Class: JSONFilePersistedHash

Inherits:
Object
  • Object
show all
Defined in:
lib/util/json_file_persisted_hash.rb

Overview

An hash that is automatically persisted to a JSON file. This class behaves similarly to a regular Hash but it persists every operation to a specified JSON file. Not all Hash operations are supported and we added some of our own.

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ JSONFilePersistedHash

Returns a new instance of JSONFilePersistedHash.



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# File 'lib/util/json_file_persisted_hash.rb', line 9

def initialize( file )
  @store = JSONStore.new(file, true)
end

Instance Method Details

#[](key) ⇒ Object

Methods borrowed from Ruby’s Hash class



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# File 'lib/util/json_file_persisted_hash.rb', line 16

def []( key )
  @store.transaction { @store[key] }
end

#[]=(key, val) ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 20

def []=( key, val )
  @store.transaction { @store[key]=val }
end

#add_key_value?(key, val) ⇒ Boolean

Adds a <key, value> pair to the PersistedHash _only if_ there is currently no value associated with the specified key. <key, value> pair was added successfully

Returns:

  • (Boolean) —

    false if the key already exists, true if the



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# File 'lib/util/json_file_persisted_hash.rb', line 67

def add_key_value?(key, val)
  @store.transaction do
    return false if @store.to_h.key? key
    @store[key]=val
  end
  true
end

#delete(key) ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 24

def delete( key )
  @store.transaction { @store.delete key }
end

#delete_key_value?(key) ⇒ Boolean

Removes a <key, value> pair from the PersistedHash _only if_ there is currently a value associated with the specified key. the specified key, true otherwise

Returns:

  • (Boolean) —

    false if there is no value associated with



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# File 'lib/util/json_file_persisted_hash.rb', line 79

def delete_key_value?( key )
  @store.transaction { return false if @store.delete(key).nil? }
  true
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/util/json_file_persisted_hash.rb', line 28

def empty?
  @store.transaction { @store.to_h.empty? }
end

#has_key?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/util/json_file_persisted_hash.rb', line 32

def has_key?( key )
  @store.transaction { @store.to_h.has_key? key }
end

#include?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/util/json_file_persisted_hash.rb', line 36

def include?( key )
  has_key? key
end

#keys ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 48

def keys
  @store.transaction { @store.to_h.keys }
end

#length ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 52

def length
  @store.transaction { @store.to_h.length }
end

#merge!(other_hash) ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 56

def merge!( other_hash )
  @store.transaction { other_hash.each { |k, v| @store[k] = v } }
end

#to_h ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 44

def to_h
  @store.transaction { @store.to_h }
end

#to_s ⇒ Object 



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# File 'lib/util/json_file_persisted_hash.rb', line 40

def to_s
  @store.transaction { @store.to_h.to_s }
end