Class: CryptoconditionsRuby::Utils::Reader

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

Constant Summary collapse

HIGH_BIT = 
0x80
LOWER_SEVEN_BITS = 
0x7F
MAX_INT_BYTES = 
6

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(buffer) ⇒ Reader

Returns a new instance of Reader.



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 7

def initialize(buffer)
  @buffer = buffer
  @cursor = 0
  @bookmarks = []
end

Instance Attribute Details

#bookmarks ⇒ Object

Returns the value of attribute bookmarks.



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 6

def bookmarks
  @bookmarks
end

#buffer ⇒ Object

Returns the value of attribute buffer.



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 6

def buffer
  @buffer
end

#cursor ⇒ Object

Returns the value of attribute cursor.



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 6

def cursor
  @cursor
end

Class Method Details

.from_source(source) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 13

def self.from_source(source)
  source.is_a?(self) ? source : new(source)
end

Instance Method Details

#bookmark ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 17

def bookmark
  self.bookmarks << cursor
end

#ensure_available(num_bytes) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 25

def ensure_available(num_bytes)
  if buffer.length < cursor + num_bytes
    raise RangeError.new("Tried to read #{num_bytes} bytes, but only #{buffer.length - cursor} bytes available")
  end
end

#peek(num_bytes) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 111

def peek(num_bytes)
  read(num_bytes, peek: true)
end

#peek_octet_string(length) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 71

def peek_octet_string(length)
  peek(length)
end

#peek_uint(length) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 41

def peek_uint(length)
  read_uint(length, peek: true)
end

#peek_uint16 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 140

def peek_uint16
  peek_uint(2)
end

#peek_uint32 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 144

def peek_uint32
  peek_uint(4)
end

#peek_uint64 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 148

def peek_uint64
  peek_uint(8)
end

#peek_uint8 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 136

def peek_uint8
  peek_uint(1)
end

#peek_var_octet_string ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 93

def peek_var_octet_string
  bookmark
  read_var_octet_string.tap { restore }
end

#peek_var_uint ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 58

def peek_var_uint
  bookmark
  read_var_uint.tap { restore }
end

#read(num_bytes, peek: false) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 103

def read(num_bytes, peek: false)
  ensure_available(num_bytes)

  value = buffer[cursor...(cursor + num_bytes)]
  self.cursor += num_bytes unless peek
  value
end

#read_length_prefix ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 79

def read_length_prefix
  length = read_uint8

  if length & HIGH_BIT > 0
    return read_uint(length & LOWER_SEVEN_BITS)
  end
  length
end

#read_octet_string(length) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 67

def read_octet_string(length)
  read(length)
end

#read_uint(length, peek: false) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 31

def read_uint(length, peek: false)
  if length > MAX_INT_BYTES
    raise RangeError.new("Tried to read too large integer (requested: #{length}, max: #{MAX_INT_BYTES})")
  end
  ensure_available(length)
  value = buffer[cursor...(cursor + length)]
  self.cursor += length unless peek
  CryptoconditionsRuby::Utils::Bytes.new(value).to_i(16)
end

#read_uint16 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 124

def read_uint16
  read_uint(2)
end

#read_uint32 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 128

def read_uint32
  read_uint(4)
end

#read_uint64 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 132

def read_uint64
  read_uint(8)
end

#read_uint8 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 120

def read_uint8
  read_uint(1)
end

#read_var_octet_string ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 88

def read_var_octet_string
  length = read_length_prefix
  read(length)
end

#read_var_uint ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 49

def read_var_uint
  buffer = read_var_octet_string
  if buffer.length > MAX_INT_BYTES
    raise RangeError.new("UInt of length #{butter.length} too large to parse as integer(#{MAX_INT_BYTES})")
  end
  value = buffer[0...buffer.length]
  CryptoconditionsRuby::Utils::Bytes.new(value).to_i(16)
end

#restore ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 21

def restore
  self.cursor = bookmarks.pop
end

#skip(num_bytes) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 115

def skip(num_bytes)
  ensure_available(num_bytes)
  self.cursor += num_bytes
end

#skip_octet_string(length) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 75

def skip_octet_string(length)
  skip(length)
end

#skip_uint(length) ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 45

def skip_uint(length)
  skip(length)
end

#skip_uint16 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 156

def skip_uint16
  skip_uint(2)
end

#skip_uint32 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 160

def skip_uint32
  skip_uint(4)
end

#skip_uint64 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 164

def skip_uint64
  skip_uint(8)
end

#skip_uint8 ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 152

def skip_uint8
  skip_uint(1)
end

#skip_var_octet_string ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 98

def skip_var_octet_string
  length = read_length_prefix
  skip(length)
end

#skip_var_uint ⇒ Object 



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# File 'lib/cryptoconditions_ruby/utils/reader.rb', line 63

def skip_var_uint
  skip_var_octet_string
end