Class: OpenC3::JsonAccessor

Inherits:
Accessor show all
Defined in:
lib/openc3/accessors/json_accessor.rb

Direct Known Subclasses

CborAccessor

Instance Attribute Summary

Attributes inherited from Accessor

#packet

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Accessor

#args, convert_to_type, #initialize, #read_item, #read_items, #write_item, #write_items

Constructor Details

This class inherits a constructor from OpenC3::Accessor

Class Method Details

.read_item(item, buffer) ⇒ Object 



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# File 'lib/openc3/accessors/json_accessor.rb', line 25

def self.read_item(item, buffer)
  return nil if item.data_type == :DERIVED
  value = JsonPath.on(buffer, item.key).first
  return convert_to_type(value, item)
end

.read_items(items, buffer) ⇒ Object 



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# File 'lib/openc3/accessors/json_accessor.rb', line 52

def self.read_items(items, buffer)
  # Prevent JsonPath from decoding every call
  if String === buffer
    decoded = JSON.parse(buffer, :allow_nan => true)
  else
    decoded = buffer
  end
  super(items, decoded)
end

.write_item(item, value, buffer) ⇒ Object 



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# File 'lib/openc3/accessors/json_accessor.rb', line 31

def self.write_item(item, value, buffer)
  return nil if item.data_type == :DERIVED

  # Convert to ruby objects
  if String === buffer
    decoded = JSON.parse(buffer, :allow_nan => true)
  else
    decoded = buffer
  end

  # Write the value
  write_item_internal(item, value, decoded)

  # Update buffer
  if String === buffer
    buffer.replace(JSON.generate(decoded, :allow_nan => true))
  end

  return value
end

.write_item_internal(item, value, decoded) ⇒ Object 



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# File 'lib/openc3/accessors/json_accessor.rb', line 85

def self.write_item_internal(item, value, decoded)
  return nil if item.data_type == :DERIVED

  # Save traversal state
  parent_node = nil
  parent_key = nil
  node = decoded

  # Parse the JsonPath
  json_path = JsonPath.new(item.key)

  # Handle each token
  json_path.path.each do |token|
    case token
    when '$'
      # Ignore start - it is implied
      next
    when /\[.*\]/
      # Array or Hash Index
      if token.index("'") # Hash index
        key = token[2..-3]
        if not (Hash === node)
          node = {}
          parent_node[parent_key] = node
        end
        parent_node = node
        parent_key = key
        node = node[key]
      else # Array index
        key = token[1..-2].to_i
        if not (Array === node)
          node = []
          parent_node[parent_key] = node
        end
        parent_node = node
        parent_key = key
        node = node[key]
      end
    else
      raise "Unsupported key/token: #{item.key} - #{token}"
    end
  end
  value = convert_to_type(value, item)
  if parent_node
    parent_node[parent_key] = value
  else
    decoded.replace(value)
  end
  return decoded
end

.write_items(items, values, buffer) ⇒ Object 



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# File 'lib/openc3/accessors/json_accessor.rb', line 62

def self.write_items(items, values, buffer)
  # Start with an empty object if no buffer
  buffer.replace("{}") if buffer.length == 0 or buffer[0] == "\x00"

  # Convert to ruby objects
  if String === buffer
    decoded = JSON.parse(buffer, :allow_nan => true)
  else
    decoded = buffer
  end

  items.each_with_index do |item, index|
    write_item_internal(item, values[index], decoded)
  end

  # Update buffer
  if String === buffer
    buffer.replace(JSON.generate(decoded, :allow_nan => true))
  end

  return values
end

Instance Method Details

#enforce_derived_write_conversion(_item) ⇒ Object

If this is true it will enfore that COSMOS DERIVED items must have a write_conversion to be written



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# File 'lib/openc3/accessors/json_accessor.rb', line 158

def enforce_derived_write_conversion(_item)
  return true
end

#enforce_encoding ⇒ Object

If this is set it will enforce that buffer data is encoded in a specific encoding



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# File 'lib/openc3/accessors/json_accessor.rb', line 138

def enforce_encoding
  return nil
end

#enforce_length ⇒ Object

This affects whether the Packet class enforces the buffer length at all. Set to false to remove any correlation between buffer length and defined sizes of items in COSMOS



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# File 'lib/openc3/accessors/json_accessor.rb', line 145

def enforce_length
  return false
end

#enforce_short_buffer_allowed ⇒ Object

This sets the short_buffer_allowed flag in the Packet class which allows packets that have a buffer shorter than the defined size. Note that the buffer is still resized to the defined length



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# File 'lib/openc3/accessors/json_accessor.rb', line 152

def enforce_short_buffer_allowed
  return true
end