list  
  end            
  @values[xref] = val if exist_list.empty?
  b_list = @backward_hash[xref]
  if b_list
    @backward_hash[xref] = b_list | ids
  else
    @backward_hash[xref] = ids
  end
end

#clear ⇒ Object 



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# File 'lib/core/utils.rb', line 201

def clear
  @keys = {}
  @values = {}
  @backward_hash = {}
end

#concat(multi_hash) ⇒ Object 



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# File 'lib/core/utils.rb', line 311

def concat(multi_hash)
  multi_hash.each do |ids,val|
    add(ids,val)
  end
end

#concat_uniq(double_hash) ⇒ Object

DEPRECATED WARN see comments in add_uniq



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# File 'lib/core/utils.rb', line 319

def concat_uniq(double_hash)
  double_hash.each do |ids,val|
    add_uniq(ids,val)
  end
end

#default ⇒ Object 



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# File 'lib/core/utils.rb', line 325

def default
  return @values.default
end

#delete_if ⇒ Object 



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# File 'lib/core/utils.rb', line 376

def delete_if
  @values.delete_if do |xref,v|  
    if yield(v)
      id_list = @backward_hash.delete(xref)
      id_list.each do |next_id|
        remove_internal(next_id,xref)
      end
      true
    else
      false
    end
  end
end

#dup ⇒ Object 



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# File 'lib/core/utils.rb', line 398

def dup
  dup_mc = MultiHash.new
  each do |ids,v|
    dup_mc.add ids, v.dup
  end
  return dup_mc      
end

#each ⇒ Object 



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# File 'lib/core/utils.rb', line 296

def each
  @values.each do |xref,val|
    ids = @backward_hash[xref]        
    yield(ids,val)
  end
end

#each_key ⇒ Object 



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# File 'lib/core/utils.rb', line 220

def each_key
  @keys.each_key do |key|
    yield(key)
  end
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/core/utils.rb', line 187

def empty?
  return @keys.empty?
end

#has_key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/core/utils.rb', line 226

def has_key?(key)
  return @keys.has_key?(key)
end

#key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/core/utils.rb', line 230

def key?(key)
  return has_key?(key)
end

#keys ⇒ Object 



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# File 'lib/core/utils.rb', line 394

def keys
  return @keys.keys
end

#rehash ⇒ Object 



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# File 'lib/core/utils.rb', line 191

def rehash
  @keys.rehash
  @values.rehash
  @backward_hash.rehash
end

#remove(id) ⇒ Object 



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# File 'lib/core/utils.rb', line 329

def remove(id)      
  xref_list = @keys.delete(id)
  if xref_list != @keys.default
    removed_values = []
    xref_list.each do |xref|
      value = @values.delete(xref)
      removed_values.push value
      id_list = @backward_hash.delete(xref)
      id_list.each do |next_id|
        remove_internal(next_id,xref) if next_id != id
      end
    end
    return removed_values
  else
  #        puts 'WARN: tried to remove from MultiHash where id does not exist'        
    return default
  end
end

#value?(mr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/core/utils.rb', line 197

def value?(mr)
  @values.value?(mr)
end

#values ⇒ Object 



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# File 'lib/core/utils.rb', line 390

def values
  return @values.values
end

#values_by_id(id) ⇒ Object 



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# File 'lib/core/utils.rb', line 207

def values_by_id(id)
  xrefs = @keys[id]
  values = []
  if xrefs
    xrefs.each do |k|
      values.push @values[k]
    end
  else
    #???
  end
  return values
end